Reactive oxygen species mediated apoptotic death of colon cancer cells: therapeutic potential of plant derived alkaloids.

Colorectal cancer (CRC) is one of the most deaths causing diseases worldwide. Several risk factors including hormones like insulin and insulin like growth factors (e.g., IGF-1) have been considered responsible for growth and progression of colon cancer. Though there is a huge advancement in the available screening as well as treatment techniques for CRC. There is no significant decrease in the mortality of cancer patients. Moreover, the current treatment approaches for CRC are associated with serious challenges like drug resistance and cancer re-growth. Given the severity of the disease, there is an urgent need for novel therapeutic agents with ideal characteristics. Several pieces of evidence suggested that natural products, specifically medicinal plants, and derived phytochemicals may serve as potential sources for novel drug discovery for various diseases including cancer. On the other hand, cancer cells like colon cancer require a high basal level of reactive oxygen species (ROS) to maintain its own cellular functions. However, excess production of intracellular ROS leads to cancer cell death via disturbing cellular redox homeostasis. Therefore, medicinal plants and derived phytocompounds that can enhance the intracellular ROS and induce apoptotic cell death in cancer cells via modulating various molecular targets including IGF-1 could be potential therapeutic agents. Alkaloids form a major class of such phytoconstituents that can play a key role in cancer prevention. Moreover, several preclinical and clinical studies have also evidenced that these compounds show potent anti-colon cancer effects and exhibit negligible toxicity towards the normal cells. Hence, the present evidence-based study aimed to provide an update on various alkaloids that have been reported to induce ROS-mediated apoptosis in colon cancer cells via targeting various cellular components including hormones and growth factors, which play a role in metastasis, angiogenesis, proliferation, and invasion. This study also provides an individual account on each such alkaloid that underwent clinical trials either alone or in combination with other clinical drugs. In addition, various classes of phytochemicals that induce ROS-mediated cell death in different kinds of cancers including colon cancer are discussed.

Tinospora sinensis (Lour.) Merr alkaloid rich extract induces colon cancer cell death via ROS mediated, mTOR dependent apoptosis pathway: "an in-vitro study".

BACKGROUND: Colorectal cancer (CRC) is the second most mortality rate causing disease after lung cancer. Though there is a significant improvement in the treatment schedule offered to CRC. However, there is no notable decrease in terms of cases as well as death rate. Hence, there is an urgent need to discover novel cancer therapeutics to treat CRC. Since ancient times, the use of phytochemicals has drawn huge attention as chemo-preventive and chemotherapeutic agents. Earlier studies on Tinospora sinensis (TS) revealed the cytotoxic effect on human colorectal carcinoma (HCT-116) cells, yet the mechanism is to be uncovered. Therefore, the present study was designed to study the cell death mechanism of TS in HCT-116 cells. METHOD: Different extracts such as n-hexane, ethyl acetate, and ethanol extracts from the root part of TS were prepared using a cold maceration process. The extracts were screened against cancer cell lines by methyl thiazoldiphenyltetrazolium bromide (MTT) assay. From the result, the most active extract was subjected to gas chromatography-mass spectrometry (GC-MS) and Fourier-Transform infrared spectroscopy (FTIR) analyses to identify the major constituents. Finally, the mechanism of cytotoxicity to cancer cells for the most active extract was evaluated using various experiments such as cell cycle analysis, Annexin-V assay, and Western blot. RESULTS: The results from the MTT assay indicated that the n-hexane extract of TS inhibits the growth of HCT-116 cells more effectively than other cancer cells like Henrietta Lacks cervical cancer cells (Hela), and Michigan cancer foundation-breast cancer (MCF-7). The GC-MS and FT-IR analyses revealed the presence of alkaloids in the n-hexane extract and were responsible for the apoptosis activity in HCT-cells via reactive oxygen species (ROS) generation, and phosphoinositide 3-kinase (PI3K)/ protein Kinase B (Akt)/ mammalian target of rapamycin (mTOR) down-regulation. CONCLUSION: This study concludes that this finding is unique of its kind, and for the first time. The anticancer effect of TS root is specific to colon cancer cells (HCT-116). This distinctive finding helps the researchers to investigate further, and to identify a novel source for anti-colon cancer drug candidates in near future.

Natural Products as the Modulators of Oxidative Stress: An Herbal Approach in the Management of Prostate Cancer.

