Hypoxia-induced aggressiveness of pancreatic cancer cells is due to increased expression of VEGF, IL-6 and miR-21, which can be attenuated by CDF treatment. PLoS One. 2012;7:e50165. [PMID: 23272057 PMCID: PMC3521759 DOI: 10.1371/journal.pone.0050165]

Dysregulated MicroRNA Fingerprints and Methylation Patterns in Hepatocellular Carcinoma, Cancer Stem Cells, and Mesenchymal Stem Cells

Hepatocellular carcinoma (HCC) is one of the top causes of cancer mortality worldwide. Although HCC has been researched extensively, there is still a need for novel and effective therapeutic interventions. There is substantial evidence that initiation of carcinogenesis in liver cirrhosis, a leading cause of HCC, is mediated by cancer stem cells (CSCs). CSCs were also shown to be responsible for relapse and chemoresistance in several cancers, including HCC. MicroRNAs (miRNAs) constitute important epigenetic markers that regulate carcinogenesis by acting post-transcriptionally on mRNAs, contributing to the progression of HCC. We have previously shown that co-culture of cancer cells with mesenchymal stem cells (MSCs) could induce the reprogramming of MSCs into CSC-like cells. In this review, we evaluate the available data concerning the epigenetic regulation of miRNAs through methylation and the possible role of this regulation in stem cell and somatic reprogramming in HCC.

Obesity promotes resistance to anti-VEGF therapy in breast cancer by up-regulating IL-6 and potentially FGF-2

Anti-vascular endothelial growth factor (VEGF) therapy has failed to improve survival in patients with breast cancer (BC). Potential mechanisms of resistance to anti-VEGF therapy include the up-regulation of alternative angiogenic and proinflammatory factors. Obesity is associated with hypoxic adipose tissues, including those in the breast, resulting in increased production of some of the aforementioned factors. Hence, we hypothesized that obesity could contribute to anti-VEGF therapy's lack of efficacy. We found that BC patients with obesity harbored increased systemic concentrations of interleukin-6 (IL-6) and/or fibroblast growth factor 2 (FGF-2), and their tumor vasculature was less sensitive to anti-VEGF treatment. Mouse models revealed that obesity impairs the effects of anti-VEGF on angiogenesis, tumor growth, and metastasis. In one murine BC model, obesity was associated with increased IL-6 production from adipocytes and myeloid cells within tumors. IL-6 blockade abrogated the obesity-induced resistance to anti-VEGF therapy in primary and metastatic sites by directly affecting tumor cell proliferation, normalizing tumor vasculature, alleviating hypoxia, and reducing immunosuppression. Similarly, in a second mouse model, where obesity was associated with increased FGF-2, normalization of FGF-2 expression by metformin or specific FGF receptor inhibition decreased vessel density and restored tumor sensitivity to anti-VEGF therapy in obese mice. Collectively, our data indicate that obesity fuels BC resistance to anti-VEGF therapy via the production of inflammatory and angiogenic factors.

Curcumin: a potent agent to reverse epithelial-to-mesenchymal transition

BACKGROUND

Epithelial-to-mesenchymal transition (EMT) is involved in tumor progression, invasion, migration and metastasis. EMT is a process by which polarized epithelial cells acquire motile mesothelial phenotypic features. This process is initiated by disassembly of cell-cell contacts through the loss of epithelial markers and replacement of these markers by mesenchymal markers. Reconstruction of the cytoskeleton and degradation of the tumor basement membrane ensures the spread of invasive malignant tumor cells to distant locations. Accumulating evidence indicates that curcumin, as a well-known phytochemical, can inhibit EMT/metastasis through various mechanisms and pathways in human tumors.

CONCLUSIONS

In this review, we summarize the mechanisms by which curcumin may affect EMT in cells under pathological conditions to understand its potential as a novel anti-tumor agent. Curcumin can exert chemo-preventive effects by inhibition and reversal of the EMT process through both TGF-β-dependent (e.g. in hepatoma and retinal pigment epithelial cancer) and -independent (e.g. in oral cancer, colorectal cancer, pancreatic cancer, hepatocellular carcinoma, breast cancer, melanoma, prostate cancer, bladder cancer, thyroid cancer and lung cancer) pathways. Curcumin can also mitigate chemoresistance through EMT suppression and promotion of the antiproliferative effects of conventional chemotherapeutics. Therefore, curcumin has the potential to be used as a novel adjunctive agent to prevent tumor metastasis, which may at least partly be attributed to its hampering of the EMT process.

Hypoxia-Induced Autophagy Degrades Stromal Lumican into Tumor Microenvironment of Pancreatic Ductal Adenocarcinoma: A Mini-Review

The extracellular matrix (ECM) in the tumor microenvironment (TME) has gained considerable interest in recent years as a crucial component in fundamental cellular processes and provides novel therapeutic targets. Lumican is a class II small leucine-rich proteoglycan with a key role in ECM organization and modulation of biological functions dependent on tumor type, abundance, and stage of disease. The presence of stromal lumican in the ECM surrounding pancreatic ductal adenocarcinoma (PDAC) inhibits cancer cell replication and is associated with improved patient outcomes after multimodal therapies. In this mini-review, were-present our novel findings describing how hypoxia (1% O2) within the TME influences stromal lumican expression and secretion. We observed that hypoxia specifically inhibited lumican expression and secretion post-transcriptionally only from pancreatic stellate cells. Hypoxia-induced increased lactate production did not influence lumican expression. Notably, autophagy was induced by hypoxia in ex vivo cultures of patient-derived primary PDAC xenograft and pancreatic stellate cells; however, the cancer cells remain unaffected. Moreover, hypoxia-inducible factor (HIF)-1α expression or inhibition of AMP-regulated protein kinase (AMPK) activation within hypoxic stellate cells restored lumican expression levels. Interestingly, AMPK inhibition attenuated hypoxia-reduced phosphorylation of the mTOR/p70S6K/4EBP signaling pathway. The aim of this mini-review is to summarize our recent publication that hypoxia reduces stromal lumican in PDAC through autophagy-mediated degradation and reduction in protein synthesis within pancreatic cancer stellate cells. This may provide another plausible mechanism by which hypoxia-induced stromal autophagy leads to cancer growth.

