Integrin αvß6 mediates the immune escape through regulation of PD-L1 and serves as a novel marker for immunotherapy of colon carcinoma.

The immune escape of colon cancer and its role in the response to immunotherapies such as PD-1/PD-L1 checkpoint inhibitors have long been of great interest. The positive outcomes of immunotherapy are limited by the immunosuppressive nature of the tumor microenvironment. Integrin αvß6, which can regulate the progression of colon cancer, was recently reported to be involved in the immune suppression of colon cancer. In the present study, we explored the correlation between αvß6 and PD-L1 expression by immunohistochemistry of colon cancer tissues. Then, the regulation of PD-L1 signaling by αvß6 in colon cancer cells was demonstrated. We constructed an in vivo model and performed immunophenotyping experiments to analyze further the regulation of the immune response by αvß6. The role of αvß6 in the response to anti-PD-1 therapy in colon cancer was also verified. αvß6-positive tissues exhibited increased PD-L1 expression. Inhibition of αvß6 not only downregulated constitutive PD-L1 expression but also decreased IFN-γ-induced PD-L1 expression. In addition, αvß6-induced PD-L1 expression was suppressed by the ERK inhibitor PD98059, and knockdown of the ß6-ERK2 binding site had the equivalent effect. αvß6 decreased CD8+ T cell infiltration and granzyme B expression in CD8+ T cells in colon cancer patients. Furthermore, mice engrafted with αvß6-expressing colon cancer cells exhibited an unsatisfactory response to anti-PD-1 therapy, and anti-PD-1-induced increases in CD4+ and CD8+ T cell infiltration could be inhibited by αvß6. These results indicate that αvß6 mediates immune escape in colon cancer by upregulating PD-L1 through the ERK/MAPK pathway. Moreover, αvß6 could serve as a marker for the efficacy of anti-PD-1 therapy in colon cancer.

Expression of Interleukin-6 and Integrin ανß6 in Colon Cancer: Association with Clinical Outcomes and Prognostic Implications.

As important factors in the tumor microenvironment, interleukin-6 (IL-6) and integrin ανß6 play significant roles in accumulating mutations that drive the progression and metastatic capacities of cancer. The aim of this study was to investigate the expression of IL-6 and integrin ανß6, their clinical significance, as well as their correlation in the colon cancer tissues of 145 cases using immunohistochemistry. Our results showed that IL-6 and integrin ανß6 are indicators of cancer progression and poor prognosis in patients with colon cancer. Moreover, their relationship may provide clues for further studies on how the tumor microenvironment mediates the development of colon cancer, as well as strategies for the identification of novel therapeutic targets in the prevention and treatment of colon cancer.

MicroRNA-21 promotes cell proliferation by targeting tumor suppressor TET1 in colorectal cancer.

MicroRNAs (miRNAs) regulate gene expression by binding to mRNA, and can function as oncogenes or tumor suppressors depending on the target. TET1 acts as tumor-suppressor, which is downregulated in colorectal cancers (CRC) and inhibits cell growth. However, it has not been studied as to whether miRNAs, suppressing target expression by binding to the 3'UTR, regulate TET1 expression in colorectal cancers. Here, our study found that miR-21 has matching sites on TET1. In the tumor tissue samples from 50 patients with CRC, the expression of miR-21 was upregulated compared with that in adjacent tissue samples while the expression of TET1 showed a significant decrease. In addition, miR-21 expression was negatively correlated with the expression of TET1. Moreover, low expression of miR-21 by the transfection of colorectal cancer cell lines with miR-21 inhibitors, the effect on TET1 expression was opposite to the change of miR-21 expression. Furthermore, our results indicated that miR-21 promoted proliferation of colorectal cancer cells by targeting TET1. These findings may provide a theoretical basis for clarifying the physiological and pathological role of miR-21 in colorectal cancer.

Overexpression of eIF4E in colorectal cancer patients is associated with liver metastasis.

PURPOSE: Liver metastasis is one of the leading causes of death in colorectal cancer (CRC) patients. The present study aimed to evaluate the value of eIF4E as a prognostic marker of colorectal liver metastasis (CLM) and identify the functional role of eIF4E in CRC metastasis. PATIENTS AND METHODS: The expression level of eIF4E in CRC tissues was analyzed by immunohistochemical staining and Western blot. Expression of eIF4E in CRC cell lines was evaluated by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot. Cell Counting Kit-8 (CCK-8) and Transwell assays were performed to assess the effects of eIF4E on cell proliferation, migration, and invasion. Western blot was further used to investigate the mechanism of eIF4E in tumor metastasis. RESULTS: The upregulation frequency of eIF4E in the CLM group (82.5%) was higher than that in the non-CLM group (65.0%). Of the 80 patients recruited for the follow-up study, 23 were in the low eIF4E group (ratio of tumor to nontumor tissue

microRNA-20a enhances the epithelial-to-mesenchymal transition of colorectal cancer cells by modulating matrix metalloproteinases.

