Adaptive EGF expression sensitizes pancreatic cancer cells to ionizing radiation through activation of the cyclin D1/P53/PARP pathway

Thymidine phosphorylase induction by ionizing radiation antagonizes 5-fluorouracil resistance in human ductal pancreatic adenocarcinoma

Chemoresistance in pancreatic ductal adenocarcinoma (PDAC) frequently contributes to failure of systemic therapy. While the radiosensitizing properties of 5-fluorouracil (FU) are well known, it is unknown whether ionizing radiation (IR) sensitizes towards FU cytotoxicity. Here, we hypothesize that upregulation of thymidine phosphorylase (TP) by IR reverses FU chemoresistance in PDAC cells. The FU resistant variant of the human PDAC cell line AsPC-1 (FU-R) was used to determine the sensitizing effects of IR. Proliferation rates of FU sensitive parental (FU-S) and FU-R cells were determined by WST-1 assays after low (0.05 Gy) and intermediate dose (2.0 Gy) IR followed by FU treatment. TP protein expression in PDAC cells before and after IR was assessed by Western blot. To analyze the specificity of the FU sensitizing effect, TP was ablated by siRNA. FU-R cells showed a 2.7-fold increase of the half maximal inhibitory concentration, compared to FU-S parental cells. Further, FU-R cells showed a concomitant IR resistance towards both doses applied. When challenging both cell lines with FU after IR, FU-R cells had lower proliferation rates than FU-S cells, suggesting a reversal of chemoresistance by IR. This FU sensitizing effect was abolished when TP was blocked by anti-TP siRNA before IR. An increase of TP protein expression was seen after both IR doses. Our results suggest a TP dependent reversal of FU-chemoresistance in PDAC cells that is triggered by IR. Thus, induction of TP expression by low dose IR may be a therapeutic approach to potentially overcome FU chemoresistance in PDAC.

Bridging Radiotherapy to Immunotherapy: The IFN-JAK-STAT Axis

The unprecedented successes of immunotherapies (IOs) including immune checkpoint blockers (ICBs) and adoptive T-cell therapy (ACT) in patients with late-stage cancer provide proof-of-principle evidence that harnessing the immune system, in particular T cells, can be an effective approach to eradicate cancer. This instills strong interests in understanding the immunomodulatory effects of radiotherapy (RT), an area that was actually investigated more than a century ago but had been largely ignored for many decades. With the "newly" discovered immunogenic responses from RT, numerous endeavors have been undertaken to combine RT with IOs, in order to bolster anti-tumor immunity. However, the underlying mechanisms are not well defined, which is a subject of much investigation. We therefore conducted a systematic literature search on the molecular underpinnings of RT-induced immunomodulation and IOs, which identified the IFN-JAK-STAT pathway as a major regulator. Our further analysis of relevant studies revealed that the signaling strength and duration of this pathway in response to RT and IOs may determine eventual immunological outcomes. We propose that strategic targeting of this axis can boost the immunostimulatory effects of RT and radiosensitizing effects of IOs, thereby promoting the efficacy of combination therapy of RT and IOs.

MicroRNA‑532‑5p regulates oxidative stress and insulin secretion damage in high glucose‑induced pancreatic β cells by downregulating the expression levels of CCND1

Diabetes mellitus is a metabolic disorder caused by insufficient insulin secretion. The expression of microRNA (miR)-532-5P is downregulated in diabetes, but its specific role in diabetes has not yet been elucidated. The present study aimed to investigate the specific mechanism underlying the effects of miR-532-5p on diabetes. Cell viability was determined using an MTT assay. The expression levels of miR-532-5P, cyclin D1 (CCND1), Insulin1 and Insulin2 were detected using reverse transcription-quantitative PCR. The expression of miR-532-5p and CCND1 were overexpressed in cells by cell transfection. ELISA was used to detect insulin secretion. 2′,7′-dichlorodihydrofluorescein diacetate was used to quantify reactive oxygen species levels in cells. Apoptosis was detected using a TUNEL assay. Western blotting was performed to detect the expression of apoptosis-related proteins, CCND1 and p53. A dual-luciferase reporter assay was conducted, and verified the targeted binding of miR-532-5p and CCND1. The expression of miR-532-5p was downregulated in high glucose (HG)-induced MIN6 cells. Overexpression of miR-532-5p could improve the HG-induced decline in insulin secretion and inhibit HG-induced oxidative stress and apoptosis in cells. miR-532-5p can target and regulate the expression of CCND1. Overexpression of miR-532-5p downregulated HG-induced cell insulin secretion, oxidative stress and apoptosis by downregulating CCND1, which is involved in regulating the expression of p53. To conclude, miR-532-5p regulated oxidative stress and insulin secretion damage in HG-induced pancreatic β cells by downregulating the expression of CCND1, which is involved in the upregulation of the expression of p53.

