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Mitochondrial calcium uniporter activity is dispensable for MDA-MB-231 breast carcinoma cell survival
Journal article   Open access   Peer reviewed

Mitochondrial calcium uniporter activity is dispensable for MDA-MB-231 breast carcinoma cell survival

Duane D Hall, Yuejin Wu, Frederick E Domann, Douglas R Spitz and Mark E Anderson
PloS one, Vol.9(5), pp.e96866-e96866
2014
DOI: 10.1371/journal.pone.0096866
PMCID: PMC4011874
PMID: 24802861
url
https://doi.org/10.1371/journal.pone.0096866View
Published (Version of record) Open Access

Abstract

Calcium uptake through the mitochondrial Ca2+ uniporter (MCU) is thought to be essential in regulating cellular signaling events, energy status, and survival. Functional dissection of the uniporter is now possible through the recent identification of the genes encoding for MCU protein complex subunits. Cancer cells exhibit many aspects of mitochondrial dysfunction associated with altered mitochondrial Ca2+ levels including resistance to apoptosis, increased reactive oxygen species production and decreased oxidative metabolism. We used a publically available database to determine that breast cancer patient outcomes negatively correlated with increased MCU Ca2+ conducting pore subunit expression and decreased MICU1 regulatory subunit expression. We hypothesized breast cancer cells may therefore be sensitive to MCU channel manipulation. We used the widely studied MDA-MB-231 breast cancer cell line to investigate whether disruption or increased activation of mitochondrial Ca2+ uptake with specific siRNAs and adenoviral overexpression constructs would sensitize these cells to therapy-related stress. MDA-MB-231 cells were found to contain functional MCU channels that readily respond to cellular stimulation and elicit robust AMPK phosphorylation responses to nutrient withdrawal. Surprisingly, knockdown of MCU or MICU1 did not affect reactive oxygen species production or cause significant effects on clonogenic cell survival of MDA-MB-231 cells exposed to irradiation, chemotherapeutic agents, or nutrient deprivation. Overexpression of wild type or a dominant negative mutant MCU did not affect basal cloning efficiency or ceramide-induced cell killing. In contrast, non-cancerous breast epithelial HMEC cells showed reduced survival after MCU or MICU1 knockdown. These results support the conclusion that MDA-MB-231 breast cancer cells do not rely on MCU or MICU1 activity for survival in contrast to previous findings in cells derived from cervical, colon, and prostate cancers and suggest that not all carcinomas will be sensitive to therapies targeting mitochondrial Ca2+ uptake mechanisms.
 AMP-Activated Protein Kinases - metabolism Cation Transport Proteins - antagonists & inhibitors Reactive Oxygen Species - metabolism Calcium Channels - metabolism Mitochondrial Membrane Transport Proteins - antagonists & inhibitors Calcium - metabolism Humans Calcium-Binding Proteins - antagonists & inhibitors Breast Neoplasms - metabolism Mitochondrial Membrane Transport Proteins - genetics RNA Interference Cation Transport Proteins - metabolism Cation Transport Proteins - genetics Female Antineoplastic Agents - pharmacology Calcium Channels - genetics Radiation, Ionizing Calcium-Binding Proteins - metabolism Cell Survival - drug effects Mitochondrial Membrane Transport Proteins - metabolism Mitochondria - metabolism Cell Survival - radiation effects Algorithms Breast Neoplasms - pathology Calcium Channels - chemistry Cell Line, Tumor HeLa Cells Calcium-Binding Proteins - genetics RNA, Small Interfering - metabolism

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