Abstract 2272: A novel epigenetic regulator histone demethylase NO66 promotes prostate cancer bone metastasis
Authors: Bagheri-Yarmand Rozita , Lahiri Sharmistha , Wan Xinhai , Navone Nora , Logothetis Christopher J. , Gagel Robert F. , Sinha Krishna M. 
Published: August 2015

Epigenetic changes by histone methylation that affect expression of key genes linked to progression and metastasis of androgen-independent prostate cancer (PCa) cells remain elusive. Histone demethylase NO66 is a JumonjiC-domain containing histone demethylase specific for H3K4me3 and H3K36me3 and acts as an inhibitor of bone formation. NO66 interacts with EZH2 (enhancer of zeste homolog 2) containing PRC2 (polycomb-repressor complex 2), which has histone K27 methyl transferase activity. EZH2 is amplified and upregulated in advanced and metastatic prostate cancer (PCa). High levels of NO66 are present in several cancers, but the role of NO66, particularly in PCa, is still unknown. We hypothesize that NO66 and EZH2 interactions at the chromatin are critical in the deregulation of key gene expression that promotes PCa progression and metastasis to bone. We found that NO66 levels are increased in prostate cancer patient samples, cell lines and xenografted samples. Our data indicate that forced expression of NO66 in prostate cancer cell lines PC3 and DU-145 promoted proliferation, colony formation, anchorage-independent growth, and invasion of these cells. In contrast, knocked-down of NO66 had reverse effects in those cells. NO66 depletion in DU145 and PC3 resulted in a two- to threefold decrease in colony formation and anchorage-independent growth. We observed that [[Unsupported Character - Symbol Font β]]-Catenin expression at both mRNA and protein levels were decreased in NO66-depleted DU145 cells. RNAseq analysis between DU145 and DU145-NO66shRNA cells revealed that tumor suppressor genes including IRX4, IL32, and the proapoptotic gene NOXA among several candidates are upregulated in DU145-NO66-shRNA. However, expression levels of proliferation/adhesion-associated genes including IGFBP5, FGF5, Wnt pathway genes-WNTs, sFRP, AXIN, TRIB2 are decreased in DU145-NO66shRNA cells. These biochemical and cellular data suggest that NO66 has oncogenic activity to PCa cells. In xenograft studies, femurs of 6 weeks old male SCID mice implanted with PC3 cells that overexpress NO66 (PC-NO66) showed significant femoral bone loss compared with mice that received control PC3 cells. Bone shaft volume and bone mineral density were also decreased in PC-NO66 xenografted femur. Gene expression analysis in xenograft femurs showed that expression of DKK1- a Wnt inhibitor, NFkB, and Cathespin K (CstK), known markers for osteolysis were indeed stimulated in femur of PC3NO66 xenograft.

These cell-based and animal studies indicate that NO66 plays an important role in cell proliferation, cell invasion and bone metastasis in prostate cancer. Our data provide several avenues to distinguish aggressive form of prostate cancer from indolent stage based on levels of NO66 and to develop effective treatments by testing epigenetic inhibitors of NO66 and EZH2 for drug therapies.

Citation Format: Rozita Bagheri-Yarmand, Sharmistha Lahiri, Xinhai Wan, Nora Navone, Christopher J. Logothetis, Robert F. Gagel, Krishna M. Sinha. A novel epigenetic regulator histone demethylase NO66 promotes prostate cancer bone metastasis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2272. doi:10.1158/1538-7445.AM2015-2272