T-Type Cav3.1 Channels Mediate Progression and Chemotherapeutic Resistance in Glioblastoma

Abstract

T-type Ca 2þ channels (TTCC) have been identified as key regulators of cancer cell cycle and survival. In vivo studies in glioblastoma (GBM) murine xenografts have shown that drugs able to block TTCC in vitro (such as tetralol derivatives mibefradil/NNC-55-096, or different 3,4-dihydroquinazolines) slow tumor progression. However, currently available TTCC pharmacologic blockers have limited selectivity for TTCC and are unable to distinguish between TTCC isoforms. Here we analyzed the expression of TTCC transcripts in human GBM cells and show a prevalence of Cacna1g/Ca v 3.1 mRNAs. Infection of GBM cells with lentiviral particles carrying short hairpin RNA against Ca v 3.1 resulted in GBM cell death by apoptosis. We generated a murine GBM xenograft via subcutaneous injection of U87-MG GBM cells and found that tumor size was reduced when Ca v 3.1 expression was silenced. Furthermore, we developed an in vitro model of temozolomide-resistant GBM that showed increased expression of Ca v 3.1 accompanied by the activation of macroautophagy. We confirmed a positive correlation between Ca v 3.1 and autophagic markers in both GBM cultures and biopsies. Of note, Ca v 3.1 knockdown resulted in transcriptional downregulation of p62/SQSTM1 and deficient autophagy. Together, these data identify Ca v 3.1 channels as potential targets for slowing GBM progression and recurrence based on their role in regulating autophagy.Significance: These findings identify Ca v 3.1 calcium channels as a molecular target to regulate autophagy and prevent progression and chemotherapeutic resistance in glioblastoma.

Mechanisms of Invasion in Glioblastoma: Extracellular Matrix, Ca2+ Signaling, and Glutamate

“…In another study, decreased expression of T-type VGCC reduced the proliferation of glioma cells ( Panner et al, 2005 ). More recently, it was shown that mibefradil treatment and silencing of T-type VGCC by shRNA reduces GBM cell survival by apoptosis ( Visa et al, 2019 ). Blocking of P/Q- and N-type VGCC affects glioma progression by inhibiting proliferation and viability in glioma cell lines and increasing astrocytes and microglia in the near tumor region in vivo and in vitro ( Nicoletti et al, 2017 ) ( Figure 1B ).…”

Ion Channels as Therapeutic Targets in High Grade Gliomas

“…Similarly, lentiviral infection of GBM cells with shRNA against Cav3.1 resulted in significant apoptosis, and in murine models, tumour size was reduced when Cav3.1 expression was silenced. TMZ resistant GBM models exhibited over-expression of Cav3.1 [ 93 ]. siRNA mediated knockdown of T-type channel subunits Cav3.1 and Cav3.2 reduced cell viability and clonogenic potential and induced apoptosis in U251 and U87 glioma cells.…”

Penfluridol as a Candidate of Drug Repurposing for Anticancer Agent

“…T-type calcium channels, another known target of penfluridol, are also involved in autophagy. The Cav3.1 channel appears to be involved in temozolomide action against GBM through the induction of autophagy [63]. Accordingly, T-type calcium channel blockers also inhibited autophagy and promoted apoptosis in malignant melanoma cells [64].…”