Abstract C40: Histone demethylase Jmjd1a: A novel preventive target in pancreatic cancer

Abstract

Abstract Purpose: Pancreatic cancer is the fourth leading cause of mortality in the United States with no significant treatment currently available. Therapeutic options for patients with advanced disease are time limited and non-curative. A growing body of evidence suggests that cancer stem cells/tumor initiating cells (CSC/TIC) within a solid tumor including in pancreatic cancer initiate and sustain tumor growth. Our preliminary data implicates Jumanji demethylases1a (Jmjd1a) as a prime regulator of stem cell renewability for cancer progression. Hypoxia most prominently controls malignant properties of cancer cells by stimulating hypoxia inducible factor 1 (HIF1). The fact that HIF1 binds to its responsible elements (HREs) in the Jmjd1 promoters and subsequently up-regulates Jmjd1 could explain why hypoxia exacerbates malignancy. In this context, the availability of small molecules will allow us to determine mechanistic aspects of the interconnection among hypoxia, Jmjd1a and CSC/TIC self-renewal. Indeed, the inhibition of the members of the Jmjd family, 2-oxoglutarate (2OG)-dependent histone lysine demethylases (KDMs), suppresses tumor growth in many types of cancer. Therefore, we hypothesize that hypoxia induces Jmjd1a that regulate self-renewability of CSC/TIC, thereby promoting tumor initiation. Recently, two small molecules analogues of crocetinic acid, a carotenoid molecule isolated from saffron, have revealed to have potent antimitotic effects in pancreatic cancer models. Experimental Procedure: In this study, we have developed pancreatic CSC/TIC during hypoxic and normoxic conditions using ultra-low binding tissue culture dishes to form multicellular spheroids called pancospheres and monitored expression of Jmjda1a using western blots and immunohistochemistry on those CSC/TIC. We also used RNA technology to silenced Jmjd1a using lenntiviral vectors different pancreatic cancer cell lines. We have also determined Jmjd1a expression in pancreatic cancer patients' samples. Results: Jmjd1a is highly expressed in pancreatic cancer cells and it is significatly reduced when it is knocked down through shRNA in those cell lines. The proliferation of those knockdown cell lines was significantly reduced using colony formation and wound healing assays. Hypoxia stimulated pancospheres formation associated with concomitant overexpression of Jmjd1a. Knockdown of Jmjd1a using shRNA demonstrated significant reduction of pancreatic pancospheres formation ability in both normoxic and hypoxic conditions. The demethylation of specific substrate of Jmjd1a, H3-K9me2, was significantly affected by knockdown of Jmjd1a in pancreatic cancer cells. Treatment with gemcitabine, drug of choice for pancreatic cancer, did not affect in Jmjd1a expression in those cell lines particularly during hypoxic conditions. Crocetinic acid and its analogues inhibited Jmjd1a expression in both in vivo and in vitro pancreatic cancer models. We also observed that Jmjd1a was significantly overexpressed in human pancreatic cancer patient samples than the adjacent normal tissues. Conclusions: Jmjd1a is overexpressed in pancreatic cancer and stimulates the self-renewability of pancospheres. Taken together, Jmjd1a is one of important factors for pancreatic cancer progression and could be a novel preventive target for pancreatic cancer. Citation Format: Kanagaraj Palaniyandi, Shamima Islam, Parthasarathy Rangarajan, Deep Kwatra, Satish Ramalingam, Dharmalingam Subramaniam, Subhash Padhye, Shrikant Anant, Animesh Dhar. Histone demethylase Jmjd1a: A novel preventive target in pancreatic cancer. [abstract]. In: Proceedings of the Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2013 Oct 27-30; National Harbor, MD. Philadelphia (PA): AACR; Can Prev Res 2013;6(11 Suppl): Abstract nr C40.