Isolation and characterization of cytotoxic and insulin-releasing components from the venom of the black-necked spitting cobra Naja nigricollis (Elapidae)

Four peptides with cytotoxic activity against BRIN-BD11 rat clonal β-cells were purified from the venom of the black-necked spitting cobra Naja nigricollis using reversed-phase HPLC. The peptides were identified as members of the three-finger superfamily of snake toxins by ESI-MS/MS sequencing of tryptic peptides. The most potent peptide (cytotoxin-1N) showed strong cytotoxic activity against three human tumour-derived cell lines (LC50 = 0.8 ± 0. 2 µM for A549 non-small cell lung adenocarcinoma cells; LC50 = 7 ± 1 µM for MDA-MB-231 breast adenocarcinoma cells; and LC50 = 9 ± 1 µM for HT-29 colorectal adenocarcinoma cells). However, all the peptides were to varying degrees cytotoxic against HUVEC human umbilical vein endothelial cells (LC50 in the range 2-22 µM) and cytotoxin-2N was moderately hemolytic (LC50 = 45 ± 3 µM against mouse erythrocytes). The lack of differential activity against cells derived from non-neoplastic tissue limits their potential for development into anti-cancer agents. In addition, two proteins in the venom, identified as isoforms of phospholipase A2, effectively stimulated insulin release from BRIN-BD11 cells (an approximately 6-fold increase in rate compared with 5.6 mM glucose alone) at a concentration (1 µM) that was not cytotoxic to the cells suggesting possible application in therapy for Type 2 diabetes

Carnosol induces ROS-mediated beclin1-independent autophagy and apoptosis in triple negative breast cancer

Background: In this study we investigated the in vitro and in vivo anticancer effect of carnosol, a naturally occurring polyphenol, in triple negative breast cancer.Results: We found that carnosol significantly inhibited the viability and colony growth induced G2 arrest in the triple negative MDA-MB-231. Blockade of the cell cycle was associated with increased p21/WAF1 expression and downregulation of p27. Interestingly, carnosol was found to induce beclin1-independent autophagy and apoptosis in MDA-MB-231 cells. The coexistence of both events, autophagy and apoptosis, was confirmed by electron micrography. Induction of autophagy was found to be an early event, detected within 3 h post-treatment, which subsequently led to apoptosis. Carnosol treatment also caused a dose-dependent increase in the levels of phosphorylated extracellular signal-regulated kinase 1 and 2 (pERK1/2). Moreover, we show that carnosol induced DNA damage, reduced the mitochondrial potential and triggered the activation of the intrinsic and extrinsic apoptotic pathway. Furthermore, we found that carnosol induced a dose-dependent generation of reactive oxygen species (ROS) and inhibition of ROS by tiron, a ROS scavenger, blocked the induction of autophagy and apoptosis and attenuated DNA damage. To our knowledge, this is the first report to identify the induction of autophagy by carnosol.Conclusion: In conclusion our findings provide strong evidence that carnosol may be an alternative therapeutic candidate against the aggressive form of breast cancer and hence deserves more exploration.Scopu

Multifunctional host-defense peptides isolated from skin secretions of the banana tree dwelling frog Boana platanera (Hylidae; Hylinae)

Five host-defense peptides (figainin 2PL, hylin PL, raniseptin PL, plasticin PL, and peptide YL) were isolated from norepinephrine-stimulated skin secretions of the banana tree dwelling frog Boana platanera (Hylidae; Hylinae) collected in Trinidad. Raniseptin PL (GVFDTVKKIGKAVGKFALGVAKNYLNS.NH 2) and figainin 2PL (FLGTVLKLGKAIAKTVVPMLTNAMQPKQ. NH 2) showed potent and rapid bactericidal activity against a range of clinically relevant Gram-positive and Gram-negative ESKAPE + pathogens and Clostridioides difficile. The peptides also showed potent cytotoxic activity (LC 50 values &lt; 30 μM) against A549, MDA-MB-231 and HT29 human tumor-derived cell lines but appreciably lower hemolytic activity against mouse erythrocytes (LC 50 = 262 ± 14 μM for raniseptin PL and 157 ± 16 μM for figainin 2PL). Hylin PL (FLGLIPALAGAIGNLIK.NH 2) showed relatively weak activity against microorganisms but was more hemolytic. The glycine-leucine-rich peptide with structural similarity to the plasticins (GLLSTVGGLVGGLLNNLGL.NH 2) and the non-cytotoxic peptide YL (YVPGVIESLL.NH 2) lacked antimicrobial and cytotoxic activities. Hylin PL, raniseptinPL and peptide YL stimulated the rate of release of insulin from BRIN-BD11 clonal β-cells at concentrations ≥100 nM. Peptide YL was the most effective (2.3-fold increase compared with basal rate at 1 μM concentration) and may represent a template for the design of a new class of incretin-based anti-diabetic drugs.</p

