Expression profile as predictor of relapse after adjuvant treatment in gastric cancer

Identification of three immune subtypes characterized by distinct tumor immune microenvironment and therapeutic response in stomach adenocarcinoma

BACKGROUND

In primary stomach adenocarcinoma (STAD), the tumor immune microenvironment (TIME) is important for cancer occurrence and progression; however, its clinical significance remains unclear. This study investigated the association between patient survival, TIME, and therapeutic response to STAD.

METHODS

Gene expression profiles of STAD cases were collected from the Cancer Genome Atlas (TCGA) database and Gene Expression Omnibus. Molecular subtypes were explored with consistent clustering methods according to 119 immune signatures and the infiltrating scores of 22 immune cells using the Multi-Omics Immuno-Oncology Biological Research algorithm. We determined IFNγ scores and immune cytolytic activity (CYT) scores on the basis of corresponding gene signatures via single-sample Gene Set Enrichment Analysis. Comparisons of survival, TIME, 10 immunity-related oncogenic pathways, immune checkpoint expression, and therapeutic response were conducted among the three subtypes. We further applied linear discriminant analysis to construct a characteristic index to classify the subtypes, and the Pearson correlation coefficient for the relationship between the index and immune checkpoint genes. Weighted Correlation Network Analysis (WGCNA) was used to mine the associated modules and specific genes.

RESULTS

We collected gene expression profiles from 352 STAD cases in the TCGA database, 300 in GSE62254, and 344 in GSE84437. Three STAD subtypes (IS1-IS3) were established according to the TIME signatures. The IS3 subtype had the highest immune score and the best prognosis, as well as markedly increased immune T-cell CYT, Th1/IFNγ scores, and immune checkpoint gene expression, compared to the other two subtypes. It was highly similar to the PD-1 response group in the previous study samples of GSE91061. The established TIME classification index performed well in classifying subtypes and was directly proportional to immune checkpoint-related gene expression levels. WGCNA explored 6 modules and 14 genes, namely DYSF, MAN1C1, HTRA3, EMCN, RFLNB, KANK3, MAGEH1, CD93, PCAT19, FUT11, BMP1, FOSB, DCHS1, and TCF3, which were associated with the established TIME classification index and STAD patient prognosis.

CONCLUSION

TIME phenotypes of STAD patients could be divided into three different molecular subtypes, which displayed different prognoses, immune features, and therapeutic responses. Our results shed new light on predicting patient outcomes and the discovery of new anti-STAD therapeutic strategies according to the TIME.

High expression of TRIM36 is associated with radiosensitivity in gastric cancer

Radiotherapy is one of the main adjuvant treatments for gastric cancer (GC) that can effectively reduce local recurrence and improve survival rates. However, radiotherapy may result in cytotoxicity and not benefit all patients. This highlights the requirement for identifying potential radiosensitivity genes in GC. The current study investigated the association between tripartite motif containing 36 (TRIM36) status and the prognosis of patients with GC receiving radiotherapy. A total of 371 patients with GC were selected from The Cancer Genome Atlas and randomly divided into test and the validation groups. The results revealed that TRIM36 expression was not associated with the overall survival (OS) rate. Patients who received radiotherapy with high TRIM36 expression had an improved OS rate compared with patients who did not receive radiotherapy in the test group, as demonstrated by univariate analysis [hazard ratio (HR), 0.062; 95% confidence interval (CI), 0.008–0.462; P=0.007] and multivariate analysis (HR, 0.095; 95% CI, 0.012–0.748; P=0.025). In the validation group, patients with high TRIM36 expression had decreased mortality risk when they received radiotherapy compared with patients who did not receive radiotherapy, as determined by univariate analysis (HR, 0.190; 95% CI, 0.067–0.540; P=0.002) and multivariate analysis (HR, 0.075; 95% CI, 0.020–0.276; P<0.001). However, for patients with low expression, no significant difference was identified in the overall survival rates between the radiotherapy and non-radiotherapy groups. Chi-squared analysis revealed that the expression status of TRIM36 was an independent factor and was not associated with clinicopathological factors. The results indicated that patients with high TRIM36 expression receiving radiotherapy exhibited an improved OS rate. TRIM36 may therefore be an important factor affecting the clinical prognosis of patients with GC receiving radiotherapy and may be considered as a potential radiosensitivity gene signature.

