Disclosed herein are compositions, constructs, cassettes, vectors, cells, nucleic acids, peptides, proteins, protocols and methods for reducing cholesterol and lipid buildup in mammalian subjects, via gene and/or cell therapeutic treatments. In many embodiments, the disclosed compositions, cells, constructs, cassettes, vectors, nucleic acids, peptides, proteins, protocols and methods may help to reduce lipid levels in mammals. In one embodiment, the disclosed compositions, cells, constructs, cassettes, vectors, nucleic acids, peptides, proteins, protocols and methods are useful in reducing lipid build-up, especially cholesterol, in liver cells.

A method of treating a cancer (e.g., a colorectal cancer, a liver cancer, a breast cancer, or a lung cancer) in a subject in need thereof by administering to the subject a therapeutically effective amount of (i) a bacterium that converts intestinal cholesterol to 4-cholesten-3-one (4-C-3) or (ii) 4-C-3. Also disclosed is a recombinant Escherichia coli TOP10 bacterium comprising a nucleic acid encoding cholesterol oxidase (CHOX), which is capable of converting cholesterol to 4-C-3 and can be used to treat gastrointestinal tract cancers including a colorectal cancer or lung cancer.