Hypoxia-Induced Autophagy Degrades Stromal Lumican into Tumor Microenvironment of Pancreatic Ductal Adenocarcinoma: A Mini-Review

The extracellular matrix (ECM) in the tumor microenvironment (TME) has gained considerable interest in recent years as a crucial component in fundamental cellular processes and provides novel therapeutic targets. Lumican is a class II small leucine-rich proteoglycan with a key role in ECM organization and modulation of biological functions dependent on tumor type, abundance, and stage of disease. The presence of stromal lumican in the ECM surrounding pancreatic ductal adenocarcinoma (PDAC) inhibits cancer cell replication and is associated with improved patient outcomes after multimodal therapies. In this mini-review, were-present our novel findings describing how hypoxia (1% O2) within the TME influences stromal lumican expression and secretion. We observed that hypoxia specifically inhibited lumican expression and secretion post-transcriptionally only from pancreatic stellate cells. Hypoxia-induced increased lactate production did not influence lumican expression. Notably, autophagy was induced by hypoxia in ex vivo cultures of patient-derived primary PDAC xenograft and pancreatic stellate cells; however, the cancer cells remain unaffected. Moreover, hypoxia-inducible factor (HIF)-1α expression or inhibition of AMP-regulated protein kinase (AMPK) activation within hypoxic stellate cells restored lumican expression levels. Interestingly, AMPK inhibition attenuated hypoxia-reduced phosphorylation of the mTOR/p70S6K/4EBP signaling pathway. The aim of this mini-review is to summarize our recent publication that hypoxia reduces stromal lumican in PDAC through autophagy-mediated degradation and reduction in protein synthesis within pancreatic cancer stellate cells. This may provide another plausible mechanism by which hypoxia-induced stromal autophagy leads to cancer growth.

Hypoxia-induced autophagy of stellate cells inhibits expression and secretion of lumican into microenvironment of pancreatic ductal adenocarcinoma

Lumican is secreted by pancreatic stellate cells and inhibits cancer progression. Extracellular lumican inhibits cancer cell replication and restrains growth of early-stage pancreatic adenocarcinoma (PDAC) such that patients with tumors containing stromal lumican experience a three-fold longer survival after treatment. In the present study, patient tumor tissues, ex-vivo cultures of patient-derived xenografts (PDX), PDAC stellate and tumor cells were used to investigate whether hypoxia (1% O2) within the tumor microenvironment influences stromal lumican expression and secretion. We observed that hypoxia significantly reduced lumican expression and secretion from pancreatic stellate cells, but not cancer cells. Although hypoxia enhanced lactate dehydrogenase A (LDHA) expression and lactate secretion from all cells, neither hypoxia-induced nor exogenous lactate influenced lumican expression. Autophagy was induced by hypoxia in ex vivo cultures of PDX and pancreatic stellate cells, but not cancer cells cultured in 2D. Autophagic flux inhibitors, bafilomycin A1, chloroquine diphosphate salt, and ammonium chloride prevented hypoxia-mediated reduction in lumican expression in stellate cells. Furthermore, inhibition of AMP-regulated protein kinase (AMPK) phosphorylation or hypoxia-inducible factor (HIF)-1α expression within hypoxic stellate cells restored lumican expression levels. Hypoxia did not affect lumican mRNA expression, indicating that hypoxia-induced reduction of lumican occurs post-transcriptionally; in addition, AMPK inhibition prevented hypoxia-reduced phosphorylation of the mTOR/p70S6K/4EBP signaling pathway, a key contributor to protein synthesis. Taken together, these findings demonstrate that hypoxia reduces stromal lumican in PDAC through autophagy-mediated degradation and reduction in protein synthesis within pancreatic cancer stellate cells.

Changes in tumor vascularity depicted by contrast-enhanced EUS as a predictor of prognosis and treatment efficacy in patients with unresectable pancreatic cancer (PEACE): A study protocol

Patients with unresectable pancreatic cancer have a poor prognosis. The analysis of prognostic factors before treatment may be helpful in determining the best therapeutic strategies. The aim of the PEACE study is to assess the vascularity of pancreatic malignant tumors using contrast-enhanced harmonic EUS (CEH-EUS) and to clarify the prognostic value of tumor vascularity in patients with locally advanced and metastatic pancreatic cancer. Hereby, we present the protocol of a prospective, nonrandomized, single-arm, multicenter study aiming to assess changes in tumor vascularity using CEH-EUS before and 2 months after treatment initiation in patients with unresectable, locally advanced/metastatic pancreatic cancer and to examine the correlation between vascular changes and treatment response, progression-free survival, and overall survival.

Curcumin analogs: Their roles in pancreatic cancer growth and metastasis

Curcumin is a polyphenolic constituent of turmeric that is known to have various molecular effects in preclinical models, leading to prevention and anticancer properties. In clinical trials, curcumin has failed to demonstrate activity against pancreatic cancer possibly due to its low bioavailability and potency. Using the curcumin molecular model, our group and others have synthesized several analogs with better bioavailability and higher potency in pancreatic cancer in vitro and xenograft models. This mini review summarizes some of the known molecular effects of curcumin analogs and their potential role as novel therapeutics for pancreatic cancer.

Relations between approved platinum drugs and non-coding RNAs in mesothelioma

Malignant mesothelioma diseases feature an increasing risk due to their severe forms and their association with asbestos exposure. Platinum(II) complexes such as cisplatin and carboplatin are clinically approved for the therapy of mesothelioma often in combination with antimetabolites such as pemetrexed or gemcitabine. It was observed that pathogenic properties of mesothelioma cells and the response of mesothelioma tumors towards platinum-based drugs are strongly influenced by non-coding RNAs, in particular, by small microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). These non-coding RNAs controlled drug sensitivity and the development of tumor resistance towards platinum drugs. An overview of the interactions between platinum drugs and non-coding RNAs is given and the influence of non-coding RNAs on platinum drug efficacy in mesothelioma is discussed. Suitable non-coding RNA-modulating agents with potentially beneficial effects on cisplatin treatment of mesothelioma diseases are mentioned. The understanding of mesothelioma diseases concerning the interactions of non-coding RNAs and platinum drugs will optimize existing therapy schemes and pave the way to new treatment options in future.

Interplay of non-coding RNAs and approved antimetabolites such as gemcitabine and pemetrexed in mesothelioma

Gemcitabine and pemetrexed are clinically approved antimetabolites for the therapy of mesothelioma diseases. These drugs are often applied in combination with platinum complexes and other drugs. The activity of antimetabolites depended on the expression levels of certain non-coding RNAs, in particular, of small microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). The development of tumor resistance towards antimetabolites was regulated by non-coding RNAs. An overview of the interplay between gemcitabine/pemetrexed antimetabolites and non-coding RNAs in mesothelioma is provided. Further to this, various non-coding RNA-modulating agents are discussed which displayed positive effects on gemcitabine or pemetrexed treatment of mesothelioma diseases. A detailed knowledge of the connections of non-coding RNAs with antimetabolites will be constructive for the design of improved therapies in future.

The regulatory role of microRNAs in angiogenesis-related diseases

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression at a post-transcriptional level via either the degradation or translational repression of a target mRNA. They play an irreplaceable role in angiogenesis by regulating the proliferation, differentiation, apoptosis, migration and tube formation of angiogenesis-related cells, which are indispensable for multitudinous physiological and pathological processes, especially for the occurrence and development of vascular diseases. Imbalance between the regulation of miRNAs and angiogenesis may cause many diseases such as cancer, cardiovascular disease, aneurysm, Kawasaki disease, aortic dissection, phlebothrombosis and diabetic microvascular complication. Therefore, it is important to explore the essential role of miRNAs in angiogenesis, which might help to uncover new and effective therapeutic strategies for vascular diseases. This review focuses on the interactions between miRNAs and angiogenesis, and miRNA-based biomarkers in the diagnosis, treatment and prognosis of angiogenesis-related diseases, providing an update on the understanding of the clinical value of miRNAs in targeting angiogenesis.

