GLIOBLASTOMA STEM CELL NUMBER REDUCTION BY SPECIFIC iNOS INHIBITOR IN HUMAN CELL LINES

HINCAPIÉ ARIAS EL ; SANDES EO ; BELGOROSKY D ; ANA MARIA EIJAN

MODALIDAD VIRTUAL

Congreso; Reunion Conjunta de Sociedades de Biociencias SAIC SAI SAFE; 2020

SAIC SAI SAFE

Introduction: Glioblastoma (GBM) is the most common and aggressive brain tumor. Despite the introduction of chemotherapy with temozolomide (TMZ), the survival does not exceed 2 years. Cancer stem cells (CSC) has been associated to tumor recurrence. On the other hand, it has been suggested that iNOS (inducible nitric oxide synthase isoform) enzyme can sustain the CSC niche.Objective: Evaluate the expression of iNOS and the effect of its inhibitor, S-methylisothiourea (SMT), alone or in combination with TMZ, on the development of CSC on human GBM cell lines.Methodology: Human GBM lines LN229, U251 and U87 were seeded in monolayer (2D) and under spheral (3D) conditions (low adhesion and high dilution). Viability in 2D was determined by MTS. The number of CSC was established by sphere forming efficiency (SFE) in relation to the seeded cells, and the diameter of the spheres was measured. iNOS expression was determined by immunofluorescence.Results: The three lines expressed iNOS. In 2D, SMT (50 µM) only reduced LN229 cell line growth (26% inhibition); however, in 3D, it decreased SFE in the three lines (inhibition, LN229 42%; U251 61%; U87 48%) and their diameters (inhibition, 33%, 17% and 28%, respectively). The combination of SMT with TMZ 250 µM, further inhibited SFE (LN229 57%, U251 70%, U87 50%) compared to SMT or TMZ alone.Conclusion: iNOS inhibition in combination of actual TMZ therapy, could be a useful reducing chemotherapy-resistant CSC. Further studies on the mechanisms of action will allow establish the differences observed between GBM cell lines.