Glucocorticoid receptor: a harmonizer of cellular plasticity in breast cancer-directs the road towards therapy resistance, metastatic progression and recurrence.

Recent therapeutic advances have significantly uplifted the quality of life in breast cancer patients, yet several impediments block the road to disease-free survival. This involves unresponsiveness towards administered therapy, epithelial to mesenchymal transition, and metastatic progression with the eventual appearance of recurrent disease. Attainment of such characteristics is a huge adaptive challenge to which tumour cells respond by acquiring diverse phenotypically plastic states. Several signalling networks and mediators are involved in such a process. Glucocorticoid receptor being a mediator of stress response imparts prognostic significance in the context of breast carcinoma. Involvement of the glucocorticoid receptor in the signalling cascade of breast cancer phenotypic plasticity needs further elucidation. This review attempted to shed light on the inter-regulatory interactions of the glucocorticoid receptor with the mediators of the plasticity program in breast cancer; which may provide a hint for strategizing therapeutics against the glucocorticoid/glucocorticoid receptor axis so as to modulate phenotypic plasticity in breast carcinoma.

Refashioning of the drug-properties of fluoroquinolone through the synthesis of a levofloxacin-imidazole cobalt (II) complex and its interaction studies on with DNA and BSA biopolymers, antimicrobial and cytotoxic studies on breast cancer cell lines.

Levofloxacin (HLVX), a quinolone antimicrobial agent, when deprotonated (LVX-) behaves as a bidentate ligand, and it coordinates to Co2+ through the pyridone oxygen and the carboxylate oxygen. Along with two imidazole (ImH) ligands, levofloxacin forms a Co(II)-Levofloxacin-imidazole complex, [CoCl(LVX)(ImH)2(H2O)]·3H2O (abbreviated henceforth as CoLevim) which was isolated and characterized by 1H and 13C NMR spectroscopy, UV-visible and FT-IR spectroscopy, powder X-ray diffraction and thermal analysis methods. CoLevim shows promise in its antimicrobial activities when tested against microorganisms (Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium and Escherichia coli). Fluorescence competitive studies with ethidium bromide (EB) revealed that CoLevim can compete with EB and displace it to bind to CT-DNA through intercalative binding mode. In addition, CoLevim exhibited a good binding propensity to BSA proteins with relatively high binding constants. The antioxidant activities of the free ligands and CoLevim were determined in vitro using ABTS+ radical (TEAC assay). The Co-complex showed a better antioxidant capacity with inhibitory concentrations (IC50) of 40 µM than the free ligands. CoLevim also showed noteworthy apoptotic potential and behaved as an efficient resistant modifying agent when its antiproliferative potential was examined by MTT assay using the breast cancer cell lines (MCF7, MCF7Dox/R and MCF7Pacli/R cells).

PEITC: A resounding molecule averts metastasis in breast cancer cells in vitro by regulating PKCδ/Aurora A interplay.

Background/aim: Intricate association and aberrant activation of serine/threonine kinase (STK) family proteins like Polo-like kinase (PLK1) and Aurora kinase (Aurora A abruptly regulate mitotic entry whereas activation of PKCδ), another important member of STK family conversely induces apoptosis which is preceded by cell cycle arrest. These STKs are considered as major determinant of oncogenicity. Therefore, the contributory role of Aurora A/PLK-1 axis in mitotic control and PKCδ in apoptosis control and their reciprocity in cancer research is an emerging area to explore. The present study investigated the intricate involvement of STKs in breast cancer cells (MCF-7 and MDA-MB-231) and their disruption by PEITC. Methods: Both MCF-7 and MDA-MB-231 cells were checked for clonogenic assay, cell-cycle analysis and the results were compared with normal MCF-10A, Western blotting, TUNEL & DNA-fragmentation assay, wound healing, transwell migration assays in presence and absence of PEITC. Results: PEITC was found to increase the expression of PKCδ with subsequent nuclear translocation. Nuclear translocation of PKCδ was accompanied by inhibition of nuclear lamin vis a vis phosphorylation of Nrf2 at Ser 40 alongside nuclear accumulation of phospho-Nrf2. Activated PKCδ furthermore exerted its apoptotic effect by negatively regulating Aurora A and consequentially PLK1; indicating activation of PLK1 by Aurora A. Involvement of PEITC induced PKCδ activation and Aurora A inhibition was ascertained by using Rottlerin/Aurora A Inhibitor. Discussion & conclusion: Natural isothiocyanates like PEITC efficiently altered the functional abilities of STKs concerning their entangled functional interplay. Such alterations in protein expression by PEITC was chaperoned with inhibition of the aggressiveness of breast cancer cells and ultimately induction of apoptosis.

Aspirin Restores Radiosensitivity in Cervical Cancer Cells by Inducing Mitotic Catastrophe through Downregulating G2/M Effectors.

