m5C regulator-mediated methylation modification phenotypes characterized by distinct tumor microenvironment immune heterogenicity in colorectal cancer.

The RNA 5-methylcytosine (m5C) modification has been demonstrated to be an important epigenetic regulator and to impact colorectal cancer (CRC) progression. However, the potential roles of m5C modification in immune cell infiltration in the CRC tumor microenvironment (TME) remain unknown. The m5C modification phenotypes were comprehensively evaluated based on 14 m5C regulators in a meta-CRC cohort of 1792 patients and systematically correlated with the m5C modification phenotypes, immune cell infiltration characteristics and known biological processes. The m5Cscore model was constructed by principal component analysis (PCA) algorithms to quantify the m5C modification phenotypes of individual CRC samples and was used to predict the immunotherapy response. We identified three m5C modification phenotypes associated with distinct clinical outcomes and biological processes among the 1792 meta-CRC patients. Three phenotypes with a highly consistent TME landscape and characteristics were revealed: immune excluded, immune desert and immune inflammation. The meta-CRC patients were divided into high and low m5Cscore subgroups based on the m5Cscore. The m5Cscore was confirmed to have a negative correlation with infiltrating immune cells and PD-L1 expression and a positive correlation with tumor mutation burden (TMB), mutation rate and microsatellite instability (MSI) score. Moreover, patients in the low m5Cscore group had better immunotherapy responses and significant durable survival benefits in independent anti-PD-1/L1 immunotherapy cohorts for the immune checkpoint inhibitor (ICI) therapeutic strategy. This study revealed that m5C modification plays a crucial role in TME composition and complexity. Comprehensive evaluation of the m5C modification phenotypes of individual patients will enhance our understanding of TME characteristics and promote the application of more appropriate and personalized treatment strategies.

ALDH1A3-Linc00284 Axis Mediates the Invasion of Colorectal Cancer by Targeting TGFß Signaling via Sponging miR-361-5p.

ALDH1A3 and Linc00284 involve in colorectal cancer (CRC) development; however, the regulatory mechanism is still unclear. In this study, we collected clinicopathological characteristics and tissue samples from 73 CRC patients to analyze the expression of ALDH1A3, Linc00284, TGFß signaling and miR-361-5p using qPCR, Western blotting, and ELISA. Multiple CRC cell lines were evaluated in this study, and the highest level of ALDH1A3 was observed in SW480 cells. To investigate the regulatory mechanism, RIP and luciferase assays were used to validate the interaction between Linc00284, miR-361-5p, and TGFß. Proliferation, viability, migration, and invasion assays were performed to profile the effects of the ALDH1A3-Linc00284 axis in CRC cell functions, which was upregulated in CRC tissues. Knockdown ALDH1A3 or Linc00284 significantly reduced TGFß expression and suppressed the EMT process, while overexpression had opposite effects. miR-361-5p targeted TGFß directly, which negatively correlated with ALDH1A3-Linc00284 expression and CRC progression. Mechanistically, upregulation of ALDH1A3-Linc00284 promotes colorectal cancer invasion and migration by regulating miR-361-5p/TGFß signaling pathway. Dysregulation of the ALDH1A3-Linc00284-miR-361-5p-TGFß axis causes CRC invasion, which might provide a new insight into the treatment of CRC.

Prognostic value and immune infiltration of novel signatures in colon cancer microenvironment.

