NOVEL TARGET FOR ANTI-CANCER AND IMMUNE-ENHANCING

Abstract

The present disclosure provides a pharmaceutical composition for treating or preventing cancer, comprising inhibitors of KIRREL3, CNTN4 and/or CD351. In addition, the present disclosure provides a pharmaceutical composition for immune-enhancing, comprising inhibitors of KIRREL3, CNTN4 and/or CD351. Furthermore, the present disclosure provides a method of screening of anti-cancer agent using KIRREL3, CNTN4 and/or CD351, and a method of providing information necessary for analysis of cancer prognosis using KIRREL3, CNTN4 and/or CD351.

Claims

1. A method of treating or preventing cancer, comprising administering one or more inhibitors of KIRREL3, CNTN4 and CD351 to a subject in need thereof.

2. The method according to claim 1, wherein the inhibitor is an antisense nucleic acid, a siRNA, a shRNA, a miRNA or a ribozyme that binds in a complementary manner to a DNA or a mRNA of one or more of KIRREL3, CNTN4 and CD351 gene.

3. The method according to claim 1, wherein the inhibitor is a compound, a peptide, a peptide mimetic, a fusion protein, an antibody or an aptamer that binds specifically to one or more of KIRREL3, CNTN4 and CD351 protein.

4. The method according to claim 1, wherein the cancer is stomach cancer, lung cancer, liver cancer, colorectal cancer, colon cancer, small intestinal cancer, pancreatic cancer, brain cancer, bone cancer, melanoma, breast cancer, sclerosing adenosis, uterine cancer, cervical cancer, head and neck cancer, esophageal cancer, thyroid cancer, parathyroid cancer, renal cancer, sarcoma, prostate cancer, urethral cancer, bladder cancer, blood cancer, leukemia, lymphoma, or fibroadenoma.

5. The method according to claim 1, wherein the inhibitor suppresses a function of cancer cells evading T cells.

6. A method of immune-enhancing, comprising administering one or more inhibitors of KIRREL3, CNTN4 and CD351 to a subject in need thereof.

7. The method according to claim 6, wherein the inhibitor inhibits expression or activity of one or more of KIRREL3, CNTN4 and CD351 in the subject to increase a level of T cell-mediated immune response.

8. The method according to claim 6, wherein the subject is in need of prevention, treatment or improvement of diseases related to immunodeficiency, lower immune function, immune system damage, or immunocompromising.

9. A method of screening an anti-cancer agent comprising: (a) treating a cancer cell with a candidate anti-cancer agent; and (b) measuring expression or activity of one or more of KIRREL3, CNTN4 and CD351 in the cancer cell.

10. The method according to claim 9, wherein the step (b) is conducted by determining a level of expression of a mRNA or a protein of one or more of KIRREL3, CNTN4 and CD351 or a level of suppression of T cell activity by one or more of KIRREL3, CNTN4 and CD351.

11. The method according to claim 9, further comprising: (c) determining the candidate anti-cancer agent to be the anti-cancer agent if a group treated with the candidate anti-cancer agent shows a significantly lower level of expression of mRNA of one or more of KIRREL3, CNTN4 and CD351 or protein of one or more of KIRREL3, CNTN4 and CD351; or a significantly lower level of suppression of T cell activity by one or more of KIRREL3, CNTN4 and CD351 compared to a group not treated with the candidate anti-cancer agent.

12. An anti-CNTN4 antibody or antigen-binding fragment thereof, wherein when bound to CNTN4, the anti-CNTN4 antibody or antigen-binding fragment thereof binds to Fibronectin 2 domain of CNTN4.

13. The anti-CNTN4 antibody or antigen-binding fragment thereof according to claim 12, wherein the Fibronectin 2 domain comprises the amino acid sequence of SEQ ID NO: 33.

14. The anti-CNTN4 antibody or antigen-binding fragment thereof according to claim 12, wherein the antibody or antigen-binding fragment thereof blocks binding of CNTN4 to amyloid precursor protein (APP).

15. A pharmaceutical composition comprising the anti-CNTN4 antibody or antigen-binding fragment thereof according to claim 12.

16. The pharmaceutical composition comprising the anti-CNTN4 antibody or antigen-binding fragment thereof according to claim 13.

17. The pharmaceutical composition comprising the anti-CNTN4 antibody or antigen-binding fragment thereof according to claim 14.

18. A method of treating or preventing cancer, comprising administering the pharmaceutical composition according to claim 15 to a subject in need thereof.

19. A method of immune-enhancing, comprising administering the pharmaceutical composition according to claim 15 to a subject in need thereof.

20. A method of screening an anti-cancer agent comprising: (a) treating a cancer cell with a candidate anti-cancer agent; and (b) measuring a binding of amyloid precursor protein (APP) to CNTN4.

Description

BRIEF DESCRIPTION OF FIGURES

[0069] FIG. 1 shows the proliferation (%) of CD4+ T cells suppressed by KIRREL3.

[0070] FIG. 2 shows the proliferation (%) of CD8+ T cells suppressed by KIRREL3.

[0071] FIG. 3 shows the proliferation (%) of CD4+ T cells suppressed by CNTN4.

[0072] FIG. 4 shows the proliferation (%) of CD8+ T cells suppressed by CNTN4.

[0073] FIG. 5 shows the proliferation (%) of CD4+ T cells suppressed by CD351.

[0074] FIG. 6 shows the proliferation (%) of CD8+ T cells suppressed by CD351.

[0075] FIGS. 7A, 7B, 7C and 7D show the cytotoxicity (%) of PBMC when lung cancer cell line A549 and PBMC were treated with KIRREL3 inhibitors.

[0076] FIGS. 8A, 8B, 8C and 8D show the cytotoxicity (%) of PBMC when colon cancer cell line HCT-116 and PBMC were treated with KIRREL3 inhibitors.