Prostate cancer is the most commonly diagnosed and frequently occurred cancer in the males globally. The current treatment strategies available to treat prostate cancer are not much effective and express various adverse effects. Hence, there is an urgent need to identify novel treatment that can improve patient outcome. From times immemorial, natural products are highly recognized for novel drug development for various diseases including cancer. Cancer cells generally maintain higher basal levels of reactive oxygen species (ROS) when compared to normal cells due to its high metabolic rate. However, initiation of excess intracellular ROS production can not be tolerated by the cancer cells and induce several cell death signals which are in contrast to normal cells. Therefore, small molecules of natural origin that induce ROS can potentially kill cancer cells in specific and provide a better opportunity to develop a novel drug therapy. In this review, we elaborated various classes of medicinal compounds and their mechanism of killing prostate cancer cells through direct or indirect ROS generation. This can generate a novel thought to develop promising drug candidate to treat prostate cancer patients.

Heat Shock Factors in Protein Quality Control and Spermatogenesis.

Proper regulation of cellular protein quality control is crucial for cellular health. It appears that the protein quality control machinery is subjected to distinct regulation in different cellular contexts such as in somatic cells and in germ cells. Heat shock factors (HSFs) play critical role in the control of quality of cellular proteins through controlling expression of many genes encoding different proteins including those for inducible protein chaperones. Mammalian cells exert distinct mechanism of cellular functions through maintenance of tissue-specific HSFs. Here, we have discussed different HSFs and their functions including those during spermatogenesis. We have also discussed the different heat shock proteins induced by the HSFs and their activities in those contexts. We have also identified several small molecule activators and inhibitors of HSFs from different sources reported so far.

Alkaloid-rich fraction of Ervatamia coronaria sensitizes colorectal cancer through modulating AMPK and mTOR signalling pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Ervatamia coronaria, a popular garden plant in India and some other parts of the world is known traditionally for its anti-inflammatory and anti-cancer properties. The molecular bases of these functions remain poorly understood. AIM OF THE STUDY: Efficacies of the existing therapies for colorectal cancer (CRC) are limited by their life-threatening side effects and unaffordability. Therefore, identifying a safer, efficient, and affordable therapeutic is urgent. We studied the anti-CRC activity of an alkaloid-rich fraction of E. coronaria leaf extracts (AFE) and associated underlying mechanism. MATERIALS AND METHODS: Activity guided solvant fractionation was adopted to identify the activity in AFE. Different cell lines, and tumor grown in syngeneic mice were used to understand the anti-CRC effect. Methodologies such as LCMS, MTT, RT-qPCR, immunoblot, immunohistochemistry were employed to understand the molecular basis of its activity. RESULTS: We showed that AFE, which carries about six major compounds, is highly toxic to colorectal cancer (CRC) cells. AFE induced cell cycle arrest at G1 phase and p21 and p27 genes, while those of CDK2, CDK-4, cyclin-D, and cyclin-E genes were downregulated in HCT116 cells. It predominantly induced apoptosis in HCT116p53+/+ cells while the HCT116p53-/- cells under the same treatment condition died by autophagy. Notably, AFE induced upregulation of AMPK phosphorylation, and inhibition of both of the mTOR complexes as indicated by inhibition of phosphorylation of S6K1, 4EBP1, and AKT. Furthermore, AFE inhibited mTOR-driven conversion of cells from reversible cell cycle arrest to senescence (geroconversion) as well as ERK activity. AFE activity was independent of ROS produced, and did not primarily target the cellular DNA or cytoskeleton. AFE also efficiently regressed CT26-derived solid tumor in Balb/c mice acting alone or in synergy with 5FU through inducing autophagy as a major mechanism of action as indicated by upregulation of Beclin 1 and phospho-AMPK, and inhibition of phospho-S6K1 levels in the tumor tissue lysates. CONCLUSION: AFE induced CRC death through activation of both apoptotic and autophagy pathways without affecting the normal cells. This study provided a logical basis for consideration of AFE in future therapy regimen to overcome the limitations associated with existing anti-CRC chemotherapy.

Prostate cancer: Therapeutic prospect with herbal medicine.

