RBBP6 increases radioresistance and serves as a therapeutic target for preoperative radiotherapy in colorectal cancer.

Radiotherapy (RT) can be used as preoperative treatment to downstage initially unresectable locally rectal carcinoma, but radioresistance and recurrence remain significant problems. Retinoblastoma binding protein 6 (RBBP6) has been implicated in the regulation of cell cycle, apoptosis and chemoresistance both in vitro and in vivo. The present study investigated whether the inhibition of RBBP6 expression would improve radiosensitivity in human colorectal cancer cells. After SW620 and HT29 cells were exposed to radiation, the levels of RBBP6 mRNA and protein increased over time in both cells. Moreover, a significant reduction in clonogenic survival and a decrease in cell viability in parallel with an obvious increase in cell apoptosis were demonstrated in irradiated RBBP6-knockdown cells. Transfection with RBBP6 shRNA improved the levels of G2-M phase arrest, which blocked the cells in a more radiosensitive period of the cell cycle. These observations indicated that cell cycle and apoptosis mechanisms may be connected with tumor cell survival following radiotherapy. In vivo, the tumor growth rate of nude mice in the RBBP6-knockdown group was significantly slower than that in other groups. These results indicated that RBBP6 overexpression could resist colorectal cancer cells against radiation by regulating cell cycle and apoptosis pathways, and inhibition of RBBP6 could enhance radiosensitivity of human colorectal cancer.

Significance and prognostic value of Gli-1 and Snail/E-cadherin expression in progressive gastric cancer.

Abnormal activation of the hedgehog (Hh) signaling pathway has been found to be involved in the occurrence, invasion, and metastasis of cancers. Epithelial-mesenchymal transition (EMT) also plays an important role in the invasion and metastasis of cancers. However, the significance of the Hh signaling pathway and EMT in the invasion and metastasis of gastric cancer is still unclear. This study aimed to investigate the significance and prognostic value of the Hh signaling pathway and EMT in progressive gastric cancer. Immunohistochemistry was performed to detect the expression of the Hh-induced transcriptional factor Gli-1 and the EMT-related molecules Snail and E-cadherin in 121 patients with progressive gastric cancer. Histological type, depth of invasion, lymph node metastasis, and pTNM stage were also recorded. In progressive gastric cancer, Gli-1 expression increased markedly, and was closely associated with increased Snail expression and decreased E-cadherin expression. Diffuse type cancer, lymph node metastasis, and abnormal expression of E-cadherin were independent factors influencing the prognosis of patients with progressive gastric cancer. These findings suggest that abnormal activation of the Hh signaling pathway is closely related to the presence of EMT and is an important factor influencing the prognosis of patients with diffuse progressive gastric cancer.

A novel model for orthotopic liver transplantation in rats using hepatic rearterialization and biliary extradrainage system.

BACKGROUND: Although the rat orthotopic liver transplantation (OLT) model has existed for many years, only a few models can be applied for dynamic bile collection. The aim of this study was to introduce a dependent rat OLT model with hepatic rearterialization and an expediently dynamic bile collection system. METHODS: Forty-five male Sprague-Dawley rats were divided into the following three groups (n = 15 each): group A, OLT without hepatic rearterialization; group B, OLT with hepatic rearterialization; group C, OLT with hepatic rearterialization and a biliary extradrainage system. In groups B and C, a modified sleeve anastomosis between the donor common hepatic artery and the recipient proper hepatic artery was performed to restore the hepatic artery blood flow. In group C, after hepatic rearterialization, biliary extradrainage and jejunum stoma were performed to reestablish the bile flow, and a waistcoat-like external fixator was introduced to protect this system. RESULTS: The surgical success rates in groups A, B, and C were 100% (15/15), 93% (14/15), and 93% (14/15), respectively. In groups B and C, the hepatic artery patency rates were 93% and 86% on postoperative day 3 and postoperative day 21, respectively. Also, the liver function and bile duct integrity were preserved better than that in group A. In group C, the biliary extradrainage system was well preserved and bile collection was easily performed. CONCLUSIONS: The rat OLT model with hepatic rearterialization and a convenient biliary extradrainage system was satisfactory in maintaining the survival rate, hepatic artery patency rate, and recovery of graft function, so it can be applied in various studies after transplantation.

