Cardiolipin Dysregulation in Glioblastoma-Effects on Mitochondrial Function Tumor Cell Death and Sensitivity to Mitochondria-Targeting Drugs

Abstract

Biological systems do not exist in isolation. Analogous to the intricate design of a spider web, the metabolic adaptations propagated by glioblastoma cells are interlaced, creating a "defense mechanism" that increases the likelihood of mutagenesis and proliferation, while mitigating stress-induced tumor cell death and immune evasion. Previous studies have observed the role of cardiolipin (CL) in the electron transport chain (ETC) function and several other intracellular signaling pathways. Our review provides a synopsis of the existing knowledge about CL in glioblastoma and its complex relationship with metabolic reprogramming at the subcellular level. Through a meticulous examination of CL defects due to its biogenesis and stress-induced modifications, we seek to elucidate the multifaceted connections between aberrant CL variants and the metabolic alterations that underlie glioblastoma progression. A comprehensive grasp of these mechanisms could provide future direction in designing chemotherapeutic agents that selectively target glioblastoma, are less harmful to normal cells, and therefore, may extend patient survival.

Keywords: cardiolipin; election transport Chain; glioblastoma; mitochondria.

FIGURE 1 |

Biosynthesis, Remodeling, and Oxidation of Cardiolipin (CL). Created in BioRender. Hunter, J. (2025) https://BioRender.com/j09t184 | [Inspired by Ahmadpour et al. (Ahmadpour et al. 2020)]. ALCAT1, Acyl-CoA-lysocardiolipin acyltransferase; CDP-diacylglycerol (CDP-DG) synthase; CRLS1, Cardiolipin synthase 1; cyt c, cytochrome c; ETC, electron transport chain; iPLA2, calcium-independent phospholipase A2; MLCLAT1, MLCL acyltransferase 1; mCL, mature CL; MLCL, monolyso-cardiolipin; PA, phosphatidic acid; pCL, premature CL; PGS-1, phosphatidyl glycerophosphate synthase 1; PGPP1, phosphatidyl glycerophosphate phosphatase 1; ROS, reactive oxygen species; TAMM-41, TAZ, Tafazzin.

FIGURE 2 |

Normal human astrocytes (NHAs) are resistant to PP1-induced cell death. (A) Quantification of cell type contribution in mixed cultures of NHAs (LONZA/Clonetics) and LN229 human glioblastoma cells expressing m-Cherry (mixed at 1:1 ratio). The histogram shows % change in cell type contribution at plating (T0) and following DMSO (control) and PP1 treatment for 96 h. Data represent average values with SD (n = 3). (B) PP1 IC50 comparison between NHAs and LN229 human glioblastoma cells, both cultured in low glucose media (1 g/L). Data represent average MTT values, (n = 3). (C) Metabolic responses to PP1 evaluated in LN-229 and NHAs using Seahorse/Agilent. Oxygen Consumption Rate (OCR) values were obtained after a single injection of PP1 (10 and 25 mM) or dimethyl sulfoxide (DMSO) (control). Data represent average values +/−SD (n = 4).

FIGURE 3 |

Glioblastoma tumors show high CLS1 and low TAZ protein levels. (A) Immunohistochemical detection of cardiolipin synthase 1 (CLS1) and Tafazzin (TAZ) in glioblastoma tumor tissue. Images were taken from a borderline between tumor tissue (GBM) and normal brain (NB). Areas of NB adjacent to GBM is labeled as transition zone (TZ). (B) Western blot showing CRLS1 and TAZ protein levels in GBM12 cells compared to normal human astrocytes (NHAs). The blot was probed with cardiolipin synthase 1 (CLS1); Tafazzin (TAZ); and GAPDH (loading control) antibodies. The histogram: densitometric analysis of western blots confirming disproportionally high CLS1 and low TAZ protein levels in GBM12 compared to NHAs. (C) CRLS1 and TAZ lentiviral expression vectors and hsRNA vectors to target CLS and TAZ transcripts. (D) Protective role of TAZ expression against PP211-induced glioblastoma cell death. LN229 cells were transfected with TAZ-, CLS1- or with empty-lentiviral expression vectors. After 2 and 6 h following PP211 treatment (12.5 μM) cell death was evaluated using trypan blue exclusion test. Data represent average values with standard deviation (n = 4). *indicate values significantly different from control at 2 h, and ** indicate values statistically different from control at 6 h (p ≤ 0.05). Inset: lentivirus-mediated transduction efficiency in LN229.