Immunohistochemical expression of insulin-like growth factor-1Ec in primary endometrial carcinoma: Association with PTEN, p53 and survivin expression

Chronic hyperinsulinemia due to insulin resistance and elevated levels of insulin-like growth factor (IGF)-1 and IGF-2 are suggestive of a significantly higher risk of endometrial carcinoma. There is a wealth of evidence showing differential expression of IGF-1 isoforms in various types of cancer. In the present study, 99 archived endometrial carcinoma tissue sections were retrospectively assessed by immunohistochemistry for IGF-1Ec isoform expression. Expression of IGF-1Ec was also assessed in nine cases of non-neoplastic endometrial tissue adjacent to the tumor, in 30 cases with normal endometrium and in 30 cases with endometrial hyperplasia. Furthermore, the association between IGF-1Ec and the concurrent expression of phosphatase and tensin homologue deleted on chromosome 10 (PTEN), p53 or survivin was assessed, as well as their combined expression in association with clinicopathological variables. In endometrial carcinoma, IGF-1Ec expression was high in non-endometrioid carcinoma (serous papillary or clear cell carcinoma) compared with that in endometrioid adenocarcinoma. IGF-1Ec expression was also high in the presence of tumoral necrosis. Furthermore, there was a significant correlation between the histological differentiation and the sum of staining intensity and the number of IGF-1Ec immunopositive cells in endometrial carcinoma. There was a moderate negative correlation between co-expression of IGF-1Ec and PTEN, for both the number of immunopositive cells (P=0.006, ρ=−0.343) and the sum of staining (scores and intensity; P=0.006, ρ=−0.343). Furthermore, there was a positive correlation between the sum of staining (scores and intensity) and co-expression of IGF-1Ec and survivin (P=0.043, ρ=0.225). However, there was no association between concomitant expression of IGF-1Ec and p53. These results emphasized the importance of IGF-1Ec expression during development of non-estrogen dependent endometrial adenocarcinoma. IGF-1Ec and PTEN may function opposingly during endometrial carcinogenesis. By contrast, IGF-1Ec and survivin may share common molecular pathways and may promote, in parallel, tumoral development.

TNF‑α promotes the malignant transformation of intestinal stem cells through the NF‑κB and Wnt/β‑catenin signaling pathways

Cancer stem cells are responsible for tumorigenesis, progression, recurrence and metastasis. Intestinal stem cells (ISCs) are regarded as the origin of intestinal neoplasia. Inflammation also serves an important role in intestinal neoplasia. To explore the molecular mechanisms underlying the inflammation‑mediated induction of intestinal tumorigenesis, the present study investigated the function of tumor necrosis factor (TNF)‑α in the malignant transformation of ISCs. NCM460 spheroid (NCM460s) cells with higher expression of stem cell genes, such as Oct4, Nanog, Sox2 and Lgr5, and with a higher ratio of CD133+, were obtained from NCM460 cells in serum‑free medium. TNF‑α accelerated cell proliferation, migration and invasion, induced chemotherapy resistance and the epithelial‑mesenchymal transition. NF‑κB and Wnt/β‑catenin pathways were activated in TNF‑α‑induced inflammatory responses, leading to the nuclear translocation of p65 and β‑catenin, as well as promoter activity of NF‑κB and TCF/LEF transcription factors. It was further demonstrated that TNF‑α‑induced activation of the NF‑κB and Wnt/β‑catenin signaling pathways, as well as the upregulation of proinflammatory cytokines, were significantly suppressed by p65‑knockdown. Notably, PDTC, an inhibitor of NF‑κB signaling, reversed TNF‑α‑induced activation of the NF‑κB and Wnt/β‑catenin pathways. A similar role was observed for IWP‑2, an inhibitor of Wnt/β‑catenin signaling. Collectively, these results demonstrated that the NF‑κB and Wnt/β‑catenin pathways were activated to promote TNF‑α‑induced malignant transformation of ISCs, in which these two pathways cross‑regulated each other.

