Background: Vascular endothelial growth factor (VEGF, namely VEGF-A) is an angiogenic polypeptide and VEGF-C is a lymphangiogenic polypeptide that has been implicated in cancer growth, invasion and metastasis. Several cytokines and growth factors play an important part in cancer progression. These cytokines and growth factors are the principal mediators of cancer cells--stromal cell interaction, which is critical for invasion of cancer cells to the surrounding tissues and metastatic dissemination to distant organs. In this study, we studied VEGF-A, C expression in cultured human pancreatic cancer cell lines and whether the presence of VEGF-A, C in the cell lines is regulated by cytokines interleukin-1alpha(IL-1alpha), and interleukin-6 (IL-6).
Methods: We used Northern blot and Western blot methods to analyze expression of the gene and protein of VEGF-A, C in all 6 tested cell lines (ASPC-1, CAPAN-1, MIA-PaCa-2, PANC-1, COLO-357 and T3M4) respectively. To analyze what is the regulator for this VEGF-A, C expression in pancreatic cancer, we used the reverse transcription-polymerase chain reaction (RT-PCR) method to analyze VEGF-A, C expression in cultured human pancreatic cancer cell lines (CAPAN-1 and COLO-357) under the stimulation with IL-1alpha(10 microg/L) or IL-6 (100 microg/L).
Results: Northern blot analysis revealed the presence of the 4.1 kb VEGF-A mRNA transcript and 2.4-kb VEGF-C mRNA transcript in all 6 tested cell lines. Immunoblotting with highly specific anti-VEGF-A, anti-VEGF-C antibody revealed the presence of a molecular weight of 43-kDa VEGF-A protein and 55-kDa VEGF-C protein in all the cell lines. RT-PCR analysis revealed the levels of the VEGF-A and VEGF-C gene were 1-2 fold and a 1-fold increase in the COLO-357 cell line by stimulation with IL-1alpha, however, no effect was found in the CAPAN-1 cell line. The levels of the VEGF-A and VEGF-C gene were 2-5 fold and a 1-fold increase in the CAPAN-1 cell line by stimulation with IL-6, but no effect was found in the COLO-357 cell line.
Conclusion: These findings suggested that the expression of VEGF-A, C and their regulation by IL-1alpha, IL-6 in pancreatic cancer contributes to the lymphatic and distant metastasis and the disease progression.