Cholesterol depletion by methyl-ß-cyclodextrin augments tamoxifen induced cell death by enhancing its uptake in melanoma.

BACKGROUND: Despite modern advances in treatment, skin cancer is still one of the most common causes of death in the western countries. Chemotherapy plays an important role in melanoma management. Tamoxifen has been used either alone or in- combination with other chemotherapeutic agents to treat melanoma. However, response rate of tamoxifen as a single agent has been comparatively low. In the present study, we investigated whether treatment with methyl-ß-cyclodextrin (MCD), a cholesterol depleting agent, increases the efficacy of tamoxifen in melanoma cells. METHODS: This was a two-part study that incorporated in vitro effects of tamoxifen and MCD combination by analyzing cell survival, apoptosis and cell cycle analysis and in vivo antitumor efficacy on tumor isografts in C57BL/6J mice. RESULTS: MCD potentiated tamoxifen induced anticancer effects by causing cell cycle arrest and induction of apoptosis. Sensitization to tamoxifen was associated with down regulation of antiapoptotic protein Bcl-2, up-regulation of proapoptotic protein Bax, reduced caveolin-1 (Cav-1) and decreased pAkt/pERK levels. Co-administration of tamoxifen and MCD caused significant reduction in tumor volume and tumor weight in mice due to enhancement of drug uptake in the tumor. Supplementation with cholesterol abrogated combined effect of tamoxifen and MCD. CONCLUSION: Our results emphasize a potential synergistic effect of tamoxifen with MCD, and therefore, may provide a unique therapeutic window for improvement in melanoma treatment.

High fat diet promotes achievement of peak bone mass in young rats.

The relationship between obesity and bone is complex. Epidemiological studies demonstrate positive as well as negative correlation between obesity and bone health. In the present study, we investigated the impact of high fat diet-induced obesity on peak bone mass. After 9 months of feeding young rats with high fat diet, we observed obesity phenotype in rats with increased body weight, fat mass, serum triglycerides and cholesterol. There were significant increases in serum total alkaline phosphatase, bone mineral density and bone mineral content. By micro-computed tomography (µ-CT), we observed a trend of better trabecular bones with respect to their microarchitecture and geometry. This indicated that high fat diet helps in achieving peak bone mass and microstructure at younger age. We subsequently shifted rats from high fat diet to normal diet for 6 months and evaluated bone/obesity parameters. It was observed that after shifting rats from high fat diet to normal diet, fat mass, serum triglycerides and cholesterol were significantly decreased. Interestingly, the gain in bone mineral density, bone mineral content and trabecular bone parameters by HFD was retained even after body weight and obesity were normalized. These results suggest that fat rich diet during growth could accelerate achievement of peak bone mass that is sustainable even after withdrawal of high fat diet.

Cholesterol reprograms glucose and lipid metabolism to promote proliferation in colon cancer cells.

Hypercholesterolemia is often correlated with obesity which is considered a risk factor for various cancers. With the growing population of hypercholesterolemic individuals, there is a need to understand the role of increased circulatory cholesterol or dietary cholesterol intake towards cancer etiology and pathology. Recently, abnormality in the blood cholesterol level of colon cancer patients has been reported. In the present study, we demonstrate that alteration in cholesterol levels (through a high-cholesterol or high-fat diet) increases the incidence of chemical carcinogen-induced colon polyp occurrence and tumor progression in mice. At the cellular level, low-density lipoprotein cholesterol (LDLc) and high-density lipoprotein cholesterol (HDLc) promote colon cancer cell proliferation by tuning the cellular glucose and lipid metabolism. Mechanistically, supplementation of LDLc or HDLc promotes cellular glucose uptake, and utilization, thereby, causing an increase in lactate production by colon cancer cells. Moreover, LDLc or HDLc upregulates aerobic glycolysis, causing an increase in total ATP production through glycolysis, and a decrease in ATP generation by OXPHOS. Interestingly, the shift in the metabolic status towards a more glycolytic phenotype upon the availability of cholesterol supports rapid cell proliferation. Additionally, an alteration in the expression of the molecules involved in cholesterol uptake along with the increase in lipid and cholesterol accumulation was observed in cells supplemented with LDLc or HDLc. These results indicate that colon cancer cells directly utilize the cholesterol associated with LDLc or HDLc. Moreover, targeting glucose metabolism through LDH inhibitor (oxamate) drastically abrogates the cellular proliferation induced by LDLc or HDLc. Collectively, we illustrate the vital role of cholesterol in regulating the cellular glucose and lipid metabolism of cancer cells and its direct effect on the colon tumorigenesis.