Thymoquinone inhibits tumor growth and induces apoptosis in a breast cancer xenograft mouse model: The role of p38 MAPK and ROS

Due to narrow therapeutic window of cancer therapeutic agents and the development of resistance against these agents, there is a need to discover novel agents to treat breast cancer. The antitumor activities of thymoquinone (TQ), a compound isolated from Nigella sativa oil, were investigated in breast carcinoma in vitro and in vivo. Cell responses after TQ treatment were assessed by using different assays including MTT assay, annexin V-propidium iodide staining, Mitosox staining and Western blot. The antitumor effect was studied by breast tumor xenograft mouse model, and the tumor tissues were examined by histology and immunohistochemistry. The level of antioxidant enzymes/molecules in mouse liver tissues was measured by commercial kits. Here, we show that TQ induced p38 phosphorylation and ROS production in breast cancer cells. These inductions were found to be responsible for TQ’s anti-proliferative and pro-apoptotic effects. Moreover, TQ-induced ROS production regulated p38 phosphorylation but not vice versa. TQ treatment was found to suppress the tumor growth and this effect was further enhanced by combination with doxorubicin. TQ also inhibited the protein expression of anti-apoptotic genes, such as XIAP, survivin, Bcl-xL and Bcl-2, in breast cancer cells and breast tumor xenograft. Reduced Ki67 and increased TUNEL staining were observed in TQ-treated tumors. TQ was also found to increase the level of catalase, superoxide dismutase and glutathione in mouse liver tissues. Overall, our results demonstrated that the antiproliferative and pro-apoptotic effects of TQ in breast cancer are mediated through p38 phosphorylation via ROS generation

Leptin and leptin receptor polymorphisms are associated with increased risk and poor prognosis of breast carcinoma

BACKGROUND: Leptin (LEP) has been consistently associated with angiogenesis and tumor growth. Leptin exerts its physiological action through its specific receptor (LEPR). We have investigated whether genetic variations in LEP and LEPR have implications for susceptibility to and prognosis in breast carcinoma. METHODS: We used the polymerase chain reaction and restriction enzyme digestion to characterize the variation of the LEP and LEPR genes in 308 unrelated Tunisian patients with breast carcinoma and 222 healthy control subjects. Associations of the clinicopathologic parameters and these genetic markers with the rates of the breast carcinoma-specific overall survival (OVS) and the disease free survival (DFS) were assessed using univariate and multivariate analyses. RESULTS: A significantly increased risk of breast carcinoma was associated with heterozygous LEP (-2548) GA (OR = 1.45; P = 0.04) and homozygous LEP (-2548) AA (OR = 3.17; P = 0.001) variants. A highly significant association was found between the heterozygous LEPR 223QR genotype (OR = 1.68; P = 0.007) or homozygous LEPR 223RR genotype (OR = 2.26; P = 0.001) and breast carcinoma. Moreover, the presence of the LEP (-2548) A allele showed a significant association with decreased disease-free survival in breast carcinoma patients, and the presence of the LEPR 223R allele showed a significant association with decreased overall survival. CONCLUSION: Our results indicated that the polymorphisms in LEP and LEPR genes are associated with increased breast cancer risk as well as disease progress, supporting our hypothesis for leptin involvement in cancer pathogenesis