Inhibition of green tea polyphenol EGCG((-)-epigallocatechin-3-gallate) on the proliferation of gastric cancer cells by suppressing canonical wnt/β-catenin signalling pathway

(-)-Epigallocatechin-3-gallate (EGCG), the major polyphenol in green tea, could affect carcinogenesis and development of many cancers. However, the effects and underlying mechanisms of EGCG on gastric cancer remain unclear. We found that EGCG significantly inhibited proliferation and increased apoptosis of SGC-7901 cells in vitro. The decreased expressions of p-β-catenin(Ser552), p-GSK3β(S9) and β-catenin target genes were detected in SGC-7901 cells after treated by EGCG. XAV939 and β-catenin plasmid were further used to demonstrate the inhibition of EGCG on canonical Wnt/β-catenin signalling. Moreover, EGCG significantly inhibited gastric tumour growth in vivo by inhibiting Wnt/β-catenin signalling. Taken together, our findings establish that EGCG suppressed gastric cancer cell proliferation and demonstrate that this inhibitory effect is related to canonical Wnt/β-catenin signalling. This study raises a new insight into gastric cancer prevention and therapy, and provides evidence that green tea could be used as a nutraceutical beverage.

Abnormal β-catenin immunohistochemical expression as a prognostic factor in gastric cancer: A meta-analysis

AIM: To evaluate the effect of β-catenin immunohistochemical expression on the prognosis of gastric cancer (GC).

METHODS: We searched Pubmed and Embase to identify eligible studies. The search ended on November 10, 2013, with no lower date limit. The citation lists associated with the studies were used to identify additional eligible studies. We included studies reporting sufficient information to estimate the HR and 95%CI, and information to estimate the OR in the analysis of clinicopathological features. The qualities of these studies were assessed using the Newcastle-Ottawa Quality Assessment Scale. HRs and ORs and their variance were calculated and pooled using Review Manager Version 5.2.

RESULTS: A total of 24 studies were identified and comprised 3404 cases. β-catenin expression was significantly correlated with poor overall survival (OS) in GC patients (HR = 1.85, 95%CI: 1.39-2.46), but showed a significant degree of heterogeneity (I² = 71%, P < 0.0001). Subgroup analysis indicated that an abnormal pattern of β-catenin expression had an unfavorable effect on OS (HR = 1.79, 95%CI: 1.39-2.32). However, accumulation in the nucleus or loss of membrane did not influence the survival of GC patients independently. Moreover, the combined OR of β-catenin indicated that β-catenin expression was associated with Lauren classification (OR = 1.98, 95%CI: 1.19-3.29), lymph node metastasis (OR = 2.00, 95%CI: 1.44-2.77), distant metastasis (OR = 2.69, 95%CI: 1.35-5.38) and grade of differentiation (OR = 2.68, 95%CI: 1.66-4.34). β-catenin expression did not correlate with TNM stage (OR = 1.34 95%CI: 0.96-1.86), the depth of invasion (OR = 1.48, 95%CI: 0.94-2.33) or vascular invasion (OR = 1.11, 95%CI: 0.70-1.76).

CONCLUSION: Abnormal β-catenin immunohistochemical expression may be associated with tumor progression and could be a predictive factor of poor prognosis in patients with GC.

The expression of Bcl-2 and BID in gastric cancer cells

Background. Bcl-2 and BID play a major role in the process of apoptosis and their dysfunction underlies carcinogenesis. The study objective was to assess the expression of Bcl-2 and BID in gastric cancer cells in correlation with chosen clinicopathological parameters, presence of Helicobacter pylori infection, and patients' survival. Materials and Methods. The study involved 88 patients operated on for gastric cancer. The expressions of Bcl-2 and BID were determined immunohistochemically. Results. Positive Bcl-2 expression was found in 55.7% and, BID in 53.6% of patients. The Bcl-2 expression correlated with stage pT3 and T4 gastric cancer (P < 0.05), with the intestinal type according to Lauren (P < 0.001), ulcerated type according to Bormann's classification (P < 0.01), and with local lymph node metastases (P < 0.05). Conclusion. The Bcl-2 protein plays a key role in the process of gastric cancer formation and is associated with the growth of definite types of gastric cancer.