Diet-induced obesity increases melanoma progression: involvement of Cav-1 and FASN.

Recent population-based epidemiological studies strongly hint towards a link between obesity and its occurrence as well as progression of several cancers including melanoma. Although effects of obesity on breast, colon and liver cancers have been extensively investigated, the links between obesity and melanoma remain largely unexplored. Present study aimed to understand the effect of high fat diet-induced weight gain on susceptibility of C57BL/6J mice to melanoma. For this, mice routinely were fed on high fat diet for 6 months (HFD mice). Subsequently, mouse melanoma cells were injected subcutaneously in control as well as HFD mice and followed for tumor initiation and progression. We provide strong evidence that diet-induced obesity leads to increased melanoma progression in male C57BL/6J mice. We observed that increased melanoma progression is associated with enhanced Cav-1 and FASN expression in tumors from HFD mice. Cav-1 and FASN are co-ordinately regulated and Cav-1 interacts with FASN in melanoma cells. Enhanced levels of Cav-1, FASN and pAkt control melanoma cell proliferation. Our study establishes a causative relationship between diet-induced obesity and melanoma progression as well as demonstrates that obesity affects important tumorigenic pathways in melanoma.

Obesity Programs Macrophages to Support Cancer Progression.

Obesity induces multifactorial effects such as dyslipidemia, insulin resistance, and arterial hypertension that influence the progression of many diseases. Obesity is associated with an increased incidence of cancers, and multiple mechanisms link obesity with cancer initiation and progression. Macrophages participate in the homeostasis of adipose tissue and play an important role in cancer. Adipose tissue expansion in obesity alters the balance between pro- and anti-inflammatory macrophages, which is a primary cause of inflammation. Chronic low-grade inflammation driven by macrophages is also an important characteristic of cancer. Adipocytes secrete various adipokines, including adiponectin, leptin, IL6, and TNFα, that influence macrophage behavior and tumor progression. Furthermore, other metabolic effects of obesity, such as hyperlipidemia, hyperglycemia, and hypercholesterolemia, can also regulate macrophage functionality in cancer. This review summarizes how obesity influences macrophage-tumor cell interactions and the role of macrophages in the response to anticancer therapies under obese conditions.

Hyperglycemia regulates MDR-1, drug accumulation and ROS levels causing increased toxicity of carboplatin and 5-fluorouracil in MCF-7 cells.

There is constant increase in number of diabetic cases thereby giving it status of a serious epidemic. Diabetes increases the risk of occurrence of several cancers including breast cancer and may also have a serious impact on the outcome of cancer treatment. In the present study we investigated effect of hyperglycemia on cytotoxic efficacy of carboplatin and 5-fluorouracil in MCF-7 cells. MCF-7 cells were grown in 5.5 or 25 mM glucose chronically. We show that hyperglycemia favors proliferation of MCF-7 cells and increases expression of cell cycle regulatory proteins cyclin E and cdk-2. Hyperglycemia enhances cytotoxicity of carboplatin and 5-fluorouracil in MCF-7 cells by approximately 30% and decreases their IC50 by 1.5- and 1.3-folds, respectively. Hyperglycemia reduces expression of P-glycoprotein and promotes cell killing by increasing drug accumulation. Treatment with 40 µM verapamil, an inhibitor of P-gp activity specifically increases killing of MCF-7 cells cultured in 5.5 mM glucose. Further, this effect is synergized by elevated reactive oxygen species and treatment with N-Acetylcysteine, an inhibitor of ROS, increases survival by 30 and 18% in carboplatin- and 5-fluorouracil-treated cells cultured in high glucose, respectively. Cytotoxicity of these drugs is associated with reduced activation of Akt and decreased transcriptional activation of NF-κB. In conclusion, hyperglycemia potentiates cytotoxicity of drugs by reducing P-gp expression and, increased ROS levels may partially or completely contribute to enhanced toxicity.

