Targeting Mitochondrial DNA Transcription by POLRMT Inhibition or Depletion as a Potential Strategy for Cancer Treatment

Mitochondria transcription and cancer

Mitochondria are major organelles involved in several processes related to energy supply, metabolism, and cell proliferation. The mitochondria function is transcriptionally regulated by mitochondria DNA (mtDNA), which encodes the key proteins in the electron transport chain that is indispensable for oxidative phosphorylation (OXPHOS). Mitochondrial transcriptional abnormalities are closely related to a variety of human diseases, such as cardiovascular diseases, and diabetes. The mitochondria transcription is regulated by the mtDNA, mitochondrial RNA polymerase (POLRMT), two transcription factors (TFAM and TF2BM), one transcription elongation (TEFM), and one known transcription termination factor (mTERFs). Dysregulation of these factors directly leads to altered expression of mtDNA in tumor cells, resulting in cellular metabolic reprogramming and mitochondrial dysfunction. This dysregulation plays a role in modulating tumor progression. Therefore, understanding the role of mitochondrial transcription in cancer can have implications for cancer diagnosis, prognosis, and treatment. Targeting mitochondrial transcription or related pathways may provide potential therapeutic strategies for cancer treatment. Additionally, assessing mitochondrial transcriptional profiles or biomarkers in cancer cells or patient samples may offer diagnostic or prognostic information.

Current strategic trends in drug discovery: the present as prologue

INTRODUCTION

Escalating costs and inherent uncertainties associated with drug discovery invite initiatives to improve its efficiency and de-risk campaigns for inventing better therapeutics. One such initiative involves recognizing and exploiting current approaches in therapeutics invention with molecular mechanisms of action that hold promise for designing and targeting new chemical entities as drugs.

AREAS COVERED

This perspective considers the current contextual framework around three drug-discovery approaches and evaluates their potential to help identify new targets/modalities in small-molecule molecular pharmacology: diversifying ligand-directed phenotypes for G protein-coupled receptor (GPCR) pharmacotherapeutic signaling; developing therapeutic-protein degraders and stabilizers for proximity-inducing pharmacology; and mining organelle biology for druggable therapeutic targets.

EXPERT OPINION

The contemporary drug-discovery approaches examined appear generalizable and versatile to have applications in therapeutics invention beyond those case studies discussed herein. Accordingly, they may be considered strategic trends worthy of note in advancing the field toward novel ways of addressing pharmacotherapeutically unmet medical needs.

CHEK2 knockout is a therapeutic target for TP53-mutated hepatocellular carcinoma

Currently, there is still a lack of novel and effective drug targets to improve the prognosis of hepatocellular carcinoma (HCC). Additionally, the role of CHEK2 in HCC has not been reported yet. The eQTLgen database and two HCC Genome-Wide Association Study (GWAS) datasets (ieu-b-4953, ICD10 C22.0) were used to find the drug target: CHEK2. Next, Colony, Edu, β-gal, and cell cycle analysis were facilitated to evaluate the role of CHEK2 knockout in HCC. In addition, Nultin-3 was added to evaluate the apoptosis of TP53-mutated HCC cells with CHEK2 knockout. Furthermore, MitoSox, electron microscopy, mitochondrial ATP, and NADH+/NADH levels were assessed in the CHEK2 knockout HCC cells with or without Metformin. Finally, cell-derived tumor xenograft was used to evaluate the role of CHEK2 knockout in vivo. We initially identified a potential drug target, CHEK2, through GWAS data analysis. Furthermore, we observed a significant upregulation of CHEK2 expression in HCC, which was found to be correlated with a poor prognosis. Subsequently, the results indicated that knocking out CHEK2 selectively affects the proliferation, cell cycle, senescence, and apoptosis of TP53-mutant HCC cells. Additionally, the introduction of Nultin-3 further intensified the functional impact on TP53-mutant cells. Then ClusterProfiler results showed high CHEK2 and TP53 mutation group was positively enriched in the mitochondrial ATP pathway. Then we used MitoSox, electron microscopy, mitochondrial ATP, and NADH + /NADH assay and found knockout of CHECK could induce the ATP pathway to inhibit the growth of HCC. Our research introduces a novel drug target for TP53-mutant HCC cells via mitochondrial ATP, addressing the limitation of Nultin-3 as a standalone treatment that does not induce tumor cell death.