The role of procollagen alpha 1 type 1 (Col1A1) on invasion and cellular signaling in glioma cells.

Abstract

e23165 Background: We have previously shown that Procollagen alpha 1 type 1 (Col1A1) is found more in low and intermediate grade glioma and less often in glioblastoma(GBM) (Cancer Invest. 23:577, 2005). We now investigate their role in cellular function. Methods: 4 glioma cell lines: Glioma 1 and U118 express high amount of Col1A1 ( Col1A1+) ; A172 and SW1783 express insignificant amount of Col1A1 ( Col1A1 - ) as the model . All four cell lines express SPARC. Scratch, transwell, and metrigel assay were used to study migration and invasion. Cell cycles were analyzed by flowcytometry. Results: U118 has the highest amount of SPARC followed by A172, SW1783 and Glioma 1. Thus it does not appear to have any relationship between these two proteins which are known as binding partner. Glioma 1 showed the least invasion and migration followed by U118, SW1783 and A172. Thus, Col1A1 expression appear to correlate with invasiveness. To further confirm this, we have silence Col1A1 in Glioma 1 and U118 using both siRNA and shRNA. All clones exhibit more migration and invasion. However, it does not affect both intracellular and extracellular levels of SPARC. Silencing Col1A1 results in increasing G2M arrest; 11% in U118 and 6% in Glioma 1. However it does not affect cellular proliferation. To further verify this, we have overexpressed Col1A1 in A172 and SW1783 using plasmid containing Col1A1 and DDK tag. These Col1A1 (+) A172 and SW1783 transfectants exhibit less migration and invasion. However, there is no effect on SPARC levels. These Col1A1 positive cells exhibit 12% increase in Go/G1 arrest and decrease in proliferation. A limited protein array also showed that silencing Col1A1 increase in STAT3, 5 and 6 and AKT levels. Interestingly, a difference in sensitivity to STAT3/5 inhibitors also noted in parental and their Col1A1 knock down transfectants. Conclusions: our results support the role of Col1A1 in glioma cell invasiveness, and hence confirm our previous data which showed that Col1A1 is found more in low grade and intermediate grade glioma. Thus, Col1A1 could be an additional useful marker to assess the aggressiveness of GBM beside histopathological grading. Col1A1 may also play a role in cellular signaling pathway.