Prostate cancer (PCa) is a major cause of morbidity and mortality in men worldwide. A geographic variation on the burden of the disease suggested that the environment, genetic makeup, lifestyle, and food habits modulate one's susceptibility to the disease. Although it has been generally thought to be an older age disease, and awareness and timely execution of screening programs have managed to contain the disease in the older population over the last decades, the incidence is still increasing in the population younger than 50. Existing treatment is efficient for PCa that is localized and responsive to androgen. However, the androgen resistant and metastatic PCa are challenging to treat. Conventional radiation and chemotherapies are associated with severe side effects in addition to being exorbitantly expensive. Many isolated phytochemicals and extracts of plants used in traditional medicine are known for their safety and diverse healing properties, including many with varying levels of anti-PCa activities. Many of the phytochemicals discussed here, as shown by many laboratories, inhibit tumor cell growth and proliferation by interfering with the components in the pathways responsible for the enhanced proliferation, metabolism, angiogenesis, invasion, and metastasis in the prostate cells while upregulating the mechanisms of cell death and cell cycle arrest. Notably, many of these agents simultaneously target multiple cellular pathways. We analyzed the available literature and provided an update on this issue in this review article.

Exploring cardioprotective potential of esculetin against isoproterenol induced myocardial toxicity in rats: in vivo and in vitro evidence.

BACKGROUND: Esculetin is a natural coumarin derivative from various plants with multiple pharmacological effects. Hence, the present study was undertaken to explore the cardio protective potential of esculetin against isoproterenol induced myocardial toxicity in rats. METHODS: The treatment schedule was fixed for 28 days and the rats were divided into five groups of six each. Rats of group I received the normal saline and served as normal control, group II was received ISO (100 mg/kg body weight) for last two consecutive days of the study and served as disease control. Groups III and IV received esculetin 10 and 20 mg/kg body weight respectively once a day per oral for 28 days along with ISO for last two consecutive days of the study. Cardiac biomarkers such as CK-MB and LDH, membrane bound Na+ /K+ ATPases activity, myocardial lysosomal enzymes activity and tissue antioxidants status were estimated in the heart tissue samples. The histopathological changes in the myocardium were also assessed. Further, DPPH assay was done to evaluate the free radicals scavenging potential of esculetin. Cytoxicity assay, intracellular ROS levels by DCFDA assay and m-RNA expression of TNF-α, IL-6 and NF-κB by quantitative RT-PCR in H9c2 cell lines. RESULTS: The increased levels of CK-MB, LDH, LPO, myocardial lysosomal enzymes and membrane bound Na+ /K+ ATPase levels by ISO administration was significantly increased with concomitant decrease in tissue antioxidant enzymes such as GSH, Catalase, and SOD. Pre-treatment with esculetin for 28 days has significantly decreased the levels of cardiac bio-markers, lysosomal enzymes, membrane bound Na+ /K+ ATPase levels as well as Lipid peroxides which is in contrary to the ISO group. Amelioration of the antioxidant levels were also found in esculetin treated groups. Histopathological examination of heart reveals that myocardial degeneration, mononuclear cell infiltration was noticed in ISO treated rats, whereas the same was restored with esculetin treatment. In H9C2 cell lines esculetin could effectively reduced intracellular ROS inhibition and m-RNA expression of pro-inflammatory cytokines including TNF-α, IL-6 and NF-κB to prevent apoptosis or cell necrosis. CONCLUSION: The study provides the evidence of cardioprotective potentials of esculetin against isoproterenol induced myocardial infarction by antioxidant and myocardial membrane stabilization along with in vitro protection from arsenic induced ROS cell necrosis or apoptosis in H9C2 cells.

Andrographolide upregulates protein quality control mechanisms in cell and mouse through upregulation of mTORC1 function.

BACKGROUND: Heat shock response (HSR), a component of cellular protein quality control mechanisms, is defective in different neurodegenerative conditions such as Parkinson's disease (PD). Forced upregulation of heat shock factor 1 (HSF1), an HSR master regulator, showed therapeutic promise in PD models. Many of the reported small-molecule HSF1 activators have limited functions. Therefore, identification and understanding the molecular bases of action of new HSF1 activating molecules is necessary. METHOD: We used a cell-based reporter system to screen Andrographis paniculata leaf extract to isolate andrographolide as an inducer of HSF1 activity. The andrographolide activity was characterized by analyzing its role in different protein quality control mechanisms. RESULT: We find that besides ameliorating the PD in MPTP-treated mice, andrographolide upregulated different machineries controlled by HSF1 and NRF2 in both cell and mouse brain. Andrographolide achieves these functions through mTORC1 activated via p38 MAPK and ERK pathways. NRF2 activation is reflected in the upregulation of proteasome as well as autophagy pathways. We further show that NRF2 activation is mediated through mTORC1 driven phosphorylation of p62/sequestosome 1. Studies with different cell types suggested that andrographolide-mediated induction of ROS level underlies all these activities in agreement with the upregulation of mTORC1 and NRF2-antioxidant pathway in mice. CONCLUSION: Andrographolide through upregulating HSF1 activity ameliorates protein aggregation induced cellular toxicity. GENERAL SIGNIFICANCE: Our results provide a reasonable basis for use of andrographolide in the therapy regimen for the treatment of PD.

