Pancreatic Stellate Cells Promote The Epithelial-Mesenchymal Transition Via Sdf-1/Cxcr4 Signaling Pathway In Pancreatic Cancer

Objective: We aimed to investigate the effect of conditioned media from pancreatic stellate cells (PSC-CM) on the epithelial-mesenchymal transition (EMT) of pancreatic cancer cells. Methods: PSC-CM was added into the culture medium of human pancreatic cancer cell lines AsPC-1, BxPC-3, and CXCR4-siRNA- AsPC-1. Cell growth was measured by MTT assay. Snail, Twist, and E-cadherin mRNA and protein expression was examined using real-time-PCR and Western blot. The invasion abilities of AsPC-1 and BxPC-3 cells were determined by cell invasion assays. The changes in related genes were detected by tumorigenesis tests in nude mice. Results: Our results showed that 1.0 mu g/mL of PSC-CM could promote the proliferation of human pancreatic cancer cell lines AsPC-1 and BxPC-3. After treatment with PSC-CM, the invasion of the two cell lines was enhanced (27.59 +/- 1.2 vs 73.99 +/- 2.29, 22.22 +/- 1.68 vs 66.01 +/- 1.86, all P<0.01). The mRNA expression level of Snail increased (2.89 +/- 0.16 vs 1.01 +/- 0.18, 1.71 +/- 0.24 vs 0.57 +/- 0.10, t=23.540, 13.060, all P<0.01), and the mRNA expression level of E-cadherin decreased (0.36 +/- 0.06 vs 1.00 +/- 0.09, 0.35 +/- 0.06 vs 0.6 +/- 0.006, t=17.820, 9.747, all P<0.01). The protein expression of Snail increased (3.33 +/- 0.20 vs 1.00 +/- 0.03, 1.71 +/- 0.25 vs 0.67 +/- 0.07, t=19.780, 6.885, all P<0.01), and the protein expression level of E-cadherin decreased (0.57 +/- 0.06 vs 1.00 +/- 0.07, 0.53 +/- 0.04 vs 0.73 +/- 0.09, t=7.981, 3.707, all P<0.01). Compared with the AsPC-1 and the CXCR4-Con- AsPC-1 groups, the mRNA expression level of Snail decreased (0.28 +/- 0.02 vs 1.01 +/- 0.18, 0.28 +/- 0.02 vs 1.03 +/- 0.25, t=12.31, 8.877, all P<0.01), and the mRNA expression level of E-cadherin increased (3.63 +/- 0.07 vs 1.00 +/- 0.09, 3.63 +/- 0.07 vs 1.03 +/- 0.21, t=69.040, 35.110, all P<0.01) in the group with silencing of CXCR4 by RNA interference. The protein expression level of Snail also decreased (0.44 +/- 0.01 vs 1.00 +/- 0.03, 0.44 +/- 0.01 vs 0.95 +/- 0.02, t=31.770, 36.910, all P<0.01), and the protein expression level of E-cadherin increased (2.21 +/- 0.03 vs 1.00 +/- 0.07, 2.21 +/- 0.03 vs 1.14 +/- 0.09, t=26.290, 18.560, all P<0.01) in this group. The positive expression rate of E-cadherin in the CXCR4-siRNA-AsPC-1 group was higher than that in the AsPC-1 group (76.90%+/- 1.69% vs 29.32%+/- 1.18%; t=73.25, P<0.01), and the positive expression rate of Snail in the CXCR4-siRNA- AsPC-1 group was lower than that in the AsPC-1 group (17.62%+/- 1.02% vs 52.58%+/- 1.74%; t=54.80, P<0.01). Conclusion: PSC can promote EMT in pancreatic cancer, and the SDF-1/CXCR4 axis may play a positive regulatory role during this process.