Tetrazolium violet induced apoptosis and cell cycle arrest in human lung cancer a549 cells

Polyphosphate Reverses the Toxicity of the Quasi-Enzyme Bleomycin on Alveolar Endothelial Lung Cells In Vitro

The anti-cancer antitumor antibiotic bleomycin(s) (BLM) induces athyminic sites in DNA after its activation, a process that results in strand splitting. Here, using A549 human lung cells or BEAS-2B cells lunc cells, we show that the cell toxicity of BLM can be suppressed by addition of inorganic polyphosphate (polyP), a physiological polymer that accumulates and is released from platelets. BLM at a concentration of 20 µg ml^-1 causes a decrease in cell viability (by ~70%), accompanied by an increased DNA damage and chromatin expansion (by amazingly 6-fold). Importantly, the BLM-caused effects on cell growth and DNA integrity are substantially suppressed by polyP. In parallel, the enlargement of the nuclei/chromatin in BLM-treated cells (diameter, 20-25 µm) is normalized to ~12 µm after co-incubation of the cells with BLM and polyP. A sequential application of the drugs (BLM for 3 days, followed by an exposure to polyP) does not cause this normalization. During co-incubation of BLM with polyP the gene for the BLM hydrolase is upregulated. It is concluded that by upregulating this enzyme polyP prevents the toxic side effects of BLM. These data might also contribute to an application of BLM in COVID-19 patients, since polyP inhibits binding of SARS-CoV-2 to cellular ACE2.

Anti-proliferative and apoptosis-inducing effects of matricin on human non-small cell lung cancer H1299 cells via MAPK pathway activation

Lung cancer in humans is majorly represented by non-small cell lung cancer cells, and there is a constant search for an efficient therapeutic approach. This study aims to find the anti-proliferative and apoptotic effects of matricin on H1299 cells via activation of MAPK pathway. Non-small cell H1299 cells were subjected to viability analysis with MTT assay and anti-proliferation analysis with different concentrations of matricin. Apoptosis was determined with annexin V/propidium iodide (PI) and flow cytometric analysis. Analysis of oxidative stress markers, reduced glutathione, lipid peroxidation (LPO), superoxide dismutase (SOD), and catalase (CAT) activities were done using standard assay kits. Apoptosis enzymes caspase-3, caspase-8, and caspase-9 levels were measured using colorimetric kit analysis. Western blot analysis on apoptotic proteins was performed to determine the involvement of MAPK pathway activation in apoptosis. Matricin significantly ( P < 0.01) exerted anti-proliferative activities on H1299 cells in a dose-dependent manner. Flow cytometric apoptosis analysis showed increasing concentrations of matricin had increased apoptosis ( P < 0.01) in the H1299 cells. Levels of oxidative stress markers were altered significantly ( P < 0.01) by matricin. Caspase-3, caspase-8, and caspase-9 levels were significantly increased ( P < 0.01) in matricin-treated H1299 cells. Western blot analysis showed decreased expression of anti-apoptotic Bcl-2, increased expressions of Bax and phosphorylated JNK, ERK 1/2, and p-38 MAPK proteins in matricin-treated H1299 cells. Matricin has significant anti-proliferative and apoptosis-inducing effects via activation of MAPK pathway in non-small cell lung cancer cells.

Impaired autophagy contributes to hepatocellular damage during ischemia/reperfusion: heme oxygenase-1 as a possible regulator

Liver ischemia and reperfusion (I/R) injury is characterized by oxidative stress that is accompanied by alterations of the endogenous defensive system. Emerging evidence suggests a protective role for autophagy induced by multiple stressors including reactive oxygen species. Meanwhile, heme oxygenase-1 (HO-1) has long been implicated in cytoprotection against oxidative stress in vitro and in vivo. Therefore, we investigated the impact of autophagy in the pathogenesis of liver I/R and its molecular mechanisms, particularly its linkage to HO-1. By using transmission electron microscopic analysis and biochemical autophagic flux assays with microtubule-associated protein 1 light chain 3-II, and beclin-1, representative autophagy markers, and p62, a selective substrate for autophagy, we found that reperfusion reduced autophagy both in the rat liver and in primary cultured hepatocytes. When autophagy was further inhibited with chloroquine or wortmannin, I/R-induced hepatocellular injury was aggravated. While livers that underwent I/R showed increased levels of mammalian target of rapamaycin and calpain 1 and 2, inhibition of calpain 1 and 2 induced an autophagic response in hepatocytes subjected to hypoxia/reoxygenation. HO-1 increased autophagy, and HO-1 reduced I/R-induced calcium overload in hepatocytes and prevented calpain 2 activation both in vivo and in vitro. Taken together, these findings suggest that the impaired autophagy during liver I/R, which is mediated by calcium overload and calpain activation, contributes to hepatocellular damage and the HO-1 system protects the liver from I/R injury through enhancing autophagy.

Activation of protein kinase C delta reduces hepatocellular damage in ischemic preconditioned rat liver

BACKGROUND

Liver ischemic preconditioning (IPC), pre-exposure of the liver to transient ischemia, has been applied as a useful surgical method to prevent liver ischemia and reperfusion (I/R) injury. Although activation of protein kinase C (PKC), especially novel PKCs, has been known as central signaling responsible for the liver protection of IPC, determination of the involved isozyme in strong protection afforded by IPC has not been elucidated.

MATERIALS AND METHODS

Rats were subjected to 90 min of partial liver ischemia followed by 3, 6, and 24 h of reperfusion. IPC was induced by 10 min of ischemia after 10 min of reperfusion before sustained ischemia. Rottlerin, a PKC-δ selective inhibitor; PKC-εV1-2 peptide, a selective PKC-ε inhibitor; and 3,7-dimethyl-1-[2-propargyl] xanthine, an adenosine A2 receptor antagonist, were intravenously injected before IPC. N-acetyl-L-cysteine, a strong antioxidant, and Nω-nitro-L-arginine methyl ester, a nonselective nitric oxide synthase inhibitor, were injected intraperitoneally before IPC.

RESULTS

IPC resulted in strong protection against liver I/R injury as evidenced by biochemical and histologic analyses. Inhibition of PKC-δ strongly attenuated the IPC-induced liver protection, whereas PKC-ε inhibition did not exert any effect on IPC-induced protection. Although inhibition of reactive oxygen species, adenosine, and nitric oxide attenuated the beneficial effects of IPC, inhibition of adenosine only attenuated PKC-δ and -ε translocation.

CONCLUSIONS

Our findings suggest that IPC protects against I/R-induced hepatic injury through activation of PKC-δ.

Cytotoxic effect of clerosterol isolated from Codium fragile on A2058 human melanoma cells

The cytotoxic effects and mechanism of action of clerosterol, isolated from the marine alga Codium fragile, were investigated in A2058 human melanoma cells. Clerosterol inhibited the growth of A2058 cells with an IC(50) of 150 µM and induced apoptotic cell death, as evidenced by DNA fragmentation, an increase in the number of sub-G(1) hypodiploid cells and the presence of apoptotic bodies. Clerosterol treatment caused the loss of mitochondrial membrane potential. Alterations in the expression of apoptosis-associated proteins in response to clerosterol treatment included upregulation of Bax, downregulation of Bcl-2 and activation of caspases 3 and 9. The pan-caspase inhibitor treatment attenuated the expression of the active form of caspases and cell death induced by clerosterol. The present results show that clerosterol exerts its cytotoxic effect in A2058 human melanoma cells by caspases-dependent apoptosis.