Azadiradione Restores Protein Quality Control and Ameliorates the Disease Pathogenesis in a Mouse Model of Huntington's Disease.

Huntington's disease (HD) is an autosomal dominantly inherited neurodegenerative disorder caused by expansion of CAG repeats in the coding area of huntingtin gene. In the HD brain, mutant huntingtin protein goes through proteolysis, and its amino-terminal portion consisting of polyglutamine repeats accumulate as inclusions that result in progressive impairment of cellular protein quality control system. Here, we demonstrate that partial rescue of the defective protein quality control in HD model mouse by azadiradione (a bioactive limonoids found in the seed of Azadirachta indica) could potentially improve the disease pathology. Prolonged treatment of azadiradione to HD mice significantly improved the progressive deterioration in body weight, motor functioning along with extension of lifespan. Azadiradione-treated HD mice brain also exhibited considerable decrease in mutant huntingtin aggregates load and improvement of striatal pathology in comparison with age-matched saline-treated HD controls. Biochemical analysis further revealed upregulation and activation of not only HSF1 (master regulator of protein folding) but also Ube3a (an ubiquitin ligase involved in the clearance of mutant huntingtin) in azadiradione-treated mice. Our results indicate that azadiradione-mediated enhanced folding and clearance of mutant huntingtin might underlie improved disease pathology in HD mice and suggests that it could be a potential therapeutic molecule to delay the progression of HD.

Azadiradione ameliorates polyglutamine expansion disease in Drosophila by potentiating DNA binding activity of heat shock factor 1.

Aggregation of proteins with the expansion of polyglutamine tracts in the brain underlies progressive genetic neurodegenerative diseases (NDs) like Huntington's disease and spinocerebellar ataxias (SCA). An insensitive cellular proteotoxic stress response to non-native protein oligomers is common in such conditions. Indeed, upregulation of heat shock factor 1 (HSF1) function and its target protein chaperone expression has shown promising results in animal models of NDs. Using an HSF1 sensitive cell based reporter screening, we have isolated azadiradione (AZD) from the methanolic extract of seeds of Azadirachta indica, a plant known for its multifarious medicinal properties. We show that AZD ameliorates toxicity due to protein aggregation in cell and fly models of polyglutamine expansion diseases to a great extent. All these effects are correlated with activation of HSF1 function and expression of its target protein chaperone genes. Notably, HSF1 activation by AZD is independent of cellular HSP90 or proteasome function. Furthermore, we show that AZD directly interacts with purified human HSF1 with high specificity, and facilitates binding of HSF1 to its recognition sequence with higher affinity. These unique findings qualify AZD as an ideal lead molecule for consideration for drug development against NDs that affect millions worldwide.

14-Deoxyandrographolide targets adenylate cyclase and prevents ethanol-induced liver injury through constitutive NOS dependent reduced redox signaling in rats.

Chronic alcoholism is one of the most common causes of liver diseases worldwide. Nitric oxide (NO) has been proposed to have potential for clinical application against chronic hepatocellular injuries. However, mechanisms underlying hepatoprotective functions of NO in ethanol-induced apoptosis are largely unknown. Sprauge-Dawley rats were exposed to ethanol for 8 weeks. Half of the ethanol-fed animals received 14-deoxyandrographolide (14-DAG) treatment for the last 4 weeks of study. Preventive effect of 14-DAG against ethanol-induced hepatotoxicity involved constitutive nitric oxide synthase (cNOS) activation followed by up-regulation of γ-glutamylcysteine synthetase activity and reduced oxidative stress. Enhanced interaction of cNOS with caveolin-1 caused down-regulation of enzyme activity and led to depletion of NO in the hepatocytes of ethanol-fed animals. 14-DAG acted as activator of adenylate cyclase and modulated cyclic AMP (cAMP) mediated expression of caveolin-1 and calmodulin. This eventually favored activation of cNOS through inhibition of cNOS-caveolin-1 interaction. Our results suggest that, protective effect of 14-DAG against ethanol-induced hepatic injury is based on its ability to reduce oxidative stress through cNOS dependent improvement of redox status. 14-DAG mediated activation of adenylate cyclase-cAMP signaling leading to up-regulation of cNOS may provide a promising approach in the prevention of liver diseases during chronic alcoholism.