Role of Dietary Cancer-Preventive Phytochemicals in Pancreatic Cancer Stem Cells

Purpose of review

This article provides a brief overview of cancer-preventive phytochemicals specifically targeting pancreatic cancer (PC) stem cells for prevention and treatment.

Recent findings

Cancer stem cells (CSCs) represent a small proportion of the total cells of a given tumor, and contribute to tumor growth, recurrence, metastasis, and treatment resistance. Many intertwined pathways, including hedgehog, Wnt Signaling, and NOTCH, have been shown to play a role in the formation of CSCs. Recently, numerous chemopreventive agents, such as genistein, (-)-epigallocatechin-3-gallate (EGCG), sulforaphane, curcumin, resveratrol, and quercetin, have been shown to target CSCs mediated through the inhibition of multiple signalling pathways, to avoid toxicity and the side effects of chemical compounds.

Summary

A growing body of research suggests that CSCs are the drivers in treatment resistance, cancer recurrence, and metastasis, in addition to tumor initiation and heterogeneity. Patient survival depends on these CSCs, which are one cause of tumor recurrence after surgery and chemotherapy. Therefore, target selection; an improved understanding of CSC biology, the genetic and molecular profiles of CSCs, and their key signaling pathways, and; appropriate clinical trials endpoints that are designed to target CSCs will help in the development of drugs that will specifically target this small population of stem cells.

Underrated enemy - from nonalcoholic fatty liver disease to cancers of the gastrointestinal tract

Nonalcoholic fatty liver disease (NAFLD) is intrahepatic ectopic lipid deposition which is present despite a lack of other causes of secondary hepatic fat accumulation. It is the most common chronic liver disorder in the welldeveloped countries. NAFLD is a multidisciplinary disease that affects various systems and organs and is inextricably linked to simple obesity, metabolic syndrome, insulin resistance and overt diabetes mellitus type 2. The positive energy balance related to obesity leads to a variety of systemic changes including modified levels of insulin, insulin- like growth factor-1, adipokines, hepatokines and cytokines. It is strongly linked to carcinogenesis and new evidence proves that NAFLD is associated with higher risk of all-cause mortality and cancer-specific mortality among cancer survivors. This article focuses on the association between NAFLD and extrahepatic gastrointestinal tract cancers, aiming to shed light on the pathomechanism of changes leading to the development of tumors.

Effects of resveratrol, curcumin, berberine and other nutraceuticals on aging, cancer development, cancer stem cells and microRNAs

Natural products or nutraceuticals have been shown to elicit anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of microRNA (miR) expression which results in cell death or prevents aging, diabetes, cardiovascular and other diseases. This review will focus on a few natural products, especially on resveratrol (RES), curcumin (CUR) and berberine (BBR). RES is obtained from the skins of grapes and other fruits and berries. RES may extend human lifespan by activating the sirtuins and SIRT1 molecules. CUR is isolated from the root of turmeric (Curcuma longa). CUR is currently used in the treatment of many disorders, especially in those involving an inflammatory process. CUR and modified derivatives have been shown to have potent anti-cancer effects, especially on cancer stem cells (CSC). BBR is also isolated from various plants (e.g., Coptis chinensis) and has been used for centuries in traditional medicine to treat diseases such as adult- onset diabetes. Understanding the benefits of these and other nutraceuticals may result in approaches to improve human health.

Cancer Stem Cells (CSCs) in Drug Resistance and their Therapeutic Implications in Cancer Treatment

Cancer stem cells (CSCs), also known as tumor-initiating cells (TICs), are suggested to be responsible for drug resistance and cancer relapse due in part to their ability to self-renew themselves and differentiate into heterogeneous lineages of cancer cells. Thus, it is important to understand the characteristics and mechanisms by which CSCs display resistance to therapeutic agents. In this review, we highlight the key features and mechanisms that regulate CSC function in drug resistance as well as recent breakthroughs of therapeutic approaches for targeting CSCs. This promises new insights of CSCs in drug resistance and provides better therapeutic rationales to accompany novel anticancer therapeutics.

Targeting Pancreatic Cancer Cell Plasticity: The Latest in Therapeutics

Mortality remains alarmingly high for patients diagnosed with pancreatic ductal adenocarcinoma (PDAC), with 93% succumbing to the disease within five years. The vast majority of PDAC cases are driven by activating mutations in the proto-oncogene KRAS, which results in constitutive proliferation and survival signaling. As efforts to target RAS and its downstream effectors continue, parallel research aimed at identifying novel targets is also needed in order to improve therapeutic options and efficacy. Recent studies demonstrate that self-renewing cancer stem cells (CSCs) contribute to metastatic dissemination and therapy failure, the causes of mortality from PDAC. Here, we discuss current challenges in PDAC therapeutics, highlight the contribution of mesenchymal/CSC plasticity to PDAC pathogenesis, and propose that targeting the drivers of plasticity will prove beneficial. Increasingly, intrinsic oncogenic and extrinsic pro-growth/survival signaling emanating from the tumor microenvironment (TME) are being implicated in the de novo generation of CSC and regulation of tumor cell plasticity. An improved understanding of key regulators of PDAC plasticity is providing new potential avenues for targeting the properties associated with CSC (including enhanced invasion and migration, metastatic outgrowth, and resistance to therapy). Finally, we describe the growing field of therapeutics directed at cancer stem cells and cancer cell plasticity in order to improve the lives of patients with PDAC.

Drug Resistance Driven by Cancer Stem Cells and Their Niche

Drug resistance represents one of the greatest challenges in cancer treatment. Cancer stem cells (CSCs), a subset of cells within the tumor with the potential for self-renewal, differentiation and tumorigenicity, are thought to be the major cause of cancer therapy failure due to their considerable chemo- and radioresistance, resulting in tumor recurrence and eventually metastasis. CSCs are situated in a specialized microenvironment termed the niche, mainly composed of fibroblasts and endothelial, mesenchymal and immune cells, which also play pivotal roles in drug resistance. These neighboring cells promote the molecular signaling pathways required for CSC maintenance and survival and also trigger endogenous drug resistance in CSCs. In addition, tumor niche components such as the extracellular matrix also physically shelter CSCs from therapeutic agents. Interestingly, CSCs contribute directly to the niche in a bilateral feedback loop manner. Here, we review the recent advances in the study of CSCs, the niche and especially their collective contribution to resistance, since increasingly studies suggest that this interaction should be considered as a target for therapeutic strategies.