Synergistic Anti-Tumour Effect of Syk Inhibitor and Olaparib in Squamous Cell Carcinoma: Roles of Syk in EGFR Signalling and PARP1 Activation

Syk is a non-receptor tyrosine kinase involved in the signalling of immunoreceptors and growth factor receptors. Previously, we reported that Syk mediates epidermal growth factor receptor (EGFR) signalling and plays a negative role in the terminal differentiation of keratinocytes. To understand whether Syk is a potential therapeutic target of cancer cells, we further elucidated the role of Syk in disease progression of squamous cell carcinoma (SCC), which is highly associated with EGFR overactivation, and determined the combined effects of Syk and PARP1 inhibitors on SCC viability. We found that pharmacological inhibition of Syk could attenuate the EGF-induced phosphorylation of EGFR, JNK, p38 MAPK, STAT1, and STAT3 in A431, CAL27 and SAS cells. In addition, EGF could induce a Syk-dependent IL-8 gene and protein expression in SCC. Confocal microscopic data demonstrated the ability of the Syk inhibitor to change the subcellular distribution patterns of EGFR after EGF treatment in A431 and SAS cells. Moreover, according to Kaplan-Meier survival curve analysis, higher Syk expression is correlated with poorer patient survival rate and prognosis. Notably, both Syk and EGFR inhibitors could induce PARP activation, and synergistic cytotoxic actions were observed in SCC cells upon the combined treatment of the PARP1 inhibitor olaparib with Syk or the EGFR inhibitor. Collectively, we reported Syk as an important signalling molecule downstream of EGFR that plays crucial roles in SCC development. Combining Syk and PARP inhibition may represent an alternative therapeutic strategy for treating SCC.

LINC02595 promotes tumor progression in colorectal cancer by inhibiting miR-203b-3p activity and facilitating BCL2L1 expression

Colorectal cancer (CRC) is one of the most prevalent tumors worldwide. Recently, long noncoding RNAs (lncRNAs) have been recognized as key regulators in postgenomic biology. Numerous lncRNAs have been identified as diagnostic biomarkers and therapeutic targets. However, the molecular mechanisms underlying the role of lncRNAs in CRC progression are not fully understood. Differentially expressed lncRNAs and messenger RNAs were investigated using a microarray approach in five paired primary CRC tumor tissues and the corresponding nontumor tissues and confirmed in an additional 116 paired tissues and 21 inflammatory bowel disease tissues and 15 adjacent normal tissues by a quantitative real‐time polymerase chain reaction. We also performed comprehensive transcriptome profiling analysis on Gene Expression Omnibus and The Cancer Genome Atlas datasets. We identified LINC02595 and evaluated its clinical significance as a plasma biomarker. The function of LINC02595 was evaluated using a panel of in vivo and vitro assays, including cell counting kit‐8, colony formation, cell cycle, apoptosis, RNA fluorescence in situ hybridization, luciferase reporter, immunohistochemistry, and CRC xenografts. We found that LINC02595 is upregulated in tumor tissues and blood samples of patients with CRC and CRC cell lines. Functional research found that LINC02595 promotes CRC cell growth, influences the cell cycle, and reduces apoptosis in vitro and vivo. Mechanistically, LINC02595 promoted BCL2‐like 1 (BCL2L1) expression through miR‐203b‐3p sponging. Our research demonstrated that LINC02595 is an oncogene in CRC and established the presence of a LINC02595‐miR‐203b‐BCL2L1 axis in CRC, which might provide a new diagnostic biomarker and therapeutic targets for the treatment of this disease.