Downregulation of metallothionein 1F, a putative oncosuppressor, by loss of heterozygosity in colon cancer tissue.

PURPOSE: Downregulation of metallothionein (MT) genes has been reported in several tumors with discrepant results. This study is to investigate molecular mechanism of MT gene regulation in colon cancer which is characterized by tumor suppressor gene alterations. EXPERIMENTAL DESIGN: Integral analysis of microarray data with loss of heterozygosity (LOH) information was employed. Quantitative real-time PCR and immunohistochemistry were used to validate MT isoform expression in colon cancer tissues and cell lines. The effects of MT1F expression on RKO cell survival and tumorigenesis was analyzed. Bisulphite sequencing PCR (BSP) and methylation-specific PCR were employed to detect the methylation status of the MT1F gene in colon cancer tissues and cell lines. DNA sequencing was used to examine the LOH at the MT1F locus. RESULTS: MT1F, MT1G, MT1X, and MT2A gene expression was significantly downregulated in colon cancer tissue (p<0.05). Exogenous MT1F expression increased RKO cell apoptosis and inhibited RKO cell migration, invasion and adhesion as well as in vivo tumorigenicity. Downregulation of MT1F gene in majority of human colon tumor tissues is mainly through mechanism by loss of heterozygosity (p=0.001) while CpG island methylation of MT1F gene promoter region was only observed in poorly differentiated, MSI-positive RKO and LoVo colon cancer cell lines. CONCLUSIONS: MT1F is a putative tumor suppressor gene in colon carcinogenesis that is downregulated mainly by LOH in colon cancer tissue. Further studies are required to elucidate a possible role for MT1F downregulation in colon cancer initiation and/or progression.

microRNA-148a suppresses human gastric cancer cell metastasis by reversing epithelial-to-mesenchymal transition.

MicroRNAs (miRNAs) are important regulators of gastric cancer development and progression. miR-148a is one of the most frequently and highly downregulated miRNAs in gastric cancer and is associated with advanced clinical stage and poor prognosis. In this study, we investigated the role of miR-148a in gastric cancer metastasis. Levels of miR-148a were determined by qRT-PCR in 60 gastric cancer samples. Cell migration and invasion assays were performed in a stably expressing miRNA-148a gastric cancer cell line established using a lentivirus expression system. Epithelial-mesenchymal transition (EMT) was evaluated using qRT-PCR and Western Blots to detect epithelial marker E-cadherin and mesenchymal marker, vimentin. Luciferase reporter assays were used to identify downstream targets and biological function of miR-148a. Gastric cancer tissue had significantly lower expression of miR-148a compared to non-tumor tissue. Low miR-148a levels were associated with lymph node metastasis, N stage, and blood vessel invasion. miR-148a overexpression inhibited metastasis of gastric cancer cells. miR-148a overexpression also downregulated vimentin expression and upregulated E-cadherin expression, suggesting that miR-148a inhibited EMT. Finally, the SMAD2 gene was identified as the direct and functional target of miR-148a. MiR-148a suppresses gastric cancer metastasis and EMT, likely via SMAD2. Restoration of miR-148a expression could have important implications in gastric cancer therapy.

Reduced expression of PER3 is associated with incidence and development of colon cancer.