Curcumin sensitizes pancreatic cancer cells to gemcitabine by attenuating PRC2 subunit EZH2, and the lncRNA PVT1 expression

Development of resistance to chemotherapeutic drugs is a major challenge in the care of patients with pancreatic ductal adenocarcinoma (PDAC). Acquired resistance to chemotherapeutic agents in PDAC has been linked to a subset of cancer cells termed 'cancer stem cells' (CSCs). Therefore, an improved understanding of the molecular events underlying the development of pancreatic CSCs is required to identify new therapeutic targets to overcome chemoresistance. Accumulating evidence indicates that curcumin, a phenolic compound extracted from turmeric, can overcome de novo chemoresistance and re-sensitize tumors to various chemotherapeutic agents. However, the underlying mechanisms for curcumin-mediated chemosensitization remain unclear. The Enhancer of Zeste Homolog-2 (EZH2) subunit of Polycomb Repressive Complex 2 (PRC2) was recently identified as a key player regulating drug resistance. EZH2 mediates interaction with several long non-coding RNAs (lncRNAs) to modulate epithelial-mesenchymal transition and cancer stemness, phenomena commonly associated with drug resistance. Here, we report the re-sensitization of chemoresistant PDAC cells by curcumin through the inhibition of the PRC2-PVT1-c-Myc axis. Using gemcitabine-resistant PDAC cell lines, we found that curcumin sensitized chemoresistant cancer cells by inhibiting the expression of the PRC2 subunit EZH2 and its related lncRNA PVT1. Curcumin was also found to prevent the formation of spheroids, a hallmark of CSCs, and to down-regulate several self-renewal driving genes. In addition, we confirmed our in vitro findings in a xenograft mouse model where curcumin inhibited gemcitabine-resistant tumor growth. Overall, this study indicates clinical relevance for combining curcumin with chemotherapy to overcome chemoresistance in PDAC.

Angiogenesis in adenosquamous cancer of pancreas

Adenosquamous carcinoma of the pancreas (ASCP) is an uncommon variant of exocrine pancreatic malignancies, characterized by a histological admixture of adenomatous and squamous cell elements. This cancer is characterized by a poorly differentiated histology and a poorer clinical outcome compared to pancreatic ductal adenocarcinoma (PDAC). Unlike PDAC, that is characterized by a low microvascular density (MVD) and collapsed vasculature, no data are available about angiogenesis in ASPC. Immunohistochemical evaluation of MVD and trypatse-positive mast cells (MCs) were performed on a single case of ASCP compared to PDAC. Moreover, the levels of angiopoietin-1 and -2 (Ang-1, Ang-2), receptor tyrosine kinase with immunoglobulin and epidermal growth factor homology domain-2 (Tie-2), vascular endothelial growth factor A (VEGFA), hypoxia-inducible factor 1 alpha (HIF1A), miR-21-5p, miR-181a-5p, miR-122-5p, and miR-27a-3p were evaluated by real-time PCR. Higher number of tryptase-positive MCs and MVD are observed in the ASCP case compared to PDAC one. Lower levels of miR-122-5p and higher expression of VEGFA, HIF1A and Ang-2 genes were observed in ASCP. Furthermore, lower Ang-1 and Tie-2 transcript levels and higher increases of miR-21-5p, miR27a-3p and miR-181a-5p levels were found in the rarest form of pancreatic carcinoma. Our data demonstrate an important angiogenic activity in ASCP with a putative role of miR-21-5p, miR-181a-5p, miR-122-5p and miR-27a-3p in the regulation of this process.

Curcumin Inhibits LIN-28A through the Activation of miRNA-98 in the Lung Cancer Cell Line A549

Metastasis is common in lung cancer and is associated with poor clinical outcomes and increased mortality. Curcumin is a natural anti-cancer agent that inhibits the metastasis of various cancers by modulating the expression of micro (mi) RNAs such as miR-98, which acts as a tumor suppressor. This study investigated the effect of curcumin on miR-98 expression and in vitro cell line growth and invasiveness in lung cancer. Curcumin treatment enhanced the expression of miR-98 and reduced that of the miR-98 target gene LIN28A as well as matrix metalloproteinase (MMP) 2 and MMP9 in vitro and in vivo. MiR-98 overexpression suppressed lung cancer cell migration and invasion by inhibiting LIN28A-induced MMP2 and MMP9 expression. Meanwhile, LIN28A level was downregulated by overexpression of miR-98 mimic. Induction of miR-98 by curcumin treatment suppressed MMP2 and MMP9 by targeting LIN28A. These findings provide insight into the mechanisms by which curcumin suppresses lung cancer cell line growth in vitro and in vivo and invasiveness in vitro.

EZH2 in Cancer Progression and Potential Application in Cancer Therapy: A Friend or Foe?

Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, catalyzes tri-methylation of histone H3 at Lys 27 (H3K27me3) to regulate gene expression through epigenetic machinery. EZH2 functions as a double-facet molecule in regulation of gene expression via repression or activation mechanisms, depending on the different cellular contexts. EZH2 interacts with both histone and non-histone proteins to modulate diverse physiological functions including cancer progression and malignancy. In this review article, we focused on the updated information regarding microRNAs (miRNAs) and long non coding RNAs (lncRNAs) in regulation of EZH2, the oncogenic and tumor suppressive roles of EZH2 in cancer progression and malignancy, as well as current pre-clinical and clinical trials of EZH2 inhibitors.

Vandetanib and ADAM inhibitors synergistically attenuate the pathological migration of EBV-infected retinal pigment epithelial cells by regulating the VEGF-mediated MAPK pathway

The extracellular signals induced by vascular endothelial growth factor (VEGF) are implicated in choroidal neovascularization (CNV) and thus, are associated with vision-limiting complications in the human retina. Vandetanib is an oral anticancer drug that selectively inhibits the activities of VEGF receptor and epidermal growth factor receptor tyrosine kinase; however, the effects of vandetanib on VEGF in retinal pigment epithelial (RPE) cells have not yet been studied. In the present study, a combined treatment of vandetanib and a disintegrin and metalloproteinase (ADAM) protein inhibitors were used to assess the regulation of Epstein-Barr virus (EBV)-infected ARPE19 cells (ARPE19/EBV) migration as a model of CNV. Vandetanib suppressed the expression of the mesenchymal markers ADAM10 and ADAM17 in ARPE19/EBV cells, and also upregulated epithelial cell markers of the RPE cells, E-cadherin and N-cadherin. The migratory activity of ARPE19/EBV induced by VEGF was efficiently blocked by vandetanib. Furthermore, co-treatment with vandetanib and an ADAM10 inhibitor (GI254023X) or ADAM17 inhibitor (Marimastat) synergistically prevented migration and the expression of vimentin, Snail and α-smooth muscle actin by regulating extracellular signal-regulated kinase and p38 mitogen-activated protein kinase. These results suggest that a combination treatment of vandetanib and ADAM inhibitors may be developed as a novel therapeutic regimen to control retina neovascular disease.