The mortality rates associated with colorectal cancer (CRC) are high due to metastasis. Epithelial-to-mesenchymal transition (EMT) is a key step in tumor metastasis. The aim of the present study was to investigate the function of microRNA-20a (miR-20a) in EMT. The expression of miR-20a was analyzed in CRC tissues and cell lines using the reverse transcription-quantitative polymerase chain reaction. Plasmids containing miR-20a short hairpin RNA and miR-20a mimics were transfected into SW620 and LS174T cell lines, respectively. Cell counting kit-8, Transwell® and wound healing assays were performed to assess the effects of miR-20a on cell proliferation, invasion and migration. EMT markers and matrix metalloproteinases (MMPs) were identified using western blotting. The results showed that increased expression of miR-20a in CRC tissues was associated with tumor invasion and lymph node metastasis (P<0.05). Further experiments indicated that miR-20a-knockdown inhibited the proliferation, invasion and migration of CRC cells, upregulated the expression of vimentin and tissue inhibitor of metalloproteinases-2 (TIMP-2) and downregulated the expression of E-cadherin, MMP-2 and MMP-9. The opposite effects were observed in CRC cell lines overexpressing miR-20a. In conclusion, these results have shown that the upregulation of miR-20a suppresses TIMP-2 expression, which subsequently increases the expression of MMP-2 and MMP-9, thereby promoting the EMT of CRC cells. These findings suggest that miR-20a represents a potential therapeutic target for patients with CRC.

MiR-492 is functionally involved in Oxaliplatin resistance in colon cancer cells LS174T via its regulating the expression of CD147.

Chemotherapy remains the core of anticancer treatment. However, despite the tremendous strides made in the development of targeted anticancer therapies, emergence of resistance to chemotherapeutic drugs is still a major obstacle in the successful management of resistant tumors. Therefore, profound investigation into the in-depth molecular mechanisms of drug resistance is essential and may hopefully translate into effective therapies that can flip the switch from drug resistance to susceptibility. To develop novel-targeted therapy holds promise for conquering chemotherapy resistance, one of the major hurdles in current colon cancer treatment. Previous studies indicate that CD147 is involved in the progression of chemotherapy resistance in breast cancer and ovarian cancer cells and its expression is negative regulated by miR-492 in muscles cells. In the present study, we found that lower level of miR-492 is accompanied with increased expression of CD147 in Oxaliplatin-resistant colon cancer cell line LS174T/L-OHP as compared with its parental cell line LS174T. Exogenous expression of miR-492 in LS174T/L-OHP could sensitize its reaction on the treatment of Oxaliplatin, which is coincided with its directly reducing the expression of CD147. Furthermore, we found that knockdown of CD147 in LS174T/L-OHP could also sensitize its reaction of the treatment with Oxaliplatin. Besides, intratumoral delivering of miR-492 could also restore Oxaliplatin treatment response in Oxaliplatin-resistant xenografts in vivo. These findings provide direct evidences that the miR-492/CD147 axis might play an essential role in the Oxaliplatin resistance of colon cancer cells, suggesting that the miR-492/CD147 signaling cohort could be served as a novel therapeutic target for the treatment of chemotherapy resistant in colon cancer.

Upregulation of CD147 promotes cell invasion, epithelial-to-mesenchymal transition and activates MAPK/ERK signaling pathway in colorectal cancer.

Colorectal cancer (CRC) is one of the most common cancers in the world. CD147, a transmembrane protein, has been reported to be correlated with various cancers. In this study, we aimed to investigate the mechanism of CD147 in regulating drug resistance, cell invasion and epithelial-to-mesenchymal transition (EMT) in CRC cells. qRT-PCR and western blotting were used to evaluated the expression of CD147 in 40 CRC cases and 4 cell lines. Increased expression of CD147 at both mRNA and protein levels was found in CRC samples, and the level of CD147 was correlated with lymph node metastasis. CD147 overexpression increased the 5-Fluorouracil (5-FU) resistance, enhanced the invasion and EMT of CRC cells by regulating EMT markers and MMPs. Adverse results were obtained in CD147 knockdown CRC cell line. Further investigation revealed that CD147 activated MAPK/ERK pathway, ERK inhibitor U0126 suppressed the CD147-induced cell invasion, migration and MMP-2, MMP-9 expression. Taken together, our study indicates that CD147 promotes the 5-FU resistance, and MAPK/ERK signaling pathway is involved in CD147-promoted invasion and EMT of CRC cells.