BACKGROUND: Growing evidence has shown that the prognosis for colon cancer depends on changes in microenvironment. The purpose of this study was to elucidate the prognostic value of long noncoding RNAs (lncRNAs) related to immune microenvironment (IM) in colon cancer. METHODS: Single sample gene set enrichment analysis (ssGSEA) was used to identify the subtypes of colon cancer based on the immune genomes of 29 immune signatures. Cox regression analysis identified a lncRNA signatures associated with immune infiltration. The Tumor Immune Estimation Resource database was used to analyze immune cell content. RESULTS: Colon cancer samples were divided into three subtypes by unsupervised cluster analysis. Cox regression analysis identified an immune infiltration-related 5-lncRNA signature. This signature combined with clinical factors can effectively improve the predictive ability for the overall survival (OS) of colon cancer. At the same time, we found that the expression of H19 affects the content of B cells and macrophages in the microenvironment of colon cancer and affects the prognosis of colon cancer. Finally, we constructed the H19 regulatory network and further analyzed the possible mechanisms. We found that knocking down the expression of H19 can significantly inhibit the expression of CCND1 and VEGFA. At the same time, the immunohistochemical assay found that the expression of CCND1 and VEGFA protein was significantly positively correlated with the infiltration of M2 type macrophages. CONCLUSION: The findings may help to formulate clinical strategies and understand the underlying mechanisms of H19 regulation. H19 may be a biomarker for targeted treatment of colon cancer.

Meta-analysis of natural orifice specimen extraction versus conventional laparoscopy for colorectal cancer.

OBJECTIVE: To compare natural orifice specimen extraction surgery (NOSES) and conventional laparoscopic (LAP) surgery in treating colorectal cancer. METHODS: The present authors conducted a systematic search in the PubMed, EMBASE, and Cochrane databases for randomized controlled trials (RCTs), prospective nonrandomized studies, and retrospective studies up to May 2019. We used postoperative complications as the main endpoints, and used hospital stay, time to first flatus, operative time, postoperative pain, cosmetic result, wound infections, and oncological outcomes as the secondary endpoints. Subgroup analyses were conducted according to the different specimen extraction sites (transanal and transvaginal). A sensitivity analysis was carried out to evaluate the reliability of the outcomes. RevMan5.3 software was used for statistical analysis. RESULT: Twelve studies (one RCT, ten retrospective studies, and one prospective nonrandomized study) involving a total of 1437 patients (NOSES group 665 patients and LAP surgery group 772 patients) were included. Meta-analysis showed that compared with LAP surgery, NOSES resulted in a shorter hospital stay (WMD = -0.79 days; 95% CI -1.17 to -0.42; P < 0.001; P = 0.02), a shorter time to first flatus (WMD = -0.58 days; 95% CI -0.75 to -0.40; P < 0.001), less postoperative pain (WMD = -1.51; 95% CI -1.99 to -1.04; P < 0.001), a better cosmetic result (WMD = 1.37; 95% CI 0.59 to 2.14; P < 0.001), and fewer wound infections (OR = 0.13; 95% CI 0.05 to 0.35; P < 0.001) and postoperative complications (OR = 0.48; 95% CI 0.36 to 0.65; P < 0.001). Oncological outcomes did not differ between the two groups, while the operative time (WMD = 13.95 min; 95% CI 4.55 to 23.35; P = 0.004) was longer in the NOSES group. CONCLUSION: The present systematic meta-analysis is an attempt to assess the impact of NOSES, namely, its oncological outcomes and surgical safety in colorectal cancer patients. Pooled comparisons revealed that NOSES was superior to LAP surgery in terms of postoperative morbidity, postoperative pain, hospital stay, the time to first flatus, cosmetic results, and wound infections; however, NOSES was associated with a longer operative time. Considering the abovementioned limitations and the very low level of evidence of the comparisons, further RCTs are required to verify the results of our study.

The efficacy of intraoperative ICG fluorescence angiography on anastomotic leak after resection for colorectal cancer: a meta-analysis.