Targeting miRNAs by polyphenols: Novel therapeutic strategy for cancer

In the recent years, polyphenols have gained significant attention in scientific community owing to their potential anticancer effects against a wide range of human malignancies. Epidemiological, clinical and preclinical studies have supported that daily intake of polyphenol-rich dietary fruits have a strong co-relationship in the prevention of different types of cancer. In addition to direct antioxidant mechanisms, they also regulate several therapeutically important oncogenic signaling and transcription factors. However, after the discovery of microRNA (miRNA), numerous studies have identified that polyphenols, including epigallocatechin-3-gallate, genistein, resveratrol and curcumin exert their anticancer effects by regulating different miRNAs which are implicated in all the stages of cancer. MiRNAs are short, non-coding endogenous RNA, which silence the gene functions by targeting messenger RNA (mRNA) through degradation or translation repression. However, cancer associated miRNAs has emerged only in recent years to support its applications in cancer therapy. Preclinical experiments have suggested that deregulation of single miRNA is sufficient for neoplastic transformation of cells. Indeed, the widespread deregulation of several miRNA profiles of tumor and healthy tissue samples revealed the involvement of many types of miRNA in the development of numerous cancers. Hence, targeting the miRNAs using polyphenols will be a novel and promising strategy in anticancer chemotherapy. Herein, we have critically reviewed the potential applications of polyphenols on various human miRNAs, especially which are involved in oncogenic and tumor suppressor pathways.

Curcumin inhibits cancer progression through regulating expression of microRNAs

Curcumin, a major yellow pigment and spice in turmeric and curry, is a powerful anti-cancer agent. The anti-tumor activities of curcumin include inhibition of tumor proliferation, angiogenesis, invasion and metastasis, induction of tumor apoptosis, increase of chemotherapy sensitivity, and regulation of cell cycle and cancer stem cell, indicating that curcumin maybe a strong therapeutic potential through modulating various cancer progression. It has been reported that microRNAs as small noncoding RNA molecules are related to cancer progression, which can be regulated by curcumin. Dysregulated microRNAs play vital roles in tumor biology via regulating expressions of target genes and then influencing multiple cancer-related signaling pathways. In this review, we focused on the inhibition effect of curcumin on various cancer progression by regulating expression of multiple microRNAs. Curcumin-induced dysregulation of microRNAs may activate or inactivate a set of signaling pathways, such as Akt, Bcl-2, PTEN, p53, Notch, and Erbb signaling pathways. A better understanding of the relation between curcumin and microRNAs may provide a potential therapeutic target for various cancers.

microRNA regulation of human pancreatic cancer stem cells

microRNAs (miRNAs) are a group of small non-coding RNAs that function primarily in the post transcriptional regulation of gene expression in plants and animals. Deregulation of miRNA expression in cancer cells, including pancreatic cancer cells, is well documented, and the involvement of miRNAs in orchestrating tumor genesis and cancer progression has been recognized. This review focuses on recent reports demonstrating that miRNAs are involved in regulation of pancreatic cancer stem cells (CSCs). A number of miRNA species have been identified to be involved in regulating pancreatic CSCs, including miR-21, miR-34, miR-1246, miR-221, the miR-17-92 cluster, the miR-200 and let-7 families. Furthermore, the Notch-signaling pathway and epithelial-mesenchymal transition (EMT) process are associated with miRNA regulation of pancreatic CSCs. Given the significant contribution of CSCs to chemo-resistance and tumor progression, a better understanding of how miRNAs function in pancreatic CSCs could provide novel strategies for the development of therapeutics and diagnostics for this devastating disease.

IL-6 roles - Molecular pathway and clinical implication in pancreatic cancer - A systemic review

Pancreatic cancer has attracted a great deal of attention owing to the poor outcome, increasing prevalence in the last years and delay diagnosis. Known as a complex disease, it involves genetic mutations, changes in tumour microenvironment and inflammatory component dominated by interleukin-6 and its activated pathways, like Janus Kinase-Signal Transducer and Activator of Translation3, Mitogen Activated Protein Kinase and Androgen receptor. The pro-inflammatory cytokine, plays a central role in oncogenesis, cancer progression, invasiveness, microenvironment changes, treatment resistance, prognosis and associated co morbidities like cachexia and depression. Fulfilling these roles IL-6 requires special attention to understand its complexity in PC development.

Hypoxia inducible factor down-regulation, cancer and cancer stem cells (CSCs): ongoing success stories

In cancers, hypoxia inducible factor 1 (HIF-1) is an over-expressed transcription factor, which regulates a large set of genes involved in tumour vascularization, metastases, and cancer stem cells (CSCs) formation and self-renewal. This protein has been identified as a relevant target in oncology and several HIF-1 modulators are now marketed or in advanced clinical trials. The purpose of this review is to summarize the advances in the understanding of its regulation and its inhibition, from the medicinal chemist point of view. To this end, we selected in the recent literature relevant examples of "hit" compounds, including small-sized organic molecules, pseudopeptides and nano-drugs, exhibiting in vitro and/or in vivo both anti-HIF-1 and anti-tumour activities. Whenever possible, a particular emphasis has been dedicated to compounds that selectively target CSCs.

The role of NANOG transcriptional factor in the development of malignant phenotype of cancer cells

NANOG is a transcription factor that is involved in the self-renewal of embryonic stem cells (ES) and is a critical factor for the maintenance of the undifferentiated state of pluripotent cells. Extensive data in the literature show that the NANOG gene is aberrantly expressed during the development of malignancy in cancer cells. ES and cancer stem cells (CSCs), a subpopulation of cancer cells within the tumor, are thought to share common phenotypic properties. This review describes the role of NANOG in cancer cell proliferation, epithelial-mesenchymal transition (EMT), apoptosis and metastasis. In addition, this paper illustrates a correlation between NANOG and signal transducer and activator of transcription 3 (STAT3) in the maintenance of cancer stem cell properties and multidrug resistance. Together, the available data demonstrate that NANOG is strictly involved in the process of carcinogenesis and is a potential prognostic marker of malignant tumors.

