A link between mucolipin channels and
tumors has been recently suggested. Herein, we aim to investigate the transient receptor potential mucolipin (TRPML)-1 relevance in
glioblastoma. The expression of this channel was evaluated via qRT-PCR and immunohistochemistry in biopsies from 66
glioblastoma patients and two human
glioblastoma cell lines and compared to normal human brain, astrocytes, and epileptic tissues. The subcellular distribution of TRPML-1 was examined via confocal microscopy in the
glioma cell lines. Then, to assess the role of TRPML-1, cell viability assays have been conducted in T98 and U251 cell lines treated with the specific TRPML-1 agonist, MK6-83. We found that MK6-83 reduced cell viability and induced caspase-3-dependent apoptosis. Indeed, the TRPML-1 silencing or the blockage of TRPML-1 dependent [Ca2+]i release abrogated these effects. In addition, exposure of
glioma cells to the
reactive oxygen species (ROS) inducer,
carbonyl cyanide m-chlorophenylhydrazone (
CCCP), stimulated a TRPML-1-dependent autophagic cell death, as demonstrated by the ability of the autophagic inhibitor
bafilomycin A, the TRPML-1 inhibitor
sphingomyelin, and the TRPML-1 silencing to completely inhibit the
CCCP-mediated effects. To test a possible correlation with patient's survival, Kaplan-Meier, univariate, and multivariate analysis have been performed. Data showed that the loss/reduction of TRPML-1
mRNA expression strongly correlates with short survival in
glioblastoma (GBM) patients, suggesting that the reduction of TRPML-1 expression represents a negative prognostic factor in GBM patients.