BACKGROUND: Period 3 (PER3), a circadian regulation protein, influences cell cycle, growth, and differentiation. The aim of the present study was to determine whether PER3 expression is associated with colon cancer incidence and progression. METHODS: PER3 expression was analyzed in the normal and cancerous tissues from patients with colon cancer by establishing a long serial analysis of gene expression (SAGE) database as well as by real-time PCR and immunohistochemistry. RESULTS: As compared with normal tissue, a 2.8-fold decrease in PER3 mRNA levels in colon cancerous tissue was observed. Real-time PCR analysis revealed that PER3 mRNA levels in tumor tissues were lower than in normal tissues (P < 0.001) in both patients with colon tumor and those with rectal tumor. In addition, PER3 expression was related to multiple clinicopathologic factors, including tumor location, differentiation, and stage. Furthermore, the incidence of death was higher in subjects with PER3-negative tumors (P = 0.025); the estimated overall survival time was 71.5 ± 2.2 months and 58.6 ± 5.0 months in subjects with PER3-positive and PER3-negative tumors, respectively (P = 0.020). CONCLUSIONS: PER3 may play a role in colon cancer progression.

HOXA13 promotes gastric cancer progression partially via the FN1-mediated FAK/Src axis.

BACKGROUND: Gastric cancer (GC) is one of the most common cancers causing a poor prognosis worldwide. HOXA13, as a member of the homeobox (HOX) family, is involved in the regulation of cancer progression and has attracted increasing attention, as a potential novel target for anticancer strategies. However, the significance of HOXA13 in GC remains unclear. This article aims to explore the potential mechanism of HOXA13 in GC progression. METHODS: Quantitative real-time PCR was carried out to detect the expression of HOXA13 and FN1 and the correlation between HOXA13 and FN1 in GC tissues. In vitro assays were conducted to investigate the role of HOXA13 and FN1 in the malignant phenotypes of GC cells and the function of HOXA13 in the activation of the FAK/Src axis in GC cells. Coimmunoprecipitation was performed to reveal the relationship between ITGA5, ITGB1 and FN1 in GC cells. A dual luciferase assay was performed to assess miR-449a-targeted regulation of HOXA13 expression. RESULTS: Quantitative real-time PCR verified that HOXA13 was elevated and positively correlated with FN1 in GC. In vitro and in vivo assays demonstrated that high expression of HOXA13 promoted GC progression, especially metastasis. Mechanistically, rescue experiments, chromatin immunoprecipitation and dual luciferase assays revealed that HOXA13 directly bound to the FN1 promoter region to enhance the activation of the FAK/Src axis, leading to GC cell proliferation and metastasis. Furthermore, the result of a dual luciferase assay suggested that HOXA13 was directly targeted by miR-449a. CONCLUSIONS: Our results show that HOXA13 is a positive regulator of the FAK/Src axis mediated by FN1 in GC and promotes GC progression. Thus, targeting HOXA13, together with FN1, may provide a novel prospective anticancer strategy.

Decreased expression of RASSF6 is a novel independent prognostic marker of a worse outcome in gastric cancer patients after curative surgery.

BACKGROUND: Our previous study observed that the expression of RASSF6, a member of the Ras-association domain family, was down-regulated in gastric cancer cells. The present study further investigated the clinical significance of RASSF6 in gastric cancer. METHODS: Using real-time PCR, Western blot analysis, tissue microarray (TMA), and immunohistochemical staining, we evaluated RASSF6 mRNA and protein levels in tumor tissues and in the paired adjacent normal mucosa from patients with gastric cancers at different stages. RESULTS: RASSF6 mRNA and protein levels were decreased in gastric cancer tissues compared with the adjacent normal mucosa. Immunohistochemical detection of RASSF6 in a TMA that contained 264 paired specimens showed that a decreased cytoplasmic RASSF6 expression was significantly associated with the extent of cancer invasion, lymph node metastasis, distant metastasis, tumor histological grade, advanced clinical stage, and Ki-67 proliferative index. Moreover, RASSF6 expression in metastatic lymph nodes was lower than in the paired primary tumors. Patients with RASSF6-negative tumors had extremely higher disease recurrence rates and poorer survival than patients with RASSF6-positive tumors even after radical surgery. Stratification analysis revealed RASSF6 as an independent predictor for tumor recurrence in patients with gastric cancers irrespective of tumor stage. CONCLUSIONS: RASSF6 might contribute to the progression of gastric carcinogenesis and may function as a novel independent prognostic marker for the prediction of the recurrence of cancer in patients after curative operations.