OBJECTIVE: The purpose of this study was to investigate whether intraoperative indocyanine green fluorescence angiography can reduce the incidence of anastomotic leak. METHODS: Present authors conducted a systematic search of PubMed, EMBASE, and Cochrane databases for randomized controlled trials (RCTs), prospective nonrandomized trials, and retrospective trials up to March 2020. Eleven papers fulfilling the screening criteria were included. INTERVENTION: Indocyanine green was injected intravenously after the division of the mesentery and colon but before anastomosis. The primary outcome measure was AL rate with at least 3 months of follow-up. Secondary outcome measure was operation time, postoperative complications, surgical site infection, reoperation, and ileus rate. The results were analyzed using STATA 12.0 software (Stata Corp, College Station, TX, USA). RESULT: A total of 3137 patients were collected in 11 studies. Meta-analysis showed that compared with conventional surgery, the ICG fluorescence angiography resulted in a fewer AL rate (OR = 0.31; 95% CI 0.21 to 0.44; P < 0.0001), postoperative complications (OR = 0.70; 95% CI 0.51 to 0.96; P < 0.025), and reoperation rate (OR = 0.334; 95% CI 0.16 to 0.68; P = 0.003). Operation time (weighted mean difference - 25.162 min; 95% CI - 58.7 to 8.375; P = 0.141), surgical site infection rate (OR = 1.11; 95% CI 0.59 to 2.09; P = 0.742) did not differ between the two groups. CONCLUSION: The result revealed that indocyanine green was associated with a lower anastomotic leakage rate after colorectal cancer resection. However, larger, multicentered, high-quality randomized controlled trials are needed to confirm the benefit of indocyanine green fluorescence angiography.

Identification of an Immune-Related Nine-lncRNA Signature Predictive of Overall Survival in Colon Cancer.

Growing evidence suggests that immune-related genes (IRGs) and long non-coding RNAs (lncRNAs) can serve as prognostic markers of overall survival (OS) in patients with colon cancer. This study aimed to identify an immune-related lncRNA signature for the prospective assessment of prognosis in these patients. Gene expression and clinical data of colon cancer patients were downloaded from The Cancer Genome Atlas (TCGA). Immune-related lncRNAs were identified by a correlation analysis between IRGs and lncRNAs. In total, 447 samples were divided into a training cohort (224 samples) and a testing cohort (223 samples). Univariate, lasso and multivariate Cox regression analyses identified an immune-related nine-lncRNA signature closely related to OS in colon cancer patients in the training dataset. A risk score formula involving nine immune-related lncRNAs was developed to evaluate the prognostic value of the lncRNA signature in the training dataset. Colon cancer patients with a high risk score had poorer OS than those with a low risk score. A multivariate Cox regression analysis confirmed that the immune-related nine-lncRNA signature could be an independent prognostic factor in colon cancer patients. The results were further confirmed in the testing cohort and the entire TCGA cohort. Furthermore, a gene set enrichment analysis revealed several pathways with significant enrichment in the high- and low-risk groups that may be helpful in formulating clinical strategies and understanding the underlying mechanisms. Finally, a quantitative real-time polymerase chain reaction assay found that the nine lncRNAs were significantly differentially expressed in colon cancer cell lines. The results of this study indicate that this signature has important clinical implications for improving predictive outcomes and guiding individualized treatment in colon cancer patients. These lncRNAs could be potential biomarkers affecting the prognosis of colon cancer.

MicroRNA-124 and microRNA-378 inhibit the proliferation and invasion of colorectal cancer by upregulating KiSS1.

BACKGROUND: The KiSS1 gene is considered a tumor suppressor in various cancers. MicroRNAs are involved in many important life processes, and their regulation of gene expression may be as important as that of transcription factors. Here, we explore the roles of miR-124-3p and miR-378-3p in colorectal cancer and their relationships with the KiSS1 gene. METHODS: The effects of miR-124-3p and miR-378-3p on KiSS1 protein expression were observed by transfecting colorectal cancer cells (SW-480) with miR-124-3p and miR-378-3p mimics and inhibitors. Moreover, cell proliferation, migration and invasion were evaluated by ethynyl-20-deoxyuridine and Transwell experiments. RESULTS: The KiSS1 mRNA and protein expression levels were significantly increased in mimic-transfected cells compared with those in untransfected cells, and the proliferation, migration and invasion abilities of the former were decreased; in addition, opposing results were obtained in the inhibitor and mimic groups. CONCLUSIONS: In conclusion, our studies indicate that miR-124-3p and miR-378-3p upregulate the expression of KiSS1 and are associated with colorectal cancer metastasis and progression. miR-124-3p, miR-378-3p and KiSS1 may play important roles in colorectal cancer.

