VDAC1 as a target in cisplatin anti-tumor activity through promoting mitochondria fusion

Cannabidiol protects C2C12 myotubes against cisplatin-induced atrophy by regulating oxidative stress

Cancer and chemotherapy induce a severe loss of muscle mass (known as cachexia), which negatively impact cancer treatment and patient survival. The aim of the present study was to investigate whether cannabidiol (CBD) administration may potentially antagonize the effects of cisplatin in inducing muscle atrophy, using a model of myotubes in culture. Cisplatin treatment resulted in a reduction of myotube diameter (15.7 ± 0.3 vs. 22.2 ± 0.5 µm, P < 0.01) that was restored to control level with 5 µM CBD (20.1 ± 0.4 µM, P < 0.01). Protein homeostasis was severely altered with a ≈70% reduction in protein synthesis (P < 0.01) and a twofold increase in proteolysis (P < 0.05) in response to cisplatin. Both parameters were dose dependently restored by CBD cotreatment. Cisplatin treatment was associated with increased thiobarbituric acid reactive substances (TBARS) content (0.21 ± 0.03 to 0.48 ± 0.03 nmol/mg prot, P < 0.05), catalase activity (0.24 ± 0.01 vs. 0.13 ± 0.02 nmol/min/µg prot, P < 0.01), whereas CBD cotreatment normalized TBARS content to control values (0.22 ± 0.01 nmol/mg prot, P < 0.01) and reduced catalase activity (0.17 ± 0.01 nmol/min/µg prot, P < 0.05). These changes were associated with increased mRNA expression of GPX1, SOD1, SOD2, and CAT mRNA expression in response to cisplatin (P < 0.01), which was corrected by CBD cotreatment (P < 0.05). Finally, cisplatin treatment increased the mitochondrial protein content of NDUFB8, UQCRC2, COX4, and VDAC1 (involved in mitochondrial respiration and apoptosis), and CBD cotreatment restored their expression to control values. Altogether, our results demonstrated that CBD antagonize the cisplatin-induced C2C12 myotube atrophy and could be used as an adjuvant in the treatment of cancer cachexia to help maintain muscle mass and improve patient quality of life.NEW & NOTEWORTHY In an in vitro model, cisplatin treatment led to myotube atrophy associated with dysregulation of protein homeostasis and increased oxidative stress, resulting in increased apoptosis. Cotreatment with cannabidiol was able to prevent this phenotype by promoting protein homeostasis and reducing oxidative stress.

Mitochondrial Calcium Uniporter (MCU) that Modulates Mitochondrial Calcium Uptake and Facilitates Endometrial Cancer Progression through Interaction with VDAC1

BACKGROUND

Although endometrial cancer represents a frequently diagnosed malignancy of the female reproductive tract, we know very little about the factors that control endometrial cancer.

OBJECTIVE

Our study was presented to investigate the function of MCU in endometrial tumorigenesis and the molecular mechanisms involved.

MATERIALS AND METHODS

A total of 94 endometrial cancer patients were recruited into our cohort. MCU and VDAC1 expression was examined in tumor and normal tissues via immunohistochemistry and immunofluorescence. Associations of MCU and VDAC1 expression with clinicopathological characteristics were evaluated. After transfection with shRNA targeting MCU or full-length MCU plasmids, clone formation, wound healing, transwell and MitoTracker Red staining were separately presented in Ishikawa and RL95-2 cells. Moreover, Western blotting or immunofluorescence was utilized to examine the expression of MCU, VDAC1, Na+/Ca2+/Li+ exchanger (NCLX), and β-catenin under VDAC1 knockdown and/or MCU overexpression or knockdown.

RESULTS

MCU and VDAC1 expression were prominently up-regulated in endometrial cancer tissues and were significantly associated with histological grade, depth of myometrial invasion and lymph node status. MCU up-regulation enhanced clone formation, migration, and mitochondrial activity of endometrial cancer cells. The opposite results were investigated when MCU was silenced. MCU or VDAC1 silencing reduced the expression of MCU, VDAC1, NCLX, and β-catenin. Moreover, VDAC1 knockdown alleviated the promoting effect of MCU overexpression on the above proteins.

CONCLUSION

This investigation demonstrated that MCU-induced mitochondrial calcium uptake plays a critical role in endometrial tumorigenesis through interaction with VDAC1.