[0077] FIGS. 9A, 9B, 9C and 9D show the cytotoxicity (%) of PBMC when breast cancer cell line MDA-MB-231 and PBMC were treated with KIRREL3 inhibitors.

[0078] FIGS. 10A, 10B, 10C and 10D show the cytotoxicity (%) of PBMC when gastric cancer cell line MKN-74 and PBMC were treated with KIRREL3 inhibitors.

[0079] FIGS. 11A, 11B, 11C and 11D show the cytotoxicity (%) of PBMC when leukemia cell line U937 and PBMC were treated with KIRREL3 inhibitors.

[0080] FIGS. 12A, 12B, 12C and 12D show the cytotoxicity (%) of PBMC when lung cancer cell line A549 and PBMC were treated with CNTN4 inhibitors.

[0081] FIGS. 13A, 13B, 13C and 13D show the cytotoxicity (%) of PBMC when colon cancer cell line HCT-116 and PBMC were treated with CNTN4 inhibitors.

[0082] FIGS. 14A, 14B, 14C and 14D show the cytotoxicity (%) of PBMC when breast cancer cell line MDA-MB-231 and PBMC were treated with CNTN4 inhibitors.

[0083] FIGS. 15A, 15B, 15C and 15D show the cytotoxicity (%) of PBMC when gastric cancer cell line MKN-74 and PBMC were treated with CNTN4 inhibitors.

[0084] FIGS. 16A, 16B, 16C and 16D show the cytotoxicity (%) of PBMC when leukemia cell line U937 and PBMC were treated with CNTN4 inhibitors.

[0085] FIGS. 17A, 17B, 17C and 17D show the cytotoxicity (%) of PBMC when lung cancer cell line A549 and PBMC were treated with CD351 inhibitors.

[0086] FIGS. 18A, 18B, 18C and 18D show the cytotoxicity (%) of PBMC when colon cancer cell line HCT-116 and PBMC were treated with CD351 inhibitors.

[0087] FIGS. 19A, 19B, 19C and 19D show the cytotoxicity (%) of PBMC when breast cancer cell line MDA-MB-231 and PBMC were treated with CD351 inhibitors.

[0088] FIGS. 20A, 20B, 20C and 20D show the cytotoxicity (%) of PBMC when gastric cancer cell line MKN-74 and PBMC were treated with CD351 inhibitors.

[0089] FIGS. 21A, 21B, 21C and 21D show the cytotoxicity (%) of PBMC when leukemia cell line U937 and PBMC were treated with CD351 inhibitors.

[0090] FIG. 22 shows the tumor size in mouse treated with KIRREL3 inhibitors.

[0091] FIG. 23 shows the tumor size in mouse treated with CNTN4 inhibitors.

[0092] FIGS. 24A, 24B and 24C show the tumor size in mouse treated with CD351 inhibitors.

[0093] FIGS. 25A and 25B depict the structure of CNTN4 and APP as prepared in accordance with Example 4.

[0094] FIG. 25A shows four deletion structures of CNTN4 (#10: full length), and FIG. 25B shows three isoform structures of APP (APP 770: full length).

[0095] FIGS. 26A and 26B show an image obtained from SDS-Page and western blotting performed in Example 4.

[0096] FIG. 27 shows the amino acid sequences of FN1-FN2 domain of CNTN4 and KPI domain of APP.

[0097] FIG. 28 shows the amino acid sequences of light chain variable region (VL) and heavy chain variable region (VH) of anti-CNTN4 antibody AB1.

[0098] FIG. 29 is a schematic diagram of the human CNTN4 domain samples prepared in accordance with Example 5.2.1.

[0099] FIG. 30 is a graph depicting binding ability between anti-CNTN4 antibody AB1 and CNTN4 domain samples in accordance with Example 5.2.2.

[0100] FIG. 31 shows the amino acid sequences of Domain 8 (FN2 domain) of CNTN4.

[0101] FIG. 32 is a graph depicting the competitive binding of anti-CNTN4 antibody AB1 and APP to CNTN4.

EXAMPLES

[0102] In the following, exemplary embodiments of the inventive concept will be explained in further detail with reference to examples. However, the following examples are meant to exemplify the present invention, and the scope of the invention is not restricted by these examples.

Example 1. Inhibition of the Proliferation and Activity of T Cells

[0103] This example is to confirm whether KIRREL3, CNTN4 and CD351 suppress the proliferation and activity of the T cell, and ensures that cancer cells evade the T cell-mediated immune system.

1.1. Preparation of CD4+ Cells and CD8+ T Cells

[0104] Human blood was placed in a 10 ml tube coated with EDTA (or heparin) and mixed with PBS at a ratio of 1:1. Ficoll-Paque PLUS was placed in a 50 ml tube, and then the blood sample was added. After centrifugation, human PBMCs (peripheral blood mononuclear cells) were collected. The resultant was centrifuged, and the supernatant was removed. Then, RBC lysis (1×) was added, pipetted, and stored on ice for 3 minutes. After that, 50 ml of 10% FBS RPMI1640 was added, and the mixture was centrifuged to remove the supernatant. Then, FACS buffer was added, and the supernatant was removed by centrifugation. Subsequently, 50 ml of MACS buffer (PBS containing 0.5% bovine serum albumin and 2 mM EDTA) was added, the number of cells was counted, and the supernatant was completely removed after centrifugation.

[0105] CD4+ T cells and CD8+ T cells were resuspended using 40 μl of MACS buffer based on the number of 1×10.sup.7 cells in a 50 ml tube. 10 μl of anti-CD4 and anti-CD8 biotin antibodies were added to the tube respectively, and then stored in the refrigerator for 5 minutes. Subsequently, 30 μl of MACS buffer based on the number of 1×10.sup.7 cells was added to the resultant, and 20 μl of anti-biotin microbeads were added and mixed. Then, CD4+ T cells and CD8+ T cells were separated using LS column, and were counted.

