Expression analysis of ovostatin 2 reveals its involvement in proliferation, invasion and angiogenesis of cutaneous malignant melanoma

A complex of novel protease inhibitor, ovostatin homolog, with its cognate proteases in immature mice uterine luminal fluid

A predominant gelatinolytic enzyme with approximately 26 kDa was observed in gelatin zymogram of immature mice uterine luminal fluid (ULF). Size exclusion analysis revealed that the native size of this enzyme was close to that of human α₂-macroglobulin (α₂-MG), a 725 kDa protein. This large protease was isolated by a series of chromatographic steps on the Sephacryl S-400 and DEAE-Sepharose columns. The results from gelatin zymography and SDS-PAGE analysis supported that this large protease consists of gelatinolytic enzyme and a 360 kDa protein. Through tandem mass spectrometry analysis followed by MASCOT database search, the 360 kDa protein was identified as ovostatin homolog (accession: NP_001001179.2) assigned as a homolog of chicken ovostatin, a protease inhibitor. The co-fractionation analysis by gel filtration and mouse ovostatin homolog (mOH) co-immunoprecipitation experiments demonstrated that the mOH formed a complex with three gelatinolytic enzymes in immature mice ULF. Substrate zymography analysis revealed that the mOH-associated gelatinolytic enzymes were suitable to digest type I collagen rather than type IV collagen. In addition, the refolded mOH-associated 26 kDa gelatinolytic enzyme displayed the type I collagen-digesting activity in the assay, but the other two enzymes did not have this function. RT-PCR analysis showed that mOH gene was abundantly expressed in brain, spinal cord, lung, uterus, and in 17-day embryo. Taken together, our data suggest that mOH/cognate protease system may play a potential role in regulation of tissue remodeling and fetal development.

Ovostatin 2 knockdown significantly inhibits the growth, migration, and tumorigenicity of cutaneous malignant melanoma cells

BACKGROUND

We previously identified ovostatin 2 (OVOS2) as a new candidate gene for cutaneous malignant melanoma (CMM) in a Chinese population. In this study, we aimed to investigate the exact role of OVOS2 in cell proliferation, invasion, and tumorigenesis of melanoma A375 cells.

METHODS

The downregulation of OVOS2 expression was performed using lentiviral vectors with specific shRNA. The effects of OVOS2 expression on cell proliferation, cell cycle, cell migration, cell invasion, and potential of tumorigenesis were further investigated.

RESULTS

The downregulation of OVOS2 significantly suppressed the proliferation of A375 cells and led to a G2/M phase block. The transwell cell migration assay showed that the reduced expression of OVOS2 also significantly inhibited the transmigration of A375 cells. The western blot results showed downregulated expression of p-FAK, p-AKT, and p-ERK. This was accompanied by the upregulated epithelial phenotypes E-cadherin and β-catenin, and downregulated expression of mesenchymal phenotype N-cadherin after OVOS2 knockdown. The transplantation tumor experiment in BALB/C nude mouse showed that after an observation period of 32 days, the growth speed and weight of the transplanted tumors were significantly suppressed in the BALB/c nude mice subcutaneously injected with OVOS2 knocked-down A375 cells.

CONCLUSION

The inhibition of OVOS2 had significant suppressive effects on the proliferation, motility, and migration capabilities of A375 cells, suggesting a crucial promotive role of OVOS2 in the pathogenesis and progression of CMM. The involved mechanisms are at least partly associated with the overactivation of FAK/MAPK/ERK and FAK/PI3K/AKT signals.

Hen egg white ovomacroglobulin promotes fibroblast migration via mediating cell adhesion and cytoskeleton

BACKGROUND

Hen egg white ovomacroglobulin (OVM) possesses a variety of bioactivities and could potentially be used as a pharmaceutical agent. It has been reported that OVM is involved in wound healing and cancer pathological processes, and previous results suggest that OVM plays a potential role in cell proliferation and migration; however, this has not yet been proven. In the present study, the effects of OVM on fibroblast proliferation and migration were evaluated.

RESULTS

Results of cell counting, cell viability, and cell cycle indicated that proliferation of fibroblasts was not altered by OVM treatment. However, scratch assays showed that OVM could promote the migration of 3 T6 mouse embryonic fibroblasts and human skin fibroblasts (HSF). Also, the adhesion of HSF to the collagen matrix was also enhanced by OVM treatment. RT-qPCR and western blot analysis showed that β1 -integrin, β-tubulin, and β-actin were up-regulated while E-cadherin was down-regulated in OVM-treated HSF cells. The effect of OVM was silenced after forming a complex with trypsin, suggesting that the protease inhibitory ability of OVM is important for its effect on cell migration.

CONCLUSION

These results suggested that promotion of OVM on cell migration was achieved by enhancing cell adhesion to extracellular matrix, reducing intercellular aggregation, and strengthening cytoskeleton. The finding of the promotion effect of OVM on cell migration is important for understanding its role in wound healing and cancer pathological processes. © 2015 Society of Chemical Industry.