Gold nanoparticles-conjugated quercetin induces apoptosis via inhibition of EGFR/PI3K/Akt-mediated pathway in breast cancer cell lines (MCF-7 and MDA-MB-231).

Epidermal growth factor plays a major role in breast cancer cell proliferation, survival, and metastasis. Quercetin, a bioactive flavonoid, is shown to exhibit anticarcinogenic effects against various cancers including breast cancer. Hence, the present study was designed to evaluate the effects of gold nanoparticles-conjugated quercetin (AuNPs-Qu-5) in MCF-7 and MDA-MB-231 breast cancer cell lines. Borohydride reduced AuNPs were synthesized and conjugated with quercetin to yield AuNPs-Qu-5. Both were thoroughly characterized by several physicochemical techniques, and their cytotoxic effects were assessed by MTT assay. Apoptotic studies such as DAPI, AO/EtBr dual staining, and annexin V-FITC staining were performed. AuNPs and AuNPs-Qu-5 were spherical with crystalline nature, and the size of particles range from 3.0 to 4.5 nm. AuNPs-Qu-5 exhibited lower IC50 value compared to free Qu. There was a considerable increase in apoptotic population with increased nuclear condensation seen upon treatment with AuNPs-Qu-5. To delineate the molecular mechanism behind its apoptotic role, we analysed the proteins involved in apoptosis and epidermal growth factor receptor (EGFR)-mediated PI3K/Akt/GSK-3ß signalling by immunoblotting and immunocytochemistry. The pro-apoptotic proteins (Bax, Caspase-3) were found to be up regulated and anti-apoptotic protein (Bcl-2) was down regulated on treatment with AuNPs-Qu-5. Additionally, AuNPs-Qu-5 treatment inhibited the EGFR and its downstream signalling molecules PI3K/Akt/mTOR/GSK-3ß. In conclusion, administration of AuNPs-Qu-5 in breast cancer cell lines curtails cell proliferation through induction of apoptosis and also suppresses EGFR signalling. AuNPs-Qu-5 is more potent than free quercetin in causing cancer cell death, and hence, this could be a potential drug delivery system in breast cancer therapy.

Inhibition of cell survival and proliferation by nimbolide in human androgen-independent prostate cancer (PC-3) cells: involvement of the PI3K/Akt pathway.

Prostate cancer is most common malignancy among men in the world. PI3K-Akt signaling appears to be critical to prostate cancer cell proliferation and survival. Our earlier study reveals that nimbolide (2 µM) prevents cell survival via IGF signaling pathway through PI3K/Akt and induces apoptosis in PC-3 cell line. Akt mediates the phosphorylation and activation of mTOR that plays a critical role in the regulation of protein translation and synthesis, angiogenesis, and cell cycle progression. The present study was aimed to investigate the effect of nimbolide on tPI3K, tAkt, pAkt, tmTOR, GSK3ß, pGSK3ß, PCNA, c-Myc, Cyclin D1, and Survivin protein levels by western blot analysis. Apoptosis was visualized by Ao/EtBr dual staining (20×), and protein expression of PCNA by immunocytochemistry was performed. Molecular docking was performed to understand the possible interaction between nimbolide and Akt, PCNA, and Cyclin D1. Nimbolide altered the PI3K-Akt-mediated cell survival and proliferative molecules. Thus, nimbolide exerted anticancer effects in vitro by representing the PI3K-Akt-mTOR pathway in PC-3 cells. Thereby, it acts as a potent anticancer drug for prostate cancer.

Anti-proliferative and apoptosis inducing effect of nimbolide by altering molecules involved in apoptosis and IGF signalling via PI3K/Akt in prostate cancer (PC-3) cell line.

Prostate cancer is responsible for major deaths globally after lung cancer. Nimbolide is an important constituent of neem, and it acts as a potent inhibitor for many cancer cells. The present study was designed to evaluate the effects of nimbolide on apoptosis and insulin-like growth factor (IGF) signalling molecules in androgen-independent prostate cancer (PC-3) cells line. Nimbolide (0.5-2 µM) treatment resulted in 50% inhibition at a dose of 2 µM in the PC-3 cell line. The mRNA expression of Fas ligand, Fas-associated death domain receptor (FADDR), Bcl-2-associated X protein (Bax), Bcl-2-associated death promoter (Bad), phosphatidylinositide 3-kinases (PI3K), Akt, IGF1, IGF1 receptor (IGF1R) and IGF binding protein 3 were quantified by reverse transcription polymerase chain reaction and protein expression of Bax, cytochrome c, X-linked inhibitor of apoptosis protein (XIAP), B-Cell Lymphoma 2 (Bcl-2), caspases -8, -9, -10 and -3, poly(ADP-ribose) polymerase (PARP), cleaved PARP, IGF1R, PI3K, Akt, p-Akt was determined by western blot analysis, in nimbolide-treated PC-3 cell line. Nimbolide-induced apoptosis by activating DNA fragmentation in PC-3 cells. Nimbolide treatment increased the mRNA of Fas ligand, FADDR, Bax, Bad and IGF binding protein 3, decreased PI3K, Akt, IGF1 and IGF1R, increased protein expression of caspases 8, 3, 10, 9, Bax and cytochrome c and decreased the expression of XIAP, Bcl2, cleaved PARP, p-Akt and IGF1R. The results suggest that nimbolide acts as a potent anti-cancer agent by inducing apoptosis and inhibiting cell proliferation via PI3K/Akt pathway in PC-3 cells.