A novel cannabinoid combination induces paraptosis-like death in breast cancer cells

Paraptosis, a caspase-independent mechanism of cell death, is characterised by cytoplasmic vacuolation arising from the endoplasmic reticulum and mitochondria [1]. The molecular mechanism of paraptosis is unclear; however, the literature indicates that it is biochemically and morphologically distinct from apoptosis and is often associated with calcium dysregulation and ROS production [2]. Recent studies have demonstrated that natural compounds can induce paraptosis in different tumour cell lines [3]. In this study, we aimed to identify and characterise the mechanism of cell death induced by a novel cannabinoid combination in MCF-7 cells. Extensive cytoplasmic vacuolation was observed within hours of treatment and significant cell death was observed after 24 hours. Combined with fluorescent DNA stains, staining for annexin V and lysosomes showed that neither apoptosis, necrosis, nor autophagy was induced. Ferroptosis was also ruled out, as experiments using ferroptosis inhibitors and fluorescent staining for lipid peroxides did not provide evidence for ferroptosis induction. Co-treatment with cycloheximide decreased vacuolation and cell death, suggesting paraptosis induction. Fluorescent staining showed a significant decrease in mitochondrial function and an increase in mitochondrial mass. Co-treatment with 4,4′- Diisothiocyanatostilbene-2,2′-sulfonic acid (DIDS), a voltage-dependent anion channel (VDAC) inhibitor, significantly reduced vacuolation, decreased cell death and improved mitochondrial function. This suggested that the cannabinoid combination may activate VDAC, leading to dysregulation of calcium signalling, significant alterations in mitochondrial function and subsequent paraptosis. These findings highlight the importance of activating alternative cell death mechanisms using natural compounds and expanding their potential for use as anticancer agents.

 

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• References

• 1 Sperandio S, de Belle I, Bredesen DE.. An alternative, nonapoptotic form of programmed cell death. Proc Natl Acad Sci U S A 2000; 97: 14376-14381
• 2 Kim E, Lee DM, Seo MJ, Lee HJ, Choi KS.. Intracellular Ca²⁺Imbalance Critically Contributes to Paraptosis. Frontiers in Cell and Developmental Biology 2021; 8: 607844
• 3 Fontana F, Raimondi M, Marzagalli M, Di Domizio A, Limonta P.. The emerging role of paraptosis in tumor cell biology: Perspectives for cancer prevention and therapy with natural compounds. Biochim Biophys Acta Rev Cancer 2020; 1873: 188338

Publikationsverlauf

Artikel online veröffentlicht:
16. November 2023