Identification of key candidate genes for colorectal cancer by bioinformatics analysis.

Colorectal cancer (CRC) is one of the most common cancers of the digestive tract. Although numerous studies have been conducted to elucidate the cause of CRC, the exact mechanism of CRC development remains to be determined. To identify candidate genes that may be involved in CRC development and progression, the microarray datasets GSE41657, GSE77953 and GSE113513 were downloaded from the Gene Expression Omnibus database. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes were used for functional enrichment analysis of differentially expressed genes (DEGs). A protein-protein interaction network was constructed, and the hub genes were subjected to module analysis and identification using Search Tool for the Retrieval of Interacting Genes/Proteins and Cytoscape. A total of 142 DEGs were identified, with enriched functions and pathways in the 'cell cycle', 'cell proliferation', 'the mitotic cell cycle' and 'one-carbon metabolic process'. In addition, 10 hub genes were identified, and functional analysis indicated that these genes are mainly enriched in 'cell division', 'cell cycle' and functions associated with nucleotide binding processes. Survival analysis demonstrated that DNA topoisomerase II α, cyclin-dependent kinase 1 and CDC28 protein kinase regulatory subunit 2 may be involved in cancer invasion or recurrence. The DEGs identified in the present study may help explain the molecular mechanisms of CRC development and progression.

MiR-506 Targets UHRF1 to Inhibit Colorectal Cancer Proliferation and Invasion via the KISS1/PI3K/NF-κB Signaling Axis.

BACKGROUND: The UHRF1 gene is an epigenetic modification factor that mediates tumor suppressor gene silencing in a variety of cancers. Related studies have reported that UHRF1 can inhibit the expression of the KISS1 gene. However, the regulatory mechanism underlying UHRF1 expression in colorectal cancer (CRC) is still unclear. The aim of this study was to gain a better understanding of the regulation of UHRF1 expression in CRC and to determine whether it regulates the mechanism by which KISS1 promotes CRC metastasis. METHODS: In the present study, the levels of miR-506, UHRF1 and KISS1 expression in CRC tissues and in human CRC cell lines were studied using quantitative real-time PCR (qRT-PCR) and Western blotting. Cell proliferation, migration, and invasion assays are used to detect cell proliferation, migration, and invasion. A dual-luciferase reporter system was used to confirm the target gene of miR-506. RESULTS: This study found that UHRF1 protein is highly expressed in CRC tissues and negatively correlated with KISS1 protein expression. UHRF1 overexpression activates the PI3K/NF-κB signaling pathway by inhibiting the mRNA expression levels of pathway mediators. Bioinformatics analysis and luciferase reporter gene assays confirmed that miR-506 targets UHRF1. CONCLUSION: This study identified the regulation of UHRF1 expression in CRC and the mechanism of CRC metastasis. UHRF1 may be a new potential target molecule for future CRC metastasis treatment.

MiR-202 inhibits the proliferation and invasion of colorectal cancer by targeting UHRF1.

