Nivedita Arora

Microenvironment mediated alterations to metabolic pathways confer increased chemo-resistance in CD133 + tumor initiating cells

Chemoresistance in pancreatic cancer has been attributed to tumor-initiating cells (TICs), a minor sub-population of tumor cells. However, the mechanism of chemo-resistance in these cells is still unclear. In the current study, immunohistochemical analysis of LSL-KrasG12D; LSL-Trp53R172H; PdxCre (KPC) murine tumors indicated that hypoxic regions developed through tumor progression. This hypoxic “niche” correlated with increased CD133+ population that had an increased HIF1A activity. Consistent with this observation, CD133+ cells had increased glucose uptake and activity of glycolytic pathway enzymes compared to CD133− cells. Mass spectrometric analysis (UPLC-TQD) following metabolic labeling of CD133+ cells with [13C]-U6 glucose confirmed this observation. Furthermore, although both populations had functionally active mitochondria, CD133+ cells had low mitochondrial complex I and complex IV activity and lesser accumulation of ROS in response to standard chemotherapeutic compounds like paclitaxel, 5FU and gemcitabine. CD133+ cells also showed increased resistance to all three chemotherapeutic compounds and treatment with Glut1 inhibitor (STF31) reversed this resistance, promoting apoptotic death in these cells similar to CD133− cells. Our study indicates that the altered metabolic profile of CD133+ pancreatic TIC protects them against apoptosis, by reducing accumulation of ROS induced by standard chemotherapeutic agents, thereby confering chemoresistance. Since resistance to existing chemotherapy contributes to the poor prognosis in pancreatic cancer, our study paves the way for identifying novel therapeutic targets for managing chemoresistance and tumor recurrence in pancreatic cancer.

Premorbid body mass index and mortality in patients with lung cancer: A systematic review and meta-analysis

OBJECTIVES We aimed to assess the association between premorbid obesity, measured using body mass index (BMI) and lung cancer-related mortality, through a systematic review and meta-analysis. MATERIALS AND METHODS Observational studies reporting statistical measures of association between premorbid BMI categories and lung cancer-related mortality were included in our study. We estimated hazard ratios (aHR) with 95% confidence intervals (CI), comparing lung cancer-related mortality across BMI categories. The main outcome measure was lung cancer-related mortality in obese (BMI≥30kg/m2) and overweight participants (BMI 25.0-29.9kg/m2), compared with normal BMI participants. RESULTS We included 14 studies (including 2 pooled cohort studies) comprising 3,008,137 cancer-free participants at inception, reporting 28,592 lung cancer-related deaths. On meta-analysis, we observed a significantly lower lung cancer-related mortality in overweight (aHR, 0.76; 95% CI, 0.68-0.85) and obese (aHR, 0.68, 95% CI; 0.57-0.81) participants as compared to participants with normal BMI, with considerable heterogeneity; after excluding one study with large effect size, a more conservative and consistent association was observed between BMI and lung cancer-related mortality (overweight vs. normal BMI: aHR, 0.84; 95% CI, 0.79-0.90; obese vs. normal BMI: aHR, 0.81; 95% CI, 0.75-0.87), with moderate heterogeneity. Were similar in men vs. women, non-smokers vs. smokers, and Western vs Asia-Pacific populations. CONCLUSIONS Based on meta-analysis, we observed an independent protective association between premorbid obesity and lung cancer-related mortality. This association was observed across sex, smoking status and geographic region. Further studies are needed to prospectively study this association.

Biological agents in gastrointestinal cancers: adverse effects and their management

Biological therapy comprises agents that by virtue of their unique mechanisms of action, are able to specifically incite a response against or target malignant cells. They differ from conventional chemotherapy with regard to mechanisms of action, indications and side effect profile. Biologic agents have revolutionized therapy for a number of malignancies. In the setting of gastrointestinal (GI) malignancies, agents targeting vascular endothelial growth factor (VEGF), human epidermal growth factor receptor 2 (Her2/Neu) and epidermal growth factor receptor (EGFR) have proven to be invaluable additions to chemotherapy. However, these agents bring with them a set of side effects attributable to their unique mechanisms of action. The anti VEGF agents-bevacizumab, aflibercept and ramucirumab, can result in renal and vascular complications such as hypertension, arterial thrombotic events (ATE), proteinuria and GI perforations. The anti EGFR agents classically cause dermatological toxicities, in addition to hypomagnesemia, which can be dose limiting for patients. Trastuzumab, a monoclonal antibody that targets Her2/Neu, is known to cause cardiotoxicity, especially when used with anthracyclines. Use of immunotherapy agents such as nivolumab is associated with the development immune related adverse events (irAEs). The use of these agents is expected to increase over the next few years and it is crucial that patients and practitioners are aware of their adverse effects and current management strategies. This review highlights the adverse events associated with the use of biologic and immunologic therapies in GI cancers, their incidence and current management strategies.

