Activation of the mTORC1/PGC-1 axis promotes mitochondrial biogenesis and induces cellular senescence in the lung epithelium.

Cellular senescence is a biological process by which cells lose their capacity to proliferate yet remain metabolically active. Although originally considered a protective mechanism to limit the formation of cancer, it is now appreciated that cellular senescence also contributes to the development of disease, including common respiratory ailments such as chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis. While many factors have been linked to the development of cellular senescence, mitochondrial dysfunction has emerged as an important causative factor. In this study, we uncovered that the mitochondrial biogenesis pathway driven by the mammalian target of rapamycin/peroxisome proliferator-activated receptor-γ complex 1α/ß (mTOR/PGC-1α/ß) axis is markedly upregulated in senescent lung epithelial cells. Using two different models, we show that activation of this pathway is associated with other features characteristic of enhanced mitochondrial biogenesis, including elevated number of mitochondrion per cell, increased oxidative phosphorylation, and augmented mitochondrial reactive oxygen species (ROS) production. Furthermore, we found that pharmacological inhibition of the mTORC1 complex with rapamycin not only restored mitochondrial homeostasis but also reduced cellular senescence to bleomycin in lung epithelial cells. Likewise, mitochondrial-specific antioxidant therapy also effectively inhibited mTORC1 activation in these cells while concomitantly reducing mitochondrial biogenesis and cellular senescence. In summary, this study provides a mechanistic link between mitochondrial biogenesis and cellular senescence in lung epithelium and suggests that strategies aimed at blocking the mTORC1/PGC-1α/ß axis or reducing ROS-induced molecular damage could be effective in the treatment of senescence-associated lung diseases.

Arsenic-induced metabolic shift triggered by the loss of miR-199a-5p through Sp1-dependent DNA methylation.

Inorganic arsenic is an environmental carcinogen that poses a major global public health risk. A high percentage of drinking water from wells in the U.S. contains higher-than-normal levels of arsenic, suggesting an increased risk of arsenic-induced deleterious effects. In addition to primary preventive measures, therapeutic strategies need to effectively address and integrate multiple molecular mechanisms underlying arsenic-induced carcinogenesis. We previously showed that the loss of miR-199a-5p in arsenic-transformed cells is pivotal to promote arsenic-induced angiogenesis and tumor growth in lung epithelial cells. In this study, we further showed that subacute or chronic exposure to arsenic diminished miR-199a-5p levels largely due to DNA methylation, which was achieved by increased DNA methyltransferase-1 (DNMT1) activity, mediated by the formation of specific protein 1 (Sp1)/DNMT1 complex. In addition to the DNA hypermethylation, arsenic exposure also repressed miR-199a transcription through a transcriptional repressor Sp1. We further identified an association between miR-199a-5p repression and the arsenic-mediated energy metabolic shift, as reflected by mitochondria defects and a switch to glycolysis, in which a glycolytic enzyme pyruvate kinase 2 (PKM2) was a functional target of miR-199a-5p. Taken together, the repression of miR-199a-5p through both Sp1-dependent DNA methylation and Sp1 transcriptional repression promotes an arsenic-mediated metabolic shift from mitochondria respiration to aerobic glycolysis via PKM2.

Combination Treatment of Biochanin A and Atorvastatin Alters Mitochondrial Bioenergetics, Modulating Cell Metabolism and Inducing Cell Cycle Arrest in Pancreatic Cancer Cells.

BACKGROUND/AIM: Pancreatic cancer is an aggressive type of cancer, with a dismally low survival rate of <5%. FDA-approved drugs like gemcitabine have shown little therapeutic success, prolonging survival by a mere six months. Isoflavones, such as biochanin A and daidzein, are known to exhibit anti-cancer activity, whereas statins reportedly have anti-proliferative effects. This study investigated the effects of combination treatment of biochanin A and atorvastatin on pancreatic cancer cells. MATERIALS AND METHODS: Pancreatic cancer cells AsPC-1, PANC-1, and MIA PaCa-2 were procured from ATCC. The cell viability studies were carried out using MTT & cell count assays. Flow cytometry was used to study cell apoptosis whereas cell metabolism studies were carried out using the Seahorse Mito stress test and XF-PMP assay. The effects of treatment on cell signaling pathways & cell cycle associated proteins were investigated using western blot whereas invasiveness of cancer cells was evaluated using gelatin zymography. RESULTS: The combination treatment decreased the survival and enhanced pro-apoptotic responses compared to single treatments in the pancreatic cancer cells. In PANC-1 cells, the combination treatment decreased invasiveness, reduced expression of activated STAT3 and expression of critical mediators of cell cycle progression. Furthermore, the combination treatment induced a differential inhibition of respiratory complexes in the pancreatic cancer cells. CONCLUSION: The combination treatment of biochanin A and atorvastatin exerts enhanced anti-cancer effects, inducing apoptosis, down-regulating cell cycle associated proteins and invasiveness in pancreatic cancer cells and merits further investigation for new, improved treatments for pancreatic cancer.