Influence of cholesterol on cancer progression and therapy.

Cholesterol is a fundamental molecule necessary for the maintenance of cell structure and is vital to various normal biological functions. It is a key factor in lifestyle-related diseases including obesity, diabetes, cardiovascular disease, and cancer. Owing to its altered serum chemistry status under pathological states, it is now being investigated to unravel the mechanism by which it triggers various health complications. Numerous clinical studies in cancer patients indicate an alteration in blood cholesterol level (either decreased or increased) in comparison to normal healthy individuals. This article elaborates on our understanding as to how cholesterol is being hijacked in the malignancy for the development, survival, stemness, progression, and metastasis of cancerous cells. Also, it provides a glimpse of how cholesterol derived entities, alters the signaling pathway towards their advantage. Moreover, deregulation of the cholesterol metabolism pathway has been often reported to hamper various treatment strategies in different cancer. In this context, attempts have been made to bring forth its relevance in being targeted, in pre-clinical and clinical studies for various treatment modalities. Thus, understanding the role of cholesterol and deciphering associated molecular mechanisms in cancer progression and therapy are of relevance towards improvement in the management of various cancers.

Resistin: A journey from metabolism to cancer.

Resistin, a small secretory molecule, has been implicated to play an important role in the development of insulin resistance under obese condition. For the past few decades, it has been linked to various cellular and metabolic functions. It has been associated with diseases like metabolic disorders, cardiovascular diseases and cancers. Numerous clinical studies have indicated an increased serum resistin level in pathological disorders which have been reported to increase mortality rate in comparison to low resistin expressing subjects. Various molecular studies suggest resistin plays a pivotal role in proliferation, metastasis, angiogenesis, inflammation as well as in regulating metabolism in cancer cells. Therefore, understanding the role of resistin and elucidating its' associated molecular mechanism will give a better insight into the management of these disorders. In this article, we summarize the diverse roles of resistin in pathological disorders based on the available literature, clinicopathological data, and a compiled study from various databases. The article mainly provides comprehensive information of its role as a target in different treatment modalities in pre as well as post-clinical studies.

Metformin induced lactic acidosis impaired response of cancer cells towards paclitaxel and doxorubicin: Role of monocarboxylate transporter.

Abnormal glucose metabolism in cancer cells causes generation and secretion of excess lactate, which results in acidification of the extracellular microenvironment. This altered metabolism aids not only in survival and proliferation but also in suppressing immune-mediated destruction of cancer cells. However, how it influences the response of cancer cells to chemotherapeutic drugs is not clearly understood. We employed appropriate in vitro approaches to explore the role of mono-carboxylate transporter 4 (MCT4) mediated altered intra and extracellular pH on the outcome of the therapeutic efficacy of chemotherapeutic drugs in breast and lung cancer models. We demonstrate by in vitro experiments that inhibition of complex I enhances glycolysis and increases expression as well as membrane translocation of MCT4. It causes a decrease in extracellular pH (pHe) and impairs doxorubicin and paclitaxel's therapeutic efficacy. Acidic pHe inhibits doxorubicin's uptake, while acidic intracellular pH (pH i) impairs the efficacy of paclitaxel. Under in vivo experimental settings, the modulation of pHe with phloretin or alkalizer (NaHCO3) enhances cytotoxicity of drugs and inhibits the growth of MCF-7 xenografts in mice. In a nutshell, this study indicates that MCT4 mediated extracellular acidosis is involved in impairing chemotherapeutic drugs' efficacy on cancer cells. Therefore, the use of pH neutralizing agents or MCT inhibitors may be beneficial towards circumventing impairment in the efficacy of certain drugs that are sensitive to pH changes.

