Effect Of Cancer-associated Fibroblasts On Sensitivity To Cisplatin In Coculture With Gastric Cancer Cells

BackgroundRecent studies have raised a promising view that cancer-associated fibroblasts may be an important factor throughout the process of tumor growth, invasion and metastasis. Our preliminary study found that the gastric cancer cell line SGC7901reduced its sensitivity to cisplatin when cocultured with cancer-associated fibroblasts isolated from the tumor tissue of a gastric cancer patient. This phenomenon indicated that the interaction between cancer-associated fibroblasts and gastric cancer cells may triggered some pathways that lead to the drug resistance in some gastric cancer patients. In the subsequent experiments, we recreated the phenomenon in vitro models and further discovered the participation of TGF-β/Smad pathway.MethodCancer-associated fibroblasts were isolated from the solid tumor of a gastric cancer patient. And a control was set by isolating normal fibroblasts from human foreskin tissue. We used two vitro coculture models, either adding conditioned medium collected from the specific fibroblasts to the culture medium of gastric cancer cell line SGC7901, or using Transwell to establish the a coculture system. The inhibition rate of cisplatin was tested by Cell Count Kit-8, and the expression level of TGF-β1and Smad2were detected by western-blot and RT-PCR.ResultsWhen cultured with conditioned medium of cancer associated fibroblasts, the inhibition rate of cisplatin on SGC7901significantly declined (p=0.0058), and the72-hour IC50raised from0.90μg/ml to9.76μg/ml. In the transwell coculture system, SGC7901also showed less sensitivity to cisplatin compared to the control group. RT-PCR showed the TGF-β1mRNA level of cancer-associated fibroblasts decreased in the coculture system after cisplatin was added. Western-blot showed a down regulating of Smad2protein in the SGC7901in the coculture group after the intervention of cisplatin.ConclusionIn our study, the cisplatin sensitivity of SGC7901declined after cocultured with cancer-associated fibroblasts, and TGF-β/Smad pathway may be involve in a way of negative regulation.