Expression Of Antibacterial Peptide LL-37 In Colon Cancer And Its Effect On The Proliferation Of Colon Cancer Cell Line

Objectives:Antibacterial peptide LL-37 is the only host defense peptide in humans and it is widely found in body tissues.The study found that the antibacterial peptide LL-37 was highly expressed in cancer tissues such as breast cancer and lung cancer,but it is low in cancer tissues such as gastric cancer and lymphoma.It can be seen that the expression of LL-37 is inconsistent in various tumor tissues.In vitro administration of LL-37 to the corresponding cell line promotes the proliferation of this cell line in breast and lung cancers,while inhibiting the proliferation of cell lines in gastric cancer,there are differences between the results of the studies.The purpose of this study included:1.To clarify the expression level of LL-37 in blood and tissue samples of colon cancer patients.2.Analysing whether exogenous LL-37 has inhibitory effects on proliferation of normal colonic epithelial cells FHC and colon cancer cells HCT116 and SW480 cultured in vitro.Understanding the relationship between the expression of LL-37 and the occurrence and development of colon cancer may provides new ideas for the diagnosis and treatment of colon cancer.Methods:1.Collect 30 cases of colon cancer patients colon tissue,intraoperative specimens from each colon cancer patient were taken for cancer(oncology center to avoid necrosis organization),adjacent tissue(tissues larger than 2cm and less than 5cm away from the lesion)and normalized tissue(the furthest from the edge of the tumor tissue Extracted from the end),the total protein was extracted from each tissue,and the expression of LL-37 in the three groups was detected by Western-blot.2.Serum from 30 patients with colon cancer and healthy human serum were collected.ELISA was used to detect the expression of LL-37 in the serum and the three groups.3.The three cell lines FHC,HCT116 and SW480 were treated with different concentrations of LL-37(1-300?g/mL).MTT assay was used to observe the effect of different concentrations of LL-37 on the proliferation of normal cells and tumor cells.Analyze whether LL-37 can inhibit the proliferation of colon cancer cells.4.Statistical analysis:All the data were analyzed using SPSS 21.0 statistical software.The experimental data with normal distribution was represented by x±s,analysis of variance was used for comparison among groups and P<0.05 was considered statistically significant.Results:1.In the pathological tissues of 30 patients with colon cancer,the results of western-blot and ELISA suggested that the expression of LL-37 was the highest in paracancerous tissues,followed by normal tissues,and The expression of LL-37 was lowest in cancer tissues.2.Accurate detection by ELISA showed that the expression of antibacterial peptide LL-37 in the serum of colon cancer patients was higher than that in 30 healthy adults,and it was statistically significant(P<0.05).3.The inhibitory effect of LL-37 on the FHC activity of normal human colonic epithelial cells was not statistically different(P>0.05)when the dose range was 1-200 ?g/mL.Only the concentration of LL-37 is greater than 300?g/mL,it can inhibited the proliferation of FHC activity,but the inhibition was minimal.For its suppression is negligible.In the HCT116 and SW480 colon cancer cell lines,when the concentration of LL-37 is less than 50 ?g/mL,there is almost no effect on cell proliferation activity.When the concentration of LL-37 was between 100?g/mL-300?g/mL,its cytotoxicity was concentration-dependent.When the concentration of LL-37 was 300 ?g/mL,almost all of HCT116 died,and only a small portion of SW480 survived.Conclusions:This study found that the expression of antibacterial peptide LL-37 in cancer tissue samples of patients with colon cancer was lower than that in normal tissues and adjacent tissues,but the expression of antibacterial peptide LL-37 in serum of colon cancer patients was higher than that in healthy controls,suggesting that LL-37 may be related to the development of colon cancer.Antibacterial peptide LL-37 inhibited the proliferation of colon cancer cell lines HCT116 and SW480,but had weaker cytotoxic effects on human normal colonic epithelial cells FHC,or could provide help for the treatment of colon cancer.An in-depth understanding of the relationship between antibacterial peptide LL-37 and colon cancer may provide a new molecular target for the the diagnosis and treatment of colon cancer.