Extracellular gamma-synuclein promotes tumor cell motility by activating ?1 integrin-focal adhesion kinase signaling pathway and increasing matrix metalloproteinase-24, -2 protein secretion.

ABSTRACT:

Background

Increasing evidence reveals a significant correlation between gamma-synuclein (SNCG) level and tumor invasion and metastasis in various human cancers. Our previous investigation showed that SNCG could secrete into extracellular environment and promoted tumor cell motility, but the mechanism is unknown.

Methods

The membrane binding ability of SNCG was characterized by immunohistochemical staining, immunofluorescence staining and fractionation of colorectal cancer (CRC) cell membrane. Association between SNCG and ?1 integrin was validated by coimmunoprecipitation and far Western blot. After inhibition of ?1 integrin and focal adhesion kinase (FAK), effect of SNCG on cell motility was measured by transwell chamber assays and changes of protein levels were detected by Western blot. Association between SNCG and activated ?1 integrin levels in human CRC tissues was determined by Spearman's rank correlation analysis. Secreted proteins in conditioned medium (CM) were screened by antibody array.

Results

Extracellular SNCG bound ?1 integrin on CRC cell membrane and increased levels of activated ?1 integrin and FAK. Correspondingly, SNCG-enhanced cell motility was counteracted by knockdown or inhibition of ?1 integrin or FAK. Further study revealed that high SNCG level indicated poor outcome and SNCG levels positively correlated with those of activated ?1 integrin and phospho-FAK (Tyr³⁹⁷) in human CRC tissues. Additionally, extracellular SNCG promoted secretion of fibronectin (FN), vitronectin (VN), matrix metalloproteinase (MMP)-2, and MMP-24 from HCT116 cells. Protease activity of MMP-2 in the CM of HCT116 cells was increased by treatment with SNCG, which was abolished by inhibiting ?1 integrin.

Conclusion

Our results highlight the potential role of SNCG in remodeling extracellular microenvironment and inducing ?1 integrin-FAK signal pathway of CRC cells.

SUBMITTER: Liu C 

PROVIDER: S-EPMC6003176 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature