Resveratrol-induced autophagy and apoptosis in cisplatin-resistant human oral cancer CAR cells: A key role of AMPK and Akt/mTOR signaling

Pterostilbene inhibits nutrient metabolism and induces apoptosis through AMPK activation in multiple myeloma cells

Multiple myeloma (MM) cells are characterized by an abnormal nutrient metabolism that is distinct from normal plasma cells. Pterostilbene (PTE), a bioactive component of blueberries, has been demonstrated to induce apoptosis in multiple types of cancer cell. The present study evaluated whether PTE treatment affected the survival of MM cells from a metabolic perspective, and the potential mechanisms of this. It was observed that the administration of PTE induced apoptosis, which was mediated by the increased activation of AMP‑activated protein kinase (AMPK). Once activated, AMPK decreased the expression and/or activity of key lipogenic enzymes, including fatty acid synthase and acetyl‑CoA carboxylase. In addition, the activation of AMPK suppressed the downstream substrate, mechanistic target of rapamycin, which dephosphorylated eukaryotic initiation factor 4E‑binding protein 1, leading to a general decrease in mRNA translation. Pre‑treatment with the AMPK inhibitor compound C prior to PTE treatment compromised the anti‑myeloma apoptosis effect, suggesting the critical role of AMPK in mediating PTE‑induced cell toxicity. Consistent results were obtained in vivo. Finally, autophagy was adaptively upregulated subsequent to PTE treatment; the pro‑apoptotic efficacy of PTE was potentiated once autophagic flux was inhibited by 3‑methyladenine. Taken together, these data demonstrated that PTE exerts anti‑tumor effects on MM cells via AMPK‑induced nutrient suppression.

Autophagy induces transforming growth factor-β-dependent epithelial-mesenchymal transition in hepatocarcinoma cells through cAMP response element binding signalling

Autophagy promotes invasion of hepatocarcinoma cells through transforming growth factor (TGF)-β-dependent epithelial-mesenchymal transition (EMT). This study investigated the mechanism by which autophagy induces TGF-β-triggered EMT and invasion of hepatocarcinoma cells. Autophagy was induced in HepG2 and BEL7402 cells by starvation in Hank's balanced salt solution. Induction of autophagy degraded phosphodiesterase (PDE) 4A and increased intracellular cAMP, PKA activity and PKA phosphorylation, resulting in increased cAMP response element binding (CREB) phosphorylation in hepatocarcinoma cells. Autophagy-induced activation of cAMP/PKA/CREB signalling further enhanced TGF-β1 expression, downregulated the expression of epithelial markers and upregulated the expression of mesenchymal markers, accelerating invasion of hepatocarcinoma cells. Inhibition of autophagy by Atg3 and Atg7 knockdown or by chloroquine treatment prevented degradation of PDE4A and activation of cAMP/PKA/CREB signalling, suppressing TGF-β1 expression, EMT and invasion in hepatocarcinoma cells. In addition, inhibition of cAMP/PKA/CREB signalling also blocked autophagy-induced TGF-β1 expression and prevented EMT and invasion of hepatocarcinoma cells under starvation. Furthermore, exogenous inhibition of PDE4A or activation of cAMP/PKA/CREB signalling rescued TGF-β1 expression, EMT and invasion in autophagy-deficient hepatocarcinoma cells. These findings suggest that autophagy induces TGF-β1 expression and EMT in hepatocarcinoma cells via cAMP/PKA/CREB signalling, which is activated by autophagy-dependent PDE4A degradation.

Nimbolide, a neem limonoid inhibits cytoprotective autophagy to activate apoptosis via modulation of the PI3K/Akt/GSK-3β signalling pathway in oral cancer

Of late, nimbolide, a limonoid from the neem tree (Azadirachta indica) has gained increasing research attention owing to its potent antiproliferative and apoptosis-inducing effects. The present study was designed to investigate the effect of nimbolide on autophagy and the time point at which the phosphorylation status of GSK-3β and PI3K dictate the choice between autophagy and apoptosis in SCC131 and SCC4 oral cancer cells. Additionally, we analysed changes in the expression of proteins involved in autophagy and apoptosis after therapeutic intervention with nimbolide in a hamster model of oral oncogenesis. Furthermore, we also demonstrate changes in the expression of key genes involved in apoptosis and autophagy during the stepwise evolution of hamster and human OSCCs. Nimbolide-induced stereotypical changes in oral cancer cells characteristic of both apoptosis and autophagy. Time-course experiments revealed that nimbolide induces autophagy as an early event and then switches over to apoptosis. Nimbolide negatively regulates PI3K/Akt signalling with consequent increase in p-GSK-3βTyr216, the active form of GSK-3β that inhibits autophagy. Downregulation of HOTAIR, a competing endogenous RNA that sponges miR-126 may be a major contributor to the inactivation of PI3K/Akt/GSK3 signalling by nimbolide. Analysis of key markers of apoptosis and autophagy as well as p-AktSer473 during sequential progression of hamster and human OSCC revealed a gradual evolution to a pro-autophagic and antiapoptotic phenotype that could confer a survival advantage to tumors. In summary, the results of the present study provide insights into the molecular mechanisms by which nimbolide augments apoptosis by overcoming the shielding effects of cytoprotective autophagy through modulation of the phosphorylation status of Akt and GSK-3β as well as the ncRNAs miR-126 and HOTAIR. Development of phytochemicals such as nimbolide that target the complex interaction between proteins and ncRNAs that regulate the autophagy/apoptosis flux is of paramount importance in cancer prevention and therapeutics.

Deciphering the metabolic role of AMPK in cancer multi-drug resistance

Multi-drug resistance (MDR) is a curious bottleneck in cancer research and chemotherapy, whereby some cells rapidly adapt to the tumor microenvironment via a myriad of heterogeneous metabolic activities. Despite being a major impediment to treatment, there is a silver lining: control over metabolic regulation could be an effective approach to overcome or correct resistance pathways. In this critical review, we comprehensively and carefully curated and analyzed large networks of previously identified proteins associated with metabolic adaptation in MDR. We employed data and text mining to study and categorize more than 600 studies in PubMed, with particular focus on AMPK, a central and fundamental modulator in the energy metabolism network that has been specifically implicated in cancer MDR pathways. We have identified one protein set of metabolic adaptations with 137 members closely related to cancer MDR processes, and a second protein set with 165 members derived from AMPK-based networks, with 28 proteins found at the intersection between the two sets. Furthermore, according to genomics analysis of the cancer genome atlas (TCGA) provisional data, the highest alteration frequency (80.0%) of the genes encoding the intersected proteins (28 proteins), ranked three cancer types with quite remarkable significance across 166 studies. The hierarchical relationships of the entire identified gene and protein networks indicate broad correlations in AMPK-mediated metabolic regulation pathways, which we use decipher and depict the metabolic roles of AMPK and demonstrate the potential of metabolic control for therapeutic intervention in MDR.

Resveratrol sensitizes lung cancer cell to TRAIL by p53 independent and suppression of Akt/NF-κB signaling

AIMS

TRAIL is a promising anticancer agent that has the potential to sensitize a wide variety of cancer or transformed cells by inducing apoptosis. However, resistance to TRAIL is a growing concern. Current manuscript aimed to employ combination treatment to investigate resveratrol induced TRAIL sensitization in NSCLC.

METHOD

A549 and HCC-15 cells were used in an experimental design. Cell viability was determined by morphological image, crystal violet staining and MTT assay. Apoptosis was evaluated by LDH assay, Annexin V and DAPI staining. Autophagy and apoptosis indicator protein were examined by western blotting. TEM and puncta assay was carried out to evaluate the autophagy. MTP and ROS activity was evaluated by JC-1 and H₂DCFDA staining.

FINDINGS

Resveratrol is a polyphenolic compound capable of activation of tumor suppressor p53 and its pro-apoptotic modulator PUMA. Herein, we showed the p53-independent apoptosis by decrease the expression of phosphorylated Akt-mediated suppression of NF-κB that is also substantiated with the downregulation of anti-apoptotic factors Bcl-2 and Bcl-xl in NSCLC, resulting in an attenuation of TRAIL resistance in combined treatment. Furthermore, apoptosis was induced in TRAIL-resistant lung cancer cells with a co-treatment of resveratrol and TRAIL assessed by the loss of MMP, ROS generations which resulting the translocation of cytochrome c from the mitochondria into the cytosol due to mitochondrial dysfunction. Moreover, autophagy flux was not affected by resveratrol-induced TRAIL-mediated apoptosis in NSCLC.

