P3-01-03: The Hominoid-Specific Gene SHON Is Oncogenic in Human Mammary Carcinoma.

Abstract

Breast cancer is still the most common malignancy and the leading cause of cancer deaths in both developed and under developed countries. Molecular targeted therapy, in particular monoclonal antibody-based treatment, has emerged as a promising approach to treat this disease because of its high specificity and reduced toxicity. As a consequence, identification of novel molecular therapeutic targets is of crucial importance. In an effort to discover new targets for monoclonal antibody-based targeted therapy, we have identified a novel and secreted hominoid-specific molecule, SHON (secreted hominoid-specific oncogene), in the human mammary carcinoma cell line, MCF-7. Like other hominoid-specific genes, SHON has no known orthologs outside of the primate lineage. It is highly expressed in all cancer cell lines tested so far including breast, lung, liver, stomach, colon and prostate cancer as determined at the mRNA level by RT-PCR and at the protein level by western blotting. Forced expression of SHON in MCF-7 cells significantly increased cell proliferation and survival as demonstrated by 5-bromo-2'-deoxyuridine (BrdU) incorporation and Annexin V/propidium iodide apoptosis assays, respectively. Forced expression of SHON also promoted MCF-7 cell anchorage independent growth in soft agar and enhanced cell migration and invasion. Moreover, forced expression of SHON in MCF-7 cells increased tumour volume in a xenograft model of human breast cancer in immunodeficient mice. Furthermore, depletion of endogenous SHON expression using small interfering RNAs, or functional inhibition using an inhibitory rabbit anti-SHON polyclonal antibody, decreased MCF-7 cell proliferation and survival, and reduced MCF-7 oncogenicity and invasiveness. Therefore, SHON is a novel oncogene for mammary carcinoma cells which may be useful as a therapeutic target for the treatment of breast cancer. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-01-03.