The purpose of this study was to investigate the expression of microRNA-202 (miR-202) and its role in colorectal cancer (CRC) in vivo and in vitro. We examined the expression of miR-202 in CRC tissues by quantitative real-time PCR (qRT-PCR) assay. Lentiviral vectors were constructed to overexpress or inhibit the expression of miR-202 in the CRC cell lines HCT116 and SW480 to determine its effects on cell invasion and proliferation. We found that overexpression of miR-202 significantly inhibited the proliferation and invasion of HCT116 cells. MiRNA target gene prediction, dual luciferase assay, and western blot analysis demonstrated that miR-202 regulated ubiquitin-like with PHD and RING finger domain 1 (UHRF1) expression in both cell lines. The effect of miR-202 on cell proliferation and invasion was partially reversed by activating the expression of UHRF1. Furthermore, miR-202 induced tumor formation in HCT116 xenograft BALB/c nude mice. Mice vaccinated with miR-202-overexpressing cells had smaller tumors and lower UHRF1 expression than the control group. These results indicate the possibility that miR-202 is under-expressed in CRC tissues, and that miR-202 inhibits the proliferation and invasion of CRC via targeting UHRF1. MiR-202 is a potential therapeutic target for CRC.

The Effects of Pre-Operative Enteral Nutrition from Nasal Feeding Tubes on Gastric Outlet Obstruction.

We examined gastric outlet obstruction (GOO) patients who received two weeks of strengthening pre-operative enteral nutrition therapy (pre-EN) through a nasal-jejenal feeding tube placed under a gastroscope to evaluate the feasibility and potential benefit of pre-EN compared to parenteral nutrition (PN). In this study, 68 patients confirmed to have GOO with upper-gastrointestinal contrast and who accepted the operation were randomized into an EN group and a PN group. The differences in nutritional status, immune function, post-operative complications, weight of patients, first bowel sound and first flatus time, pull tube time, length of hospital stay (LOH), and cost of hospitalization between pre-operation and post-operation were all recorded. Statistical analyses were performed using the chi square test and t-test; statistical significance was defined as p < 0.05. The success rate of the placement was 91.18% (three out of 31 cases). After pre-EN, the levels of weight, albumin (ALB), prealbumin (PA), and transferrin (TNF) in the EN group were significantly increased by pre-operation day compared to admission day, but were not significantly increased in the PN group; the weights in the EN group were significantly increased compared to the PN group by pre-operation day and day of discharge; total protein (TP), ALB, PA, and TNF of the EN group were significantly increased compared to the PN group on pre-operation and post-operative days one and three. The levels of CD3+, CD4+/CD8+, IgA, and IgM in the EN group were higher than those of the PN group at pre-operation and post-operation; the EN group had a significantly lower incidence of poor wound healing, peritoneal cavity infection, pneumonia, and a shorter first bowel sound time, first flatus time, and post-operation hospital stay than the PN group. Pre-EN through a nasal-jejunum feeding tube and placed under a gastroscope in GOO patients was safe, feasible, and beneficial to the nutrition status, immune function, and gastrointestinal function, and sped up recovery, while not increasing the cost of hospitalization.

X-ray-induced epithelial-mesenchymal transition in SW480 colorectal cancer cells and its potential mechanisms.

PURPOSE: The purpose of this study was to investigate the relation between X-ray irradiation and epithelial-mesenchymal transition (EMT), as well as the potential mechanisms of X-ray-induced EMT in SW480 colorectal cancer (CRC) cells. METHODS: It is well known that EMT plays a critical role in invasive and metastatic of colorectal cancer progression. However, the possible role of X-ray irradiation on EMT in colorectal cancer is widely disputed and its potential mechanisms are unclear. SW480 CRC were irradiated (0, 2, 4, 6, 8 Gy) and cultured for 48 hrs, and then the cellular morphology was observed. Protein and mRNA expressions were examined by Western blot and QRT-PCR. Cell migratory and invasive capacity was evaluated by Transwell assay. RESULTS: In the 2, 4, 6, 8 Gy groups, SW480 CRC exhibited a classical mesenchymal phenotype compared with the 0 Gy group. The expression of E-cadherin was significantly decreased, while the expression of vimentin and Smad3 was significantly increased in the 2, 4, 6, 8 Gy groups (p<0.05) compared with the 0 Gy group; still, the expression of K-ras decreased in the 4, 6, 8 Gy groups (p<0.05) compared with the 0 and 2 Gy groups. Furthermore, the cell migration and invasion capacity was significantly enhanced in the 4 and 8 Gy groups compared with the 0 Gy group (p<0.05). CONCLUSION: These results support the fact that X-ray irradiation can induce EMT through promoting Vimentin and Smad3 expression in SW480 CRC cells.