SIGNIFICANCE

Overall, targeting the NF-κB (p65) pathway via resveratrol attenuates TRAIL resistance and induces TRAIL-mediated apoptosis which could be the effective TRAIL-based cancer therapy regimen.

A Sterol from Soft Coral Induces Apoptosis and Autophagy in MCF-7 Breast Cancer Cells. Mar Drugs. 2018;16. [PMID: 30018246 PMCID: PMC6071057 DOI: 10.3390/md16070238]

The peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear receptor that plays a key role in regulating cellular metabolism, and is a therapeutic target for cancer therapy. To search for potential PPARγ activators, a compound library comprising 11 marine compounds was examined. Among them, a sterol, 3β,11-dihydroxy-9,11-secogorgost-5-en-9-one (compound 1), showed the highest PPARγ activity with an IC₅₀ value of 8.3 μM for inhibiting human breast adenocarcinoma cell (MCF-7) growth. Western blotting experiments showed that compound 1 induces caspase activation and PARP cleavage. In addition, compound 1 modulated the expression of various PPARγ-regulated downstream biomarkers including cyclin D1, cyclin-dependent kinase (CDK)6, B-cell lymphoma 2 (Bcl-2), p38, and extracellular-signal-regulated kinase (ERK). Moreover, compound 1 increased reactive oxygen species (ROS) generation, upregulated the phosphorylation and expression of H2AX, and induced autophagy. Interestingly, pre-treatment with the autophagy inhibitor 3-methyladenine rescued cells from compound 1-induced growth inhibition, which indicates that the cytotoxic effect of compound 1 is, in part, attributable to its ability to induce autophagy. In conclusion, these findings suggest the translational potential of compound 1 in breast cancer therapy.

Resveratrol inhibits the proliferation and induces the apoptosis in ovarian cancer cells via inhibiting glycolysis and targeting AMPK/mTOR signaling pathway

Aerobic glycolysis is an important metabolic rewiring in cancer cells to promote glucose uptake and lactate production, and targeting aerobic glycolysis becomes a promising therapeutic approach for cancer. Here we reported that a small polyphenol resveratrol exhibited profound anti-tumor efficacy on human ovarian cancer. Resveratrol markedly inhibited the proliferation, migration, and invasion of A2780 and SKOV3 ovarian cancer cells, while impaired glycolysis, and induced apoptosis in these cells. Exposure to resveratrol increased the expression and activation of AMPK and Caspase 3, and decreased the expression and activation of AMPK downstream kinase mTOR. Moreover, AMPK inhibitor Compound C significantly abolished the effects of resveratrol on the activation of AMPK and Caspase 3 and the inhibition of mTOR. In addition, in vivo data indicated that resveratrol suppressed ovarian cancer growth and liver metastasis in xenograft mouse model. In conclusion, our findings provide new insight into the mechanism underlying anticancer efficacy of resveratrol and help the utilization of resveratrol as a novel agent for the treatment of ovarian cancer.

microRNA-135b expression silences Ppm1e to provoke AMPK activation and inhibit osteoblastoma cell proliferation

Forced-activation of AMP-activated protein kinase (AMPK) can possibly inhibit osteoblastoma cells. Here, we aim to provoke AMPK activation via microRNA silencing its phosphatase Ppm1e (protein phosphatase Mg²⁺/Mn²⁺-dependent 1e). We showed that microRNA-135b-5p (“miR-135b-5p”), the anti-Ppm1e microRNA, was significantly downregulated in human osteoblastoma tissues. It was correlated with Ppm1e upregulation and AMPKα1 de-phosphorylation. Forced-expression of miR-135b-5p in human osteoblastoma cells (MG-63 and U2OS lines) silenced Ppm1e, and induced a profound AMPKα1 phosphorylation (at Thr-172). Osteoblastoma cell proliferation was inhibited after miR-135b-5p expression. Intriguingly, Ppm1e shRNA knockdown similarly induced AMPKα1 phosphorylation, causing osteoblastoma cell proliferation. Reversely, AMPKα1 shRNA knockdown or dominant negative mutation almost abolished miR-135b-5p's actions in osteoblastoma cells. Further in vivo studies demonstrated that U2OS tumor growth in mice was dramatically inhibited after expressing miR-135b-5p or Ppm1e shRNA. Together, our results suggest that miR-135b-induced Ppm1e silence induces AMPK activation to inhibit osteoblastoma cell proliferation.

