Background: Expressions of c-Myc and PKM2 are high in many tumors. However, studies on the regulation of mTOR/PKM2 and STAT3/c-Myc signaling pathways in gastric cancer are rare. Aims: To investigate the mechanism of crosstalk between mTOR/PKM2 and STAT3/c-Myc signaling pathways in regulating energy metabolism and acidic microenvironment of gastric cancer. Methods: Human gastric cancer AGS and HGC-27 cells were transfect with PKM2 and c-Myc lentivirus to construct cell models of knockdown of PKM2, c-Myc. CCK-8 assay was used to detect cell proliferation, cell migration was detected by Transwell chamber, cell apoptosis was determined by flow cytometry. The mRNA and protein expressions of PKM2, c-Myc, LDHA, STAT3, p-STAT3, and GLUT-1 were determined by real-time quantitative PCR and Western blotting, respectively. Lactic acid and glucose levels were detected by colorimetric method. Results: Expressions of PKM2 and c-Myc were up-regulated in gastric cancer. Knockdown of c-Myc could inhibit cell proliferation and migration, decrease protein expressions of LDHA, GLUT-1 and levels of glucose and lactic acid. The inhibition of gastric cancer was more obvious when both PKM2 and c-Myc were knockdown. mTOR/PKM2 signaling pathway was correlated to STAT3/c-Myc signaling pathway. Conclusions: PKM2 combined with c-Myc may be considered as a new therapeutic target for gastric cancer.

Background: Intestinal flora disorder plays an important role in the pathogenesis of chronic constipation. Either microbial agents or fecal microbiota transplantation has therapeutic effect on chronic constipation by regulating the intestinal flora. Aims: To study the characteristics of intestinal flora structure in elderly chronic constipation patients. Methods: Thirty elderly patients with chronic constipation from January 2019 to December 2019 at Nanjing Central Hospital were enrolled, and 30 elderly healthy subjects were served as controls. Stool was collected, and 16S rRNA high-throughput sequencing method was used to analyze the structure of intestinal flora. Results: Alpha diversity analysis showed that there were no significant differences in Ace, Chao, Shannon and Simpson indices between chronic constipation group and healthy control group. Twenty dominant genera accounting for more than 80% of all genera were identified in the two groups, Bacteroides was the most abundant genus. Beta diversity analysis showed that the species composition between the two groups was different, the characteristics of the two groups were not similar (R=0.098, P=0.001). Relative abundances of Prevotella, Faecalibacterium and Lachnospira were higher in the healthy control group, while Ruminococcus, Shigella, Parabacteroides and Alistipes were higher in chronic constipation group. Numbers of species with significantly different relative abundance in healthy control group and chronic constipation group were 25 and 2, respectively. Compared with healthy control group, the abundance of Alistipes, Oscillospira, Ruminococcus and Parabacteroides were higher in chronic constipation group (P< 0.05), while Megasphaera was lower (P< 0.05). Conclusions: There is no difference in the diversity of intestinal flora between elderly chronic constipation patients and elderly healthy controls, however, significant difference is detected in species composition. Therefore, targeting at modifying intestinal flora may be a promising therapeutic strategy for chronic constipation.