[0106] The prepared CD4+ T cells and CD8+ T cells were mixed with 1 μl of CFSE (carboxyfluorescein succinimidyl ester) based on the number of 2×10.sup.6 cells, and stored at 37° C. for 3 minutes. Then, FBS was added into tubes containing the CD4+ T cells and CD8+ T cells respectively, and stored on ice 10 minutes. Thereafter, the supernatant was removed by centrifugation. The resultant was added with 30 ml of FACS buffer, pipetted, and centrifuged to remove the supernatant. Then, the resultant was mixed with 10 ml of 10% FBS RPMI1640, and the number of cells was counted.

1.2. Measurement of T Cell Activity

1.2.1. Inhibition of T Cell Activity by KIRREL3

[0107] The recombinant human IgG1 Fc protein (Cat. No. 110-HG) and the recombinant human PD-L1/B7-H1 Fc chimera protein (Cat. No. 156-B7) were purchased from R&D systems. The recombinant human KIRREL3 His Tag protein (Cat. No. 4910-K3) was purchased from R&D systems.

[0108] 7.5 μg/ml or 10 μg/ml of each protein was mixed with 2.5 μg/ml of anti-CD3 antibody (BioLegend, Cat. No. 317325) in PBS, respectively. The resultant mixture was coated on 96-well plates at 4° C., and the wells were washed three times with PBS.

[0109] The CD4+ T cells and CD8+ T cells prepared in the Example 1.1 were added to each well of the 96-well plate at the number of 2×10.sup.6 cells in an amount of 200 μl, and then incubated.

[0110] CD4+ T cells and CD8+ T cells were activated by anti-CD3 antibody for 72 hours. The proliferation of CD4+ T cells and CD8+ T cells can be confirmed by the degree of CFSE fluorescent cell staining, and was analyzed by flow cytometry using FACSDiVa software (BD Biosciences).

1.2.2. Inhibition of T-Cell Activity by CNTN4

[0111] The recombinant human IgG1 Fc protein (Cat. No. 110-HG) and the recombinant human PD-L1/B7-H1 Fc chimera protein (Cat. No. 156-B7) were purchased from R&D systems. The recombinant human CNTN4 His Tag protein (Cat. No. 2205-CN) was purchased from R&D systems.

[0112] 7.5 μg/ml or 10 μg/ml of each protein was mixed with 2.5 μg/ml of anti-CD3 antibody (BioLegend, Cat. No. 317325) in PBS, respectively. The resultant mixture was coated on 96-well plates at 4° C., and the wells were washed three times with PBS.

[0113] The CD4+ T cells and CD8+ T cells prepared in the Example 1.1 were added to each well of the 96-well plate at the number of 2×10.sup.6 cells in an amount of 200 μl, and then incubated.

[0114] CD4+ T cells and CD8+ T cells were activated by anti-CD3 antibody for 72 hours. The proliferation of CD4+ T cells and CD8+ T cells can be confirmed by the degree of CFSE fluorescent cell staining, and was analyzed by flow cytometry using FACSDiVa software (BD Biosciences).

1.2.3. Inhibition of T-Cell Activity by CD351

[0115] The recombinant human IgG1 Fc protein (Cat. No. 110-HG) and the recombinant human PD-L1/B7-H1 Fc chimera protein (Cat. No. 156-B7) were purchased from R&D systems. The recombinant human CD351 His Tag protein (Cat. No. 9278-FC) was purchased from R&D systems.

[0116] 10 μg/ml of each protein was mixed with 1.0 μg/ml, 2.0 μg/ml, 4.0 μg/ml, or 6.0 μg/ml of anti-CD3 antibody (BioLegend, Cat. No. 317325) in PBS, respectively. The resultant mixture was coated on 96-well plates at 4° C., and the wells were washed three times with PBS.

[0117] The CD4+ T cells and CD8+ T cells prepared in the Example 1.1 were added to each well of the 96-well plate at the number of 2×10.sup.6 cells in an amount of 200 μl, and then incubated.

[0118] CD4+ T cells and CD8+ T cells were activated by anti-CD3 antibody for 72 hours. The proliferation of CD4+ T cells and CD8+ T cells can be confirmed by the degree of CFSE fluorescent cell staining, and was analyzed by flow cytometry using FACSDiVa software (BD Biosciences).

1.3. Results

1.3.1. Inhibition of T-Cell Activity by KIRREL3

[0119] FIG. 1 and FIG. 2 show the percent proliferation (%) of CD4+ T cells and CD8+ T cells, respectively.

[0120] The control group treated with PD-L1 inhibited the proliferation of both CD4+ T cells and CD8+ T cells compared to the control group treated with IgG1. The PD-L1 binds to PD-1, a protein on the surface of T cells, and inhibits the proliferation of T cells. Accordingly, it results in suppressing the function of T cells attacking and killing cancer cells.

[0121] The group treated with KIRREL3 remarkably inhibited the proliferation of both CD4+ T cells and CD8+ T cells compared to the control group treated with IgG1. And also, the group treated with KIRREL3 inhibited the proliferation of both CD4+ T cells and CD8+ T cells similarly to the control group treated with PD-L1.

[0122] It means that if KIRREL3 is neutralized by blocking or knockdown, the T cell proliferation inhibition of KIRREL3 can be suppressed. Accordingly, the cancer treatment can be effectively achieved.

1.3.2. Inhibition of T-Cell Activity by CNTN4

[0123] FIG. 3 and FIG. 4 show the percent proliferation (%) of CD4+ T cells and CD8+ T cells, respectively.

[0124] The control group treated with PD-L1 inhibited the proliferation of both CD4+ T cells and CD8+ T cells compared to the control group treated with IgG1.

[0125] The group treated with CNTN4 remarkably inhibited the proliferation of both CD4+ T cells and CD8+ T cells compared to the control group treated with IgG1. And also, the group treated with CNTN4 inhibited the proliferation of both CD4+ T cells and CD8+ T cells similarly to the control group treated with PD-L1.