Hypoglycemia Enhances Epithelial-Mesenchymal Transition and Invasiveness, and Restrains the Warburg Phenotype, in Hypoxic HeLa Cell Cultures and Microspheroids

The accelerated growth of solid tumors leads to episodes of both hypoxia and hypoglycemia (HH) affecting their intermediary metabolism, signal transduction, and transcriptional activity. A previous study showed that normoxia (20% O₂ ) plus 24 h hypoglycemia (2.5 mM glucose) increased glycolytic flux whereas oxidative phosphorylation (OxPhos) was unchanged versus normoglycemia in HeLa cells. However, the simultaneous effect of HH on energy metabolism has not been yet examined. Therefore, the effect of hypoxia (0.1-1% O₂ ) plus hypoglycemia on the energy metabolism of HeLa cells was analyzed by evaluating protein content and activity, along with fluxes of both glycolysis and OxPhos. Under hypoxia, in which cell growth ceased and OxPhos enzyme activities, ΔΨm and flux were depressed, hypoglycemia did not stimulate glycolytic flux despite increasing H-RAS, p-AMPK, GLUT1, GLUT3, and HKI levels, and further decreasing mitochondrial enzyme content. The impaired mitochondrial function in HH cells correlated with mitophagy activation. The depressed OxPhos and unchanged glycolysis pattern was also observed in quiescent cells from mature multicellular tumor spheroids, suggesting that these inner cell layers are similarly subjected to HH. The principal ATP supplier was glycolysis for HH 2D monolayer and 3D quiescent spheroid cells. Accordingly, the glycolytic inhibitors iodoacetate and gossypol were more effective than mitochondrial inhibitors in decreasing HH-cancer cell viability. Under HH, stem cell-, angiogenic-, and EMT-biomarkers, as well as glycoprotein-P content and invasiveness, were also enhanced. These observations indicate that HH cancer cells develop an attenuated Warburg and pronounced EMT- and invasive-phenotype. J. Cell. Physiol. 232: 1346-1359, 2017. © 2016 Wiley Periodicals, Inc.

KDM6B histone demethylase is an epigenetic regulator of estrogen receptor β expression in human pleural mesothelioma

AIM

To assess the correlation between KDM6B and estrogen receptor β (ERβ) expression in malignant pleural mesothelioma (MPM).

MATERIALS & METHODS

We evaluated gene expression by in silico analysis of microarray data, real-time PCR and western blot in MPM tumors and cell lines.

RESULTS & CONCLUSION

We report a strong positive correlation between the expression of KDM6B and ERβ in MPM tumors and cell lines. We describe that, in hypoxia, the HIF2α-KDM6B axis induces an epithelioid morphology and ERβ expression in biphasic MPM cells with estrogen receptor-negative phenotype. Reduced histone H3K27 tri-methylation confirms KDM6B activity under hypoxic conditions. Importantly, cells treated during reoxygenation with the selective ERβ agonist, KB9520, maintain ERβ expression and the less aggressive phenotype acquired in hypoxia.

Current state of phenolic and terpenoidal dietary factors and natural products as non-coding RNA/microRNA modulators for improved cancer therapy and prevention

The epigenetic regulation of cancer cells by small non-coding RNA molecules, the microRNAs (miRNAs), has raised particular interest in the field of oncology. These miRNAs play crucial roles concerning pathogenic properties of cancer cells and the sensitivity of cancer cells towards anticancer drugs. Certain miRNAs are responsible for an enhanced activity of drugs, while others lead to the formation of tumor resistance. In addition, miRNAs regulate survival and proliferation of cancer cells, in particular of cancer stem-like cells (CSCs), that are especially drug-resistant and, thus, cause tumor relapse in many cases. Various small molecule compounds were discovered that target miRNAs that are known to modulate tumor aggressiveness and drug resistance. This review comprises the effects of naturally occurring small molecules (phenolic compounds and terpenoids) on miRNAs involved in cancer diseases.

Liposome encapsulated curcumin-difluorinated (CDF) inhibits the growth of cisplatin resistant head and neck cancer stem cells

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer, with 600,000 new cases every year worldwide. Although chemotherapeutics exist, five-year survival is only 50%. New strategies to overcome drug resistance are required to improve HNSCC treatment. Curcumin-difluorinated (CDF), a synthetic analog of curcumin, was packaged in liposomes and used to evaluate growth inhibition of cisplatin resistant HNSCC cell lines CCL-23R and UM-SCC-1R generated from the parental cell lines CCL-23 and UM-SCC-1 respectively. Growth inhibition in vitro and expression levels of the CD44 (cancer stem cell marker), cytokines, and growth factors were investigated after liposomal CDF treatment. The in vivo growth inhibitory effect of liposomal CDF was evaluated in the nude mice xenograft tumor model of UM-SCC-1R and the inhibition of CD44 was measured. Treatment of the resistant cell lines in vitro with liposomal CDF resulted in a statistically significant growth inhibition (p < 0.05). The nude mice xenograft study showed a statistically significant tumor growth inhibition of UM-SCC-1R cells and a reduction in the expression of CD44 (p < 0.05), indicating an inhibitory effect of liposomal CDF on CSCs. Our results demonstrate that delivery of CDF through liposomes may be an effective method for the treatment of cisplatin resistant HNSCC.

A novel tumor-promoting mechanism of IL6 and the therapeutic efficacy of tocilizumab: Hypoxia-induced IL6 is a potent autophagy initiator in glioblastoma via the p-STAT3-MIR155-3p-CREBRF pathway

Hypoxia induces protective autophagy in glioblastoma cells and new therapeutic avenues that target this process may improve the outcome for glioblastoma patients. Recent studies have suggested that the autophagic process is upregulated in glioblastomas in response to extensive hypoxia. Hypoxia also induces the upregulation of a specific set of proteins and microRNAs (miRNAs) in a variety of cell types. IL6 (interleukin 6), an inflammatory autocrine and paracrine cytokine that is overexpressed in glioblastoma, has been reported to be a biomarker for poor prognosis because of its tumor-promoting effects. Here, we describe a novel tumor-promoting mechanism of IL6, whereby hypoxia-induced IL6 acts as a potent initiator of autophagy in glioblastoma via the phosphorylated (p)-STAT3-MIR155-3p pathway. IL6 and p-STAT3 levels correlated with the abundance of autophagic cells and HIF1A levels in human glioma tissues and with the grade of human glioma, whereas inhibition of exogenous or endogenous IL6 repressed autophagy in glioblastoma cells in vitro. Knockdown of endogenous MIR155-3p inhibited IL6-induced autophagy, and enforced expression of MIR155-3p restored the anti-autophagic activity of IL6 inhibitors. We show that the hypoxia-IL6-p-STAT3-MIR155-3p-CREBRF-CREB3-ATG5 pathway plays a central role in malignant glioma progression, with blockade of the IL6 receptor by tocilizumab demonstrating a certain level of therapeutic efficacy in a xenograft model in vivo, especially in combination with temozolomide. Moreover, tocilizumab inhibits autophagy by promoting tumor apoptosis. Collectively, our findings provide new insight into the molecular mechanisms underlying hypoxia-induced glioma cell autophagy and point toward a possible efficacious adjuvant therapy for glioblastoma patients.

