Menin Maintains Cholesterol Content in Colorectal Cancer via Repression of LXR-Mediated Transcription.

BACKGROUND AND AIMS: Menin is a nuclear scaffold protein that regulates gene transcription in an oftentimes tissue-specific manner. Our previous work showed that menin is over-expressed in colorectal cancer (CRC); however, the full spectrum of menin function in colonic neoplasia remains unclear. Herein, we aimed to uncover novel menin-regulated pathways important for colorectal carcinogenesis. METHODS: RNA-Seq analysis identified that menin regulates LXR-target gene expressions in CRC cell lines. Isolated colonic epithelium from Men1f/f;Vil1-Cre and Men1f/f mice was used to validate the results in vivo. Cholesterol content was quantified via an enzymatic assay. RESULTS: RNA-Seq analysis in the HT-29 CRC cell line identified that menin inhibition upregulated LXR-target genes, specifically ABCG1 and ABCA1, with protein products that promote cellular cholesterol efflux. Similar results were noted across other CRC cell lines and with different methods of menin inhibition. Consistent with ABCG1 and ABCA1 upregulation, and similarly to LXR agonists, menin inhibition reduced the total cellular cholesterol in both HT-29 and HCT-15 cells. To confirm the effects of menin inhibition in vivo, we assessed Men1f/f;Vil1-Cre mice lacking menin expression in the colonic epithelium. Men1f/f;Vil1-Cre mice were found to have no distinct baseline phenotype compared to control Men1f/f mice. However, similarly to CRC cell lines, Men1f/f;Vil1-Cre mice showed an upregulation of Abcg1 and a reduction in total cellular cholesterol. Promoting cholesterol efflux, either via menin inhibition or LXR activation, was found to synergistically suppress CRC cell growth under cholesterol-depleted conditions and when administered concomitantly with small molecule EGFR inhibitors. CONCLUSIONS: Menin represses the transcription of LXR-target genes, including ABCA1 and ABCG1 in the colonic epithelium and CRC. Menin inhibition conversely upregulates LXR-target genes and reduces total cellular cholesterol, demonstrating that menin inhibition may be an important mechanism for targeting cholesterol-dependent pathways in colorectal carcinogenesis.

Patient Frustration with Pelvic Organ Prolapse Education Met with Resilient Response.

INTRODUCTION: Limited patient understanding due to challenges in physician-patient communication and inadequate patient education materials (PEMs) can result in poor outcomes after pelvic organ prolapse (POP) repair. Our objective was to identify how patients learned about POP and review their perception of available educational tools. METHODS: Patients with a history of POP were recruited using ResearchMatch and invited to participate in a virtual semi-structured interview where they were shown a website, brochure, and video pertaining to POP. Information regarding patient preference for PEMs was obtained. The interviews were transcribed, coded, and qualitative data analysis was performed using grounded theory methodology. RESULTS: Qualitative analysis of interviews of 13 participants averaging 58 years old yielded several preliminary themes including: insufficient information to guide treatment decisions, preference for multimodal, dynamic, and comprehensive materials, and lack of support leading to avoidance of care, misinformation, and self-advocacy mechanisms. Emerging concepts included: lack of complete information regarding POP treatment resulted in misinformation, stress and desperation, distrust of healthcare providers leading to feelings of isolation, desire of support groups, and loss of follow up, and a desire for well-organized, detailed, multimodal, and destigmatizing materials as a guide to their disease process, prevention and risk factors, its natural progression, and treatment decisions. Participants developed self-reliant strategies for making treatment decisions, including the use of online resources, advice from friends, and independent search for more specialized physicians. CONCLUSIONS: Women with POP reported a lack of information and support which resulted in the generation of self-coping mechanisms. This led to significant anxiety surrounding their diagnosis and treatment and poor satisfaction. Developing a reproducible methodology to create evidence-based PEMs will significantly decrease patient misinformation, apprehension, and use of inaccurate sources of information.

Menin-mediated Repression of Glycolysis in Combination with Autophagy Protects Colon Cancer Against Small-molecule EGFR Inhibitors.

Menin serves both tumor suppressor and promoter roles in a highly tumor-specific manner. In colorectal cancer, menin is overexpressed and plays a critical role in regulating transcription of SKP2, and combined treatment with a menin inhibitor and small-molecule EGFR inhibitor (EGFRi) leads to synergistic killing of colorectal cancer cells. However, the full spectrum of menin function in colorectal cancer remains uncertain. Herein, we demonstrate that menin inhibition increases glycolysis in colorectal cancer cells. This menin inhibitor-induced increase in glycolysis occurs in an mTOR-independent manner and enhances the sensitivity of colorectal cancer cells to EGFRis. In addition, we show that EGFRis induce autophagy in colorectal cancer cells, which is important for cell survival in the setting of combined treatment with an EGFRi and menin inhibitor. Inhibition of autophagy with chloroquine further sensitizes colorectal cancers to treatment with the combination of an EGFRi and menin inhibitor. Together, these findings uncover a novel role for menin in colorectal cancer as a repressor of glycolysis and demonstrate that menin inhibitor-induced increases in glycolysis sensitize colorectal cancer cells to EGFRis. In addition, these findings illustrate the importance of autophagy as a protective mechanism against EGFRis, especially in the presence of menin inhibition. Ultimately, these data open the possibility of using menin-mediated regulation of glycolysis to potentially improve treatment modalities for colorectal cancer.

Combined Menin and EGFR Inhibitors Synergize to Suppress Colorectal Cancer via EGFR-Independent and Calcium-Mediated Repression of SKP2 Transcription.

Menin is a nuclear epigenetic regulator that can both promote and suppress tumor growth in a highly tissue-specific manner. The role of menin in colorectal cancer, however, remains unclear. Here, we demonstrate that menin was overexpressed in colorectal cancer and that inhibition of menin synergized with small-molecule inhibitors of EGFR (iEGFR) to suppress colorectal cancer cells and tumor xenografts in vivo in an EGFR-independent manner. Mechanistically, menin bound the promoter of SKP2, a pro-oncogenic gene crucial for colorectal cancer growth, and promoted its expression. Moreover, the iEGFR gefitinib activated endoplasmic reticulum calcium channel inositol trisphosphate receptor 3 (IP3R3)-mediated release of calcium, which directly bound menin. Combined inhibition of menin and iEGFR-induced calcium release synergistically suppressed menin-mediated expression of SKP2 and growth of colorectal cancer. Together, these findings uncover a molecular convergence of menin and the iEGFR-induced, IP3R3-mediated calcium release on SKP2 transcription and reveal opportunities to enhance iEGFR efficacy to improve treatments for colorectal cancer. SIGNIFICANCE: Menin acts as a calcium-responsive regulator of SKP2 expression, and small molecule EGFR inhibitors, which induce calcium release, synergize with Menin inhibition to reduce SKP2 expression and suppress colorectal cancer.