Activation of hypermethylated P2RY1 mitigates gastric cancer by promoting apoptosis and inhibiting proliferation

Background P2RY1 receptor is known to cause cancer by activating the ERK signal pathway, its DNA methylation status or even the corresponding regulatory mechanism remains unknown. Methods In this study, DNA methylation chip was used to profile the genome-wide DNA methylation level in gastric cancer tissues. Then validated by the bioinformatics analysis in the TCGA database, Immunohistochemistry staining data obtained from the HPA database to verify the difference in protein expression between normal tissues and tumor tissues . Results The promoter region of P2RY1 was found to be highly methylated with 4 hypermethylated sites (|Δβ value| >0.2) in diffuse gastric cancer and the expression level of P2RY1 is relatively low compared with non-cancerous tissues. We also showed that MRS2365, a selective agonist of the P2RY1 receptor, can induce phosphorylation of ERK1/2, inhibit cell proliferation/migration and induce apoptosis. Conclusion High DNA methylation in the promoter region of P2RY1 may have contributed to the reduced expression of P2RY1’s mRNA, which is likely responsible for the “aggressive” nature of the diffuse type gastric cancer.

Genomic landscape of a mouse model of diffuse-type gastric adenocarcinoma

Background There is a need for a model of diffuse-type gastric cancer that captures the features of the disease, facilitates the study of its mechanisms, and aids the development of potential therapies. One such model may be Cdh1 and Trp53 double conditional knockout (DCKO) mice, which have histopathological features similar to those of human diffuse-type gastric cancer. However, a genomic profile of this mouse model has yet to be completed. Methods Whole-genome sequences of tumors from eight DCKO mice were analyzed and their molecular features were compared with those of human gastric adenocarcinoma. Results DCKO mice gastric cancers harbored single nucleotide variations and indel patterns comparable to those of human genomically stable gastric cancers, whereas their copy number variation fraction and ploidy were more similar to human chromosomal instability gastric cancers (perhaps due to Trp53 knockout). Copy number variations dominated changes in cancer-related genes in DCKO mice, with typical high-level amplifications observed for oncogenic drivers, e.g., Myc, Ccnd1, and Cdks, as well as gastrointestinal transcription factors, e.g., Gata4, Foxa1, and Sox9. Interestingly, frequent alterations in gastrointestinal transcription factors in DCKO mice indicated their potential role in tumorigenesis. Furthermore, mouse gastric cancer had a reproducible but smaller number of mutational signatures than human gastric cancer, including the potentially acid-related signature 17, indicating shared tumorigenic etiologies in humans and mice. Conclusions Cdh1/Trp53 DCKO mice have similar genomic features to those found in human gastric cancer; hence, this is a suitable model for further studies of diffuse-type gastric cancer mechanisms and therapies.

Asporin Expression on Stromal Cells and/or Cancer Cells Might Be A Useful Prognostic Marker in Patients with Diffuse-Type Gastric Cancer

<b><i>Background:</i></b> Asporin (ASPN), a member of the proteoglycan family, has been shown to have a close correlation with cancer progression. It is not known whether ASPN is an oncogenic driver or a tumor suppressor in human gastric cancer. We sought herein to determine the relationship between ASPN expression and clinicopathological features of gastric cancer. <b><i>Patients and Methods:</i></b> A total of 296 gastric cancer patients (diffuse type, <i>n</i> = 144; intestinal type, <i>n</i> = 152) were enrolled. The ASPN expression level in each case was analyzed by immunohistochemistry. <b><i>Results:</i></b> ASPN was mainly found on stromal cells, especially on fibroblasts in tumor stroma, i.e., cancer-associated fibroblasts. The ASPN expression on either cancer cells or stromal cells was significantly high in macroscopic scirrhous-type tumors (<i>p</i> &#x3c; 0.001) and histologically abundant stroma-type tumors (<i>p</i> &#x3c; 0.001). Interestingly, a Kaplan-Meier survival curve of the 144 cases of diffuse-type gastric cancer revealed a significantly poorer prognosis in patients with ASPN-positive expression (<i>p</i> = 0.043; log rank) compared to those with ASPN-negative expression, but the prognoses were not significantly different in these subgroups of the 152 cases of intestinal-type gastric cancer. A multivariate analysis with respect to overall survival showed that ASPN expression on stromal cells and/or cancer cells was significantly correlated with overall survival in patients with diffuse-type gastric cancer (<i>p</i> = 0.041). <b><i>Conclusion:</i></b> In gastric cancer, ASPN was expressed mainly on stromal cells and partially on cancer cells. ASPN expression on stromal cells and/or cancer cells might be a useful prognostic marker in patients with diffuse-type gastric cancer.