Curcumin inhibits hypoxia-induced epithelial‑mesenchymal transition in pancreatic cancer cells via suppression of the hedgehog signaling pathway

Hypoxic microenvironment, a common feature of pancreatic cancer, is associated with tumor proliferation, metastasis and epithelial-mesenchymal transition (EMT) changes. In recent years, many natural agents, including curcumin, have been proven to possess the ability to inhibit the progression of pancreatic cancer. However, whether curcumin is able to suppress hypoxia-induced pancreatic cancer progression and the underlying mechanisms are still not fully elucidated. The aim of the present study was to evaluate whether curcumin affects hypoxia-induced EMT and the activation of Hh signaling pathway in pancreatic cancer. The human pancreatic cancer cell line Panc-1, was treated with hypoxic condition and curcumin. Cell proliferation was assessed by the MTT assay. Wound healing assay and transwell invasion assay were used to detect the migratory and invasive activity of cancer cells. The EMT-related factors, E-cadherin, N-cadherin, vimentin were detected by QT-PCR, western blot analysis and immunofluorescence staining. The Hh signaling-related factors, SHH, SMO and GLI1 were detected by western blot analysis. The results of present study showed that curcumin could not only inhibit the hypoxia-induced cell proliferation, migration and invasion in pancreatic cancer, but also mediate the expression of EMT-related factors. In addition, curcumin remarkably inhibited hypoxia-mediated activation of Hh signaling pathway. Taken together, these data indicate that curcumin plays an important role in suppressing hypoxia-induced pancreatic cancer metastasis by inhibiting the Hh signaling pathway. Curcumin might be a potential candidate for chemoprevention of this severe disease.

Cancer stem cells and chemoresistance: The smartest survives the raid

Chemoresistant metastatic relapse of minimal residual disease plays a significant role for poor prognosis of cancer. Growing evidence supports a critical role of cancer stem cell (CSC) behind the mechanisms for this deadly disease. This review briefly introduces the basics of the conventional chemotherapies, updates the CSC theories, highlights the molecular and cellular mechanisms by which CSC smartly designs and utilizes multiple lines of self-defense to avoid being killed by chemotherapy, and concisely summarizes recent progress in studies on CSC-targeted therapies in the end, with the hope to help guide future research toward developing more effective therapeutic strategies to eradicate tumor cells in the patients.

The bounty of nature for changing the cancer landscape

The landscape of cancer has changed considerably in past several years, due mainly to aggressive screening, accumulation of data from basic and epidemiological studies, and the advances in translational research. Natural anticancer agents have always been a part and parcel of cancer research. The initial focus on natural anticancer agents was in context of their cancer chemopreventive properties but their ability to selectively target oncogenic signaling pathways has also been recognized. In light of the rapid advancements in our understanding of the role of microRNAs, cancer stem cells, and epigenetic events in cancer initiation and progression, a number of natural anticancer agents are showing promise in vitro, in vivo as well as in preclinical studies. Moreover, parent structures of natural agents are being extensively modified with the hope of improving efficacy, specificity, and bioavailability. In this article, we focus on two natural agents, 3,3'-diindolylmethane and garcinol, along with 3,4-difluorobenzo curcumin, a synthetic analog of natural agent curcumin. We showcase how these anticancer agents are changing cancer landscape by modulating novel microRNAs, epigenetic factors, and cancer stem cell markers. These activities are relevant and being appreciated for overcoming drug resistance and inhibition of metastases, the two overarching clinical challenges in modern medicine.

Reprogramming carcinoma associated fibroblasts by AC1MMYR2 impedes tumor metastasis and improves chemotherapy efficacy

Carcinoma associated fibroblasts (CAFs) produce a nutrient-rich microenvironment to fuel tumor progression and metastasis. Reactive oxygen species (ROS) levels and the inflammation pathway co-operate to transform CAFs. Therefore, elucidating the mechanism mediating the activity of CAFs might identify novel therapies. Abnormal miR-21 expression was reported to be involved in the conversion of resident fibroblasts to CAFs, yet the factor that drives transformation was poorly understood. Here, we reported that high miR-21 expression was strongly associated with lymph node metastasis in breast cancer, and the activation of the miR-21/NF-кB was required for the metastatic promoting effect of CAFs. AC1MMYR2, a small molecule inhibitor of miR-21, attenuated NF-кB activity by directly targeting VHL, thereby blocking the co-precipitation of NF-кB and ß-catenin and nuclear translocation. Taxol failed to constrain the aggressive behavior of cancer cells stimulated by CAFs, whereas AC1MMYR2 plus taxol significantly suppressed tumor migration and invasion ability. Remodeling and depolarization of F-actin, decreased levels of β-catenin and vimentin, and increased E-cadherin were also detected in the combination therapy. Furthermore, reduced levels of FAP-α and α-SMA were observed, suggesting that AC1MMYR2 was competent to reprogram CAFs via the NF-кB/miR-21/VHL axis. Strikingly, a significant reduction of tumor growth and lung metastasis was observed in the combination treated mice. Taken together, our findings identified miR-21 as a critical mediator of metastasis in breast cancer through the tumor environment. AC1MMYR2 may be translated into the clinic and developed as a more personalized and effective neoadjuvant treatment for patients to reduce metastasis and improve the chemotherapy response.

miR-21 Is Linked to Glioma Angiogenesis: A Co-Localization Study

MicroRNA-21 (miR-21) is the most consistently over-expressed microRNA (miRNA) in malignant gliomas. We have previously reported that miR-21 is upregulated in glioma vessels and subsets of glioma cells. To better understand the role of miR-21 in glioma angiogenesis and to characterize miR-21-positive tumor cells, we systematically stained consecutive serial sections from ten astrocytomas for miR-21, hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), phosphatase and tensin homolog (PTEN), octamer-binding transcription factor 4 (Oct4), sex-determining region Y box 2 (Sox2) and CD133. We developed an image analysis-based co-localization approach allowing global alignment and quantitation of the individual markers, and measured the miR-21 in situ hybridization signal against the immunohistochemical staining of the six different markers. miR-21 significantly co-localized with the hypoxia- and angiogenesis-associated markers HIF-1α (p=0.0020) and VEGF (p=0.0096), whereas the putative miR-21 target, PTEN, was expressed independently of miR-21. Expression of stem cell markers Oct4, Sox2 and CD133 was not associated with miR-21. In six glioblastoma cultures, miR-21 did not correlate with the six markers. These findings suggest that miR-21 is linked to glioma angiogenesis, that miR-21 is unlikely to regulate PTEN, and that miR-21-positive tumor cells do not possess stem cell characteristics.

Measurement of Tumor Hypoxia in Patients with Advanced Pancreatic Cancer Based on 18F-Fluoroazomyin Arabinoside Uptake

Pancreatic cancers are thought to be unusually hypoxic, which might sensitize them to drugs that are activated under hypoxic conditions. In order to develop this idea in the clinic, a minimally invasive technique for measuring the oxygenation status of pancreatic cancers is needed.

