Mitochondrial DNA variations in tongue squamous cell carcinoma

The Uprising of Mitochondrial DNA Biomarker in Cancer

Cancer is a heterogeneous group of diseases, the progression of which demands an accumulation of genetic mutations and epigenetic alterations of the human nuclear genome or possibly in the mitochondrial genome as well. Despite modern diagnostic and therapeutic approaches to battle cancer, there are still serious concerns about the increase in death from cancer globally. Recently, a growing number of researchers have extensively focused on the burgeoning area of biomarkers development research, especially in noninvasive early cancer detection. Intergenomic cross talk has triggered researchers to expand their studies from nuclear genome-based cancer researches, shifting into the mitochondria-mediated associations with carcinogenesis. Thus, it leads to the discoveries of established and potential mitochondrial biomarkers with high specificity and sensitivity. The research field of mitochondrial DNA (mtDNA) biomarkers has the great potential to confer vast benefits for cancer therapeutics and patients in the future. This review seeks to summarize the comprehensive insights of nuclear genome cancer biomarkers and their usage in clinical practices, the intergenomic cross talk researches that linked mitochondrial dysfunction to carcinogenesis, and the current progress of mitochondrial cancer biomarker studies and development.

Artesunate targets oral tongue squamous cell carcinoma via mitochondrial dysfunction-dependent oxidative damage and Akt/AMPK/mTOR inhibition

Although mitochondrial metabolism has recently gained attention as a promising therapeutic strategy in cancer, little is known on the impact of mitochondrial respiration inhibition on oral tongue squamous cell carcinoma (OTSCC). Using in vitro and in vivo OTSCC models, our work demonstrates that inducing mitochondrial dysfunction by anti-malarial drug artesunate is effective in targeting OTSCC stem-cell like and bulk cells. Artesunate inhibits anchorage-independent colony formation, proliferation and survival in all tested OTSCC cell lines although with varying efficacy. Artesunate displays preferential anti-OTSCC activity by sparing normal cells. Mechanism analysis indicates that artesunate inhibits mitochondrial respiration via suppressing mitochondrial complex I and II but not IV or V, resulting in oxidative stress and damage. Interestingly, OTSCC cells that are more sensitive to artesunate have higher level of basal mitochondrial respiration and reversed respiratory capacity compared to those with less sensitivity to artesunate, suggesting the varying dependence on mitochondrial respiration among OTSCC cell lines. In addition, artesunate induces oxidative stress and damage in cells with low sensitivity to a less extent than in those with high sensitivity. We confirm that mitochondrial respiration inhibition is required for the action of artesunate in OTSCC. Mitochondrial dysfunction by artesunate further activates AMPK and suppresses Akt/mTOR. Importantly, the in vitro observations are reproducible in vivo OTSCC xenograft mouse model. Our findings provide pre-clinical evidence on the efficacy of artesunate and emphasize the therapeutic value of targeting mitochondrial respiration in OTSCC.

Mitochondrion: I am more than a fuel server

Apart from reliable management of the "powerhouse" of the cell, mitochondria faithfully orchestrate a diverse array of important and critical functions in governing cellular signaling, apoptosis, autophagy, mitophagy and innate and adaptive immune system. Introduction of instability and imbalance in the mitochondrial own genome or the nuclear encoded mitochondrial proteome would result in the manifestation of various diseases through alterations in the oxidative phosphorylation system (OXPHOS) and nuclear-mitochondria retrograde signaling. Understanding mitochondrial biology and dynamism are thus of paramount importance to develop strategies to prevent or treat various diseases caused due to mitochondrial alterations.