Nimbolide, a Neem Limonoid, Inhibits Angiogenesis in Breast Cancer by Abrogating Aldose Reductase Mediated IGF-1/PI3K/Akt Signalling.

BACKGROUND & OBJECTIVE: The insulin/IGF-1R/PI3K/Akt signalling cascade is increasingly being linked to breast cancer development, with aldose reductase (AR) playing a key role in mediating the crosstalk between this pathway and angiogenesis. The current study was designed to investigate whether nimbolide, a neem limonoid, targets the oncogenic signaling network to prevent angiogenesis in breast cancer. METHODS: Breast cancer cells (MCF-7, MDA-MB-231), EAhy926 endothelial cells, MDA-MB-231 xenografted nude mice, and tumour tissues from breast cancer patients were used for the study. The expression of AR and key players in IGF-1/PI3K/Akt signaling and angiogenesis was evaluated by qRT-PCR, immunoblotting, and immunohistochemistry. Molecular docking and simulation, overexpression, and knockdown experiments were performed to determine whether nimbolide targets AR and IGF-1R. RESULTS: Nimbolide inhibited AR with consequent blockade of the IGF-1/PI3K/Akt and /HIF-1alpha/VEGF signalling circuit by influencing the phosphorylation and intracellular localisation of key signaling molecules. The downregulation of DNMT-1, HDAC-6, miR-21, HOTAIR, and H19 with the upregulation of miR-148a/miR-152 indicated that nimbolide regulates AR and IGF-1/PI3K/Akt signaling via epigenetic modifications. Coadministration of nimbolide with metformin and the chemotherapeutic drugs tamoxifen/cisplatin displayed higher efficacy than single agents in inhibiting IGF-1/PI3K/Akt/AR signaling. Grade-wise increases in IGF-1R and AR expression in breast cancer tissues underscore their value as biomarkers of progression. CONCLUSION: This study provides evidence for the anticancer effects of nimbolide in cellular and mouse models of breast cancer besides providing leads for new drug combinations. It has also opened up avenues for investigating potential molecules such as AR for therapeutic targeting of cancer.

Nimbolide, a Neem Limonoid, Is a Promising Candidate for the Anticancer Drug Arsenal.

Nimbolide, a major limonoid constituent of Azadirachta indica, commonly known as neem, has attracted increasing research attention owing to its wide spectrum of pharmacological properties, predominantly anticancer activity. Nimbolide is reported to exert potent antiproliferative effects on a myriad cancer cell lines and chemotherapeutic efficacy in preclinical animal tumor models. The potentiality of nimbolide to circumvent multidrug resistance and aid in targeted protein degradation broaden its utility in enhancing therapeutic modalities and outcome. Accumulating evidence indicates that nimbolide prevents the acquisition of cancer hallmarks such as sustained proliferation, apoptosis evasion, invasion, angiogenesis, metastasis, and inflammation by modulating kinase-driven oncogenic signaling networks. Nimbolide has been demonstrated to abrogate aberrant activation of cellular signaling by influencing the subcellular localization of transcription factors and phosphorylation of kinases in addition to influencing the epigenome. Nimbolide, with its ever-expanding repertoire of molecular targets, is a valuable addition to the anticancer drug arsenal.

Activation of PI3K/Akt/NF-kB Signaling Mediates Swedish Snus Induced Proliferation and Apoptosis Evasion in the Rat Forestomach: Modulation by Blueberry.

