Abstract 2591: miR-193b is a novel regulator of Inhibition of Notch signaling by for targeting cancer stem cell and tumor microenvironment
Authors: Guven Ummu , Mokhlis Hamada Ahmed , Kahraman Nermin , Ivan Cristina , Duzagac Fahriye , Lopez-Berestein Gabriel , Oktem Gulperi , Ozpolat Bulent 
Published: August 2019

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive human cancers with extremely poor survival rates with 6 months of median patient survival, representing an unmet therapeutic challenge. The exact mechanisms by which PDAC progresses and still remain poorly understood. Strategies targeting only tumor cells have proven to be unsuccessful in eliminating PDAC and prevent metastasis, drug resistance and patient deaths. Accumulating evidence suggests that cancer stem cells (CSC) are also responsible for relapses and resistance to therapies as well as promoting invasive and metastatic growth of the tumor. Notch signaling has been implicated in the survival of CSC, suggesting that NOTCH pathway can be targeted for treatment of PDAC. In four known transmembrane Notch receptors, antibodies targeting Notch 2/3 have shown efficacy in solid tumors and PDAC in phase I clinical trials, suggesting that these are viable targets. Targeting Notch 2 expression has been shown to induce apoptosis in PDAC but its role and regulation of in PDAC CSC is not well understood. We found that Notch2 significantly upregulated in pancreatic cancer stem cells and its expression is associated with shorter overall patient survival in pancreatic cancer. Recent discoveries revealed that small non-coding RNAs such as microRNAs (miRNAs) play significant role in the pathogenesis of human cancers. Therefore, microRNAs have attracted great interest as a tool for cancer treatment and entered clinical trials in the US. Using in silico prediction algorithms we found that miR-193b-3p has binding sites on the 3’-untranslated region (3’-UTR) of NOTCH2 gene and demonstrated that transfection of PDAC and CD133+/CD44+/EpCam+ pancreatic CSC cells with miR193b-3p mimic or NOTCH 2 siRNA suppressed NOTCH2 expression by Western blot and qPCR analysis and proliferation, migration and metastasis of PDAC (Panc-1 and MiaPaCa-2) and the tumorosphere forming ability of CSC cells in Mammocult Human Tumorosphere Culture. CD133+/CD44+/EpCam+ pancreatic cancer stem cells transfected with miR-193b inhibited Notch 2 and colony forming capabilities in soft agar. Currently we are performing a gene reporter assay to show miR193b directly binds to 3’-UTR of NOTCH2 mRNA and inhibits its expression. We demonstrated that injection of nanoliposome incorporated miR193b-3p into mice from tail vein (0.15 mg/kg once a week) significantly inhibited PDAC tumor growth. However, animal studies transplanted with CD133+/CD44+/EpCam+ pancreatic cancer stem cells after miR193b-3p transfection are underway to detect in vivo effects of targeting miR193 in CSC and tumor growth. Overall, our findings provide new insights into the tumor suppressor role of miR-193b by targeting of Notch 2 signaling and suggest that miR-193b-based therapy may be a potential therapeutic strategy to targeted pancreatic cancer stem cells.

Citation Format: Ummu Guven, Hamada Ahmed Mokhlis, Nermin Kahraman, Cristina Ivan, Fahriye Duzagac, Gabriel Lopez-Berestein, Gulperi Oktem, Bulent Ozpolat. miR-193b is a novel regulator of Inhibition of Notch signaling by for targeting cancer stem cell and tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2591.