Abstract 17: Ex-vivo assessment of the effect of Simvastatin in intestinal epithelium of Lynch Syndrome patients
Authors: Bommi Prashant , Wu Wenhui , Reyes Laura , Evans Kyera , Thirumurthi Selvi , Lynch Patrick , Sinha Krishna , Vilar Eduardo 
Published: September 2020

Background: Lynch Syndrome (LS) is a hereditary condition secondary to germline mutations in DNA mismatch repair (MMR) genes, which predisposes patients to develop different tumor types but mainly colorectal and endometrial cancers. Due to the genetic predisposition, chemopreventive strategies become critical in these individuals. One such chemopreventive compound, statin, a potent pharmacologic inhibitor of cholesterol biosynthesis, is known to exert other pleotropic effects such as modulation of cell proliferation, apoptosis, and inflammation, mainly due to inhibition of the mevalonate pathway. Although, chemoprevention studies in the past were performed in cancer stem cell models the effects have not been previously assessed in the physiologic and MMR-deficient stem cell niche. Here, we have successfully established ex-vivo cultures of crypt-villus structures (termed ‘mini-guts' or organoids) in order to interrogate the chemopreventive effects of statins in Lynch Syndrome patients.

Methods: Fresh endoscopic biopsy samples from a total of six LS patients followed at The University of Texas MD Anderson Cancer Center were obtained and ex-vivo organoid cultures were established. Each organoid line (passage &lt; P6) was treated with two different doses of Simvastatin (5 and 10 µM) or DMSO (control) for 48 hours. Total RNA was isolated from organoids treated with control and Simvastatin 10 µM and RNASeq analysis was performed using Illumina HiSeq 4000. Validation of several critical genes was performed by qRT-PCR assay.

Results: RNAseq analysis accounted for a total of 4,386 genes dysregulated in organoids treated with Simvastatin as compared to control. Stem cell markers, LGR5 and ASCL2, and differentiation markers, KRT20 (enterocytes) and MUC2 (goblet), were found to be induced by simvastatin. Gene Set Enrichment Analysis (GSEA) using Hallmark pathway gene sets showed significant enrichment for E2F target genes apart from canonical cholesterol homeostasis pathway. Ingenuity pathways analysis (IPA) revealed a list of top 10 genes which are upregulated/downregulated and implicated in cancer pathway. Validation of selected E2F Hallmark pathway genes (E2F1, TOP2A, Survivin, and KI-67) and IPA cancer pathway genes (KLF2, KLF6, EZH2, p57, and p21) showed a significant and dose dependent modulation upon treatment with Simvastatin.

Conclusions: Treatment with Simvastatin exhibited a profound effect on key genes involved in maintenance of stem cell niche in patient-derived organoids from LS. Simvastatin had a significant effect on E2F target genes implicated in regulation of cell cycle and proliferation via modulation of Ki-67, TOP2A, and Survivin. Along with increase in cyclin-dependent kinase inhibitor p21, there was significant induction of p57, a candidate tumor suppressor gene. Hence, Simvastatin, while it maintains the stem niche, exerts its anti-proliferative effects by specifically modulating genes involved in cell cycle and apoptosis.

Citation Format: Prashant Bommi, Wenhui Wu, Laura Reyes, Kyera Evans, Selvi Thirumurthi, Patrick Lynch, Krishna Sinha, Eduardo Vilar. Ex-vivo assessment of the effect of Simvastatin in intestinal epithelium of Lynch Syndrome patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 17.