Resistance to oxaliplatin (OXA) is a major cause of recurrence in gastric cancer (GC) patients. Autophagy is an important factor ensuring the survival of cancer cells under chemotherapeutic stress. We aimed to investigate the role of OXA‐related genes in autophagy and chemoresistance of gastric cancer cells. We established OXA‐resistant gastric cancer cells and used RNA‐seq to profile gene expression within OXA‐resistant GC and corresponding parental cells. Immunohistochemistry and RT‐qPCR was performed to detect gene expression in tissues of two cohorts of GC patients who received OXA‐based chemotherapy. The chemoresistant effects of the gene were assessed by cell viability, apoptosis, and autophagy assays. The effects of the gene on autophagy were assessed with mRFP‐GFP‐LC3 and Western blotting (WB). Gene set enrichment analysis (GSEA) and WB were performed to detect the activity of PI3K/AKT/mTOR signaling under the regulation of the gene. The OXA‐resistant property of GC cells is related to their enhanced autophagic activity. Based on RNA‐seq profiling, ANXA1 was selected as a candidate, as it was upregulated significantly in OXA‐resistant cells. Furthermore, we found that higher ANXA1 expression before chemotherapy was associated with subsequent development of resistance to oxaliplatin, and overexpression of ANXA1 promoted the resistance of gastric cancer cells to oxaliplatin. So, it may serve as a key regulator in GC chemo‐resistance knockdown of ANXA1, via inhibiting autophagy, enhancing the sensitivity of OXA‐resistant GC cells to OXA in vitro and in vivo. Mechanically, we identified that PI3K/AKT/mTOR signaling pathway was activated in the ANXA1 stable knockdown AGS/OXA cells, which leads to the suppression of autophagy. ANXA1 functions as a chemoresistant gene in GC cells by targeting the PI3K/AKT/mTOR signaling pathway and might be a prognostic predictor for GC patients who receive OXA‐based chemotherapy.

Selenium binding protein 1 (SELENBP1) is frequently downregulated in malignancies such as colorectal cancer (CRC), however, whether it is involved in tumor angiogenesis is still unknown. We analyzed the expression and localization of SELENBP1 in vessels from CRC and neighboring tissues. We investigated the in vitro and in vivo activity of SELENBP1 in angiogenesis and explored the underlying mechanism. SELENBP1 was localized to endothelial cells in addition to glandular cells, while its vascular expression was decreased in tumor vessels compared to that in vessels from neighboring non-tumor tissues. Gain-of-function and loss-of-function experiments demonstrated that SELENBP1 inhibited angiogenesis in vitro, and blocked communications between HUVECs and CRC cells. Overexpression of SELENBP1 in CRC cells inhibited tumor growth and angiogenesis, and enhanced bevacizumab-sensitivity in a mouse subcutaneous xenograft model. Mechanic analyses revealed that SELENBP1 may suppress tumor angiogenesis by binding with Delta-like ligand 4 (DLL4) and antagonizing the DLL4/Notch1 signaling pathway. The inhibitory effects of SELENBP1 on in vitro angiogenesis could largely be rescued by DLL4. These results revealed a novel role of SELENBP1 as a potential tumor suppressor that antagonizes tumor angiogenesis in CRC by intervening the DLL4/Notch1 signaling pathway.

Angiogenesis is critical for many diseases. Previously, we reported that Down Syndrome Candidate Region 1 isoform 1L (DSCR1-1L) was one of the most up-regulated genes in endothelial cells induced by VEGF and histamine, and regulated endothelial cell proliferation and Matrigel angiogenesis in mice. However, it was not known whether DSCR1-1L regulated angiogenesis in vivo and what was the molecular mechanism underlying it. In this study, gene knockdown and overexpression models were established to study the role of DSCR1-1L in angiogenesis in vivo. Further, the downstream regulatory target of DSCR1-1L was explored with molecular biological methods in vascular endothelial cells. We found that DSCR1-1L shRNAs significantly inhibited angiogenesis induced by VEGF in mice (p < 0.0001). In the gain-of-function assay, overexpression of DSCR1-1L cDNA in mouse endothelium of EC-FH-DSCR1-1L transgenic mice was sufficient to induce angiogenesis significantly (p < 0.01). DSCR1-1L regulated angiogenesis in the early stage by down-regulation of the VE-cadherin expression through targeting its transcription, but not mRNA stability. Three DSCR1-1L-targeted DNA elements in the VE-cadherin promoter were identified by promoter reporter assays, among which, a novel specific transcriptional complex was found. The DNA sequence (CTTCTG) in the VE-cadherin promoter was identified to directly interact with proteins by Electrophoresis Mobility Shift Assays and DNase I footprint assay. Hence, DSCR1-1L is an excellent therapeutic target for angiogenic diseases through down-regulating the formation of a novel transcriptional complex on the VE-cadherin promoter. DSCR1-1L shRNAs and cDNA have the potential to be developed for clinical application. Our results also contribute significantly to the field of mechanistic studies.

Human cancer cell lines serve as essential in vitro models for investigating tumor biology, carcinogenesis, molecular genetics, metastasis, and tumor evolution. In this study, we establish and characterize the OT17 cell line, derived from a moderately to poorly differentiated colorectal adenocarcinoma surgical specimen. Genetic analysis of OT17 revealed key mutations, including BRAF V600E, APC, and ERBB2, along with a deletion in TP53. Immunohistochemical profiling confirmed the expression of MLH1, MSH2, MSH6, and PMS2, indicating a microsatellite-stable (MSS) phenotype consistent with the primary tumor. The OT17 cell line demonstrated robust tumorigenicity in vivo, achieving a 100 % success rate in forming subcutaneous tumors in NOD-scid Il2rg^−/−(NSG)(NSG) mice. Additionally, a corresponding 3D organoid model (CO17) was established, which retained genetic concordance with OT17, further validating its relevance for preclinical applications. Together, the OT17 cell line and CO17 organoid system represent robust models for advancing colorectal cancer research, with potential applications in therapeutic screening, immunotherapy development, and MSS tumor biology studies.