Effect of music therapy on pain behaviors in rats with bone cancer pain.

PURPOSE: To investigate the effects of music therapy on the pain behaviors and survival of rats with bone cancer pain and analyze the mediating mechanism of mitogen activated protein kinase (MAPK) signal transduction pathway. METHODS: Male Wistar rats aged 5-8 weeks and weighing 160-200 g were collected. The rat models of colorectal cancer bone cancer pain was successfully established. Animals were divided into experimental and control group, each with 10 rats. The animals in the observation group were given Mozart K448 sonata, sound intensity of 60 db, played the sonata once every 1 hr in the daytime, stopped playing during the night, and this cycle was kept for 2 weeks. On the other hand, rats in the control group were kept under the same environment without music. RESULTS: Animals in the experimental group consumed more feed and gained significant weight in comparison to the control group. The tumor volume of the experimental group was significantly smaller than that of the control group (p<0.05). After 1-2 weeks of treatment, spontaneous foot withdrawal reflection caused by pain in the experimental group was significantly lower than that in the control group, heat pain threshold and free walking pain scoring in the experimental group were also significantly higher as compared with the control group (p<0.05). The expression of p38á and p38ß in animals' spinal cord and dorsal root ganglion was significantly lower in the experimental group than in the control group (p< 0.05). CONCLUSION: Music therapy may improve the pain behaviors in rats with bone cancer pain, which might be related with low expression of p38á and p38ß in the MAPK signal transduction pathway.

Overexpression of KiSS-1 reduces colorectal cancer cell invasion by downregulating MMP-9 via blocking PI3K/Akt/NF-κB signal pathway.

Metastasis of colorectal cancer (CRC) depends critically on MMP-9. KiSS-1 is a human malignant melanoma metastasis-suppressor gene. Thus, the interaction between MMP-9 and KiSS-1 has drawn considerable attention in recent years. In the present study, it was hypothesized that KiSS-1 gene could repress the metastatic potential of colorectal cancer cells by inhibiting the expression of MMP-9. Stable transfection of KiSS-1 specific siRNA and KiSS-1 expression vector in human CRC cell line HCT-116 was achieved by lentivirus infection. Moreover, the cell proliferation, invasiveness, and apoptosis were evaluated by CCK-8 method, transwell experiment, and fluorescence activated cell sorter, respectively. We also investigated the expression of MMP-9, PI3K, Akt, pAKt, and NF-кB subunit p65 using western blotting. KiSS-1 overexpression significantly decreased the cell proliferation and invasiveness of HCT-119 cells, while apoptosis was enhanced. The result of western blotting showed that synthesis of MMP-9, PI3K, p65, and phosphorylation of Akt were significantly blocked by overexpression of KiSS-1. Concatenated treatment of KiSS-1 overexpression vector with PI3K and Akt agonists attenuated the effect of KiSS-1 on the biological activity of CRC cells and also released the expression of MMP-9, PI3K, p65, and phosphorylation of Akt from the influence of overexpression of KiSS-1. Overexpression of KiSS-1 suppressed the invasiveness of CRC cells, and the gene exerted its function by reducing the expression of MMP-9 via blocking of tge PI3K/Akt/NF-κB pathway.

[Suppression of Kiss-1 gene inhibits HCT116 human colorectal carcinoma cell migration in vitro via nuclear factor-κB signaling pathway].