[0126] It means that if CNTN4 is neutralized by blocking or knockdown, the T cell proliferation inhibition of CNTN4 can be suppressed. Accordingly, the cancer treatment can be effectively achieved.

1.3.3. Inhibition of T-Cell Activity by CD351

[0127] FIG. 5 and FIG. 6 show the percent proliferation (%) of CD4+ T cells and CD8+ T cells, respectively.

[0128] The control group treated with PD-L1 significantly inhibited the proliferation of CD4+ T cells compared to the control group treated with IgG1, whereas it did not show a significant inhibition on the proliferation of CD8+ T cells compared to the control group treated with IgG1.

[0129] The group treated with CD351 remarkably inhibited the proliferation of both CD4+ T cells and CD8+ T cells compared to the control group treated with IgG1 as well as the control group treated with PD-L1.

[0130] It means that CD351 is neutralized by blocking or knockdown, the T cell proliferation inhibition of CD351 can be suppressed. Accordingly, the cancer treatment can be effectively achieved.

Example 2. PBMC Cytotoxic Function Assay

[0131] This example is to confirm whether the cytotoxic ability of PBMC against cancer cells is increased when KIRREL3, CNTN4 or CD351 is neutralized using inhibitors of KIRREL3, CNTN4 or CD351.

2.1. Preparation of PBMC

[0132] Human blood was placed in a 10 ml tube coated with EDTA (or heparin) and mixed with PBS at a ratio of 1:1. Ficoll-Paque PLUS was placed in a 50 ml tube, and then the blood sample was added. After centrifugation, human PBMCs were collected. The resultant was centrifuged, and the supernatant was removed. Then, RBC lysis (1×) was added, pipetted, and stored on ice for 3 minutes. After that, 50 ml of 10% FBS RPMI1640 was added, and the mixture was centrifuged to remove the supernatant. Then, FACS buffer was added, and the supernatant was removed by centrifugation. Subsequently, 50 ml of MACS buffer (PBS containing 0.5% bovine serum albumin and 2 mM EDTA) was added, the number of cells was counted, and the supernatant was completely removed after centrifugation.

[0133] 96-well plates were coated with 1.0 μg/ml of anti-CD3 antibody (BioLegend, Cat. No. 317325) in PBS at 4° C., and the wells were washed three times with PBS. The PBMC prepared in the above was mixed with 10% FBS RPMI1640, and was added to each well of the 96-well plate at the number of 6×10.sup.5 cells in an amount of 100 μl. The PBMC was activated by anti-CD3 antibody for 72 hours.

2.2. Preparation of Cancer Cells

[0134] Lung cancer cell line A549, colon cancer cell line HCT-116, breast cancer cell line MDA-MB-231, gastric cancer cell line MKN-74, and leukemia cell line U937 were respectively mixed with 1 μl of CFSE (carboxyfluorescein succinimidyl ester), and then stored at 37° C. for 3 minutes. Subsequently, FBS was added into tubes containing cancer cells and stored on ice for 10 minutes. Thereafter, the supernatant was removed by centrifugation. The resultant was added with 30 ml of FACS buffer, pipetted, and centrifuged to remove the supernatant. Then, 10% FBS RPMI1640 was added, pipetted, and centrifuged to remove the supernatant. Thereafter, the resultant was mixed with 10 ml of 10% FBS RPMI1640, and the number of cells was counted.

[0135] Each PBMC-containing well of the 96-well plate prepared in the Example 2.1 was added with the cancer cells at the number of 3×10.sup.4 cells in an amount of 100 μl.

2.3. Measurement of Cytotoxicity of PBMC Against Cancer Cells

[0136] The mixtures of PBMCs and cancer cells were prepared in the Example 2.2. These mixtures were incubated for 24 hours with 10 μg/mL of anti-human KIRREL3 antibody, anti-human CNTN4 antibody or anti-human CD351 antibody, or 50 nM of KIRREL3 siRNA, CNTN4 siRNA or CD351 siRNA.

[0137] Table 1 below provides the non-treated control group and Groups 1 to 4 using four neutralizing antibodies for blocking KIRREL3, and Table 2 below provides the non-treated control group and Groups 5 to 7 using three siRNAs for knockdown of KIRREL3.

TABLE-US-00001 TABLE 1 human KIRREL3 neutralizing antibody Control group Not treated Group1 anti-human KIRREL3 antibody (R&D, AF4910) Group2 anti-human KIRREL3 antibody (Bioss, bs-11864R) Group3 anti-human KIRREL3 antibody (genetex, GTX32140) Group4 anti-human KIRREL3 antibody (LSbio, LS-C336219)

TABLE-US-00002 TABLE 2 human KIRREL3 siRNA Control group Not treated Group 5 Sense (5′-CUCUCAAGUUACCCACAGUtt-3′) (SEQ ID NO: 1) Antisense (5′-ACUGUGGGUAACUUGAGAGtt-3′) (SEQ ID NO: 2) Group 6 Sense (5′-GGAGAGGUGUACAGGACCAtt-3′) (SEQ ID NO: 3) Antisense (5′-UGGUCCUGUACACCUCUCCtt-3′) (SEQ ID NO: 4) Group 7 Sense (5′-UCUCAAGUUACCCACAGUAtt-3′) (SEQ ID NO: 5) Antisense (5′-UACUGUGGGUAACUUGAGAtt-3′) (SEQ ID NO: 6)

[0138] Table 3 below provides the non-treated control group and Groups 1 to 5 using five neutralizing antibodies for blocking CNTN4, and Table 4 below provides the non-treated control group and Groups 6 to 8 using three siRNAs for knockdown of CNTN4.