Pterostilbene modulates the suppression of multidrug resistance protein 1 and triggers autophagic and apoptotic mechanisms in cisplatin-resistant human oral cancer CAR cells via AKT signaling

Pterostilbene is a natural polyphenolic compound that is primarily found in fruits, such as blueberries and has a similar structure to resveratrol. Pterostilbene exhibits antioxidant, anti-inflammatory and antitumor activity but the effects of pterostilbene on drug-resistant oral cancer cells and its underlying mechanisms of action have not yet been explored. Therefore, the present study was performed to clarify the anticancer effects of pterostilbene on cisplatin-resistant human oral cancer CAR cells. The results demonstrated that CAR cells exhibited marked shrinkage, cell membrane breakage and autophagic vacuole formation following treatment with pterostilbene. Pterostilbene also effectively inhibited cell viability and suppressed cell confluence in a time- and concentration-dependent manner. Probing with acridine orange, monodansylcadaverine and LysoTracker Red demonstrated that the number of acidic vesicular organelles was increased, indicating increased autophagy. Furthermore, Heochst 33342 staining determined that DNA condensation, a characteristic of apoptosis, was enhanced following treatment with pterostilbene. Furthermore, pterostilbene upregulated mRNA levels of LC3-II and Atg12, as well as the expression of Atgs/Beclin-1/LC3-associated signaling, suggesting that it enhances autophagy. The autophagy inhibitors 3-methyladenine and chloroquine were used to confirm that pterostilbene induces autophagy. It was also determined that pterostilbene triggered caspase-dependent apoptosis by directly testing DNA breakage and using the pan-caspase inhibitor carbobenzoxyvalyl-alanyl-aspartyl fluoromethyl ketone. The results demonstrated that pterostilbene mediates the apoptosis of CAR cells via the intrinsic apoptotic cascade. In addition, pterostilbene inhibited MDR1 expression and the phosphorylation of AKT on the Ser473 site in CAR cells. Therefore, pterostilbene may elicit an oral anticancer response in drug-resistant cells and may be used as a chemotherapeutic adjuvant to treat patients with oral cancer.

Resveratrol protects muscle cells against palmitate-induced cellular senescence and insulin resistance through ameliorating autophagic flux

Skeletal muscle, a highly metabolic tissue, is particularly vulnerable to increased levels of saturated free fatty acids (FFAs). The role of autophagy in saturated FFAs-induced cellular senescence and insulin resistance in skeletal muscle remains unclear. Therefore, the present study was aimed to explore autophagic flux in cellular senescence and insulin resistance induced by palmitate in muscle cells, and whether resveratrol limited these responses. Our results showed that palmitate induced cellular senescence in both myoblasts and myotubes. In addition, palmitate delayed differentiation in myoblasts and inhibited expression of insulin-stimulated p-AKTSer473 in myotubes. The accumulations of autophagosome assessed by tandem fluorescent-tagged LC3 demonstrated that autophagic flux was impaired in both palmitate-treated myoblasts and myotubes. Resveratrol protected muscle cells from palmitate-induced cellular senescence, apoptosis during differentiation, and insulin resistance via ameliorating autophagic flux. The direct influence of autophagic flux on development of cellular senescence and insulin resistance was confirmed by blockage of autophagic flux with chloroquine. In conclusion, impairment of autophagic flux is crucial for palmitate-induced cellular senescence and insulin resistance in muscle cells. Restoring autophagic flux by resveratrol could be a promising approach to prevent cellular senescence and ameliorate insulin resistance in muscle.

Ubenimex, an APN inhibitor, could serve as an anti‑tumor drug in RT112 and 5637 cells by operating in an Akt‑associated manner

