| Background:Lung cancer is one of the most common malignant tumor and its incidence and mortality rates are higher. With the development of molecular biology, the treatment of lung cancer have made great progress. However,5-year survival rate in patients with non-small cell lung cancer (NSCLC) is still very low, only about 21%. So looking for a new safe and effective treatment method is particularly important. At present, a number of studies suggested that there is a close relationship between genes and tumorgenesis. Gene therapy will therefore represent a new potential prospect for the treatment of cancer.Aging is an extremely important and independent risk factor in the development of cancer. With the increase of age, cancer risk was also significantly raised. Klotho is a new anti-aging gene. Recent studies suggested that Klotho not only had anti-aging effect, but also closely related to tumorgenesis, especially for the development of lung cancer. Experiments have shown that as a tumor suppressor factor, Klotho may play a role in regulating the IGF-1, bFGF, Wnt/β-catenin and PI3k/Akt pathway in NSCLC cells. Klotho gene can transcribe a secreted form by alternative RNA splicing encoding only the KL1 domain or KL1 can cleavage by ADAM10/17 from KL. Some studies had indicated that KL1 internal repeat mediates klotho tumor suppressor activities and inhibits bFGF and IGF-I signaling in pancreatic cancer. KL1 did not affect signaling by FGF23 in MDCT cells may have a better safety profile. There are many similar mechanisms between pancreatic cancer and non-small cell lung cancer. So we suppose that KL1 may suppress the development of NSCLC and be safer.Objective:To study the effects and possible mechanisms of KL1 in the A549, A549/DDP, PC9 cells.Methods:Western blot was used to observe the overexpression of KL1 or KL in cells after transfected with PCDNA3.1-KL1 or PCDNA3.1-KL. MTT assay, Colony-forming assay and flow-cytometry analysis assay were designed to determine the changes of cell growth, proliferation and apoptosis of NSCLC cells introduced by KL1 or KL. The activation of IGF-1, bFGF, FGF23 signal pathways treated by PCDNA3.1-KL1, PCDNA3.1-KL or PCDNA3.1 were evaluated by Western blot.Results:48 h after transfection, exogenous KL1 or KL was overexpressed significantly in A549, A549/DDP, PC9 cells respectively. Compared with the control group, the cell growth was remarkably inhibited in A549, A549/DDP, PC9 cells after transfected with KL1 or KL (P<0.01). Overexpression of KL1 or KL could reduce the proliferation of A549, A549/DDP cells compared with the control group (P<0.01). Overexpression of KL1 or KL could promote apoptosis of A549 cells (P＜0.01). Overexpression of KL1 or KL could inhibite motility of A549, A549/DDP, PC9 cells (P<0.01). Overexpression of KL1 or KL could attenuate the resistance of A549/DDP to cisplatin (P＜0.01). Compared with KL, KL1 showed similar inhibition activity in IGF-1 and bFGF pathways but did not active FGF23 signaling pathway.Conclusion:KL1 and KL had a similar ability to inhibit the growth, proliferation and motility of NSCLC cells, to promote the apoptosis of A549 cells and also to attenuate the resistance of cells to cisplatin. This may be due to the same ability to inhibit the IGF-1 and bFGF pathways. Thus, KL1 may be the main functional fragment of KL protein. Furthermore, KL1 has higher security without activiting FGF23 signaling pathway and smaller environmental impact on the body. |
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