Understanding the molecular drivers of biologically aggressive behavior in breast cancer will improve diagnosis and treatment. We have discovered that EZH2 overexpression in breast carcinomas is associated with ER negative (ER-) status, and is an independent biomarker of poor survival. While the oncogenic role of EZH2 in breast and other malignancies has been established, the mechanisms are far from clear. EZH2 is the histone H3 lysine 27 methyltransferase of the Polycomb Repressive Complex 2 (PRC2), responsible for epigenetic silencing. However, recent studies show that in invasive carcinomas with poor outcome, high EZH2 is associated with low H3K27me3, suggesting that in a subset of aggressive tumors, EZH2 functions through non-canonical H3K27me3-independent mechanisms. In the previous cycle, we have reported one such mechanism by which EZH2 activates NOTCH1. We have now discovered a new mechanism by which p38?-mediated phosphorylation of EZH2 at T367 leads to EZH2 cytoplasmic localization to promote migration and invasion of breast cancer cells. Using breast cancer tissues, our new preliminary data show that cytoplasmic pEZH2 T367 is significantly upregulated in distant metastasis compared to their matched primary tumors, and that primary tumors with high pEZH2 T367 metastasize earlier than those with low pEZH2. Previous studies have identified EZH2 in the cytoplasm, but the significance to human cancer was unknown. Further, p38? has been reported to phosphorylate EZH2 at T367 in muscle stem cells, but this event has never been linked to cytoplasmic EZH2 or with cancer. Our central hypothesis is that phosphorylated EZH2 at T367 promotes biologically aggressive breast cancer by localizing to the cytoplasm to enhance tumor cell migration, invasion and metastasis through H3K27me3-independent methyltransferase activity. We propose four independent hypothesis-driven aims.
AIM 1 : To investigate the consequences of inducible mammary- specific EZH2 overexpression on breast cancer progression, and the in vivo relevance of EZH2 non- canonical mechanisms.
AIM 2 : To elucidate the effect of pEZH2 T367 on neoplastic functions in vivo and in vitro.
AIM 3 : To investigate the molecular mechanism of pEZH2 T367-mediated breast cancer progression.
AIM 4 : To evaluate the translational impact of EZH2 non-canonical pathways in human breast tissue samples. We have developed critical reagents including an anti-pEZH2(T367) antibody, EZH2 T367A and T367D mutants (phospho-OFF and phospho-ON, respectively), characterized unique cohorts of human breast cancer tissues (n=500) with well-annotated clinical information and over 10 years of follow-up, and have generated new critical preliminary data. Our innovative studies have the potential to discover novel biomarkers and lead to mechanism-based therapies against breast cancer with EZH2 non-canonical pathway activation.
Breast cancer is the second leading cause of cancer deaths in women and is the most common cancer among women. This study addresses an important aspect of women?s health; that of how EZH2 regulates the oncogenic pathways to promote preneoplastic lesions that progress to invasive carcinoma and metastasis. We will study how EZH2 triggers breast cancer progression through the investigation of a new mechanism discovered by our laboratory. We made the novel observation that EZH2 undergoes phosphorylation at threonine 367 which is associated with the development of metastasis in human breast cancer samples. Our lab has discovered a previously unknown mechanism by which phosphorylated EZH2 functions in breast cancer progression, which will be investigated in this application. Our functional, mechanistic, and translational studies are expected to provide the foundation for treatment and prognostic clinical application.
|Gonzalez, Maria E; Martin, Emily E; Anwar, Talha et al. (2017) Mesenchymal Stem Cell-Induced DDR2 Mediates Stromal-Breast Cancer Interactions and Metastasis Growth. Cell Rep 18:1215-1228|
|Martin, E E; Huang, W; Anwar, T et al. (2017) MMTV-cre;Ccn6 knockout mice develop tumors recapitulating human metaplastic breast carcinomas. Oncogene 36:2275-2285|
|Huang, Wei; Martin, Emily E; Burman, Boris et al. (2016) The matricellular protein CCN6 (WISP3) decreases Notch1 and suppresses breast cancer initiating cells. Oncotarget 7:25180-93|
|Kleer, Celina G (2016) Dual roles of CCN proteins in breast cancer progression. J Cell Commun Signal 10:217-222|
|Hertz, Daniel L; Henry, N Lynn; Kidwell, Kelley M et al. (2016) ESR1 and PGR polymorphisms are associated with estrogen and progesterone receptor expression in breast tumors. Physiol Genomics 48:688-98|
|Gonzalez-Guerrico, Anatilde M; Espinoza, Ingrid; Schroeder, Barbara et al. (2016) Suppression of endogenous lipogenesis induces reversion of the malignant phenotype and normalized differentiation in breast cancer. Oncotarget 7:71151-71168|
|Proctor, Erica; Kidwell, Kelley M; Jiagge, Evelyn et al. (2015) Characterizing Breast Cancer in a Population with Increased Prevalence of Triple-Negative Breast Cancer: Androgen Receptor and ALDH1 Expression in Ghanaian Women. Ann Surg Oncol 22:3831-5|
|Toy, Kathy A; Valiathan, Rajeshwari R; Núñez, Fernando et al. (2015) Tyrosine kinase discoidin domain receptors DDR1 and DDR2 are coordinately deregulated in triple-negative breast cancer. Breast Cancer Res Treat 150:9-18|
|Gonzalez, Maria E; Moore, Heather M; Li, Xin et al. (2014) EZH2 expands breast stem cells through activation of NOTCH1 signaling. Proc Natl Acad Sci U S A 111:3098-103|
|Arps, David P; Jorns, Julie M; Zhao, Lili et al. (2014) Re-excision rates of invasive ductal carcinoma with lobular features compared with invasive ductal carcinomas and invasive lobular carcinomas of the breast. Ann Surg Oncol 21:4152-8|
Showing the most recent 10 out of 61 publications