Bladder cancer, a common urinary tract tumor, has high mortality and recurrence rates associated with metastasis. Aminopeptidase N (APN) expression and metastasis have been indicated to be associated with one another. Ubenimex may function as an APN inhibitor to inhibit the degradation of the extracellular matrix during tumorigenesis. Furthermore, APN has been widely used as an adjuvant therapy for the treatment of tumors; however, little information is available regarding the impact of ubenimex on patients. Autophagy is suggested to be important in the transformation and progression of cancer. Additionally, apoptosis, which leads to the rapid demolition of cellular organelles and structures, has also been suggested as an important factor. Thus, the present study investigated the role of ubenimex in inhibiting migration and invasion by downregulating APN expression levels to induce autophagic cell death and apoptosis in bladder cancer cells. RT112 and 5637 cell lines were treated with varying doses of ubenimex. Cell viability was measured by CCK8 colorimetry and flow cytometry. Using fluorescence microscopy, autophagic cell death was assessed using acridine orange/ethidium bromide staining. Furthermore, apoptotic cell death was assessed using flow cytometry and Trypan blue staining was used to evaluate the cell death rate. Protein expression was determined by western blot analysis. Matrigel invasion assays were exploited to assess the invasion capabilities of 5637 cells. Wound-healing migration assays and Matrigel migration assays were exploited to assess the migratory abilities of 5637 cells. Treatment with ubenimex was accompanied by decreased Akt expression, indicating that ubenimex may have similar functions to Akt inhibitors. Results also indicated that ubenimex inhibited cell migration and invasion in bladder cancer cells. Furthermore, ubenimex also induced autophagic cell death and apoptosis, which suggested that mixed programmed cell death occurred in ubenimex-treated bladder cancer cells. The results from the present study suggest that ubenimex may be a potential adjuvant therapy for the treatment of bladder cancer.

Live or let die: Neuroprotective and anti-cancer effects of nutraceutical antioxidants

Diet sources are closely involved in the pathogenesis of diverse neuropsychiatric disorders and cancers, in addition to inherited factors. Currently, natural products or nutraceuticals (commonly called medical foods) are increasingly employed for adjunctive therapy of these patients. However, the potential molecular mechanisms of the nutrient efficacy remain elusive. In this review, we summarized the neuroprotective and anti-cancer mechanisms of nutraceuticals. It was concluded that the nutraceuticals exerted neuroprotection and suppressed tumor growth possibly through the differential modulations of redox homeostasis. In addition, the balance between reactive oxygen species (ROS) production and ROS elimination was manipulated by multiple molecular mechanisms, including cell signaling pathways, inflammation, transcriptional regulation and epigenetic modulation, which were involved in the therapeutic potential of nutraceutical antioxidants against neurological diseases and cancers. We specifically proposed that ROS scavenging was integral in the neuroprotective potential of nutraceuticals, while alternation of ROS level (either increase or decrease) or disruption of redox homeostasis (ROS addiction) constituted the anti-cancer property of these compounds. We also hypothesized that ROS-associated ferroptosis, a novel type of lipid ROS-dependent regulatory cell death, was likely to be a critical mechanism for the nutraceutical antioxidants. Targeting ferroptosis is advantageous to develop new nutraceuticals with more effective and lower adverse reactions for curing patients with neuropsychiatric diseases or carcinomas.

Autophagy induction enhances tetrandrine-induced apoptosis via the AMPK/mTOR pathway in human bladder cancer cells

Tetrandrine, a bisbenzylisoquinoline alkaloid isolated from the roots of Stephania tetrandra is a traditional Chinese medicine and exerts anticancer capacity in various types of cancers. Previous studies have shown that tetrandrine induces apoptosis in bladder cancer cells via activation of the caspase cascade. However, the underlying mechanism has not yet been reported. Autophagy is a cellular process involved in the degradation of broken proteins and aging organelles to maintain homeostasis. Recent studies indicate that autophagy is implicated in cancer therapy. Thus, we focused on the correlation between autophagy and apoptosis upon tetrandrine treatment in human bladder cancer cells. Firstly, our results observed a marked increase in autophagic double-membrane vacuoles and fluorescent puncta of red fluorescence protein-green fluorescence protein-LC3 (GRP-RFP-LC3) upon tetrandrine treatment, as evidenced by transmission electron microscopy and confocal fluorescence microscopy. Secondly, the expression of LC3-II was increased in tetrandrine-treated T24 and 5637 cells in a time- and concentration-dependent manner. Subsequently, downregulation of p62 and LC3 turnover assay further confirmed that tetrandrine induced autophagic flux in bladder cancer T24 and 5637 cells. Thirdly, the protein levels of phosphorylated-AMP-activated protein kinase (AMPK) and phosphorylated-acetyl-coenzyme A carboxylase (ACC) were upregulated in the tetrandrine-treated cells, while the mammalian target of rapamycin (mTOR)-related proteins were downregulated. Moreover, AICAR, a common AMPK activator, further increased the expression the LC3-II, while AMPK inhibitor compound C partially reversed the LC3-II protein levels in bladder cancer T24 cells. Finally, AICAR significantly reinforced the growth inhibition and apoptosis induction of tetrandrine in T24 and 5637 cells, while compound C had an opposite effect, suggesting that AMPK-mediated autophagy enhanced the cytotoxic and pro-apoptosis effect of tetrandrine in human bladder cancer cells. Taken together, the present study showed that tetrandrine induced autophagy in human bladder cancer cells by regulating the AMPK/mTOR signaling pathway, which contributed to the apoptosis induction by tetrandrine, indicating that tetrandrine may be a potential anticancer candidate for the treatment of bladder cancer, and autophagy may be a possible mechanism for cancer therapy.