Identification and validation of Kallikrein-ralated peptidase 11 as a novel prognostic marker of gastric cancer based on immunohistochemistry.

BACKGROUND AND OBJECTIVES: It is important to identify and validate the differentially expressed genes in gastric cancer to screen diagnostic and/or prognostic tumor markers. METHODS: cDNA expression microarray, gene set enrichment analysis, and bioinformatics approaches were used to screen the differentially expressed genes between gastric cancer tissues and adjacent non-cancerous mucosa. A novel candidate prognostic marker, Kallikrein-related peptidase 11 (KLK11), was validated in 400 Chinese gastric cancer patients. KLK11 expression in gastric cancer tissues was detected using real-time PCR and Western blot. KLK11 protein expression was further analyzed by immunostaining on tissue microarray, followed with clinicopathological significance and survival analysis. RESULTS: KLK11 expression was significantly decreased in gastric cancer compared with that in normal gastric mucosa (P<0.001). Furthermore, KLK11 expression was much lower in poorly differentiated cancer samples than that in well-differentiated group (P<0.01). Survival analysis showed that negative KLK11 expression was associated with nearly fivefold increased risk of distant metastasis after curative gastrectomy (HR 4.65, P<0.01). Multivariate Cox regression analysis showed that KLK11 expression emerged as a significant independent prognostic factor for disease-free survival and overall survival (P<0.05). CONCLUSIONS: The results indicated that KLK11 expression was decreased in gastric cancer and might serve as a novel independent prognostic marker.

HOXA10 mediates epithelial-mesenchymal transition to promote gastric cancer metastasis partly via modulation of TGFB2/Smad/METTL3 signaling axis.

BACKGROUND: Homeobox A10 (HOXA10) belongs to the HOX gene family, which plays an essential role in embryonic development and tumor progression. We previously demonstrated that HOXA10 was significantly upregulated in gastric cancer (GC) and promoted GC cell proliferation. This study was designed to investigate the role of HOXA10 in GC metastasis and explore the underlying mechanism. METHODS: Immunohistochemistry (IHC) was used to evaluate the expression of HOXA10 in GC. In vitro cell migration and invasion assays as well as in vivo mice metastatic models were utilized to investigate the effects of HOXA10 on GC metastasis. GSEA, western blot, qRT-PCR and confocal immunofluorescence experiments preliminarily analyzed the relationship between HOXA10 and EMT. ChIP-qPCR, dual-luciferase reporter (DLR), co-immunoprecipitation (CoIP), colorimetric m6A assay and mice lung metastasis rescue models were performed to explore the mechanism by which HOXA10 accelerated the EMT process in GC. RESULTS: In this study, we demonstrated HOXA10 was upregulated in GC patients and the difference was even more pronounced in patients with lymph node metastasis (LNM) than without. Functionally, HOXA10 promoted migration and invasion of GC cells in vitro and accelerated lung metastasis in vivo. EMT was an important mechanism responsible for HOXA10-involved metastasis. Mechanistically, we revealed HOXA10 enriched in the TGFB2 promoter region, promoted transcription, increased secretion, thus triggered the activation of TGFß/Smad signaling with subsequent enhancement of Smad2/3 nuclear expression. Moreover, HOXA10 upregulation elevated m6A level and METTL3 expression in GC cells possible by regulating the TGFB2/Smad pathway. CoIP and ChIP-qPCR experiments demonstrated that Smad proteins played an important role in mediating METTL3 expression. Furthermore, we found HOXA10 and METTL3 were clinically relevant, and METTL3 was responsible for the HOXA10-mediated EMT process by performing rescue experiments with western blot and in vivo mice lung metastatic models. CONCLUSIONS: Our findings indicated the essential role of the HOXA10/TGFB2/Smad/METTL3 signaling axis in GC progression and metastasis.