Decreased expression of miR-126 correlates with metastatic recurrence of hepatocellular carcinoma.

The liver transplant (LT) situation represents an attractive model for studying hepatocellular carcinoma (HCC) metastasis. Based on microarray data, we previously found that miR-126 expression was lower in tumor tissues of patients with post-LT HCC recurrence compared with non-recurrence. In this study, we examined the expression of miR-126 in HCC samples from 68 patients who had undergone LT using quantitative real-time PCR and analyzed its correlation with clinicopathological features and prognosis of patients. Furthermore, we performed experimental analyses to explore the involvement of miR-126 in HCC metastasis. We found that miR-126 levels were lower in tumor tissues of patients with post-LT HCC recurrence in comparison to patients with no-recurrence (p = 0.009). Lower expression of miR-126 in HCC was associated significantly with tumor recurrence (p = 0.011) and poor survival (p = 0.009) of patients. Functional studies indicated that ectopic expression of miR-126 significantly inhibits HCC cells migration, invasion, proliferation and colony formation in vitro, and suppresses experimental lung colonization in vivo. Our study revealed that down-regulation of miR-126 plays an important role in HCC metastasis, and suggest a potential application of miR-126 in prognosis prediction and HCC treatment.

Up-regulation of T-lymphoma and metastasis gene 1 in gastric cancer and its involvement in cell invasion and migration.

BACKGROUND: T-lymphoma and metastasis gene 1 (Tiam1) produces a guanine nucleotide exchange factor (GNEF) that regulates guanosine triphosphatase, which transforms guanosine diphosphate to guanosine triphosphate. Recently published data indicate that Tiam1 was associated with gastric cancer. The aim of this study was to investigate biological effects and potential mechanisms of Tiam1 in gastric carcinoma. METHODS: We analyzed the expression of Tiam1 in 114 pair-matched gastric neoplastic and adjacent non-neoplastic tissues by quantitative real-time PCR. We investigated Tiam1 expression and its prognostic value for gastric cancer. Furthermore, the functions of Tiam1 over-expression were analyzed with stable-expression Tiam1 plasmid in human gastric cancer cell lines. RESULTS: Tiam1 expression was significantly associated with cell differentiation and lymphatic metastasis; expression of Tiam1 mRNA was up-regulated in gastric cancer compared to pair-matched adjacent non-tumor tissues. Analyses of surgical tissue samples and 5-year survival of gastric cancer patients showed that those with strong Tiam1 expression had significantly shorter overall survival time than those with negative Tiam1 expression. Ectopic expression of Tiam1 promoted cell growth, migration and invasion of gastric cancer cells in vitro. CONCLUSIONS: In gastric cancer cells, Tiam1 affects multiple properties associated with acquisition of the metastatic phenotype, and may be a marker of gastric cancer progression and metastasis in a subset of cancer.

Activity of heme oxygenase-1 affects expression levels of hypoxia inducible factor-1 gene in vitro.

BACKGROUND: One effect of solid tumors is severe hypoxia of local tissues. Heme oxygenase-1 (HO-1) is highly expressed in a variety of human tumor tissues; its induction and activity are closely related to growth of solid tumors. Hypoxia inducible factor-1 (HIF-1) is a transcription factor that regulates hypoxia signal transduction and plays a central role in tumor hypoxia regulation. However, whether and how changes in HO-1 activity affect HIF-1 gene expression has not been reported previously. METHODS: Hypoxia-inducible models were established using gastric cancer cell lines (SGC-7901) in a hypoxia incubator. Cells were placed in four groups: Group A, transfected by plasmid harboring HO-1 shRNA; Group B, transfected with scrambled shRNA vector; Group C, treated with hemin; and Group D, exposed to hypoxia only. Expressions of HO-1 and HIF-1 mRNAs were quantified by reverse transcription-polymerase chain reaction. Expressions of HO-1 and HIF-1 proteins were determined by immunohistochemistry and Western blotting. RESULTS: mRNA and protein levels of HO-1 and HIF-1 in the control group were significantly higher than in Group A (P < 0.01), but lower than in Group C (P < 0.01). Chromatin immunoprecipitation analysis showed that HIF-1 was identified as the direct HO-1 target gene. CONCLUSION: While affected by HIF-1, HO-1 up-regulation promotes the expression of HIF-1 and the down-regulation of HO-1 suppresses the expression of HIF-1 gene.