Two novel cell culture models of buccal mucosal oral cancer from patients with no risk-habits of tobacco smoking or chewing.

OBJECTIVE: Tobacco consumption is one of the major etiological factors for oral cancer, but it also develops in non-tobacco users, with unknown etiologies. Cellular models for tobacco associated oral cancer are available, however; reports of cellular models for studying non-tobacco associated oral cancer are limiting. We report here the establishment and characterization of two novel buccal mucosal cancer cell lines 'GBC02' and 'GBC035' derived from non-tobacco users. MATERIALS AND METHODS: Short tandem repeats (STR) profiling, Next-generation sequencing for whole-genome, exome and copy number alterations, immunofluorescence, flow-cytometry, proliferation, live-cell chemotaxis, 3D-spheroid formation, chemotherapy response, gene-expression microarray, gene-set enrichment analysis and xenograft development were performed. RESULTS: Sources of the established cultures were matched to their donors through STR profiling. Genome sequence analysis revealed somatic mutations in TP53, CASP8, CDKN2A for GBC02 with deletions and amplifications encompassing CDKN2A, FAT1 and CCND1, PIK3CA, SOX2, EGFR, MYC genes, respectively. GBC035 harbored mutations in FAT1, NOTCH1, HRAS, CDKN2A, HLA-B, HLA-A genes. While GBC035 cells showed higher E-Cadherin positive cell-cell junctions and collective cell migration in chemotaxis; GBC02 cells were vimentin-positive and demonstrated individual cell migration. Further, exhibiting their relevance to preclinical research, GBC02 3D-spheroids demonstrated enrichment of development-related gene-signatures in microarray transcriptome analysis and were resistant to Cisplatin, but showed sensitivity to cancer stem cells-targeting drug, Salinomycin. Additionally, tumorigenic ability of GBC02 was demonstrated. CONCLUSIONS: Altogether, we present here comprehensively characterized unique cell lines established from non-tobacco associated tumors, which may serve as models for preclinical investigations of oral cancers caused independent of tobacco usage.

Atomic force microscopy, biochemical analysis of 3T3-L1 cells differentiated in the absence and presence of insulin.

BACKGROUND: There are ample evidences to demonstrate that differentiation of preadipocytes is associated with deposition of fat in cells. Still, it is unclear whether the differentiation process also alters membrane topology as well as cholesterol levels and whether insulin contributes to it. METHODS: Membrane scanning of differentiated cells, along with freshly plated and 11 day preadipocytes, was performed using Atomic Force Microscopy (AFM) to gain qualitative information about cell surface properties as well as roughness. Moreover, glucose uptake, lipid analysis, expression profiling of transcription factors and signaling molecules involved in the process of differentiation was also performed. RESULTS: We report (i) differentiation in the presence of 500 microM isobutylmethylxanthine (IBMX), 0.25 microM dexamethasone (DEX) with or without 0.1 microM (0.57 microg/ml) insulin directly alters membrane topology. (ii) At nano-levels, addition of insulin maintains plasma membrane roughness during differentiation in comparison with IBMX and DEX only. (iii) At macro levels, decreased fat accumulation in preadipocytes exposed to insulin during the initial stages of differentiation is a result of reduced expression and nuclear localization of sterol regulatory element binding protein (SREBP)-1. GENERAL SIGNIFICANCE: This study reports a significant reduction of membrane cholesterol and total cholesterol (p<0.01) in cells differentiated in the presence of insulin.

Hyperthermia-associated carboplatin resistance: differential role of p53, HSF1 and Hsp70 in hepatoma cells.

