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Loss of MEN1 function impairs DNA repair capability of pancreatic neuroendocrine tumors.

ABSTRACT: Somatic MEN1 mutations occur in up to 50% of pancreatic neuroendocrine tumors (PanNETs). Clinical studies have shown that radiation therapy (IR) is effective in a subset of PanNETs, but it remains unclear why some patients respond better to IR than others. Herein, we study whether MEN1 loss of function increases radiosensitivity of PanNETs and determine its effect on DNA double-strand break (DSB) repair. After creating a MEN1 knockout PanNET cell line, we confirmed reduced DSB repair capacity in MEN1-deficient cells and linked these findings to a defect in homologous recombination, as well as reduced BRCA2 expression levels. Consistent with this model, we found that MEN1 mutant cells displayed increased sensitivity to the highly trapping poly (ADP-ribose) polymerase (PARP) 1 inhibitor talazoparib in vitro. Our results suggest that combining IR with PARP inhibition may be beneficial in patients with PanNETs and MEN1 loss of function.

SUBMITTER: Lakiza O

PROVIDER: S-EPMC9045673 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature

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Loss of MEN1 function impairs DNA repair capability of pancreatic neuroendocrine tumors.

Lakiza Olga O Lutze Julian J Vogle Alyx A Williams Jelani J Abukdheir Abde A Miller Paul P Liao Chih-Yi 'Andy' C' Pitroda Sean P SP Martinez Carlos C Olivas Andrea A Setia Namrata N Kron Stephen J SJ Weichselbaum Ralph R RR Keutgen Xavier M XM

Endocrine-related cancer 20220321 4

Somatic MEN1 mutations occur in up to 50% of pancreatic neuroendocrine tumors (PanNETs). Clinical studies have shown that radiation therapy (IR) is effective in a subset of PanNETs, but it remains unclear why some patients respond better to IR than others. Herein, we study whether MEN1 loss of function increases radiosensitivity of PanNETs and determine its effect on DNA double-strand break (DSB) repair. After creating a MEN1 knockout PanNET cell line, we confirmed reduced DSB repair capacity in ...[more]

PMID: 35171113

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Project description:Multiple Endocrine Neoplasia type 1 (MEN1, OMIM 131100) is an autosomal dominant disorder characterized by endocrine tumors of the parathyroids, pancreatic islets and pituitary. The disease is caused by the functional loss of the tumor suppressor protein menin, coded by the MEN1 gene. The protein sequence has no significant homology to known consensus motifs. In vitro studies have shown menin binding to JunD, Pem, Smad3, NF-kappaB, nm23H1, and RPA2 proteins. However, none of these binding studies have led to a convincing theory of how loss-of-menin leads to neoplasia.Global gene expression studies on eight neuroendocrine tumors from MEN1 patients and 4 normal islet controls was performed utilizing Affymetrix U95Av2 chips. Overall hierarchical clustering placed all tumors in one group separate from the group of normal islets. Within the group of tumors, those of the same type were mostly clustered together. The clustering analysis also revealed 19 apoptosis-related genes that were under-expressed in the group of tumors. There were 193 genes that were increased/decreased by at least 2-fold in the tumors relative to the normal islets and that had a t-test significance value of p < or = 0.005. Forty-five of these genes were increased and 148 were decreased in the tumors relative to the controls. One hundred and four of the genes could be classified as being involved in cell growth, cell death, or signal transduction. The results from 11 genes were selected for validation by quantitative RT-PCR. The average correlation coefficient was 0.655 (range 0.235-0.964).This is the first analysis of global gene expression in MEN1-associated neuroendocrine tumors. Many genes were identified which were differentially expressed in neuroendocrine tumors arising in patients with the MEN1 syndrome, as compared with normal human islet cells. The expression of a group of apoptosis-related genes was significantly suppressed, suggesting that these genes may play crucial roles in tumorigenesis in this syndrome. We identified a number of genes which are attractive candidates for further investigation into the mechanisms by which menin loss causes tumors in pancreatic islets. Of particular interest are: FGF9 which may stimulate the growth of prostate cancer, brain cancer and endometrium; and IER3 (IEX-1), PHLDA2 (TSS3), IAPP (amylin), and SST, all of which may play roles in apoptosis.

Dataset Information

Loss of MEN1 function impairs DNA repair capability of pancreatic neuroendocrine tumors.

Publications

Loss of MEN1 function impairs DNA repair capability of pancreatic neuroendocrine tumors.

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