Rosiglitazone and retinoic acid inhibit proliferation and induce apoptosis in the HCT-15 human colorectal cancer cell line.

The aim of this study was to explore the effects of rosiglitazone (RSG) in combination with all-trans retinoic acid (ATRA) on the proliferation and apoptosis of the HCT-15 human colorectal cancer cell line. HCT-15 cells were divided into a blank control group, a vehicle control group and experimental groups (RSG only or ATRA only or RSG plus ATRA). Growth inhibition was examined using the MTT assay. Apoptosis and cell cycle progression were examined by flow cytometry. The expression of COX-2, MMP-7 and TIMP-1 was examined by immunocytochemistry. RSG alone inhibited HCT-15 cell proliferation in a concentration- and time-dependent manner (P<0.05). The combination of RSG and ATRA exhibited significant synergy (q>1.15). RSG or ATRA alone effectively increased the proportion of cells in the G0/G1 phase and decreased the proportion of cells in the S phase, thus inducing apoptosis (P<0.05). The combination of RSG and ATRA resulted in even stronger G1 cell cycle arrest (P<0.05). HCT-15 cells expressed COX-2, MMP-7 and TIMP-1, with positive expression rates in the control group of 66.79, 73.21 and 64.08%, respectively. After the combined application of RSG and ATRA, the positive rates significantly declined to only 19.33, 20.58 and 13.13%, respectively (P<0.01). In conclusion, the combination of RSG and ATRA reduced the expression of COX-2, MMP-7 and TIMP-1, caused cell cycle arrest at the G1 phase and induced apoptosis, which resulted in the inhibition of cell proliferation in the HCT-15 human colorectal cancer cell line.

Coexpression of cyclooxygenase-2 and vascular endothelial growth factor in gastrointestinal stromal tumor: possible relations to pathological parameters and clinical behavior.

BACKGROUND/AIMS: Currently, the clinicopathological significance of coexpression of cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF) in gastrointestinal stromal tumors (GISTs) has not been fully described. METHODOLOGY: The present study was designed to investigate the co-expression of the two markers and its significance in 54 patients with GIST by means of immunohistochemistry. RESULTS: We demonstrated that the expressions of COX-2 and VEGF were significantly higher in malignant GIST than those in benign and potentially malignant GIST (p<0.01). A significant correlation was found between COX-2 and VEGF expression. In addition, the expressions of COX-2 and VEGF were significantly correlated with pattern of tumor growth, the size of tumors, and the central necrosis of tumors (p<0.01 or p<0.05). Five-year survival rates were much lower in patterns with high expression of COX-2 and VEGF than those with low expression (p<0.01). Overexpression of COX-2 and VEGF in GIST may enhance the possibility of growth, invasion, and metastasis. CONCLUSIONS: The levels of COX-2 and VEGF expression can be used as objective parameters in distinguishing benign from malignant, judging the malignant degree, and predicting the prognosis of patients with GIST.

[Expression and clinical significance of matrix metalloproteinase in gastric stromal tumor].

OBJECTIVE: To investigate the expression and clinical significance of matrix metalloproteinase (MMP) in gastric stromal tumor (GST). METHODS: MMP-2 and MMP-9 expression were determined by immunohistochemistry in tumor tissues in 44 patients with GST, and their relationship with clinicopathologic factors of the neoplasm was also investigated. RESULTS: MMP-2 and MMP-9 were expressed in the cytoplasm in 84.1% (37/44) and 81.8% (36/44) of tumors, respectively. The positive rates of MMP-2 and MMP-9 increased significantly in parallel to the increase in tumor malignancy (P < 0.05) and associated with pattern of tumor growth, tumor size, and centre necrosis (P < 0.05). In addition, there was a statistically significant positive correlation between the expression of the two markers in GST (r = 0.6523, P < 0.05). Furthermore, the 5-year postoperative survival rates of patients with positive expressions of MMP-2 and MMP-9 were significantly lower than those of patients with negative expressions of the two markers (P < 0.05). CONCLUSION: Over expression of MMP-2 and MMP-9 can be served as objective markers to judge the malignant degree and, to predict the prognosis of patients with GST.