Due to substantial technical improvements, clinical application of heat as a co-adjuvant in cancer treatment is acquiring new interest. The effect of hyperthermia on hepatoma cell lines Hep3B (p53 defective) and HepG2 (p53 wild type) when investigated led to an interesting observation that Hep3B cells are more susceptible to heat stress than HepG2 cells. In addition, heat-induced carboplatin resistance was observed in HepG2 cells only. To investigate the reasons, heat shock response was explored and it was observed that heat stress augmented heat shock protein 70 (Hsp70) expression levels in HepG2 and not in Hep3B cells. Furthermore, in HepG2 cells, induced Hsp70 is regulated by both p53 and heat shock transcription factor 1 (HSF1) wherein HSF1 levels are modulated by p53. The data implies that Hep3B are more susceptible to death upon heat stress than HepG2 cells because of non-induction of Hsp70. In addition, it was observed that inhibition of heat-induced p53/HSF1 diminishes Hsp70 levels, thereby restoring the sensitivity of heat-stressed HepG2 cells to carboplatin-triggered cell death. Collectively, the present study establishes interplay of p53, HSF1, and Hsp70 upon heat stress in HepG2 cells and also defines novel strategies to overcome constraints of utility of hyperthermia in cancer therapy through p53/HSF1-targeted therapeutic intervention.

Sensitization of hepatocellular carcinoma cells towards doxorubicin and sorafenib is facilitated by glucosedependent alterations in reactive oxygen species, P-glycoprotein and DKK4.

Altered glucose uptake and metabolism is the key characteristic of cancer cells including hepatocellular carcinoma (HCC). However, role of glucose availability in chemotherapeutic outcome of HCC is unclear. The present study investigates the effect of glucose facilitated sensitization of HCC cells towards doxorubicin (DOX) and sorafenib (SORA). In HCC cells, we observed that hyperglycemic culture condition (HG) is associated with increased sensitivity towards DOX and SORA. P-glycoprotein (P-gp), a transporter involved in drug efflux, was elevated in HCC cells in NG, rendering them less susceptible to DOX and SORA. Further, this study demonstrated that knockdown of dickkopf protein 4 (DKK4), a Wnt antagonist protein, causes enhanced glucose uptake and reduction in P-gp level rendering HCC cells in NG sensitive to DOX and SORA. Moreover, HG elevates the level of intracellular reactive oxygen species (ROS), which regulates P-gp. Alteration in intracellular ROS did not directly affect regulation of DKK4 in HCC cells. Functional assays suggest that alterations in DKK4 and P-gp level in HCC cells are dependent on glucose availability and changes in ROS level because of enhanced glucose utilization, respectively. Collectively, the present study highlights direct involvement of glucose-induced ROS, DKK4 and P-gp in altering the sensitivity of HCC cells towards DOX and SORA.

Role of TNFα and leptin signaling in colon cancer incidence and tumor growth under obese phenotype.

Epidemiological studies over the last few decades have shown a strong influence of obesity on colon cancer risk and its progression. These studies have primarily focussed on the role of adipokines in driving cancer progression. We investigated the incidence of cancerous polyp formation and tumor progression in presence and absence of functional leptin along with exploring the role of tumor necrosis factor α (TNFα), under obese condition. By utilizing diet induced obese and genetically obese mice, carcinogen induced colon polyp formation was investigated. Experiments were performed using tumor tissues and cell lines to delineate the inter-relationship between leptin and TNFα. Data shown in this report indicates that in leptin knockdown obese mice, AOM/DSS induced polyps are smaller and lesser in numbers as compared to AOM/DSS induced polyps in diet induced obese mice. Further in vitro experiments suggest that abrogation of leptin associated pathways promote TNFα induced apoptosis. Mechanistically, we report that TNFα induces p53 independent cell death through up regulation of p53 upregulated modulator of apoptosis (PUMA). TNFα induced PUMA was inhibited upon pre- exposure of cells to leptin, prior to TNFα treatment. Collectively these results indicate that obesity due to leptin non-functionality facilitates TNFα induced colon cancer cell death.