BACKGROUND AND OBJECTIVES: The present study was undertaken to ascertain whether the modulatory effects of blueberries on cell proliferation induced by Swedish snus in the rat forestomach epithelium is mediated via abrogation of the PI3K/Akt/NFκB signaling axis that regulates cell fate decision. METHODS: The transcript and protein expression of genes involved in cell cycle progression and apoptosis, as well as canonical PI3K/Akt/NF-κB signaling pathways, were analyzed by qRT-PCR, immunoblotting and ELISA. Expression profiling of noncoding RNAs (ncRNAs) that influence PI3K/Akt/NF-κB signaling was undertaken. TUNEL assay was performed using flow cytometry. RESULTS: Administration of snus induced basal cell hyperplasia in the rat forestomach with increased cell proliferation and inhibition of apoptosis. This was associated with the activation of PI3K/Akt/NFκB signaling. Coadministration of blueberries significantly suppressed snus-induced hyperplasia. Analysis of the molecular mechanisms revealed that blueberries suppress the phosphorylation of Akt, NF-κB and IKKß, prevent nuclear translocation of NF-κB and modulate the expression of microRNAs that influence PI3K/Akt/NF-κB signaling. CONCLUSION: Taken together, the results of the current study provide compelling evidence that blueberries exert significant protective effects against snus-induced soft tissue changes in the rat forestomach epithelium mediated by inhibiting key molecular players in the PI3K/Akt/NF-κB signaling axis. Long-term studies on the impact of snus exposure on various cellular processes, signaling pathways, and the interplay between genetic and epigenetic mechanisms are however warranted. The results of this investigation may contribute to the development of protection against soft tissue changes induced by smokeless tobacco in the human oral cavity.

Astaxanthin inhibits hallmarks of cancer by targeting the PI3K/NF-κΒ/STAT3 signalling axis in oral squamous cell carcinoma models.

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.

Blueberry and malvidin inhibit cell cycle progression and induce mitochondrial-mediated apoptosis by abrogating the JAK/STAT-3 signalling pathway.

Blueberries, a rich source of anthocyanins have attracted considerable attention as functional foods that confer immense health benefits including anticancer properties. Herein, we assessed the potential of blueberry and its major constituent malvidin to target STAT-3, a potentially druggable oncogenic transcription factor with high therapeutic index. We demonstrate that blueberry abrogates the JAK/STAT-3 pathway and modulates downstream targets that influence cell proliferation and apoptosis in a hamster model of oral oncogenesis. Further, we provide mechanistic evidence that blueberry and malvidin function as STAT-3 inhibitors in the oral cancer cell line SCC131. Blueberry and malvidin suppressed STAT-3 phosphorylation and nuclear translocation thereby inducing cell cycle arrest and mitochondrial-mediated apoptosis. However, the combination of blueberry and malvidin with the STAT-3 inhibitor S3I-201 was more efficacious in STAT-3 inhibition relative to single agents. The present study has provided leads for the development of novel combinations of compounds that can serve as inhibitors of STAT-mediated oncogenic signalling.

ATM is required for SOD2 expression and homeostasis within the mammary gland.

PURPOSE: ATM activates the NF-κB transcriptional complex in response to genotoxic and oxidative stress. The purpose of this study was to examine if the NF-κB target gene and critical antioxidant SOD2 (MnSOD) in cultured mammary epithelium is also ATM-dependent, and what phenotypes arise from deletion of ATM and SOD2 within the mammary gland. METHODS: SOD2 expression was studied in human mammary epithelial cells and MCF10A using RNAi to knockdown ATM or the NF-κB subunit RelA. To study ATM and SOD2 function in mammary glands, mouse lines containing Atm or Sod2 genes containing LoxP sites were mated with mice harboring Cre recombinase under the control of the whey acidic protein promoter. Quantitative PCR was used to measure gene expression, and mammary gland structure was studied using histology. RESULTS: SOD2 expression is ATM- and RelA-dependent, ATM knockdown renders cells sensitive to pro-oxidant exposure, and SOD mimetics partially rescue this sensitivity. Mice with germline deletion of Atm fail to develop mature mammary glands, but using a conditional knockout approach, we determined that Atm deletion significantly diminished the expression of Sod2. We also observed that these mice (termed AtmΔ/Δ) displayed a progressive lactation defect as judged by reduced pup growth rate, aberrant lobulo-alveolar structure, diminished milk protein gene expression, and increased apoptosis within lactating glands. This phenotype appears to be linked to dysregulated Sod2 expression as mammary gland-specific deletion of Sod2 phenocopies defects observed in AtmΔ/Δ dams. CONCLUSIONS: We conclude that ATM is required to promote expression of SOD2 within the mammary epithelium, and that both ATM and SOD2 play a crucial role in mammary gland homeostasis.