Synthesis and characterization of fumaric acid functionalized AgCl/titania nanocomposite with enhanced antibacterial activity.

Silver based antimicrobial agents with TiO2 as a host support (AgCl/TiO2) are increasingly being evaluated for disinfection and therapeutic applications. In this work TiO2 supported silver chloride nanocomposites were synthesized and functionalized with fumaric acid. X-ray diffraction results showed that the TiO2 was in anatase phase and AgCI was in the cubic chalcoargyrite phase. The functionalization was confirmed by FTIR analysis. The fumaric acid functionalized AgCl/TiO2 (Fu-AgCl/TiO2) showed uniform particle size distribution in the range of 4-5 nm. The intensity size distribution of Fu-AgCl/TiO2 nanocomposite by DLS showed an average particle diameter of -290 nm with a polydispersity index (P. I.) of 0.47. Further, a high BET surface area of -320.7 m2/g was observed for Fu-AgCl/TiO2 with an average pore size distribution of 3.8 nm. The antimicrobial activity of Fu-AgCl/TiO2 and AgCl/TiO2 was evaluated by determining the MIC and MBC values, and it was observed that Fu-AgCl/TiO2 exhibited better antimicrobial activity as compared to the unfunctionalized nanocomposite. The antimicrobial activity of Fu-AgCl/TiO2 is mainly attributed to its superior physicochemical properties coupled with the synergistic action of both fumaric acid and silver ions. The changes in the cytoplasmic membrane of the cells due to the formation of intracellular ROS were observed by SEM imaging.

Combination of Biochanin A and Temozolomide Impairs Tumor Growth by Modulating Cell Metabolism in Glioblastoma Multiforme.

BACKGROUND/AIM: Several epidemiological studies have reported the chemopreventive potential of biochanin A, in cancer development and progression. We investigated the anticancer potential of combination of biochanin A and temozolomide against U-87 MG and T98 G [glioblastoma multiforme (GBM)] cells. MATERIALS AND METHODS: We evaluated the effect of biochanin A and temozolomide treatment on cell viability, expression of survival proteins, cell cycle, cell metabolism and mitochondrial function. RESULTS: Enhanced inhibitory effects of the combination treatment were observed on cell viability, expression of cell survival proteins EGFR, p-ERK, p-AKT, c-myc and MT-MMP1, and increased expression of the tumor suppressor, p-p53. Combination treatment also induced arrest in the G1 phase of the cell cycle. A shift in the metabolic phenotype of cells from glycolytic to oxidative phosphorylation was observed on combination treatment and the permeabilized cells showed a significant impairment in complex IV activity. CONCLUSION: Biochanin A significantly enhanced the anticancer efficacy of temozolomide in GBM cells.

D-cycloserine nasal formulation development for anxiety disorders by using polymeric gels.

D-cycloserine (DCS), a partial agonist at N-methyl-D-aspartate (NMDA) receptors, is used as an enhancer of exposure therapy for anxiety disorders. The purpose of the present study was to investigate the feasibility of using polymeric gels to increase the viscosity of the formulation and thereby increase the nasal residence time and sustained release of DCS in vitro. Hydroxypropyl methylcellulose (HPMC), hydroxypropyl cellulose (HPC), and methyl cellulose (MC) were prepared at concentrations of 0.5 to 5% w/v. Pluronic F-127 (PF-127) was prepared at concentrations of 15 to 35% w/v. pH, viscosity and in vitro DCS release behavior of the formulated gels were analyzed. All four gels that were tested, demonstrated sustained DCS release behavior over a 24-hour period, but with different rates. Based on the results of this study, HPMC, HPC, MC, and PF-127 are capable of increasing the viscosity of nasal gel formulations and of releasing DCS in sustained manner. Therefore, these polymeric gels can be suitable carriers for DCS nasal gel formulation.

Natural Bioactive Compounds: Alternative Approach to the Treatment of Glioblastoma Multiforme.

Glioblastoma multiforme (GBM) is the most frequent, primary malignant brain tumor prevalent in humans. GBM characteristically exhibits aggressive cell proliferation and rapid invasion of normal brain tissue resulting in poor patient prognosis. The current standard of care of surgical resection followed by radiotherapy and chemotherapy with temozolomide is not very effective. The inefficacy of the chemotherapeutic agents may be attributed to the challenges in drug delivery to the tumor. Several epidemiological studies have demonstrated the chemopreventive role of natural, dietary compounds in the development and progression of cancer. Many of these studies have reported the potential of using natural compounds in combination with chemotherapy and radiotherapy as a novel approach for the effective treatment of cancer. In this paper, we review the role of several natural compounds individually and in combination with chemotherapeutic agents in the treatment of GBM. We also assess the potential of drug delivery approaches such as the Gliadel wafers and role of nanomaterial based drug delivery systems for the effective treatment of GBM.