TABLE-US-00003 TABLE 3 human CNTN4 neutralizing antibody Control group Not treated Group 1 anti-human CNTN4 antibody (R&D, MAB2205) Group 2 anti-human CNTN4 antibody (abcam, ab137107) Group 3 anti-human CNTN4 antibody (abcam, ab131285) Group 4 anti-human CNTN4 antibody (LSbio, LS-C119876) Group 5 anti-human CNTN4 antibody (Abnova, PAB27653)

TABLE-US-00004 TABLE 4 human CNTN4 siRNA Control group Not treated Group 6 Sense (5′-CAGUAUCUUUGCCAGAAGUtt-3′) (SEQ ID NO: 7) Antisense (5′-ACUUCUGGCAAAGAUACUGtt-3′) (SEQ ID NO: 8) Group 7 Sense (5′-GAUAAUGAGUCGGAAGUAAtt-3′) (SEQ ID NO: 9) Antisense (5′-UUACUUCCGACUCAUUAUCtt-3′) (SEQ ID NO: 10) Group 8 Sense (5′-GUGACAAUAGACGAAAUCAtt-3′) (SEQ ID NO: 11) Antisense (5′-UGAUUUCGUCUAUUGUCACtt-3′) (SEQ ID NO: 12)

[0139] Table 5 below provides the non-treated control group and Groups 1 to 3 using three neutralizing antibodies for blocking CD351, and Table 6 below provides the non-treated control group and Groups 4 to 6 using three siRNAs for knockdown of CD351.

TABLE-US-00005 TABLE 5 human CD351 neutralizing antibody Control group Not treated Group 1 anti-human CD351 antibody (Biolegend, 13730) Group 2 anti-human CD351 antibody (Creative diagnostics, CABT-BL4657) Group 3 anti-human CD351 antibody (Biobyt, orb183662)

TABLE-US-00006 TABLE 6 human CD351 siRNA Control group Not treated Group 4 Sense (5′-GAGAGAUGAACUGCUCAGUtt-3′) (SEQ ID NO: 13) Antisense (5′-ACUGAGCAGUUCAUCUCUCtt-3′) (SEQ ID NO: 14) Group 5 Sense (5′-GAGAACUUCCAACUCAGUAtt-3′) (SEQ ID NO: 15) Antisense (5′-UACUGAGUUGGAAGUUCUCtt-3′) (SEQ ID NO: 16) Group 6 Sense (5′-AGAGAACUUCCAACUCAGUtt-3′) (SEQ ID NO: 17) Antisense (5′-ACUGAGUUGGAAGUUCUCUtt-3′) (SEQ ID NO: 18)

[0140] After twenty-four hours from incubating the mixtures of PBMCs and cancer cells with antibody or siRNA, cells were stained with 7-aminoactinomycin D (7-AAD; BD Pharmingen, San Diego, Calif., USA) to detect lysed cells. The cytotoxicity of PBMC against cancer cells was analyzed by determining FL-1 (CFSE) and FL-3 (7-AAD) staining using a FACSDiVa software (BD Biosciences).

2.4. Results

[0141] For the lung cancer cell line A549, FIGS. 7A, 7B, 7C and 7D show the results treated with KIRREL3 neutralizing antibody or siRNA, FIGS. 12A, 12B, 12C and 12D show the results treated with CNTN4 neutralizing antibody or siRNA, and FIGS. 17A, 17B, 17C and 17D show the results treated with CD351 neutralizing antibody or siRNA.

[0142] When the lung cancer cell line A549 and PBMC were treated with KIRREL3 neutralizing antibody, CNTN4 neutralizing antibody or CD351 neutralizing antibody, the cytotoxicity against lung cancer cell was significantly increased compared to the non-treated control group even though there is more or less degree of difference depending on the type of antibody. Further, the cytotoxicity against lung cancer cell was also significantly increased when it was treated with KIRREL3 siRNA, CNTN4 siRNA or CD351 siRNA.

[0143] Using KIRREL3 neutralizing antibody or siRNA, the results on the colon cancer cell line HCT-116 are shown in FIGS. 8A, 8B, 8C and 8D, the result on the breast cancer cell line MDA-MB-231 are shown in FIGS. 9A, 9B, 9C and 9D, the results on the gastric cancer cell line MKN-74 are shown in FIGS. 10A, 10B, 10C and 10D, and the results on the leukemia cell line U937 are shown in FIGS. 11A, 11B, 11C and 11D.

[0144] In addition, using CNTN4 neutralizing antibody or siRNA, the results on the colon cancer cell line HCT-116 are shown in FIGS. 13A, 13B, 13C and 13D, the results on the breast cancer cell line MDA-MB-231 are shown in FIGS. 14A, 14B, 14C and 14D, the results on the gastric cancer cell line MKN-74 are shown in FIGS. 15A, 15B, 15C and 15D, and the results on the leukemia cell line U937 are shown in FIGS. 16A, 16B, 16C and 16D.

[0145] In addition, using CD351 neutralizing antibody or siRNA, the results on the colon cancer cell line HCT-116 are shown in FIGS. 18A, 18B, 18C and 18D, the results on the breast cancer cell line MDA-MB-231 are shown in FIGS. 19A, 19B, 19C and 19D, the results on the gastric cancer cell line MKN-74 are shown in FIGS. 20A, 20B, 20C and 20D, and the results on the leukemia cell line U937 are shown in FIGS. 21A, 21B, 21C and 21D.

[0146] As shown in FIGS. 8A to 11D, 13A to 16D, and 18A to 21D, when one or more of KIRREL3, CNTN4 and CD351 were neutralized by antibodies or siRNAs, the results of increasing the cytotoxicity of PBMC were also observed in colon cancer, breast cancer, gastric cancer and leukemia.

Example 3. Tumor-Mouse Model Experiment

[0147] This example is to confirm whether the growth of tumor in mouse is suppressed when KIRREL3, CNTN4 or CD351 is neutralized using inhibitors of KIRREL3, CNTN4 or CD351.

