Impact of a haplotype (composed of the APC, KRAS, and TP53 genes) on colorectal adenocarcinoma differentiation and patient prognosis.

BACKGROUND: Many types of gene mutation are associated with the drug resistance of cancer cells. XELOX is a new and efficient surgical adjuvant chemotherapy for colorectal adenocarcinoma. However, drug-resistant related genetic mutations associated with this treatment remain unknown. METHODS: Next-generation sequencing (NGS) was performed on 36 colorectal cancer patients to identify mutations among patients with residual tumors following preoperative chemotherapy. Enrichment and prognosis of these mutations were evaluated in a TCGA cohort. The pathology of cases with poor prognosis-related mutations was also determined. RESULTS: A sequence of SNPs associated with the APC, KRAS, and TP53 genes in 13 of 19 subjects with residual tumors after preoperative chemotherapy was identified. Using survival analysis data from 317 cases in the TCGA database, a prognosis-related haplotype composed of SNPs from APC, KRAS, and TP53 was assembled. Colorectal cancer patients with these mutations had a lower 5-year tumor-specific survival rate than those without (p < 0.05). Most patients with these mutations were at a higher clinical stage (III-IV) of disease. Enrolled subjects with the identified haplotype tended to have poor cancer cell differentiation. CONCLUSIONS: The prognosis-related haplotype can be used as a marker of drug resistance and prognosis in colorectal cancer patients after preoperative chemotherapy.

Protein Phosphatase PPM1B Inhibits Gastric Cancer Progression and Serves as a Favorable Prognostic Biomarker.

BACKGROUND: Protein phosphatase PPM1B, also named as PP2Cß, is a member of serine/threonine phosphatase family. Dysregulated expression of PPM1B has been reported in several malignancies; nevertheless, its role in gastric cancer remains unknown. Here, we aimed to initially investigate the expression and function of PPM1B in gastric adenocarcinoma. METHODS: We firstly evaluated the protein expression of PPM1B in our enrolled retrospective cohort (n=161) via immunohistochemistry staining. Univariate and multivariate analyses were conducted to assess its prognostic value. Cellular experiments and xenografts in mice model were also performed to validate the role of PPM1B in gastric adenocarcinoma progression. RESULTS: The advanced tumor stage was characterized with a lower PPM1B level. Lower PPM1B was associated with poor prognosis in both The Cancer Genome Atlas (TCGA) dataset and our cohort (P<0.05). Furthermore, Cox regression analysis demonstrated that PPM1B was a novel independent prognostic factor for gastric adenocarcinoma patients (hazard ratio=0.35, P=0.001). Finally, cellular and xenografts data confirmed that overexpressing PPM1B can remarkably attenuated gastric adenocarcinoma growth. CONCLUSION: Low expression of PPM1B may be a potential molecular marker for poor prognosis in gastric adenocarcinoma.

Bioinformatic identification of candidate genes induced by trichostatin A in BGC-823 gastric cancer cells.

The aim of the present study was to identify the candidate genes induced by trichostatin A (TSA) in BGC-823 gastric cancer (GC) cells and to explore the possible inhibition mechanism of TSA in GC. Gene expression data were obtained through chip detection, and differentially expressed genes (DEGs) between GC cells treated with TSA and untreated GC cells (control group) were identified. Gene ontology analysis of the DEGs was performed using the database for annotation, visualization and integrated discovery. Then sub-pathway enrichment analysis was performed and a microRNA (miRNA) regulatory network was constructed. We selected 76 DEGs, among which 43 were downregulated genes and 33 were upregulated genes. By sub-pathway enrichment analysis of the DEGs, the propanoate metabolism pathway was selected as the sub-pathway. By constructing a miRNA regulatory network, we identified that DKK1 and KLF13 were the top hub nodes. The propanoate metabolism pathway and the genes DKK1 and KLF13 may play significant roles in the inhibition of GC induced by TSA. These genes may be potential therapeutic targets for GC. However, further experiments are still required to confirm our results.

PAQR3 gene expression and its methylation level in colorectal cancer tissues.

The aim of the present study was to investigate the PAQR3 gene expression and its methylation level in colorectal cancer tissues, as well as the association with colorectal cancer clinical data. In total, 54 cases of colorectal cancer tissue samples and normal adjacent tissue samples were collected between June, 2013 and July, 2014. RT-PCR and western blot analysis were used to detect the mRNA and protein levels of PAQR3 in colorectal samples, respectively. MSP was used to detect the methylation level of PAQR3 gene in colorectal samples, which was compared with colorectal data. The results showed that a decreased expression level of PAQR3 mRNA in colorectal cancer tissues and the expression reduction rate was 57.4% (31/54). Similarly, the expression level of PAQR3 protein was reduced in cancer tissues, and the reduction rate was 46.3% (25/54), while the protein expression reduction rate in cancer adjacent tissue was 5.6% (3/54), and the difference was statistically significant (P<0.05). Furthermore, the methylation rates of PAQR3 in cancer tissues and cancer adjacent tissues were 33.3% (18/54) and 5.6% (3/54), respectively. In addition, PAQR3 mRNA and protein levels in colorectal cancer tissues were associated with the differentiation degree, lymphatic metastasis and tumor infiltration depth. The methylation level of PAQR3 was associated with age, differentiated degree, lymphatic metastasis and tumor infiltration depth. In conclusion, the expression of PAQR3 mRNA and protein in colorectal cancer was reduced and methylation of PAQR3 occurred. Although the PAQR3 mRNA and protein levels were not associated with gender, age or the location of tumor, there was an association with differentiation degree, lymphatic metastasis and tumor infiltration depth. In addition, the methylation level of PAQR3 was not correlated with gender or tumor location, but was correlated with age, differentiation degree, lymphatic metastasis and tumor infiltration depth.

Multiple differential expression networks identify key genes in rectal cancer.

BACKGROUND: Rectal cancer is an important contributor to cancer mortality. OBJECTIVE: The objective of this paper is to identify key genes across three phenotypes (fungating, polypoid and polypoid & small-ulcer) of rectal cancer based on multiple differential expression networks (DENs). METHODS: Differential interactions and non-differential interactions were evaluated according to Spearman correlation coefficient (SCC) algorithm, and were selected to construct DENs. Topological analysis was performed for exploring hub genes in largest components of DENs. Key genes were denoted as intersections between nodes of DENs and rectal cancer associated genes from Genecards. Finally, we utilized hub genes to classify phenotypes of rectal cancer on the basis of support vector machines (SVM) methodology. RESULTS: We obtained 19 hub genes and total 12 common key genes of three largest components of DENs, and EGFR was the common element. The SVM results revealed that hub genes could classify phenotypes, and validated feasibility of DEN methods. CONCLUSIONS: We have successfully identified significant genes (such as EGFR and UBC) across fungating, polypoid and polypoid & small-ulcer phenotype of rectal cancer. They might be potential biomarkers for classification, detection and therapy of this cancer.