Analysis of Surgical Resident Operative Volumes on China's Resident Training.

Doctors entering surgical residency with different educational degrees and from different specialties is a unique feature of the Chinese medical system. The effect of this on the experience of surgical residents is not known. We retrospectively investigated whether residents' operative volumes were based on highest educational degree or postgraduate specialty. Using our operating data management system, a retrospective analysis of surgical resident operative experience at Shanghai General Hospital from 2012 to 2017 was conducted. The overall monthly average operative volume for surgical residents was 17.7 (12.6-26.5), but this decreased with each advanced degree of education from 26.0 (19.2-34.5) for those with a bachelor's degree only, to 19.5 (16.0-28.1) for a master's degree, to 15.9 (12.2-22.9) for those with a doctorate. Regarding specialty, residents in plastic surgery had the highest operative volume, and those in cardiothoracic surgery and neurosurgery had the lowest. At Shanghai General Hospital, the operative volumes of surgical residents differed according to their highest educational degree and postgraduate specialty. This analysis should be useful for the future planning of surgical residency programs in China.

Long non-coding RNA MINCR aggravates colon cancer via regulating miR-708-5p-mediated Wnt/ß-catenin pathway.

BACKGROUND: Increasing evidence has found that the dysregulation of long non-coding RNAs (lncRNAs) may be important indicators in tumorigenesis. MYC-induced long non-coding RNA (MINCR) has been found to be related with some cancers, such as non-small cell lung cancer and gallbladder cancer. Besides, MINCR has potentially prognostic value for colon cancer (CC) patients' prognosis, yet its function and molecular mechanism in CC are not explored. METHODS: qRT-PCR evaluated gene expression, and western blot detected protein level. In vitro and in vivo experiments were adopted to understand the biological role of MINCR in CC. TOP/FOP Flash assay was performed to measure the activity of Wnt/ß-catenin pathway. RNA pull down, luciferase reporter and RIP assays were utilized to analyze the relationship among genes. Immunohistochemistry and HE staining techniques were utilized to evaluate Ki67 staining in xenografts. RESULTS: MINCR was up-regulated in CC cells. Knockdown of MINCR suppressed cell proliferation and migration. MINCR could up-regulate CTNNB1 via sequestering miR-708-5p, resulting in activated Wnt/ß-catenin pathway. The addition of LiCl treatment, miR-708-5p inhibitor or pcDNA3.1/CTNNB1 abolished the inhibitory impacts induced by MINCR silence in CC progression. CONCLUSION: MINCR sponges miR-708-5p to up-regulate CTNNB1 and activate Wnt/ß-catenin pathway, thus promoting the development CC. Targeting MINCR might shed new light on the therapeutic strategies of CC.

IMP3 is a novel prognostic marker that correlates with colon cancer progression and pathogenesis.

BACKGROUND: Insulin-like growth factor-II mRNA-binding protein 3 (IMP3) plays a vital role in carcinogenesis; however, its significance and prognostic value in colon cancer remain unclear. METHODS: In this study, a tissue microarray (TMA) containing 203 samples of primary colon cancer was assessed for IMP3 expression by immunohistochemistry. The TMA included 66 lymph node metastasis (LNM) samples. The mRNA and protein expression levels of IMP3 were evaluated by reverse transcription-PCR and Western blot analysis, respectively. RESULTS: Cytoplasmic immunoreactivity of IMP3 was significantly higher in LNM (93%) than in primary colon cancer (65%) or normal mucosa (3.9%). Increased IMP3 levels were significantly correlated with higher clinical stage, T classification, LNM, presence of distant metastasis, and Ki-67 positivity. IMP3 was up-regulated in colon cancer compared with paired normal colonic mucosa. IMP3 expression was associated with an 11-fold increased risk of distant metastases (hazard ratio (HR) 10.7; 95% confidence interval (CI) 3.3-34.5; P < 0.0001). Patients with IMP3-positive localized tumors had lower 5-year disease-free survival (DFS) (HR 2.87; 95% CI 1.65-4.98; P < 0.0001) and overall survival (OS) (HR 4.2; 95% CI 2.51-10.17; P < 0.0001) than those with IMP3-negative tumors. Multivariate survival analysis showed that IMP3 was an independent prognostic marker for DFS (HR 1.92; 95% CI 1.06-3.47; P = 0.03) and OS (HR 2.37; 95% CI 1.2-4.7; P = 0.014). CONCLUSIONS: IMP3 may play an important role in colon cancer progression and could serve as a prognostic biomarker to identify patients at risk of developing metastasis or recurrence after colonectomy.