3.1. Establishment of Tumor-Mouse Model

[0148] MC-38 cell line derived from C57bL6 colon adenocarcinoma cells was resuspended in 50 μl PBS at the number of 2×10.sup.5 cells, and was subcutaneously injected into the flanks of 6-week-old female C57bL6 mice.

[0149] Table 7 below provides the non-treated control group and Group 8 using a siRNA for knockdown of KIRREL3.

TABLE-US-00007 TABLE 7 mouse KIRREL3 siRNA Control group Not treated Group 8 Sense (5′-GUAAAGGAGAGGUCAUCAA-3′) (SEQ ID NO: 19) Antisense (5′-UUGAUGACCUCUCCUUUAC-3′) (SEQ ID NO: 20)

[0150] Table 8 below provides the non-treated control group and Group 9 using a siRNA for knockdown of CNTN4.

TABLE-US-00008 TABLE 8 mouse CNTN4 siRNA Control group Not treated Group 9 Sense (5′-GUGUAGACAAACUCUCUGU-3′) (SEQ ID NO: 21) Antisense (5′-ACAGAGAGUUUGUCUACAC-3′) (SEQ ID NO: 22)

[0151] Table 9 below provides the non-treated control group and Groups 7, 8 and 9 using three siRNAs for knockdown of CD351.

TABLE-US-00009 TABLE 9 mouse CD351 siRNA Control group Not treated Group 7 Sense (5′-GUCCAUCCAACACCACCUA-3′) (SEQ ID NO: 23) Antisense (5′-UAGGUGGUGUUGGAUGGAC-3′) (SEQ ID NO: 24) Group 8 Sense (5′-CUGAUGAGGGAAAGAACUU-3′) (SEQ ID NO: 25) Antisense (5′-AAGUUCUUUCCCUCAUCAG-3′) (SEQ ID NO: 26) Group 9 Sense (5′-CAGCUAAGCCCAGUGAACA-3′) (SEQ ID NO: 27) Antisense (5′-UGUUCACUGGGCUUAGCUG-3′) (SEQ ID NO: 28)

[0152] In all Groups, the siRNA targeting mouse KIRREL3, mouse CNTN4 or mouse CD351 was injected into the tumor of mice three times at the interval of 5 days from the 11th day after injecting MC-38 cells. Specifically, 10 μg siRNA and 7.5 μl oligofectamine (Invitrogen) in PBS were mixed according to manufacturer's instruction, and then injected into the tumor tissue induced in mice at a dose of 0.5 mg/kg.

3.2. Results

[0153] FIG. 22 provides the result on the size of tumor in mice of the non-treated control group and Group 8 wherein KIRREL3 was knocked down. FIG. 23 provides the result on the size of tumor in mice of the non-treated control group and Group 9 wherein CNTN4 was knocked down. FIGS. 24A, 24B and 24C provide the results on the size of tumor in mice of the non-treated control group and Groups 7 to 9 wherein CD351 was knocked down.

[0154] In the non-treated control group, the tumor continued to grow after it occurred. Compared to the non-treated control group, the growth rate of tumor in mouse was remarkably inhibited in Groups wherein KIRREL3, CNTN4 or CD351 was knocked down. It means that when one or more of KIRREL3, CNTN4 and CD351 are blocked or knocked down to inhibit its activity or expression, the development of cancer is delayed or stopped and the occurrence of cancer is inhibited. Accordingly, one or more inhibitors of KIRREL3, CNTN4 and CD351 can be efficiently used to prevent cancer.

Example 4. Analysis on Binding Site of CNTN4 and APP

[0155] This example is to confirm the binding site of CNTN4 and its receptor, APP.

4.1. Preparation of Overexpression Cell (Transient Transfection)

[0156] HEK293FT cell was spread in a culture dish plate at the number of 3×10.sup.6 cells. After 24 hours, jetPRIME transfection buffer 200 μL; CNTN4 expression plasmid 10 μg or APP expression plasmid 10 μg; and RIME transfection reagent 20 μL were mixed, incubated at room temperature (RT) for 10 min, and adding the mixture in the cell, so that the HEK293FT cell was transfected with each plasmid.

[0157] The four plasmids in total were prepared for CNTN4 expression. CNTN4 consists of a total of ten (10) domains, i.e., Ig1 to Ig6 and FN1 to FN4. Ig1 to Ig4, Ig1 to Ig6, Ig1 to FN2, and Ig1 to FN4 were expressed in each plasmid (Ig; Ig like domain, FN; fibronection), wherein the deletion structures expressed in each plasmid were named as #4, #6, #8, and #10 (FIG. 25A).

[0158] The three plasmids in total were prepared for APP expression. Each of the three isoforms of APP was expressed in each plasmid, which was named as 770, 751, and 695. The 770 and 751 isoforms include KPI (Kunitz-type protease inhibitor) domain, while the 695 isoform do not KPI domain (FIG. 25B).

4.2. Immunoprecipitation (IP)

4.2.1. Protein to Protein Interaction

[0159] Each of the total seven groups of the transfected cells prepared in Example 4.1. was centrifuged at 1,200 rpm and 4° C. for 3 min to remove the supernatant. The cell pellet was lysed with 1×lysis buffer, reacted at 4° C. for 10 mins, and again centrifuged at 13,000 rpm and 4° C. for 10 min to obtain cell lysates.

[0160] 6 μL of cell lysate sample and 24 μL of UltraPure distilled water were mixed in a new 1.5 mL tube to dilute the sample 1/5. Separately, 2 mg/mL standard BSA was diluted with UltraPure distilled water as a 1/2 serial dilution (i.e., 2, 1, 0.5, 0.25, 0.125, 0.0625, 0.031, 0 mg/mL). Samples and standard BSA as diluted were placed in a non-coated 96 well plate in an amount of 10 μL/well in duplication. Reagents A and B comprised in BCA assay kit were mixed in a ratio of 50:1 to be added into each well in an amount of 200 L/well, followed by reacting at 37° C. for 30 mins. The protein concentration was determined by using SpectraMax M2 Microplate Readers.

