Induction of protective autophagy against apoptosis in HepG2 cells by isoniazid independent of the p38 signaling pathway

Recent advances in research of modes of hepatocyte death in anti-tuberculosis drug-induced liver injury

Antituberculosis drug-induced liver injury (ATB-DILI) is the most common and most serious side effect of antituberculous drug therapy, which brings great challenges to drug treatment of tuberculosis. Isoniazid and rifampicin as first-line anti-tuberculosis drugs produce a variety of toxic metabolites that directly cause liver cell necrosis, and a large amount of free radicals that induce oxidative stress, leading to programmed death of liver cells such as apoptosis, ferroptosis, and autophagy. Iron death is a recently discovered mode of cell death, and its role in ATB-DILI has not been fully elucidated. Blocking the pathway of hepatocyte death is an important means to treat ATB-DILI. In this paper, we discuss the mechanism and characteristics of different cell death modes in order to help identify new diagnostic markers and therapeutic drug targets.

GPRC5A Is a Negative Regulator of the Pro-Survival PI3K/Akt Signaling Pathway in Triple-Negative Breast Cancer

Breast cancer is one of the most common types of malignancy worldwide; however, its underlying mechanisms remain unclear. In the present study, we investigated the roles of G-protein-coupled receptor family C, member 5, group A (GPRC5A) in cell apoptosis in triple-negative breast cancer (TNBC). The expression of GPRC5A in breast cancer cell lines was detected by real time PCR and western blot. And the results suggested that GPRC5A was downregulated in breast cancer cell lines compared to normal breast epithelial cell lines. Additionally, the expression of GPRC5A in TCGA database was analyzed in silico. GPRC5A exhibited the lowest expression levels in TNBC compared to ER⁺ and HER2⁺ breast cancer. Overexpression of GPRC5A in MDA-MB-231 and MDA-MB-468 cells promoted apoptosis, whereas depletion of GPRC5A in T47D and MCF7 cells inhibited cell apoptosis via the intrinsic apoptotic pathway. We performed RNA-sequencing in GPRC5A overexpressed MDA-MB-231 and the control cells. The results facilitated the identification of a number of signaling pathways involved in this process, and the PI3K/Akt signaling pathway was found to be one the most important. A specific activator of the PI3K/Akt signaling pathway inhibited apoptosis of breast cancer cells, whereas cotreatment of this activator with a GPRC5A-expressing plasmid reduced this effect. Similarly, a specific inhibitor of the PI3K/Akt signaling pathway increased cell apoptosis by activating caspase-3 and caspase-9, whereas co-incubation of the inhibitor with a short hairpin RNA targeting GPRC5A significantly reduced the cell apoptotic rate. Additionally, the overexpression of GPRC5A suppressed tumor growth by inducing cell apoptosis in vivo. Taken together, the present study identified GPRC5A as a protective factor against the progression of human triple-negative breast cancer by increasing cell apoptosis via the regulation of the PI3K/Akt signaling pathway.

Mitochondrial dysfunction, autophagy stimulation and non-apoptotic cell death caused by nitric oxide-inducing Pt-coated Au nanoparticle in human lung carcinoma cells

BACKGROUND

Reactive oxygen species (ROS)-mediated cancer therapeutic has been at higher appreciation than those mediated by reactive nitrogen species. Cytotoxic mechanism of a novel nitric oxide (NO) inducing-Pt coated Au nanoparticle (NP) has been comparatively studied with the well-established ROS inducing Pt-based anticancer drug cisplatin in human lung A549 carcinoma cells.

METHODS

Cytotoxicity was evaluated by MTT assay, lactate dehydrogenase (LDH) release, thiobarbituric acid substances (TBARS) and C11-Boron dipyrromethene (BODIPY). ROS (O^2·- and H₂O₂) was measured with dihydroethidium (DHE) and H₂O₂-specific sensor. Nitric oxide (NO) and mitochondrial dysfunction were evaluated respectively by NO-specific probe DAR-1 and JC-1. Autophagy was determined by lysotracker (LTR) and monodansylcadaverine (MDC) applied tandemly whereas apoptosis/necrosis by Hoechst/PI and caspase 3 activity.

RESULTS

IC50 (concentration that inhibited cell viability by 50%) of Pt coated Au NP came to be 0.413 μM whereas IC50 of cisplatin came out to 86.5 μM in A549 cells treated for 24 h meaning NPs toxicity was over 200 times higher than cisplatin. However, no significant stimulation of intracellular ROS was observed at the IC50 of Pt coated Au NPs in A549 cells. However, markers like LDH release, TBARS, BODIPY and ROS were significantly higher due to cisplatin in comparison to Pt coated Au NP.

CONCLUSIONS

Pt coated Au NP caused NO-dependent mitochondrial dysfunction and autophagy. Mode of cell death due to NP was much different from ROS-inducing cisplatin.

GENERAL SIGNIFICANCE

Pt coated Au NP offer promising opportunity in cancer therapeutic and warrants advanced study in vivo models of cancer.

Hydroxysafflor yellow A suppresses angiogenesis of hepatocellular carcinoma through inhibition of p38 MAPK phosphorylation

The antitumor effect of hydroxysafflor yellow A (HSYA), an active ingredient of the herb Carthamus tinctorius L. (Asteraceae) (safflower), was investigated in the current work. Researches of HSYA on vasculogenesis inhibition, along with the related molecular mechanisms, including the expression of MMP-2, MMP-9, and p38MAPK (COX-2, ATF-2, p-p38MAPK, and p38MAPK) signaling pathway in H22 tumor-bearing mice or HepG2 cells were performed. The animal experiments proved the level of MMP-2 and MMP-9 in H22-transplanted tumor tissue in mice markedly decreased by HSYA, and results both in vivo and in vitro confirmed that COX-2 expression was reduced significantly via p38MAPK|ATF-2 signaling pathway. According to the outcomes, HSYA suppressed p38MAPK phosphorylation in a concentration-dependent manner, while exerting no effect on the total p38MAPK protein expression. It was also showed that suppression of p38 activation by SB203580 decreased the HepG2 cell viability, proliferation, and migration, wherein HSYA exhibited a similar effect. Furthermore, Western blot analysis on caspase-3 and cleaved-caspase-3 revealed that HSYA could induce apoptosis of HepG2 cells. These findings provided experimental evidences that HSYA might be a promising anticancer agent for HCC.