The relationship between periodontal disease and gastric cancer: A bidirectional Mendelian randomization study.

BACKGROUND: Previous observational studies have suggested a possible association between periodontal disease and gastric cancer (GC); however, a causal relationship has not yet been established. This study aimed to explore the causal relationship between the 2 through a 2-sample bidirectional Mendelian randomization (MR) study. METHODS: Genome-wide association studies (GWAS) summary statistics were obtained from publicly available GWAS and relevant databases. Two-sample bidirectional MR analysis was conducted to investigate the causal relationship between periodontal disease and GC using the inverse-variance weighted (IVW) method selected as the primary analytical approach. Cochran Q test, MR-PRESSO, MR-pleiotropy, and leave-one-out analyses were performed to assess heterogeneity, pleiotropy, and sensitivity. RESULTS: In European ancestry, IVW analysis revealed no causal relationship between periodontal disease and GC (OR = 1.873; 95% CI [4.788e-10, 7.323e + 09]; P = .956), or between loose teeth and GC (OR = 1.064; 95% CI [0.708, 1.598]; P = .765). In East Asian ancestry, there was no causal relationship between periodontitis and GC according to IVW (OR = 0.948; 95% CI [0.886, 1.015]; P = .126). Conversely, according to the results of the IVW analysis, there was no causal relationship between GC and periodontal disease, regardless of European or East Asian ancestry. Furthermore, there was no heterogeneity or pleiotropy in the causal relationships between these variables (all P > .05), suggesting a certain level of reliability in our results. CONCLUSION: Within the limitations of this MR study, we found no mutual causal relationship between periodontal disease and GC. This finding can prevent overtreatment by clinical physicians and alleviate the psychological burden on patients.

LncRNA CASC2 inhibited the viability and induced the apoptosis of hepatocellular carcinoma cells through regulating miR-24-3p.

Cancer susceptibility candidate 2 (CASC2), a recently discovered long non-coding RNA (lncRNA), was confirmed to play numerous roles in several human cancers. However, the involvement and concrete mechanism of CASC2 in hepatocellular carcinoma (HCC) still need to be further elucidated. The relative expressions of CASC2 and miR-24-3p in HCC tissue and cell lines were determined by quantitative real-time PCR (qRT-PCR). The effects of CASC2 and miR-24-3p on HCC cells were further assessed via cell viability and apoptosis. In vivo tumorigenesis assay was performed to verify the inhibition effect of CASC2 on the tumor growth and further clarify the important role of miR-24-3p in this mechanism. Compared with the paired normal tissues, the relative expression of CASC2 significantly reduced in the HCC tissues, while miR-24-3p as determined by qRT-PCR obviously increased in the HCC tissues. This observation was also found in HCC cell lines. Meanwhile, the expression of CASC2 was negatively related to miR-24-3p expression in the HCC tissues (r = -0.804, P < 0.001). CASC2 could negatively regulate the expression of miR-24-3p in vitro. Moreover, CASC2 overexpression resulted in the growth inhibitory and apoptosis-inducing effects on HCC cells, but the up-regulation of miR-24-3p greatly eliminated the CASC2-induced effects. The tumorigenesis of HCC cells was restrained significantly by CASC2 overexpression as shown by decreased tumor volume and growth rate. However, miR-24-3p up-regulation rescued the inhibition of CASC2 on the tumor growth in tumor-bearing mice. LncRNA CASC2 inhibited the viability and induced the apoptosis of HCC cells through regulating miR-24-3p.