gms | German Medical Science

Objective: Arlts1 (ADP-ribosylation factor-like tumor suppressor gene) is a newly characterized tumor suppressor gene involved in the pathogenesis of several types of cancer: lung, breast cancer, ovarian tumor, B-cell chronic lymphatic leukemia. Transfection of wild type Arlts1 in ovarian, breast and lung cancer cells inhibits tumor cell proliferation and induces the apoptosis signaling pathway through regulation of apoptosis-related proteins, which indicate the tumor suppressor effect of Artls1. Here we examined its potential role in glioblastoma (GBM) tumorigenesis.

Methods: U87MG GBM cell line was transfected with wildtype-Arlts1. Annexin V and Propidium iodide staining was used to determine cell death by flow cytometry. The expression levels of pro-apoptotic (Caspases), anti-apoptotic (Bcl-2) genes and the Matrix metalloproteinases (MMP) 2 and 9 were examined by qRT-PCR. Western Blot was used to evaluate qRT-PCR results on protein level and zymography to reveal activity of MMPs.

Results: GBM cells transfected with wildtype-Arlts1 did not show an increase in cell death rate. Furthermore, these cells showed no differences in apoptosis compared to control; there was no significant increase of Caspase 3, 7 or 9. Surprisingly, the expression of the anti-apoptotic gene Bcl-2 was significantly reduced in U87MG cells overexpressing Arlts1. Since Bcl-2 is also involved in migration of tumors, expression of MMP 2 and 9 as markers for migration were also examined. The mRNA expression of these matrix metalloproteinases was significantly decreased.

Conclusion: As a consequence of Artls1 expression, the level of Bcl-2 decreased and MMP2 and 9 were downregulated. Since the connection between Bcl-2 expression and invasiveness of GBM is already known, these results would suggest a role of Arlts1 in migration and invasiveness of the tumor. Further investigation would include at first, confirmation of its involvement in migration of GBM. The search for interacting protein partners and drugs that can either positively modulate its expression or stimulate the signaling downstream of this gene in GBM could be a promising option for therapy, particularly for the invasiveness of gliomas, which is the reason for the poor patient's survival.