The Expression Levels Of Heat Shock Protein 70B' In Lung Cell Lines And Its Significance

Heat shock proteins are highly conserved proteins that are triggered in all organisms exposed to environmental stressors such as elevated temperature, UV, polycyclic aromatic hydrocarbon (PAHs), heavy metals, etc. Based upon their apparent molecular weight, HSPs are divided into many groups such as high-molecular-mass HSP100, HSP90, Hsp70, HSP60, HSP40 and small HSPs. The Hsp70 family have been extensively studied which are found to function as molecular chaperones, binding to the nascent polypeptides to assist them proper refolding, assembling and translocation, and facilitating the misfolding peptides to repair or targeting damaged polypeptides for degradation. Many studies had indicated that Hsp70 expression was correlated to the tolerance or susceptible ability to environmental harmful factors. In fact, specific increasing the expression of Hsp70 protected cells from ultraviolet radiation, and inhibition of Hsp70 produced profound impairment of cellular integrity. HSPs have been found to participate in physiological and pathological processes. They also may serve as biomarkers for evaluating disease status and damage resulting from exposure to environmental stresses. HSPs are very important in the processes of aging, immunological regulation and cancers.HSPs play an important role in the incidence of cancer and the process of diseases'development, it becomes more popular to research the relationships between Hsp70 and lung cancer. Studying the HSPs'functions in the processes of lung cancer and the possibility to become a specific target in early diagnosis of lung cancer are very important for lung cancer's prevention, diagnosis and treatment. Many studies confirm that Hsp70 expression increases in cancer, suggesting that Hsp70 plays an important role in lung cancer proliferation, differentiation and may become a meaningful reference in lung cancer prognosis'judgement. Hsp70B', Hsp72 were thought as the two inducible and with important biological significance Hsp70 proteins, the protection of Hsp72 in cells and tissues has been very clear, Hsp70B'was only found under the high temperature in cancer cells. Its unique heat-induced character suggests some special biological functions. Therefore, it is very necessary to explore Hsp70B's functions and the possibility roles in lung cancer. In this study, we detected the dynamic expression of Hsp70B'and cell activity in the A549 lung cancer cells under the heat stress. Comparating with Hsp72, we analyzed Hsp70B'in A549 cells, 16HBE cells and BPDE transformed 16HBE cells under high temperatures, UV, benzo(a)pyrene. We found Hsp70B'generates only under high temperature in the cancer cells and serious deterioration transformed 16HBE cells.PartⅠThe dynamic expression of Hsp70B'under heat stress in A549 cellsAs a new member of Hsp70, Hsp70B'was only found under the high temperature in Hela and colon carcinoma cells. We detected the expressions of Hsp70B'and Hsp72 under the heat stressed A549 cells. The results show that there is no basal expression in normal lung cells, but Hsp70B'could be detect in heat stressed cells, the level of expression increased following with the stress time, and got the top in 120min, then decreased for the serious damage under 45℃. After the heat stress in 42℃, Hsp70B'reached the max in 6h recovery, but it turned to be feeble at 24h. Its transient expression suggests Hsp70B'may participate in the cells'early recovery from the stress. The expression of Hsp70B'in the heat stress shows that it generates under the heat stress, and may play a role in the stress response. PartⅡComparison of Hsp70B'and Hsp72 in the heat stress A549 cells and Hsp70B's possible function in heat stress cellsIn this part, we explored Hsp70B's functions in the lung cell lines. By cultivating of human lung cancer cell line A549, we did not found Hsp70B'in normal cells, preliminary analysis that Hsp70B'may play a role with the heat tolerance, but we did not find any relationship by analyzing cell activity and Hsp70B'expression. The results show that Hsp72, Hsp70B'have a similar expression lines, which provide some basis for the common roles of the two proteins. In addition, we first detected Hsp70B'in the lung cancer, while in the adjacent organizations and non-lung cancer patient's tissues the Hsp70B'expression is much less. The result suggests Hsp70B'may play a role in lung cancer, but whether it can be taken as a tumor marker needs further studies.PartⅢComparison of Hsp70B'and Hsp72 expressions in the stressed lung cells by heat, ultra-violet and benzo(a)pyreneTo explore the Hsp70B's inducible specificity in the lung cells, three common stressors (Heat, UVC and BaP) were used for stimulating the cells. The three different types of Lung cells A549 cells, 16HBE cells and BPDE transformed 16HBE cells were stressed under different doses, the expression of Hsp70B'were detected in three kinds of lung cells under the different stressors. The expression of Hsp72 protein in the cells rapidly increases after heat stress, reaching the highest level at 120min in all three cell-lines. The Hsp70B'increased to the top expression at 60min and sustained a short period of time, these showed that Hsp70B'may participate in the early recovery of the tolerance to the heat. By comparing Hsp70B'protein expressing levels with Hsp72 under different doses of UVC radiation, Hsp72 increases in the expression when elevated the radiation dose in the three cell-lines, it prevents the degenerated protein from irreversible aggregation. However, Hsp70B'generated only in BPDE transformed 16HBE cells. In normal cells 16HBE and cancer cells A549 cells it was not found, suggesting that Hsp70B'was induced only in the injured or serious deterioration cells to response to the protein or DNA damage by UVC. In the BaP group, the results showed that only in BPDE transformed 16HBE cells can detected the weak zone of Hsp70B'in the X-ray pictures, but in normal cells failed to find its expression. Base on the trend of Hsp72 expression, the cells'survival is the worse than the other two cells. It implys that Hsp70B'only induced in serious injured and deteriorated of cells or cancer cells, but its specific roles need further studies to be confirmed.Conclusions:1) Our study detected Hsp70B'in the heat stressed A549 cells and its dynamic expression for the first time, we did not found Hsp70B'in normal cells, in A549 cells the Hsp70B'optimal inducible conditions for the stress is heating at 42℃for 1h then recover to normal for 6h. It thought that Hsp70B'may be involved in regulation and early recovery after heat stress, sustaining the activity of cells and promoting the tolerance of heat stress.2) Through cultivating of human lung cancer cell line A549, preliminary analysis that Hsp70B'may play a role with the heat tolerance, but we didn't find any relation by analyzing cell activity and Hsp70B'expression. In addition, we first detected Hsp70B'in the lung cancer, and in the adjacent organizations and non-lung cancer patient's tissue the Hsp70B'the expression is much less. The result suggests Hsp70B'may play a role in lung cancer, and whether be considered as a tumor markers needs further studies.3) To explore the Hsp70B'specificity of heat inducible in the lung cells, three common stressors were deployed for stimulating the the three different types of Lung cells. By comparing Hsp70B'protein expressing level with Hsp72 under different stress doses, we found Hsp70B'generated mainly in the heat stressed cancer cells to response to the protein or DNA damage. In serious injured and deteriorated cells, Hsp70B'also could feebly express for the weak cell condition. However, its specific roles need further studies to be confirmed. Perspectives:1) The study detected the Hsp70B'in lung cancer tissues, it can be further verified Hsp70B's roles and significance in the staging, differentiation processes of lung cancer. There could do more studies on the possibility of Hsp70B'to be a reference and the biomarkers of the lung cancer diagnosis and prognosis.2) To check more Hsp70B'inducible stressors, we should apply more representative stressors such as heavy metals, protease inhibitors, hydrogen peroxide, and study its expressing rules in other cell lines, those could provided more information for studying the roles of Hsp70B'in the stress cells.3) It needs more studies to analyze and verify Hsp70B'functions, and explore its biological significance in cells and tissues.