Mitomycin C induces bystander killing in homogeneous and heterogeneous hepatoma cellular models.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide that is particularly refractory to chemotherapy. Several studies have proposed combination chemotherapy regimen for HCC treatment. However, these therapies are not effective in regressing tumor and prolonging survival of patient's suffering from HCC. Therefore, the development of more effective therapeutic tools and new strategies for the treatment of HCC are urgently needed. Over the last decade much attention has been focused on "bystander effect" as a possible therapeutic strategy for the treatment of certain human tumors. Interest in this therapeutic approach originated from numerous reports describing the radiation induced bystander effect. However, the knowledge about chemotherapy induced bystander effect is still limited. Hence, chemotherapy induced bystander phenomenon in hepatoma cells was explored by utilizing Mitomycin C (MMC). RESULTS: MMC induced bystander killing was observed only in hepatoma cells and it did not occur in cervical cancer cells. MMC induced bystander killing was transferable via medium. It occurred in co-cultured cells indicating the involvement of secreted as well as membrane bound factors. FasL and TRAIL were detected in the conditioned medium from treated cells. In medium transfer experiment, pre-treatment with EDTA (a broad range protease inhibitor) diminished MMC induced bystander killing. Following drug exposure, expression of Fas and TRAIL receptors increased and treatment with neutralizing antibodies against FasL and TRAIL inhibited bystander killing. CONCLUSION: Our results highlight the therapeutic importance of MMC in the treatment of HCC and implicate role of membrane bound and secreted forms of FasL and TRAIL in MMC induced bystander killing.

Hyperglycemia Associated Metabolic and Molecular Alterations in Cancer Risk, Progression, Treatment, and Mortality.

Cancer and diabetes are amongst the leading causes of deaths worldwide. There is an alarming rise in cancer incidences and mortality, with approximately 18.1 million new cases and 9.6 million deaths in 2018. A major contributory but neglected factor for risk of neoplastic transformation is hyperglycemia. Epidemiologically too, lifestyle patterns resulting in high blood glucose level, with or without the role of insulin, are more often correlated with cancer risk, progression, and mortality. The two conditions recurrently exist in comorbidity, and their interplay has rendered treatment regimens more challenging by restricting the choice of drugs, affecting surgical consequences, and having associated fatal complications. Limited comprehensive literature is available on their correlation, and a lack of clarity in understanding in such comorbid conditions contributes to higher mortality rates. Hence, a critical analysis of the elements responsible for enhanced mortality due to hyperglycemia-cancer concomitance is warranted. Given the lifestyle changes in the human population, increasing metabolic disorders, and glucose addiction of cancer cells, hyperglycemia related complications in cancer underline the necessity for further in-depth investigations. This review, therefore, attempts to shed light upon hyperglycemia associated factors in the risk, progression, mortality, and treatment of cancer to highlight important mechanisms and potential therapeutic targets.

Hypoglycemic effect of a novel dialysed fenugreek seeds extract is sustainable and is mediated, in part, by the activation of hepatic enzymes.

A novel preparation of a dialysed aqueous extract of fenugreek seeds (FSE) that stimulates the insulin signalling pathway was reported previously (Vijayakumar et al., 2005). The present study was designed to investigate the long-term effects (multiple dose effect) of this FSE preparation on the blood glucose level and body weight, and a short-term effect (single dose effect) on serum insulin and hepatic enzymes, in experimentally induced diabetic conditions. The multiple dose effect of FSE on the glucose level and body weight was studied in alloxan (AXN)-diabetic mice in comparison with the vehicle treated control diabetic mice. Intraperitoneal (i.p.) administration of FSE (15 mg/kg body weight (BW)) for 5 consecutive days reduced hyperglycemia in AXN-diabetic mice on day 5 and this effect was further sustained for 10 days. The FSE-induced hypoglycemic effect was accompanied without any reduction in the body weight compared with the diabetic mice in which the body weight was reduced significantly. A single dose effect of FSE on hepatic glucokinase (GK) and hexokinase (HK) enzymes was studied in streptozotocin (STZ)-diabetic mice. Intraperitoneal administration of FSE (15 mg/kg BW) by 90 min decreased the blood glucose levels significantly (p < 0.01) in STZ-diabetic mice and the effect was comparable to that achieved by insulin (1.5 U/kg BW) injection. This effect was associated with a significant enhancement in the liver GK and HK activities on a par with that of insulin. In normal glucose loaded mice, FSE improved the intraperitoneal glucose tolerance accompanied by a reduction in serum insulin concentration. These results are indicative of an extra-pancreatic mode of action of FSE. The present study concludes that this novel FSE preparation corrects metabolic alterations associated with diabetes by exhibiting insulin-like properties and has a potential for clinical applications.

