RhoC, a member of the Rho GTPase family, has been shown to have a role specifically in facilitating metastasis of breast cancer cells1, however no conclusive mechanism for how RhoC promotes metastasis currently exists. We demonstrate that CRISPR-Cas9 knockout of RhoC in SUM149 and MDA-MB231 cells results in increased epithelial morphology, cell-cell connections, and tight junction marker (ZO-1, occludin, PATJ/PALS1/CRB3) colocalization compared to wild type cells, as studied via immunofluorescent staining. These results suggest that high expression of RhoC in cancer cells destabilizes tight junctions, which could allow for the increased metastatic potential observed with RhoC-overexpressing cells in prior studies2-4. Ongoing work investigates whether these morphological and molecular changes are observed in other breast cancer cell lines, such as SUM190 and VARI-068, a low-passage PDX-derived triple negative breast cancer cell line. Furthermore, we will determine whether RhoC knockout in these cells lines actively modulates tight junction stability as measured via transepithelial electrical resistance (TEER). Taken together, these data support an important role for RhoC in tight junction modulation, thereby revealing a potential highly specific new therapeutic target in RhoC-driven metastases control.

References

1. Hakem, A. et al. RhoC is dispensable for embryogenesis and tumor initiation but essential for metastasis. Genes Dev. 19, 1974-1979 (2005).

2. van Golen, K. L., Wu, Z. F., Qiao, X. T., Bao, L. W. & Merajver, S. D. RhoC GTPase, a novel transforming oncogene for human mammary epithelial cells that partially recapitulates the inflammatory breast cancer phenotype. Cancer Res. 60, 5832-8 (2000).

3. van Golen, K. L., Wu, Z. F., Qiao, X. T., Bao, L. & Merajver, S. D. RhoC GTPase overexpression modulates induction of angiogenic factors in breast cells. Neoplasia 2, 418-25 (2000).

4. Wu, M., Wu, Z. F., Rosenthal, D. T., Rhee, E. M. & Merajver, S. D. Characterization of the roles of RHOC and RHOA GTPases in invasion, motility, and matrix adhesion in inflammatory and aggressive breast cancers. Cancer 116, 2768-2782 (2010).

Citation Format: Hannah Cheriyan, Zhi-Fen Wu, Joel Yates, Sofia D. Merajver. RhoC decreases tight junction stabilization in breast cancer cells, revealing a potential therapeutic target [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5156.