Elevated HOXA13 expression promotes the proliferation and metastasis of gastric cancer partly via activating Erk1/2.

PURPOSE: HOXA13 is a transcription factor of the Homeobox (HOX) gene family, which is highly evolutionarily conserved. HOXA13 is upregulated and associated with oncogenic properties in some cancers. Here, we studied the potential mechanism of HOXA13-mediated proliferation and metastasis in gastric cancer (GC). METHODS: Quantitative real-time PCR, Western blot, and immunohistochemistry were used to detect HOXA13 expression levels in GC. In vitro and in vivo assays were performed to investigate the function of HOXA13 in GC cell proliferation, migration, and invasion. RNA-Seq transcriptome analysis was performed to study the underlying mechanism of HOXA13-mediated aggressiveness in GC. RESULTS: HOXA13 mRNA and protein expression levels were upregulated in GC tissues. According to Cell Counting Kit-8 and colony formation assays, we found that HOXA13 over-expression promoted proliferation. Flow cytometry analysis showed that HOXA13 overexpression or knockdown led to G1-S phase transition or G1 phase arrest, respectively. Western blot analysis results showed that HOXA13 overexpression increased cyclin D1 expression, while knockdown decreased its expression. Wound healing and transwell assay results demonstrated that HOXA13 overexpression promoted the migration and invasion of GC cells. Western blot analysis results also showed that HOXA13 overexpression upregulated N-cadherin and vimentin and downregulated E-cadherin, while HOXA13 knockdown led to the opposite results, indicating that HOXA13 might participate in epithelial to mesenchymal transition. These results were verified in vivo by tumor xenograft and metastasis assays. Mechanistically, using RNA-Seq transcriptome analysis, we found that Erk1/2 activation played an important role in HOXA13-induced GC progression. CONCLUSION: Our results show that HOXA13 plays an important role in GC development. HOXA13 overexpression promotes proliferation and metastasis partly via activation of Erk1/2 in GC. Thus, HOXA13, together with Erk1/2, may be promising targets for novel anticancer strategies.

HOXA10 induces BCL2 expression, inhibits apoptosis, and promotes cell proliferation in gastric cancer.

Homeobox A10 (HOXA10) has been implicated critical for the promotion of carcinogenesis, but the underlying mechanism between HOXA10 and malignant gastric cancer (GC) phenotype remains elusive. In the present study, we analyzed and validated that HOXA10 and BCL2 expressions were elevated both at the mRNA and protein levels in GC tissues. Upregulated HOXA10 promoted GC cell proliferation with reduced apoptosis in vitro and accelerated GC tumor growth in vivo. Bioinformatics analysis and quantitative real-time polymerase chain reaction (qRT-PCR) experiment inferred that HOXA10 might upregulate the expression of BCL2. By performing western blot, chromatin immunoprecipitation and quantitative PCR (ChIP-qPCR), and rescue experiment, we found that HOXA10 might bind to BCL2 promoter region, induce its expression, and thus inhibit intrinsic apoptosis pathway. Moreover, higher expression of HOXA10 and BCL2 predicted poor overall survival (OS) in GC patients. In summary, our study indicated that HOXA10 was upregulated in GC, and that HOXA10 might promote cell proliferation by elevating BCL2 expression and inhibiting apoptosis.