[0161] Then, CNTN4 #10 was reacted with APP 770, 751, or 695 to confirm whether the CNTN4-APP protein complex was produced. Similarly, APP 700 was reacted with CNTN4 #4, #6, #8, or #10 to confirm the same.

[0162] 100 μg protein of each of total cell lysates, 500 μL PBS, and 2 μg IP Ab (anti-CNTN4 antibody or anti-APP antibody) were mixed and then was under rotation at 4° C. for overnight (O/N).

[0163] 30 μL of 50% protein A/G agarose bead was then added, followed by being under rotation at RT for 2 h. The supernatant was removed by centrifugation at 4,000 rpm and 4° C. for 4 min, adding 1 mL of PBS, and then being under rotation at RT for 10 min, which was repeated three times in total. The supernatant was removed by centrifugation at 4,000 rpm and 4° C. for 4 min, adding 20 μL of 1× sample buffer that was prepared by mixing a sample buffer and a reducing agent, followed by reacting for 10 min at 95° C. heat block. Reaction was done in ice for 5 min and then spined down (IP sample).

[0164] The sample buffer and the reducing agent were added to 20 μg of cell lysates in total to become 20 μL, followed by reacting for 10 min at 95° C. heat block. Reaction was done in ice for 5 min and then spined down (Input sample).

4.2.2. SDS-PAGE and Western Blotting

[0165] NuPAGE 4-12% Bis-Tris gel was used in combination of NuPAGE® electrophoresis system. Gel was fixed in a chamber and a MES running buffer was filled between a gel cassette and an electrode assembly. A marker 5 μL and a sample (20 μL per well) were loaded and the electrophoresis was performed in accordance with the manufacturer manual.

[0166] After the completion of transfer, the membrane was blocked with 3% BSA blocking buffer at RT for 60 mins. After the blocking, washing process was repeated with PBST three times, diluting primary antibody with 0.3% BSA blocking buffer (1:1,000), and then stored in 4° C. frigo. Washing process was repeated with PBST three times, diluting secondary antibody with 0.3% BSA blocking buffer (1:5,000), and then reacting at RT for 60 mins. Again, the washing with PBST was done three times.

[0167] 500 μL of Luminol/Enhancer solution and 500 μL of peroxide solution (commercially available in SuperSignal™ West Pico PLUS Chemiluminescent Substrate) were mixed in 1.5 mL tube and spread in the membrane. The image was scanned by using LOURMAT CHEMI-DOC.

[0168] The results were shown in FIGS. 26A and 26B.

[0169] It was confirmed that CNTN4 #10 (full length) binds to APP (770 & 751) including KPI (kunitz-type protease inhibitor) domain (FIG. 26A), while APP 770 (full length) binds to CNTN4 (#8 & #10) including FN1 to FN2 domain (domain 7˜domain 8) (FIG. 26B). As such, it was confirmed that the APP binding site to CNTN4 is the KPI domain, and the corresponding CNTN4 binding site is FN1 to FN2 domain (domain 7˜domain 8). The sequences of each domain were depicted in Table 10 and FIG. 27.

TABLE-US-00010 TABLE 10 SEQ ID FN1 to FN2 PPEAVTIDEITDTTAQLSWRPGPDNHSPITMYVIQARTP NO: 29 domain FSVGWQAVSTVPELIDGKTFTATVVGLNPWVEYEFRT VAANVIGIGEPSRPSEKRRTEEALPEVTPANVSGGGGS KSELVITWETVPEELQNGRGFGYVVAFRPYGKMIWM LTVLASADASRYVFRNESVHPFSPFEVKVGVFNNKGE GPFSPTTVVYSAEE SEQ ID KPI domain RAMISRWYFDVTEGK NO: 30

Example 5. Analysis on Antibody Binding Site of CNTN4 Using Anti-CNTN4 Antibody(AB1)

[0170] This example is to confirm binding between anti-CNTN4 antibody (AB1) and CNTN4 domain to confirm an antibody binding site of CNTN4.

5.1. Preparation of Anti-CNTN4 Antibody AB1

[0171] 5.1.1. scFv Antibody Library Preparation and Selection

[0172] Mouse CNTN4 and/or human CNTN4 was inoculated in fifteen (15) chickens to produce the antibody. The production of the antibody was found in total four chickens under the ELISA analysis. The chickens were sacrificed, removing blood, spleen, bone marrow, and bursa fabricius, extracting total RNA, and synthesizing cDNA, to obtain a scFv fragment linking VH and VL via a linker. The phage display was then performed. Through the phase ELISA screening, positive clones binding to CNTN4 were selected and then the corresponding scFv sequences were confirmed (scFv AB1). It was labelled with constant human kappa (hCk) to be prepared and expressed in a fusion protein form, and then analyzing the binding ability to CNTN4. The amino acid sequences of VH and VL of the selected scFv AB1 were shown in Table 11 and FIG. 28.

TABLE-US-00011 TABLE 11 SEQ ID light chain ALTQPSSVSANLGETVKITCSGSSGSYGWYQQKSPGSA NO: 31 variable region PVTLIYDNTNRPSDIPSRFSGSGSGSTGTLTITGVRAEDE (VL) AVYYCGGYDGSTDVFGAGTTLTVL SEQ ID heavy chain AVTLDESEGGLQTPGGALSLVCKASGFTFSSFNMFWVR NO: 32 variable region QAPGKGLEYVAEISGGGGSTWYAPAVKGRATISRDNGQ (VH) STVRLQLNNLRAEDTGTYYCAKSADTWSYGAATIDAW GHGTEVIVSS

5.1.2. Preparation of Anti-CNTN4 Chicken-Human Chimeric IgG4 Antibody AB1

[0173] Light chain and heavy chain regions of the scFv selected in 5.1.1. were cloned in a bicistronic expression vector. The transient transfection of Expi293F cell were done with the DNA, culturing up to 50% of viability, performing the IgG expression. The culture was bound to the Kappa select resin (kappa region capture) to elute IgG in the primary purification. Mabselect (Fc region capture) was then bound to remove light chain impurities and to elute IgG in the secondary purification. Anti-CNTN4 129 chimeric IgG4 antibody was prepared with purity 72.4% in SEC-HPLC analysis (hereinafter, referred to as “AB1”).