Downregulation of Sp1 by Minnelide leads to decrease in HSP70 and decrease in tumor burden of Gastric cancer

Background Gastric cancer is the third leading cause of cancer related mortality worldwide with poor survival rates. Even though a number of chemotherapeutic compounds have been used against this disease, stomach cancer has not been particularly sensitive to these drugs. In this study we have evaluated the effect of triptolide, a naturally derived diterpene triepoxide and its water soluble pro-drug Minnelide on several gastric adenocarcinoma cell lines both as monotherapy and in combination with CPT-11. Methods Gastric cancer cell lines MKN28 and MKN45 were treated with varying doses of triptolide in vitro. Cell viability was measured using MTT based assay kit. Apoptotic cell death was assayed by measuring caspase activity. Effect of the triptolide pro-drug, Minnelide, was evaluated by implanting the gastric cancer cells subcutaneously in athymic nude mice. Results Gastric cancer cell lines MKN28 and MKN45 cells exhibited decreased cell viability and increased apoptosis when treated with varying doses of triptolide in vitro. When implanted in athymic nude mice, treatment with Minnelide reduced tumor burden in both MKN28 derived tumors as well as MKN45 derived tumors. Additionally, we also evaluated Minnelide as a single agent and in combination with CPT-11 in the NCI-N87 human gastric tumor xenograft model. Conclusion Our results indicated that the combination of Minnelide with CPT-11 resulted in significantly smaller tumors compared to control. These studies are extremely encouraging as Minnelide is currently undergoing phase 1 clinical trials for gastrointestinal cancers.

Obesity is Independently Associated With Increased Risk of Hepatocellular Cancer–related Mortality: A Systematic Review and Meta-Analysis

Objective: Excess body weight is associated with increased risk of developing hepatocellular cancer (HCC), but its effect on HCC-related mortality remains unclear. We performed a systematic review and meta-analysis to assess the association between premorbid obesity and HCC-related mortality. Materials and Methods: Through a systematic literature search-up to March 2016, we identified 9 observational studies (1,599,453 individuals, 5705 HCC-related deaths) reporting the association between premorbid body mass index (BMI), and HCC-related mortality. We estimated summary adjusted hazard ratio (aHR) with 95% confidence intervals (CIs), comparing obese (BMI>30 kg/m2) and overweight (BMI, 25 to 29.9 kg/m2) individuals with normal BMI individuals using random-effects model. Results: On meta-analysis, compared with individuals with normal BMI, obese (aHR, 1.95; 95% CI, 1.46-2.46), but not overweight individuals (aHR, 1.08; 95% CI, 0.97-1.21), had higher HCC-related mortality, with moderate heterogeneity. On subgroup analysis, magnitude of increased mortality was higher in obese men (aHR, 2.50; 95% CI, 2.02-3.09; 3 studies) as compared with obese women (aHR, 1.45; 95% CI, 1.08-1.97; 2 studies). The impact of premorbid obesity on HCC-related mortality was observed only in western populations (aHR, 2.10; 95% CI, 1.77-2.48; 4 studies), but not Asian populations (aHR, 1.10; 95% CI, 0.63-1.92; 1 study). There was limited assessment of competing risk because of advanced liver disease. Conclusions: On the basis of this meta-analysis, premorbid obesity may be independently associated with a 2-fold risk of HCC-related mortality. This association was more pronounced in men and western populations. Strategies targeting obesity-associated metabolic abnormalities may provide novel pathways for HCC therapy.

Minnelide Inhibits Androgen Dependent, Castration Resistant Prostate Cancer Growth by Decreasing Expression of Androgen Receptor Full Length and Splice Variants

With almost 30,000 deaths per year, prostate cancer is the second‐leading cause of cancer‐related death in men. Androgen Deprivation Therapy (ADT) has been the corner stone of prostate cancer treatment for decades. However, despite an initial response of prostate cancer to ADT, this eventually fails and the tumors recur, resulting in Castration Resistant Prostate Cancer (CRPC). Triptolide, a diterpene triepoxide, has been tested for its anti‐tumor properties in a number of cancers for over a decade. Owing to its poor solubility in aqueous medium, its clinical application had been limited. To circumvent this problem, we have synthesized a water‐soluble pro‐drug of triptolide, Minnelide, that is currently being evaluated in a Phase 1 clinical trial against gastrointestinal tumors. In the current study, we assessed the therapeutic potential of Minnelide and its active compound triptolide against androgen dependent prostate cancer both in vitro as well as in vivo.