BACKGROUND/AIM: Compromised cell-cycle checkpoint is a major obstacle for rendering radiotherapeutic success of radioresistant cells. Aspirin (ASA), an anti-inflammatory agent was repurposed previously for improving radiotherapy by limiting radiation toxicity. However, the underlying mechanism was unclear. The present study aimed to identify the mechanism of ASA mediated reversal of radioresistance in cervical cancer cells. METHODS: Radioresistant subline SiHa/RR was developed from parental cervical squamous carcinoma cell line SiHa by chronic fractionated irradiation (IR). The radioresistance property of SiHa/RR was confirmed by clonogenic assay. Alteration in cell-cycle by ASA was determined by flow cytometry. ASA induced nuclear damage as consequence of mitotic catastrophe was confirmed by microscopic observation. The interaction between ASA and G2/M regulators was explored through in silico docking analysis and expressional change of them was affirmed by western blotting. Immunofluorescence study to examine Aurora Kinase A localization in presence and absence of ASA treatment was conducted. Finally the radiosensitizing ability of ASA was verified by apoptotic parameters (flow cytometrically and by western blotting). RESULT: Higher colony forming ability of SiHa/RR compared to SiHa became restrained upon ASA (5µM) treatment prior to IR. Flow cytometric analysis of ASA treated cells showed increased G2/M population followed by enlargement of cells displaying giant multinucleated morphology; typical characteristics of mitotic catastrophe. Underlying noteworthy mechanisms involved decreased expressions of G2/M regulatory proteins (Cyclin B1, CDK1, Aurora A Kinase, pAurora A Kinase) in IR/ASA along with inhibiting nuclear localization of Aurora Kinase A in SiHa/RR. Docking results also supported the findings. Prolonged treatment (12 h) with ASA led to apoptosis by altering expressions of Bcl2, Bax and Cytochrome C; which was achieved through the event of mitotic catastrophe. CONCLUSION: This work established that G2/M arrest and mitotic catastrophe can be considered as the principle mechanism of restoration of radiosensitivity in SiHa/RR by ASA pretreatment.

Phenethylisothiocyanate Potentiates Platinum Therapy by Reversing Cisplatin Resistance in Cervical Cancer.

Acquired cisplatin resistance in cervical cancer therapy is principally caused by reduction in intracellular drug accumulation, which is exerted by hyperactivation of the oncogenic PI3K/Akt signaling axis and overexpression of cisplatin-exporter MRP2 along with prosurvival effectors NF-κB and IAPs in cervical cancer cells. These activated prosurvival signaling cascades drive drug efflux and evasion of apoptosis for rendering drug-resistant phenotypes. Our study challenges the PI3K/Akt axis in a cisplatin-resistant cervical cancer scenario with phenethylisothiocyanate (PEITC) for chemosensitization of SiHaR, a cisplatin-resistant sub-line of SiHa and 3-methylcholanthrene-induced cervical cancer mice models. SiHaR exhibited higher MRP2, p-AktThr308, NF-κB, XIAP, and survivin expressions which cumulatively compromised cisplatin retention capacity and accumulated PEITC better than SiHa. SiHaR appeared to favor PEITC uptake as its accumulation rates were found to be positively correlated with MRP2 expressions. PEITC treatment in SiHaR for 3 h prior to cisplatin exposure revived intracellular platinum levels, reduced free GSH levels, generated greater ROS, and altered mitochondrial membrane potential compared to SiHa. Western blot and immunofluorescence results indicated that PEITC successfully downregulated MRP2 in addition to suppressing p-AktThr308, XIAP, survivin, and NF-κB expressions. In mice models, administration of 5 mg/kg body-weight PEITC priming dosage prior to treatment with 3 mg/kg body-weight of cisplatin remediated cervical histology and induced tumor regression in contrast to the group receiving the same dosage of cisplatin only. This suggested PEITC as a potential chemosensitizing agent in light of acquired cisplatin resistance in cervical cancer and established its candidature for Phase I clinical trial.

Curcumin Rescues Doxorubicin Responsiveness via Regulating Aurora a Signaling Network in Breast Cancer Cells.

BACKGROUND: Insensitivity towards anthracycline drugs like doxorubicin poses a significant challenge in the treatment of breast cancer. Among several factors, Aurora A (a mitotic serine threonine kinase) plays crucial roles in acquiring non-responsiveness towards doxorubicin. However, the mechanisms underlying need to be elucidated. The present study was therefore designed to evaluate the underlying mechanisms of Aurora A mediated doxorubicin insensitivity in MCF-7Dox/R, an isolated resistant-subline of MCF-7 (breast adenocarcinoma cell line). Effect of curcumin, a natural phytochemical in restoring doxorubicin sensitivity by targeting Aurora A was assessed furthermore. METHODS: A doxorubicin resistant subline (MCF-7Dox/R) was isolated from the parental MCF-7 cells by treating the cell with gradual step-wise increasing concentration of the drug. Expressions of Aurora A and its target proteins (Akt, IκBα and NFκB) were assessed in both parental and MCF-7Dox/R cells. Both the cell lines were pretreated with curcumin prior to doxorubicin treatment. Cellular proliferation rate was measured using BrdU (5-bromo-2'-deoxyuridine) assay kit. Intracellular doxorubicin accumulation was estimated spectrofluorimetrically. Cellular uptake of curcumin (spectrophotometric and spectrofluorimetric method) and its nuclear localization was confirmed by confocal microscopic study. Protein expressions were determined by western blot analysis. Localization of Aurora A was ascertained by immunofluorescence assay. To explore the possible outcome of impact of curcumin on Aurora A, cell-cycle distribution and apoptosis were performed subsequently. RESULTS: Higher expressions of Aurora A in MCF-7Dox/R cells led to phosphorylation of Akt as well as IκBα. Phosphorylated IκBα preceded release of NFκB. Phospho-Akt, NFκB consequentially decreased doxorubicin accumulation by enhancing the expressions of ABCG2 and Pgp1 respectively. Curcumin by regulating Aurora A and its target molecules sensitized resistant subline towards doxorubicin mediated G2/M-arrest and apoptosis. CONCLUSION: Molecular targeting of Aurora A by curcumin restores chemosensitivity by increasing the efficacy of doxorubicin in breast cancer.
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