astaxanthine and Mouth-Neoplasms

Aberrant activation of the PI3K/Akt signalling pathway, a major driving force of diverse cellular processes has been implicated in tumour development and progression. Here, we report that astaxanthin (AXT), a potent antioxidant ketocarotenoid prevents cancer hallmarks by inhibiting PI3K/Akt and the associated downstream NF-κB and STAT-3 signalling pathways in SCC131 and SCC4 oral cancer cells as well as in the hamster buccal pouch carcinogenesis model. Using small molecule inhibitors of NF-κB, STAT-3 and PI3K and by overexpression of PI3K, we provide evidence to show that AXT inhibits NF-κB and STAT-3 signalling and cancer hallmarks by restraining the kinase activity of PI3K/Akt. Additionally, AXT downregulated the noncoding RNAs (ncRNAs), miR-21 and HOTAIR that influence PI3K/Akt signalling emphasising its modulatory effects on epigenetic regulation. Ethyl cellulose-based AXT nanoparticles showed greater chemotherapeutic efficacy in the hamster oral carcinogenesis model compared to native AXT. We suggest that AXT prevents cell proliferation, apoptosis evasion, invasion and angiogenesis by intercepting the crosstalk between the PI3K/Akt, NF-κB and STAT-3 signalling circuits both in vitro and in vivo. Astaxanthin that abrogates the PI3K/Akt signalling axis, a central hub that orchestrates acquisition of cancer hallmarks is a promising candidate for anticancer drug development.

Topics: Apoptosis; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; Epigenesis, Genetic; Gene Expression Regulation, Neoplastic; Humans; Mouth Neoplasms; Neovascularization, Pathologic; NF-kappa B; Phosphatidylinositol 3-Kinases; Phosphorylation; Signal Transduction; STAT3 Transcription Factor; Transcription Factor RelA; Xanthophylls

Identifying agents that inhibit STAT-3, a cytosolic transcription factor involved in the activation of various genes implicated in tumour progression is a promising strategy for cancer chemoprevention. In the present study, we investigated the effect of dietary astaxanthin on JAK-2/STAT-3 signaling in the 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis model by examining the mRNA and protein expression of JAK/STAT-3 and its target genes. Quantitative RT-PCR, immunoblotting and immunohistochemical analyses revealed that astaxanthin supplementation inhibits key events in JAK/STAT signaling especially STAT-3 phosphorylation and subsequent nuclear translocation of STAT-3. Furthermore, astaxanthin downregulated the expression of STAT-3 target genes involved in cell proliferation, invasion and angiogenesis, and reduced microvascular density, thereby preventing tumour progression. Molecular docking analysis confirmed inhibitory effects of astaxanthin on STAT signaling and angiogenesis. Cell culture experiments with the endothelial cell line ECV304 substantiated the role of astaxanthin in suppressing angiogenesis. Taken together, our data provide substantial evidence that dietary astaxanthin prevents the development and progression of HBP carcinomas through the inhibition of JAK-2/STAT-3 signaling and its downstream events. Thus, astaxanthin that functions as a potent inhibitor of tumour development and progression by targeting JAK/STAT signaling may be an ideal candidate for cancer chemoprevention.

Topics: Animals; Cricetinae; Janus Kinases; Male; Mesocricetus; Mouth Neoplasms; Neovascularization, Pathologic; Phosphorylation; Signal Transduction; STAT3 Transcription Factor; Xanthophylls

The oncogenic transcription factors NF-κB and β-catenin, constitutively activated by upstream serine/threonine kinases control several cellular processes implicated in malignant transformation including apoptosis evasion. The aim of this study was to investigate the chemopreventive effects of astaxanthin, an antioxidant carotenoid, in the hamster buccal pouch (HBP) carcinogenesis model based on its ability to modulate NF-κB and Wnt signaling pathways and induce apoptosis.. We determined the effect of dietary supplementation of astaxanthin on the oncogenic signaling pathways - NF-κB and Wnt/β-catenin, their upstream activator kinases - Erk/MAPK and PI-3K/Akt, and the downstream event - apoptosis evasion by real-time quantitative RT-PCR, western blot, and immunohistochemical analyses.. We found that astaxanthin inhibits NF-κB and Wnt signaling by downregulating the key regulatory enzymes IKKβ and GSK-3β. Analysis of gene expression and docking interactions revealed that inhibition of these pathways may be mediated via inactivation of the upstream signaling kinases Erk/Akt by astaxanthin. Astaxanthin also induced caspase-mediated mitochondrial apoptosis by downregulating the expression of antiapoptotic Bcl-2, p-Bad, and survivin and upregulating proapoptotic Bax and Bad, accompanied by efflux of Smac/Diablo and cytochrome-c into the cytosol, and induced cleavage of poly (ADP-ribose) polymerase (PARP).. The results provide compelling evidence that astaxanthin exerts chemopreventive effects by concurrently inhibiting phosphorylation of transcription factors and signaling kinases and inducing intrinsic apoptosis.. Astaxanthin targets key molecules in oncogenic signaling pathways and induces apoptosis and is a promising candidate agent for cancer prevention and therapy.

Topics: Animals; Apoptosis; beta Catenin; Cricetinae; Disease Models, Animal; Male; Mesocricetus; Mitogen-Activated Protein Kinases; Mouth Neoplasms; NF-kappa B; Real-Time Polymerase Chain Reaction; Signal Transduction; Wnt Proteins; Xanthophylls

The chemopreventive effects of two xanthophylls, astaxanthin (AX) and canthaxanthin (CX) on oral carcinogenesis induced by 4-nitroquinoline 1-oxide (4-NQO) was investigated in male F344 rats. Rats were given 20 ppm of 4-NQO in their drinking water for 8 weeks to induce oral neoplasms or preneoplasms. Animals were fed diets containing 100 ppm AX or CX during the initiation or postinitiation phase of 4-NQO-induced oral carcinogenesis. The others contained the groups of rats treated with AX or CX alone and untreated. At the end of the study (week 32), the incidences of preneoplastic lesions and neoplasms in the oral cavity of rats treated with 4-NQO and AX or CX were significantly smaller than those of rats given 4-NQO alone (P < 0.001). In particular, no oral neoplasms developed in rats fed AX and CX during the 4-NQO exposure and in those given CX after the 4-NQO administration. Similarly, the incidences of oral preneoplastic lesions (hyperplasia and dysplasia) in rats treated with 4-NQO and AX or CX were significantly smaller than that of the 4-NQO-alone group (P < 0.05). In addition to such tumor inhibitory potential, dietary exposure of AX or CX decreased cell proliferation activity in the nonlesional squamous epithelium exposed to 4-NQO as revealed by measuring the silver-stained nucleolar organizer regions protein number/nucleus and 5'-bromodeoxyuridine-labeling index. Also, dietary AX and CX could reduce polyamine levels of oral mucosal tissues exposed to 4-NQO. These results indicate that AX and CX are possible chemopreventers for oral carcinogenesis, and such effects may be partly due to suppression of cell proliferation.

Topics: Animals; Anticarcinogenic Agents; beta Carotene; Bromodeoxyuridine; Canthaxanthin; Carotenoids; Male; Mouth Neoplasms; Nucleolus Organizer Region; Precancerous Conditions; Rats; Rats, Inbred F344; Xanthophylls