Inhibition of the growth and metastasis of human colon cancer by restoration of RUNX3 expression in cancer cells.

Recent studies demonstrated an epigenetic inactivation of the runt-related transcription factor 3 (RUNX3) gene in human colon cancer. However, it remains unclear whether RUNX3 is tumor suppressive in colon cancer and, if so, the underlying molecular mechanisms of this activity are still unknown. In the present study, we sought to determine the level of RUNX3 expression in human colon tumor specimens and used an animal model of colon cancer to determine the impact of RUNX3 expression on tumor growth and metastasis. First, we analyzed RUNX3 expression in 83 human colon tumor specimens using immunohistochemical, reverse transcriptase-polymerase chain reaction, and Western blot analysis. RUNX3 mRNA and protein expression levels were consistently lower in tumor tissue specimens than in matched normal colon tissue specimens. Also, restoration of RUNX3 expression in colon cancer cells using gene transfer inhibited colon tumor growth and metastasis in our animal model, which was consistent with inhibition of colon tumor growth in vitro. Collectively, our clinical and experimental data support the notion that RUNX3 is a tumor suppressor in human colon cancer.

Refined mapping of loss of heterozygosity on 1q31.1-32.1 in sporadic colorectal carcinoma.

AIM: To explore precise deleted regions and screen the candidate tumor suppressor genes related to sporadic colorectal carcinoma. METHODS: Six markers on 1q31.1-32.1 were chosen. These polymorphic microsatellite markers in 83 colorectal cancer patients tumor and normal DNA were analyzed via PCR. PCR products were electrophoresed on an ABI 377 DNA sequencer. Genescan 3.1 and Genotype 2.1 software were used for Loss of heterozygosity (LOH) scanning and analysis. Comparison between LOH frequency and clinicopathological factors was performed by c2 test. RESULTS: 1q31.1-32.1 exhibited higher LOH frequency in colorectal carcinoma. The average LOH frequency of 1q31.1-32.1 was 23.0%, with the highest frequency of 36.7% (18/49) at D1S2622, and the lowest of 16.4% (11/67) at D1S412, respectively. A minimal region of frequent deletion was located within a 2 cM genomic segment at D1S413-D1S2622 (1q31.3-32.1). There was no significant association between LOH of each marker on 1q31.1-32.1 and the clinicopathological data (patient sex, age, tumor size, growth pattern or Dukes stage), which indicated that on 1q31.1-32.1, LOH was a common phenomenon in all kinds of sporadic colorectal carcinoma. CONCLUSION: Through our refined deletion mapping, the critical and precise deleted region was located within 2 cM chromosomal segment encompassing 2 loci (D1S413, D1S2622). No significant association was found between LOH and clinicopathologic features in 1q31.1-32.1.

Are there tumor suppressor genes on chromosome 4p in sporadic colorectal carcinoma?