VDAC1 Protein Regulation of Oxidative Damage and Mitochondrial Dysfunction-Mediated Cytotoxicity by Silica Nanoparticles in SH-SY5Y Cells

Silica nanoparticles (SiNPs) have been widely used in industry, electronics, and pharmaceutical industries. In addition, it is also widely used in medicine, tumor treatment and diagnosis, as well as other biomedical and biotechnology fields. The opportunities for people to contact SiNPs through iatrogenic, occupational, and environmental exposures are gradually increasing. The damage and biological effects of SiNPs on the nervous system have attracted widespread attention in the field of toxicology. Central nerve cells are rich in mitochondria. It is suggested that the effects of SiNPs on mitochondrial damage of nerve cells may involve the maintenance of neuronal membrane potential, the synthesis and operation of neurotransmitters, and the transmission of nerve pulses, and so on. We established an experimental model of SH-SY5Y cells to detect the cell survival rate, apoptosis, changes of reactive oxygen species and mitochondrial membrane potential, and the expression of mitochondrial function-related enzymes and proteins, so as to reveal the possible mechanism of SiNPs on neuronal mitochondrial damage. It was found that SiNPs could cause oxidative damage to cells and mitochondria, destroy some normal functions of mitochondria, and induce apoptosis in SH-SY5Y cells. The voltage-dependent anion channel 1(VDAC1) protein inhibitor DIDS could effectively reduce intracellular oxidative stress, such as the reduction of ROS content, and could also usefully restore some functional proteins of mitochondria to normal levels. The inhibition of VDAC1 protein may play an important role in the oxidative damage and dysfunction of neuronal mitochondria induced by SiNPs.

The transcription factor c-Jun inhibits RBM39 to reprogram pre-mRNA splicing during genotoxic stress

Genotoxic agents, that are used in cancer therapy, elicit the reprogramming of the transcriptome of cancer cells. These changes reflect the cellular response to stress and underlie some of the mechanisms leading to drug resistance. Here, we profiled genome-wide changes in pre-mRNA splicing induced by cisplatin in breast cancer cells. Among the set of cisplatin-induced alternative splicing events we focused on COASY, a gene encoding a mitochondrial enzyme involved in coenzyme A biosynthesis. Treatment with cisplatin induces the production of a short isoform of COASY lacking exons 4 and 5, whose depletion impedes mitochondrial function and decreases sensitivity to cisplatin. We identified RBM39 as a major effector of the cisplatin-induced effect on COASY splicing. RBM39 also controls a genome-wide set of alternative splicing events partially overlapping with the cisplatin-mediated ones. Unexpectedly, inactivation of RBM39 in response to cisplatin involves its interaction with the AP-1 family transcription factor c-Jun that prevents RBM39 binding to pre-mRNA. Our findings therefore uncover a novel cisplatin-induced interaction between a splicing regulator and a transcription factor that has a global impact on alternative splicing and contributes to drug resistance.

VDAC1 oligomerization may enhance DDP-induced hepatocyte apoptosis by exacerbating oxidative stress and mitochondrial DNA damage

Cisplatin (DDP)‐based chemotherapy is a preferred treatment for a broad spectrum of cancers, but the precise mechanisms of its hepatotoxicity are not yet clear. Recently, the role of voltage‐dependent anion channel protein 1 (VDAC1) in mitochondrial activity and cell apoptosis has attracted much attention. Our aim was to investigate the effects of mitochondrial outer membrane protein VDAC1 oligomerization in DDP‐induced hepatocyte apoptosis. L‐02 hepatocytes were divided into 4 groups: (a) control group, (b) 4,4'diisothiocyanate‐2,2'‐disulfonic acid (DIDS; 40 μm) group, (c) DDP (5 μm) group, and (d) DDP and DIDS combination group. Cell apoptosis was tested by Annexin V/FITC assay, protein expression of caspase‐3, γH2AX and NDUFB6 were observed by western blot assay, reactive oxygen species (ROS), and mitochondrial superoxide anion radical (O₂^•−) were detected by DCFH‐DA and MitoSOX probe, and DNA damage was assessed by comet assay. Moreover, the activity of mitochondrial respiratory chain complex I was determined by the colorimetry method. Compared with the control group, apoptosis rate and activated cleaved‐caspase‐3 protein, ROS and O₂^•− generation, DNA damage marker comet tail length, and γH2AX protein level increased in the DDP treatment group (P < 0.05). Activity of mitochondrial COXI decreased after DDP treatment (P < 0.05). DIDS, as a VDAC1 oligomerization inhibitor, antagonized DDP‐induced apoptosis by diminishing oxidative stress and DNA damage and protecting mitochondrial complex protein. These results show that VDAC1 oligomerization may play an important role in DDP‐induced hepatocyte apoptosis by increasing ROS and mtDNA leakage from VDAC1 pores, exacerbating oxidative stress and mtDNA damage.