The role of PIWI-interacting RNAs (piRNA) in small extracellular vesicles (sEV) derived from pancreatic neuroendocrine neoplasms (PNEN) in the tumor microenvironment (TME) remains unexplored. We used multiplex IHC to analyze the expression of CD68, CD276 (B7H3), and CD3 on PNEN. CD276+ tumor-associated macrophages (TAM) were more abundant in tumor tissues than nontumor tissues and negatively correlated with T-cell infiltration. Serum sEV piRNA sequencing was performed to identify piRNAs enriched in patients with PNEN. We then investigated the function and mechanism of sEV piR-hsa-30937 in the cross-talk between tumor cells and macrophages in the PNEN TME. PNEN-derived sEV piR-hsa-30937 targeted PTEN to activate the AKT pathway and drive CD276 expression. CD276+ macrophages inhibited T-cell proliferation and IFNγ production. piR-hsa-30937 knockdown and anti-CD276 treatment suppressed progression and metastasis in a preclinical model of PNEN by enhancing T-cell immunity. Thus, our data show that PNEN-derived sEV piR-hsa-30937 promotes CD276 expression in macrophages through the PTEN/AKT pathway and that CD276+ TAMs suppress T-cell antitumor immunity. sEV piR-hsa-30937 and CD276 are potential therapeutic targets for immunotherapy of PNEN.

It has been shown that long noncoding RNAs (lncRNAs) are involved in the carcinogenesis of multiple cancers. However, the roles of lncRNAs in gastroenteropancreatic neuroendocrine neoplasms (GEP‐NENs) remain elusive. In the present study, we found that lncNEN885 was markedly decreased in human gastric NEN samples compared to adjacent normal tissues by transcriptome sequencing. Functionally, silencing or overexpression of lncNEN885 could not obviously affect cell proliferation or apoptosis in BON‐1 or LCC‐18 cells but could affect cell migration and invasion as well as wound‐healing rates. Furthermore, dysregulation of lncNEN885 affected these biological functions by activating epithelial‐mesenchymal transition through increased expression of Snail, vimentin, and N‐cadherin as well as decreased E‐cadherin levels in BON‐1 and LCC‐18 cells. Silencing of lncNEN885 could dramatically increase the phosphorylation of glycogen synthase kinase‐3β and decrease the expression of adenomatous polyposis coli and Axin, with the subsequent accumulation of β‐catenin. Taken together, dysregulation of lncNEN885 can regulate cell migration and invasion by activating epithelial‐mesenchymal transition process partially through canonical Wnt/β‐catenin signaling in GEP‐NEN cells, which may be a novel biomarker for the metastasis of GEP‐NENs.

Aberrant microRNA (miRNA) expressions contribute to the development and progression of various diseases, including Crohn’s disease (CD). However, the accurate mechanisms of miRNAs in CD are definitely unclear. We employed colonic tissue samples from normal volunteers and CD patients, an acute mice colitis model induced by 2,4,6-trinitro-benzene-sulfonic acid (TNBS), and a cellular oxidative stress model induced by H₂O₂ in HT-29 cells to determine the effects of oxidative stress on expressions of miR-122, selenium-binding protein 1 (SELENBP1, SBP1), p65 nuclear factor κB (p65NF-κB) signaling, and DNA methylation. We found that SBP1 was mainly located on epithelial cells and was significantly increased in patients with active CD. SBP1 was the target gene of miR-122. miR-122 expression was downregulated while SBP1 expression was upregulated under TNBS-induced colitis or oxidative stress. Pre-miR-122 or siRNA SBP1 (si-SBP1) treatment ameliorated acute TNBS-induced colitis and H₂O₂-induced oxidative stress. Cotreatment of pre-miR-122 and si-SBP1 enhanced these effects. Besides, pre-miR-122 and si-SBP1 obviously activated the p65NF-κB signaling by phosphorylation of IκBα. Bisulfite sequencing of the CpG islands in the promoter region of miR-122 showed that CpG methylation was significantly increased under oxidative stress. Treating cells with 5′-AZA which was well known as a DNA-demethylating agent significantly increased miR-122 expression. Our results suggest that oxidative stress-induced DNA methylation of miR-122 aggravates colitis targeting SELENBP1 partially by p65NF-κB signaling and may promote the progression of CD.

In recent years, EZH2 inhibitors have shown potential therapeutic value in certain hematological malignancies and solid tumors. However, the role and mechanisms of EZH2 in pancreatic neuroendocrine neoplasms (pNENs) remain unclear. This study investigated the effects and mechanism of the EZH2 inhibitor GSK126 on pNENs. Public database analysis revealed that increased EZH2 expression correlates with poor prognosis in pNEN patients. We found that EZH2 is significantly upregulated in pNEN tissues and cell lines, and its knockdown or treatment with GSK126 inhibits proliferation and induces ferroptosis in vitro. In vivo, EZH2 knockdown or GSK126 treatment suppressed subcutaneous tumor growth in nude mice. Mechanistic studies showed that GSK126 induces ferroptosis by inhibiting the PI3K/AKT/mTOR pathway. In addition, GSK126 upregulated HMGCS1, a gene linked to ferroptosis. HMGCS1 may act as an oncogene by activating the PI3K/AKT/mTOR pathway, and the knockdown of HMGCS1 can enhance GSK126-induced ferroptosis and the inhibitory effect of GSK126 on the PI3K/AKT/mTOR pathway. Furthermore, combining GSK126 with everolimus, an mTOR inhibitor used clinically for pNENs, more effectively inhibited cell proliferation and tumor growth. In summary, our findings reveal that the EZH2 inhibitor GSK126 induces ferroptosis by inhibiting the PI3K/AKT/mTOR pathway, suppressing pNENs progression, and HMGCS1 may mediate resistance to EZH2 inhibitors, offering new insights into pNEN treatment.