5.2. Analysis on Antibody Binding Site of CNTN4

5.2.1. Preparation of Human CNTN4 Domain Sample

[0174] Human CNTN4 domain sample was prepared according to FIG. 29. CNTN4 consists of a total of ten (10) domains (i.e., Ig1 to Ig6 and FN1 to FN4; represented as Domain 1 to Domain 10, respectively, in FIG. 29). “Full” represents the sample in which all of the 10 domains are included. D1-9 was prepared by deleting Domain 10 from Full, and D1-8 was prepared by deleting Domain 9 from D1-9. In the same manner, the domain samples of D1-4 to D1-7 were prepared.

[0175] The concentration 4 μg/mL of Full domain was used as the standard, and in order to have the same molar concentration, the concentrations of the respective domains were determined in view of their molecular weights (see Table 12).

TABLE-US-00012 TABLE 12 Domain Number Full 1-4 1-5 1-6 1-7 1-8 1-9 Concentration 4  1.6 2.0 2.3 2.8 3.2 3.6 (μg/mL) Molecular 111.08 44.43 54.48 64.83 76.83 87.93 99.03 Weight (kDa)

5.2.2. Binding of Antibody AB1 and CNTN4 Domain Sample

[0176] CNTN4 domain as prepared in 5.2.1 was distributed in the 96-well plate by 50 μL/well. The wells were sealed with sealing tape and incubated overnight at 4° C. The next day, the sealing tape was ripped off and buffer was removed. Blocking buffer was distributed in the respective wells by 150 μL, and the wells were sealed and incubated for one hour at 37° C.

[0177] Blocking buffer was removed, and the respective primary antibody (Antibody AB1) diluted with blocking buffer as in Table 13 were distributed in the respective wells by 50 μL. The wells were sealed with sealing tape and incubated for 2 hours at 37° C. After the sealing tape was removed, the wells were washed three times.

TABLE-US-00013 TABLE 13 Tube Number 1 2 3 4 5 6 7 8 9 Conc. 2.5 0.625 0.156 0.0391 0.00977 0.00244 0.00061 0.000153 0.00004 (nM)

[0178] 50 μL of the diluted secondary antibody (Anti-human IgG Fc-HRP) was distributed to each well. The wells were sealed with sealing tape and incubated at 37° C. for 1 hour. The wells were washed tree times after Sealing tape was removed.

[0179] 50 μL of ABTs were distributed in each well. The wells were incubated at room temperature for 30 minutes. The absorbance was detected at 405 nm by using Microplate reader.

[0180] The results were shown in Table 14 and FIG. 30.

TABLE-US-00014 TABLE 14 Domain Full 1-4 1-5 1-6 1-7 1-8 1-9 Binding + − − − − + +

[0181] Anti-CNTN4 antibody AB1 binds to only D1-8, D1-9, Full of the total 7 Human CNTN4-domain samples (three graphs were overlapped with each other in FIG. 30), whereas it does not bind to D1-4 to D1-7 (four graphs were overlapped with each other, except for D1-6 at the antibody concentration of approximately 0.0001 to 0.01 nM). Given that D1-7 and D1-8 differ in Domain 8 being present or not, it was recognized that Domain 8 (i.e., FN2) is the important binding site for the binding of CNTN4 to anti-CNTN4 antibody.

[0182] Table 15 and FIG. 31 show amino acid sequences of Domain 8 of CNTN4.

TABLE-US-00015 TABLE 15 SEQ ID Domain 8 TPANVSGGGGSKSELVITWETVPEELQNGRGFGYVVA NO: 33 (Fibronectin FRPYGKMIWMLTVLASADASRYVFRNESVHPFSPFEV 2 Domain) KVGVFNNKGEGPFSPTTVVYSAEE

Example 6: Analysis on Competitive Binding of APP and Antibody AB1 to CNTN4

[0183] This example is to confirm whether the binding of APP to CNTN4 is blocked by anti-CNTN4 antibody AB1.

[0184] The plate was coated with 4 mg/mL of CNTN4. APP (his tagged, 0.64 mg/mL) was diluted at 40 mg/mL using ELISA buffer. Separately, anti-CNTN4 antibody AB1 (4.98 mg/mL; 35 mM) was serially diluted by 1/10 at 1 to 0 mM by using ELISA buffer. Each of the diluted APP and AB1 antibodies was treated at 25 mL/well at 96-well half plate coated with CNTN4. The reaction was carried out at room temperature for 4 hours (in duplicate), followed by washing. Anti-his tag was diluted by 1:2,000 using ELISA buffer, treated at 50 mL/well, incubated at room temperature for 1 hour, and then washed. Subsequently, ABTS was treated at 50 μL/well. The absorbance was detected at 405 nm by using plate reader.

[0185] The results were shown in FIG. 32.

[0186] When APP 40 mg/mL and antibody AB1 at different concentration were treated under the condition where the plate was coated with 4 mg/mL of CNTN4, it was confirmed that the absorbance was reduced in accordance with the increase in the concentration of AB1. It shows that antibody AB1 binds to CNTN4 in competition with APP and blocks the binding of APP to CNTN4.

[0187] Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the present disclosure described herein. Such equivalents are intended to be encompassed by the following claims.