Metastasis of tumor cells poses great difficulties for tumor therapy. Tumor microenvironment is a complex and rich multicellular environment for the development of tumors, in which tumor-associated immune cells induce tumor cells to undergo epithelial-mesenchymal transition (EMT) which enhances the invasiveness and motility of tumor cells and prompts tumor cells to metastasize, and tumor cells undergoing EMT secrete cytokines and other substances to reorganize the tumor microenvironment. The interaction between EMT and the tumor microenvironment aggravate tumor invasion and metastasis. This paper collects research literature on tumor microenvironment and EMT of tumor cells from 2015 to 2023, and reviews the role of tumor microenvironment in tumor EMT, providing the basis for research into tumor metastasis mechanism and development of anti-tumor drugs.

Hypoxia is the most common tumor microenvironment caused by rapid proliferation of tumor cells, and hypoxia-inducible factor (HIF) is the main transcription factor for tumor cells to adapt to hypoxia. Current research has found that HIF can interact with a variety of mesenchymal cells such as fibroblasts, endothelial cells and immune cells in the tumor microenvironment, leading to the transcription and expression of target genes in response to hypoxia, which ultimately promotes tumor angiogenesis, and induces physiological changes such as migration, invasion, and immune escape of tumor cells. However, the signaling pathways involved in the HIF regulatory mechanism are complex, and the mechanism of HIF in the tumor microenvironment need to be further investigated, also most HIF inhibitors are still in the preclinical research stage. This paper reviews the research progress on the effects of HIF on tumor mesenchymal stromal cells to provide a theoretical basis for the diagnosis, prevention and treatment of tumors targeting HIF.

【Objective】 To investigate the relationship between maternal oral health behavior during pregnancy and premature birth. 【Methods】 A total of 248 preterm and 700 non-preterm pregnant women who delivered in Northwest Women’s and Children’s Hospital in Shaanxi Province from January to December 2022 were included in case group and control group, respectively. General demographic characteristics and oral health behavior during pregnancy were collected by questionnaires, and the oral health impact profile-14 (OHIP-14) was used to assess the oral health related life quality of pregnant women. Logistic regression model was used to analyze the relationship between maternal oral health behavior during pregnancy and premature birth. 【Results】 During pregnancy, maternal frequent eating after brushing teeth (OR=1.62, 95% CI: 1.03-2.57), unused fluoride toothpaste (OR=2.03, 95%CI: 1.25-3.05), late visit to the doctor for oral discomfort (OR=1.41, 95%CI: 1.02-1.96), brushing teeth less than twice one day (OR=1.77, 95%CI: 1.13-2.78) or less than 3 minutes each time (OR=1.52, 95%CI: 1.09-2.11), and elevated OHIP-14 score (OR=1.07, 95%CI: 1.04-1.10) increased the risk of premature birth. 【Conclusion】 Poor oral health behavior during pregnancy may increase the risk of premature birth. Therefore, more efforts should be made to publicize oral health knowledge and guide pregnant women to establish good oral health habits so as to improve oral health and promote maternal and child health.