A Novel Immunocompetent Mouse Model of Pancreatic Cancer with Robust Stroma: a Valuable Tool for Preclinical Evaluation of New Therapies

A valid preclinical tumor model should recapitulate the tumor microenvironment. Immune and stromal components are absent in immunodeficient models of pancreatic cancer. While these components are present in genetically engineered models such as KrasG12D; Trp53R172H; Pdx-1Cre (KPC), immense variability in development of invasive disease makes them unsuitable for evaluation of novel therapies. We have generated a novel mouse model of pancreatic cancer by implanting tumor fragments from KPC mice into the pancreas of wild type mice. Three-millimeter tumor pieces from KPC mice were implanted into the pancreas of C57BL/6J mice. Four to eight weeks later, tumors were harvested, and stromal and immune components were evaluated. The efficacy of Minnelide, a novel compound which has been shown to be effective against pancreatic cancer in a number of preclinical murine models, was evaluated. In our model, consistent tumor growth and metastases were observed. Tumors demonstrated intense desmoplasia and leukocytic infiltration which was comparable to that in the genetically engineered KPC model and significantly more than that observed in KPC tumor-derived cell line implantation model. Minnelide treatment resulted in a significant decrease in the tumor weight and volume. This novel model demonstrates a consistent growth rate and tumor-associated mortality and recapitulates the tumor microenvironment. This convenient model is a valuable tool to evaluate novel therapies.

Inhibition of hypoxic response decreases stemness and reduces tumorigenic signaling due to impaired assembly of HIF1 transcription complex in pancreatic cancer

Pancreatic tumors are renowned for their extremely hypoxic centers, resulting in upregulation of a number of hypoxia mediated signaling pathways including cell proliferation, metabolism and cell survival. Previous studies from our laboratory have shown that Minnelide, a water-soluble pro-drug of triptolide (anti-cancer compound), decreases viability of cancer cells in vitro as well as in vivo. However, its mechanism of action remain elusive. In the current study we evaluated the effect of Minnelide, on hypoxia mediated oncogenic signaling as well as stemness in pancreatic cancer. Minnelide has just completed Phase 1 trial against GI cancers and is currently awaiting Phase 2 trials. Our results showed that upon treatment with triptolide, HIF-1α protein accumulated in pancreatic cancer cells even though hypoxic response was decreased in them. Our studies showed even though HIF-1α is accumulated in the treated cells, there was no decrease in HIF-1 binding to hypoxia response elements. However, the HIF-1 transcriptional activity was significantly reduced owing to depletion of co-activator p300 upon treatment with triptolide. Further, treatment with triptolide resulted in a decreased activity of Sp1 and NF-kB the two major oncogenic signaling pathway in pancreatic cancer along with a decreased tumor initiating cell (TIC) population in pancreatic tumor.

Inhibition of Sp1 prevents ER homeostasis and causes cell death by lysosomal membrane permeabilization in pancreatic cancer

Endoplasmic reticulum (ER) stress initiates an important mechanism for cell adaptation and survival, named the unfolded protein response (UPR). Severe or chronic/prolonged UPR can breach the threshold for survival and lead to cell death. There is a fundamental gap in knowledge on the molecular mechanism of how chronic ER stress is stimulated and leads to cell death in pancreatic ductal adenocarcinoma (PDAC). Our study shows that downregulating specificity protein 1 (Sp1), a transcription factor that is overexpressed in pancreatic cancer, activates UPR and results in chronic ER stress. In addition, downregulation of Sp1 results in its decreased binding to the ER stress response element present in the promoter region of Grp78, the master regulator of ER stress, thereby preventing homeostasis. We further show that inhibition of Sp1, as well as induction of ER stress, leads to lysosomal membrane permeabilization (LMP), a sustained accumulation of cytosolic calcium, and eventually cell death in pancreatic cancer.

Primary effusion lymphoma: current concepts and management

Purpose of review To summarize the current epidemiology, management, and outcomes of primary effusion lymphoma (PEL) and highlight possible future research efforts. Recent findings Cyclophosphamide, doxorubicin, vincristine, prednisone-based chemotherapy regimens alone or in combination with immunomodulatory agents (e.g., lenalidomide), or proteasome inhibitors (e.g., bortezomib), or targeted therapies, are commonly used to treat PEL. Highly active antiretroviral therapy should be continued or initiated in patients with HIV infection. Randomized controlled trials are lacking. Prognosis remains grim and there exists a need for further investigation into optimal treatment strategies. Summary PEL is an aggressive mature B-cell neoplasm primarily seen in young to middle aged men with HIV, though immunosuppression related to age and comorbidities such as cirrhosis or organ transplantation also predisposes to PEL. Classic cavitary PEL presents as an effusion in the pleural, pericardial, or peritoneal space. Human herpes virus-8/Kaposis sarcoma herpes virus) is classically detected. Given its rarity, randomized controlled trials evaluating optimal treatment regimens are lacking, and cyclophosphamide, doxorubicin, vincristine, prednisone-based chemotherapy has been the mainstay of treatment. Advancement in knowledge of the oncogenic signaling pathways involved in Kaposis sarcoma herpes virus-induced tumorigenesis may pave the way to develop targeted therapies. Video abstract http://links.lww.com/COPM/A19