Hepatocellular carcinoma-associated hypercholesterolemia: involvement of proprotein-convertase-subtilisin-kexin type-9 (PCSK9).

BACKGROUND: PCSK9 regulates low-density lipoprotein cholesterol (LDLc) level and has been implicated in hypercholesterolemia. Aberrant plasma lipid profile is often associated with various cancers. Clinically, the relationship between altered serum lipid level and hepatocellular carcinoma (HCC) has been documented; however, the underlying cause and implications of such dyslipidemia remain unclear. METHODS: The present study includes the use of HepG2 tumor xenograft model to study the potential role of glucose (by providing 15% glucose via drinking water) in regulating PCSK9 expression and associated hypercholesterolemia. To support in vivo findings, in vitro approaches were used by incubating HCC cells in culture medium with different glucose concentrations or treating the cells with glucose uptake inhibitors. Impact of hypercholesterolemia on chemotherapy was demonstrated by exogenously providing LDLc followed by appropriate in vitro assays. RESULTS: We observed that serum and hepatic PCSK9 level is decreased in mice which were provided with glucose containing water. Interestingly, serum and tumor PCSK9 level was upregulated in HepG2-tumor-bearing mice having access to water containing glucose. Additionally, elevated LDLc is detected in sera of these mice. In vitro studies indicated that PCSK9 expression was increased by high glucose availability with potential involvement of reactive oxygen species (ROS) and sterol regulatory element binding protein-1 (SREBP-1). Furthermore, it is also demonstrated that pre-treatment of cells with LDLc diminishes cytotoxicity of sorafenib in HCC cells. CONCLUSION: Taken together, these results suggest a regulation of PCSK9 by high glucose which could contribute, at least partly, towards understanding the cause of hypercholesterolemia in HCC and its accompanied upshots in terms of altered response of HCC cells towards cancer therapy.

Elevated circulatory levels of leptin and resistin impair therapeutic efficacy of dacarbazine in melanoma under obese state.

BACKGROUND: Obesity is associated with increased risk, poor prognosis and outcome of therapy, in various cancers. Obesity-associated factors or adipokines, especially leptin and resistin, are purported to promote growth, survival, proliferation, and invasiveness of cancer cells. However, the mechanistic link between these adipokines and therapeutic response in malignancies is not clearly understood. METHODS: ob/ob and db/db mouse models were used in this study to evaluate the role of leptin and resistin towards the outcome of dacarbazine (DTIC) therapy in melanoma. Unique in vitro approaches were employed to complement in vivo findings by culturing melanoma cells in the serum collected from the experimental mice. RESULTS: Here, we have shown the role of important adipokines leptin and resistin in growth and the outcome of DTIC therapy in melanoma. Both leptin and resistin not only enhance proliferation of melanoma cells but also are involved in impairing the therapeutic efficacy of DTIC. Leptin and resistin treatment caused an increase in the protein levels of fatty acid synthase (FASN) and caveolin 1 (Cav-1) respectively, through their stabilization in A375 cells. Further, it was observed that leptin and resistin impaired the response of melanoma cells to DTIC via upregulation of heat shock protein 90 (Hsp90) and P-glycoprotein (P-gp) respectively. CONCLUSION: These findings unraveled the involvement of adipokines (leptin and resistin) in melanoma progression, and more importantly, in the outcome of DTIC therapy.