RAB8 Enhances TMEM205-Mediated Cisplatin Resistance

To determine whether the small endosomal recycling GTPase, RAB8, plays a role in TMEM205-associated resistance to the chemotherapeutic drug cisplatin. Antibodies were used as markers for both genes; confocal microscopy was used to visualize their localization in cisplatin-resistant cells. Both single and dual-transfections were performed. Expression of RAB8 was markedly elevated in human cisplatin-resistant cells. We found that TMEM205 was co-localized with RAB8. Dual transfectants with over-expression of both TMEM205 and RAB8 were found to be up to 4-fold more resistant to cisplatin, while cells transfected with RAB8 alone were similar to 2-fold more resistant. The development of cisplatin resistance appears to be a consequence of pleotropic epigenetic alterations. We unravel the role of one gene, the GTPase RAB8, in this process. Because its highest expression was at an early step of cisplatin resistance, it may be involved in early development of resistance. Increased expression of TMEM205 and RAB8 in double-transfected cells and their increased resistance to cisplatin indicate an additive effect of these two genes, mediating cisplatin resistance. These two proteins are potential biomarkers or targets for gene or chemotherapy.