OBJECTIVE: To investigate the effect of Kiss-1 gene suppression on the metastatic capacity of HCT116 human colorectal carcinoma cells in vitro and the involvement of nuclear factor-κB (NF-κB) signaling pathway. METHODS: A recombinant lentiviral vector of Kiss-1 gene pGC-LV-Kiss-1-EGFP or the empty vector was transfected in HCT116 cells. Cell Counting Kit-8 (CCK8) and Transwell chamber assay were used to detect the changes in cell proliferation, invasion and migration ability after the transfection. Western blotting was used to detect the expression of I-κB, the inhibitive protein of NF-κB signal pathway, and the expression of the downstream effector MMP-9 before and after transfection. RESULTS: In cells over-expressing Kiss-1, I-κB expression increased and MMP-9 expression decreased significantly compared to those in the blank control and vector-transfected cells (P<0.05). Kiss-1 gene over-expression resulted in significant inhibition of HCT116 cell proliferation, invasion, and migration as compared to the control cells (P<0.05). CONCLUSION: Lentivirus-mediated Kiss-1 gene over-expression can inhibit the proliferation, invasion, and migration of HCT116 cells via the NF-B signaling pathway.

KISS1 methylation and expression as predictors of disease progression in colorectal cancer patients.

AIM: To examine the effect of aberrant methylation of the KISS1 promoter on the development of colorectal cancer (CRC) and to investigate reversing aberrant methylation of the KISS1 promoter as a potential therapeutic target. METHODS: KISS1 promoter methylation, mRNA expression and protein expression were detected by methylation-specific polymerase chain reaction (PCR), real-time quantitative PCR and Western blotting, respectively, in 126 CRC tissues and 142 normal colorectal tissues. Human CRC cells with KISS1 promoter hypermethylation and poor KISS1 expression were treated in vitro with 5-aza-2'-deoxycytidine (5-Aza-CdR). After treatment, KISS1 promoter methylation, KISS1 mRNA and protein expression and cell migration and invasion were evaluated. RESULTS: Hypermethylation of KISS1 occurred frequently in CRC samples (83.1%, 105/126), but was infrequent in normal colorectal tissues (6.34%, 9/142). Moreover, KISS1 methylation was associated with tumor differentiation, the depth of invasion, lymph node metastasis and distant metastasis (P < 0.001). KISS1 methylation was also associated with low KISS1 expression (P < 0.001). Furthermore, we observed re-expression of the KISS1 gene and decreased cell migration after 5-Aza-CdR treatment in a CRC cell line. CONCLUSION: These data suggest that KISS1 is down-regulated in cancer tissues via promoter hypermethylation and therefore may represent a candidate target for treating metastatic CRC.

[Kiss-1 gene expression after radiation and its association with proliferation and apoptosis in colorectal cancer cells].

OBJECTIVE: To investigate the change of expression level of metastasis suppressor gene Kiss-1 in the colorectal cancer cell line SW480 after radiation, and to determine its association with the proliferation and apoptosis of SW480 cells. METHODS: SW480 cells were divided into control group (0 Gy) and study groups (2, 4, 6, 8 Gy). Cells in the study groups were irradiated by 6-MV X-ray radiation for 48 hours. Immunohistochemistry and real-time PCR methods were used to investigate the influence of radiation on Kiss-1 gene expression of SW480. Colony formation assay was used to detect the proliferation of SW480. Flow cytometry-Annexin- V/PI assay was used to observe the change of the apoptosis rate. RESULTS: Compared with the control group, Kiss-1 protein expression increased after radiation of 6, 8 Gy (P<0.05), but no significant changes were observed after radiation of 2, 4 Gy(P>0.05). Kiss-1 gene mRNA level increased after radiation of 2, 4, 6 Gy, while no obvious change was observed for 8 Gy radiation. The apoptosis rates increased for 4, 6, 8 Gy radiation(P<0.05), however, there was no significant difference for 2 Gy radiation (P<0.05). CONCLUSION: Radiation may increase Kiss-1 gene expression in SW480 cells, which results in decreases proliferation and increases apoptosis in residual surviving cells.