Therapeutic Implications of Autophagy Inducers in Immunological Disorders, Infection, and Cancer

Autophagy is an essential catabolic program that forms part of the stress response and enables cells to break down their own intracellular components within lysosomes for recycling. Accumulating evidence suggests that autophagy plays vital roles in determining pathological outcomes of immune responses and tumorigenesis. Autophagy regulates innate and adaptive immunity affecting the pathologies of infectious, inflammatory, and autoimmune diseases. In cancer, autophagy appears to play distinct roles depending on the context of the malignancy by either promoting or suppressing key determinants of cancer cell survival. This review covers recent developments in the understanding of autophagy and discusses potential therapeutic interventions that may alter the outcomes of certain diseases.

Pharmacological synergism of 2,2-dichloroacetophenone and EGFR-TKi to overcome TKi-induced resistance in NSCLC cells

Combination treatment has been used as one of the therapeutic approaches for patients suffering from lung cancer, either to cope with the issue of acquired drug resistance due to prolong the use of a particular EGFR-TKi treatment, or to decrease the doses of each compound in order to reduce potential toxicity. 2,2-dichloroacetophenone (DAP) was reported as a PDK inhibitor recently, which is much more potent than dichloroacetate (DCA) in anti-cancer therapy. In this study, we applied DAP in combined with EGFR-TKis, erlotinib or gefitinib in NSCLC cell lines and NSCLC xenograft model. Synergistic anti-cancer effects in two NSCLC cell lines with EGFR mutation, NCI-H1975 and NCI-H1650, as well as in NCI-H1975 xenograft model were observed. In comparison with either DAP or EGFR-TKi applied alone, the combination treatment not only further suppressed the EGFR signaling in vitro and in vivo, but also significantly promoted cell apoptosis. Interestingly, this synergistic anti-cancer effect was also observed in NCI-H1975 gefitinib induced-resistant cell line. Taken together, our results suggested that the combined use of DAP and EGFR-TKi exhibited anti-cancer synergy which may offer an additional treatment option for patients with EGFR-TKi induced-resistance.

In vitro polyphenol effects on apoptosis: An update of literature data

Polyphenols are secondary plant metabolites which have been studied extensively for their health-promoting properties, and which could also exert pharmacological activities ranging from anti-inflammatory effects, to cytotoxic activity against cancer cells. The main mechanism for programmed cell death is represented by apoptosis, and its dysregulation is involved in the etiopathology of cancer. As such, substances able to induce apoptosis in cancer cells could be used as new anticancer agents. The aim of this paper is to review literature data on the apoptotic effects of polyphenols and the molecular mechanisms through which they induce these effects in cancer cells. In addition, a brief summary of the new delivery forms used to increase the bioavailability, and clinical impact of polyphenols is provided. The studies reported show that many polyphenol rich plant extracts, originating from food and herbal medicine, as well as isolated polyphenols administered individually or in combination, can regulate cell apoptosis primarily through intrinsic and extrinsic mechanisms of action in in vitro conditions. Due to these promising results, the use of polyphenols in the treatment of cancer should therefore be deeply investigated. In particular, because of the low number of clinical trials, further studies are required to evaluate the anticancer activity of polyphenols in in vivo conditions.

Significance of Resveratrol in Clinical Management of Chronic Diseases

Resveratrol could be beneficial to health and provides protection against a wide array of pathologies and age-associated problems, as evident from preclinical studies. However, a comparison of animal and human studies reveals that this dietary polyphenol cannot protect against metabolic diseases and their associated complications. The clinical outcomes are affected by many factors such as sample size. This article not only presents a comprehensive review of the current advances concerning the dose, the extent of absorption, interaction and toxicity of resveratrol in human studies, but also describes its therapeutic effects against several chronic diseases such as diabetes mellitus, obesity, cardiovascular diseases, cancer and aging and the related diseases.