AIM: To study the candidate tumor suppressor genes (TSG) on chromosome 4p by detecting the high frequency of loss of heterozygosity (LOH) in sporadic colorectal carcinoma in Chinese patients. METHODS: Seven fluorescent labeled polymorphic microsatellite markers were analyzed in 83 cases of colorectal carcinoma and matched normal tissue DNA by PCR. PCR products were electrophoresed on an ABI 377 DNA sequencer. Genescan 3.7 and Genotype 3.7 software were used for LOH scanning and analysis. The same procedure was performed by the other six microsatellite markers spanning D4S3013 locus to make further detailed deletion mapping. Comparison between LOH frequency and clinicopathological factors was performed by c2 test. RESULTS: Data were collected from all informative loci. The average LOH frequency on 4p was 24.25%, and 42.3% and 35.62% on D4S405 and D4S3013 locus, respectively. Adjacent markers of D4S3013 displayed a low LOH frequency (< 30%) by detailed deletion mapping. Significant opposite difference was observed between LOH frequency and tumor diameter on D4S412 and D4S1546 locus (0% vs 16.67%, P = 0.041; 54.55% vs 11.11%, P = 0.034, respectively). On D4S403 locus, LOH was significantly associated with tumor gross pattern (11.11%, 0, 33.33%, P = 0.030). No relationship was detected on other loci compared with clinicopathological features. CONCLUSION: By deletion mapping, two obvious high frequency LOH regions spanning D4S3013 (4p15.2) and D4S405 (4p14) locus are detected. Candidate TSG, which is involved in carcinogenesis and progression of sporadic colorectal carcinoma on chromosome 4p, may be located between D4S3017 and D4S2933 (about 1.7 cm).

PD-L2 expression in colorectal cancer: Independent prognostic effect and targetability by deglycosylation.

Colorectal cancer (CRC) is the second leading cause of cancer death worldwide, and immune checkpoint blockade therapy provides an opportunity for improving the outcome of CRC patients. Recent studies suggest that programmed death ligand-1 (PD-L1) is only expressed in 12% of CRCs. Here, we demonstrate that PD-L2 is expressed in approximately 40% CRCs, and its expression independently associates with poor survival of CRC patients. By detection of PD-L2 expression by immunofluorescence in 124 CRC cases with 10-y survival data, we found significant association between PD-L2 overexpression in cancer cells and worse overall survival (46.3 vs 69.1 mo; p = 0.0004). The association remained significant in multivariate COX regression analysis (hazard ratio = 2.778, 95% confidence interval [CI] = 1.668-4.627; p < 0.0001). In the validation CRC data set, significant association between PD-L2 overexpression and poor survival was supported by the univariate analysis (27.1 vs. 88.9 mo; p = 0.0002) and multivariate model (hazard ratio = 7.09, 95%CI 1.78-28.16; p = 0.005). Western Blot revealed strong induction of PD-L2 expression by interferon-γ (IFNγ) in CRC cells, and the mRNA levels of both genes were significantly correlated in CRC tissue samples. Suppression of glycosylation with tunicamycin caused a shift in molecular weight and significant decrease in the expression of PD-L2 protein. In conclusion, PD-L2 overexpression in CRC cells, under the regulation by IFNγ and glycosylation, associates with poor survival of patients with colorectal cancer. These findings highlight PD-L2 as a promising therapeutic target in CRC and suggest potential routes to control PD-L2 expression in CRC cells.

miR-181a-5p promotes the progression of gastric cancer via RASSF6-mediated MAPK signalling activation.

We previously discovered that Ras association domain family member 6 (RASSF6) was downregulated and predicted poor prognosis in GC patients. However, the mechanisms of the down regulation of RASSF6 in GC remained unclear. Increasing evidence indicates that dysregulation of microRNAs promotes the progression of cancer through the repression of tumour suppressors. Here, we identified miR-181a-5p as a novel regulator of RASSF6 in GC. Functionally, ectopic expression or silencing of miR-181a-5p, respectively, promoted or inhibited GC cell proliferation, colony formation and cell cycle transition, as well as enhanced or prevented the invasion, metastasis of GC cells and epithelial to mesenchymal transition of GC cells in vitro and in vivo. Molecularly, miR-181a-5p functioned as an onco-miRNA by activating the RASSF6-regulated MAKP pathway. Overexpression or silencing of RASSF6 could partially reverse the effects of the overexpression or repression of miR-181a-5p on GC progress caused by activation of the MAKP pathway in vitro and in vivo. Clinically, high miR-181a-5p expression predicted poor survival in GC patients, especially combined with low RASSF6 expression. Collectively, we identified miR-181a-5p as an onco-miRNA, which acts by directly repressing RASSF6 in GC.