Ras-Association Domain Family 1C Protein Enhances Breast Tumor Growth In Vivo

The Ras association domain family 1 (RASSF1) gene is a Ras effector that plays an important role in carcinogenesis. We have previously shown that silencing of RASSF1C decreases and over-expression of RASSF1C increases cell proliferation, migration, and attenuates apoptosis of breast cancer cells in vitro. To further confirm our working hypothesis that RASSF1C may play a role as a growth promoter, we have tested the growth of human breast cancer cells stably over-expressing RASSF1A or RASSF1C in nude mice. Our studies show that breast cancer cells over-expressing HA-RASSF1A developed significantly smaller tumors and cells over-expressing HA-RASSF1C developed significantly larger tumors compared to control cells expressing the vector back bone. We have confirmed the expression of HA-RASSF1A and HA-RASSF1C in tumor tissue using RT-PCR, western blotting and immunohistochemical analyses using HA-antibody. Together, our previous in vitro and current in vivo findings further support our hypothesis that RASSF1C, unlike RASSF1A, is not a tumor suppressor and rather it appears to function as tumor growth promoter in breast cancer cells.