Therapeutic Targeting of Histone Lysine Demethylase KDM4B Blocks the Growth of Castration-Resistant Prostate Cancer

Background: Accumulating evidence points to epigenetic mechanisms as essential in tumorigenesis. Treatment that targets epigenetic regulators is becoming an attractive strategy for cancer therapy. The role of epigenetic therapy in prostate cancer (PCa) remains elusive. Previously we demonstrated a correlation of levels of histone lysine demethylase KDM4B with the appearance of castration resistant prostate cancer (CRPC) and identified a small molecular inhibitor of KDM4B, B3. In this study, we aim to define the role of KDM4B in promoting PCa progression and test the efficacy of B3 using clinically relevant PCa models. Methods: KDM4B was overexpressed in LNCaP cells or knocked down (KD) in 22Rv1 cells. The specificity of B3 was determined in vitro using recombinant KDM proteins and in vivo using 22Rv1 cell lysates. The efficacy of B3 monotherapy or in combination with androgen receptor (AR) antagonist enzalutamide or the mTOR inhibitor rapamycin was tested using xenograft models in castrated mice. Comparative transcriptomic analysis was performed on KDM4B KD and B3-treated 22Rv1 cells to determine the on-target (KDM4B-dependent) and off-target (non-KDM4B-associated) effects of B3.Results: Overexpression of KDM4B in LNCaP cells enhanced its tumorigenicity whereas knockdown of KDM4B in 22Rv1 cells reduced tumor growth in castrated mice. B3 suppressed the growth of both 22Rv1 and VCaP xenografts and sensitized 22Rv1 cells to enzalutamide inhibition. B3 also inhibited 22Rv1 tumor growth synergistically with rapamycin that resulted in cell apoptosis. Mechanistically, B3 inhibited expression of AR-V7 and genes involved in epithelial-to-mesenchymal transition. DNA replication stress marker gH2A.X was upregulated by B3, which is further increased when combined with rapamycin. Based on transcriptomic and biochemical analyses, B3 inhibits both H3K9me3 and H3K27me3 demethylase activity, which is believed to underlie its anti-tumor action. Conclusions: Our studies establish KDM4B as a potent target for CRPC and B3 as a potential therapeutic agent. B3 as monotherapy or in combination with other anti-PCa therapeutics offers proof of principle for the clinical translation of epigenetic therapy targeting KDMSs for CRPC patients.

Therapeutic Targeting of Histone Lysine Demethylase KDM4B Blocks the Growth of Castration-resistant Prostate Cancer

Background: Accumulating evidence points to epigenetic mechanisms as essential in tumorigenesis. Treatment that targets epigenetic regulators is becoming an attractive strategy for cancer therapy. The role of epigenetic therapy in prostate cancer (PCa) remains elusive. Previously we demonstrated a correlation of levels of histone lysine demethylase KDM4B with the appearance of castration resistant prostate cancer (CRPC) and identified a small molecular inhibitor of KDM4B, B3. In this study, we aim to define the role of KDM4B in promoting PCa progression and test the efficacy of B3 using clinically relevant PCa models. Methods: KDM4B was overexpressed in LNCaP cells or knocked down (KD) in 22Rv1 cells. The specificity of B3 was determined in vitro using recombinant KDM proteins and in vivo using 22Rv1 cell lysates. The efficacy of B3 monotherapy or in combination with androgen receptor (AR) antagonist enzalutamide or the mTOR inhibitor rapamycin was tested using xenograft models in castrated mice. Comparative transcriptomic analysis was performed on KDM4B KD and B3-treated 22Rv1 cells to determine the on-target (KDM4B-dependent) and off-target (non-KDM4B-associated) effects of B3.Results: Overexpression of KDM4B in LNCaP cells enhanced its tumorigenicity whereas knockdown of KDM4B in 22Rv1 cells reduced tumor growth in castrated mice. B3 suppressed the growth of both 22Rv1 and VCaP xenografts and sensitized 22Rv1 cells to enzalutamide inhibition. B3 also inhibited 22Rv1 tumor growth synergistically with rapamycin that resulted in cell apoptosis. Mechanistically, B3 inhibited expression of AR-V7 and genes involved in epithelial-to-mesenchymal transition. DNA replication stress marker γH2A.X was upregulated by B3, which is further increased when combined with rapamycin. Based on transcriptomic and biochemical analyses, B3 inhibits both H3K9me3 and H3K27me3 demethylase activity, which is believed to underlie its anti-tumor action.Conclusions: Our studies establish KDM4B as a potent target for CRPC and B3 as a potential therapeutic agent. B3 as monotherapy or in combination with other anti-PCa therapeutics offers proof of principle for the clinical translation of epigenetic therapy targeting KDMSs for CRPC patients.

Histone Lysine Demethylase 1A Is a Master Regulator of Genes Necessary for Trophoblast Cell Proliferation

Histone lysine demethylase 1A is a master regulator of genes necessary for trophoblast cell proliferation. A proper functioning placenta is critical for pregnancy, fetal growth and development and postnatal health. Trophoblast cell proliferation and differentiation is critical for placental development and function. Recently we demonstrated that the histone lysine demethylase KDM1A binds to androgen receptor (AR) in human and sheep trophoblast cells, and targets the same promoter region of vascular endothelial growth factor A (VEGFA), suggesting a role for KDM1A and AR in early placental angiogenesis. The goal of this study was to determine the function of KDM1A during early placental development. We hypothesized that KDM1A regulates genes that are necessary for trophoblast cell proliferation, and early placental development. To this end, both in vitro and in vivo approaches were used in this study. ACH-3P cells (human first trimester trophoblast cells (CT and EVT) fused with the choriocarcinoma cell line AC1-1) were used, and a KDM1A knock out (KO) cell line was generated using CRISPR-Cas 9 based genome editing. KDM1A KO in ACH-3P cells led to significant (P<0.05) reduction in AR and VEGFA. Furthermore, factors important for cell proliferation and trophoblast cell development high mobility group AT-hook 1 (HMGA1), LIN28, and MYC protooncogene (cMYC) were significantly (P<0.05) lower in KDM1A KO ACH-3P cells. Cell proliferation assays revealed a significant (P<0.05) reduction in KDM1A KO ACH-3P cells compared to scramble controls. An in vivo experiment was conducted to demonstrate a role for KDM1A in placental development, using the sheep as a model. Day 9 hatched blastocysts were flushed and infected with a Lenti-CRISPRv2 KDM1A target construct (n=4) to knockout KDM1A specifically in the trophectoderm, or with SC (n=5). Infected embryos were transferred to recipient ewes and embryos were collected at gestational day 16. Data suggests that KDM1A KO in trophoblast cells is necessary for conceptus elongation. Current experiments are ongoing to determine the effects of KDM1A and AR knockdown using shRNA lentiviral target vectors on conceptus elongation and pregnancy. Collectively these results indicate that KDM1A plays a central role in regulating genes necessary for trophoblast cell proliferation. This project was supported by Agriculture and Food Research Initiative Competitive Grant no. 2019-67015-29000 from the USDA National Institute of Food and Agriculture.