The differential regulation of microRNAs is associated with oral cancer

Oral squamous cell carcinoma (OSCC), is the most frequently occurring malignant head and neck tumor, generally it exhibits a poor prognosis, and metastasis is the main cause of death in these cancer patients. The discovery of reliable prognostic indicators for tumors progression would greatly improve clinical treatments. MicroRNAs (miRNAs) play a critical role in the degradation of mRNA and the inhibition of protein synthesis. The miRNAs function either as tumor suppressors or as oncogenes in tumorigenesis, and little is known about the clinical significance of miRNA expression profiles in oral cancers. In the present study, we investigated the expression profiles of miR-375, miR-204 and miR-196a in 39 healthy and tumor tissue pairs of oral cancer patients using TaqMan real-time quantitative polymerase chain reaction (qPCR). The predicted target genes for miR-375, miR-204 and miR-196a were confirmed using luciferase reporter-based assays and western blot analyses. In oral cancer tissue, the expression of miR-375 and miR-204 decreased, whereas the expression of miR-196a was significantly elevated. In OSCC, HOXB8 and p27 (CDKN1B) were the direct target genes of miR-196a, whereas HMGA2 was the direct target gene of miR-204. HOXB8 and p27 (CDKN1B) protein expression levels were inhibited by miR-196a, whereas the protein expression level of HMGA2 was inhibited by miR-204. Furthermore, the miR-196a inhibitor blocked cell proliferation. Our results indicate that the combined expression signatures of miR-375, miR-204 and miR-196a are promising biomarkers for the diagnosis, prognosis and treatment of OSCC.

YC-1 induces G0/G1 phase arrest and mitochondria-dependent apoptosis in cisplatin-resistant human oral cancer CAR cells

Oral cancer is a serious and fatal disease. Cisplatin is the first line of chemotherapeutic agent for oral cancer therapy. However, the development of drug resistance and severe side effects cause tremendous problems clinically. In this study, we investigated the pharmacologic mechanisms of YC-1 on cisplatin-resistant human oral cancer cell line, CAR. Our results indicated that YC-1 induced a concentration-dependent and time-dependent decrease in viability of CAR cells analyzed by MTT assay. Real-time image analysis of CAR cells by IncuCyte™ Kinetic Live Cell Imaging System demonstrated that YC-1 inhibited cell proliferation and reduced cell confluence in a time-dependent manner. Results from flow cytometric analysis revealed that YC-1 promoted G₀/G₁ phase arrest and provoked apoptosis in CAR cells. The effects of cell cycle arrest by YC-1 were further supported by up-regulation of p21 and down-regulation of cyclin A, D, E and CDK2 protein levels. TUNEL staining showed that YC-1 caused DNA fragmentation, a late stage feature of apoptosis. In addition, YC-1 increased the activities of caspase-9 and caspase-3, disrupted the mitochondrial membrane potential (AYm) and stimulated ROS production in CAR cells. The protein levels of cytochrome c, Bax and Bak were elevated while Bcl-2 protein expression was attenuated in YC-1-treated CAR cells. In summary, YC-1 suppressed the viability of cisplatin-resistant CAR cells through inhibiting cell proliferation, arresting cell cycle at G₀/G₁ phase and triggering mitochondria-mediated apoptosis. Our results provide evidences to support the potentially therapeutic application of YC-1 on fighting against drug resistant oral cancer in the future.

Autophagy and its link to type II diabetes mellitus

Autophagy, a double-edged sword for cell survival, is the research object on 2016 Nobel Prize in Physiology or Medicine. Autophagy is a molecular mechanism for maintaining cellular physiology and promoting survival. Defects in autophagy lead to the etiology of many diseases, including diabetes mellitus (DM), cancer, neurodegeneration, infection disease and aging. DM is a metabolic and chronic disorder and has a higher prevalence in the world as well as in Taiwan. The character of diabetes mellitus is hyperglycemia resulting from defects in insulin secretion, insulin action, or both. Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance and failure of producing insulin on pancreatic beta cells. In T2DM, autophagy is not only providing nutrients to maintain cellular energy during fasting, but also removes damaged organelles, lipids and miss-folded proteins. In addition, autophagy plays an important role in pancreatic beta cell dysfunction and insulin resistance. In this review, we summarize the roles of autophagy in T2DM.