METHODS

We tested the potential for minimally invasive imaging of hypoxia in pancreatic cancer patients, using the 2-nitroimidazole PET tracer (18)F-fluoroazomycin arabinoside (or (18)F-1-α-D-[5-fluoro-5-deoxyarabinofuranosyl]-2-nitroimidazole [(18)F-FAZA]). Dynamic and static scans were obtained in 21 patients with either locally advanced or metastatic disease. The hypoxic fraction was determined in the 2-h static scans as the percentage of voxels with SUVs more than 3 SDs from the mean values obtained for skeletal muscle.

RESULTS

Hypoxia was detected in 15 of 20 evaluable patients, with the hypoxic fraction ranging from less than 5% to greater than 50%. Compartmental analysis of the dynamic scans allowed us to approximate the tumor perfusion as mL/min/g of tissue, a value that is independent of the extent of hypoxia derived from tracer uptake in the 2-h static scan. There was no significant correlation between tumor perfusion and hypoxia; nor did we see an association between tumor volume and hypoxia.

CONCLUSION

Although pancreatic cancers can be highly hypoxic, a substantial proportion appears to be well oxygenated. Therefore, we suggest that a minimally invasive technique such as the one described in this study be used for patient stratification in future clinical trials of hypoxia-targeting agents.

The critical roles of miR-21 in anti-cancer effects of curcumin

Curcumin is a well-known phytochemical that has various anti-cancer effects. Although it has been demonstrated that curcumin can inhibit multiple signalling pathways, the exact mechanisms for its demonstrated anti-cancer effects are not fully understood. Recent studies have revealed that curcumin may affect cancer initiation and progression through regulating microRNAs (miRs). In this review, we focus on the roles of microRNA-21 (miR-21) in the anti-cancer effects of curcumin and regulatory mechanisms for the effects of curcumin on miR-21. MiR-21 mediates various effects of curcumin on cancer cells including proliferation, apoptosis, metastasis and anti-cancer drug resistance. Several downstream pathways of miR-21 have been identified including phosphatase and tensin homolog (PTEN)/phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), programmed cell death protein 4 (PDCD4) and NF-κB pathways. Curcumin decreases miR-21 levels through both increasing miR-21 exosome exclusion from the cells and inhibiting the transcription of the miR-21 gene in the cells by binding to its promoter.

Novel Holistic Approaches for Overcoming Therapy Resistance in Pancreatic and Colon Cancers

Gastrointestinal (GI) cancers, such as of the colon and pancreas, are highly resistant to both standard and targeted therapeutics. Therapy-resistant and heterogeneous GI cancers harbor highly complex signaling networks (the resistome) that resist apoptotic programming. Commonly used gemcitabine or platinum-based regimens fail to induce meaningful (i.e. disease-reversing) perturbations in the resistome, resulting in high rates of treatment failure. The GI cancer resistance networks are, in part, due to interactions between parallel signaling and aberrantly expressed microRNAs (miRNAs) that collectively promote the development and survival of drug-resistant cancer stem cells with epithelial-to-mesenchymal transition (EMT) characteristics. The lack of understanding of the resistance networks associated with this subpopulation of cells as well as reductionist, single protein-/pathway-targeted approaches have made 'effective drug design' a difficult task. We propose that the successful design of novel therapeutic regimens to target drug-resistant GI tumors is only possible if network-based drug avenues and agents, in particular 'natural agents' with no known toxicity, are correctly identified. Natural agents (dietary agents or their synthetic derivatives) can individually alter miRNA profiles, suppress EMT pathways and eliminate cancer stem-like cells that derive from pancreatic cancer and colon cancer, by partially targeting multiple yet meaningful networks within the GI cancer resistome. However, the efficacy of these agents as combinations (e.g. consumed in the diet) against this resistome has never been studied. This short review article provides an overview of the different challenges involved in the understanding of the GI resistome, and how novel computational biology can help in the design of effective therapies to overcome resistance.

Cancer prevention and therapy through the modulation of the tumor microenvironment

Cancer arises in the context of an in vivo tumor microenvironment. This microenvironment is both a cause and consequence of tumorigenesis. Tumor and host cells co-evolve dynamically through indirect and direct cellular interactions, eliciting multiscale effects on many biological programs, including cellular proliferation, growth, and metabolism, as well as angiogenesis and hypoxia and innate and adaptive immunity. Here we highlight specific biological processes that could be exploited as targets for the prevention and therapy of cancer. Specifically, we describe how inhibition of targets such as cholesterol synthesis and metabolites, reactive oxygen species and hypoxia, macrophage activation and conversion, indoleamine 2,3-dioxygenase regulation of dendritic cells, vascular endothelial growth factor regulation of angiogenesis, fibrosis inhibition, endoglin, and Janus kinase signaling emerge as examples of important potential nexuses in the regulation of tumorigenesis and the tumor microenvironment that can be targeted. We have also identified therapeutic agents as approaches, in particular natural products such as berberine, resveratrol, onionin A, epigallocatechin gallate, genistein, curcumin, naringenin, desoxyrhapontigenin, piperine, and zerumbone, that may warrant further investigation to target the tumor microenvironment for the treatment and/or prevention of cancer.

PTEN inhibits macrophage polarization from M1 to M2 through CCL2 and VEGF-A reduction and NHERF-1 synergism

PTEN has been studied in several tumor models as a tumor suppressor. In this study, we explored the role of PTEN in the inhibition state of polarized M2 subtype of macrophage in tumor microenvironment (TME) and the underlying mechanisms. To elucidate the potential effect in TME, RAW 264.7 macrophages and 4T1 mouse breast cancer cells were co-cultured to reconstruct tumor microenvironment. After PTEN was down-regulated with shRNA, the expression of CCL2 and VEGF-A, which are definited to promote the formation of M2 macrophages, have a dramatically increase on the level of both gene and protein in co-cultured RAW 264.7 macrophages. And at the same time, NHERF-1 (Na(+)/H(+) exchanger regulating factor-1), another tumor suppressor has a similar tendency to PTEN. Q-PCR and WB results suggested that PTEN and NHERF-1 were consistent with one another no matter at mRNA or protein level when exposed to the same stimulus. Coimmunoprecipitation and immunofluorescence techniques confirmed that PTEN and NHERF-1 were coprecipitated, and NHERF-1 protein expression was properly reduced with rCCL2 effect. In addition, cell immunofluorescence images revealed a profound transferance, in co-cultured RAW 264.7 macrophages, an up-regulation of NHERF-1 could promote the PTEN marked expression on the cell membrane, and this form for the interaction was not negligible. These observations illustrate PTEN with a certain synergy of NHERF-1, as well as down-regulation of CCL2 suppressing M2 macrophage transformation pathway. The results suggest that the activation of PTEN and NHERF-1 may impede the evolution of macrophages beyond the M1 into M2 phenotype in tumor microenvironment.

Emerging role of microRNAs in cancer stem cells: Implications in cancer therapy

A small subset of cancer cells that act as tumor initiating cells or cancer stem cells (CSCs) maintain self-renewal and growth promoting capabilities of cancer and are responsible for drug/treatment resistance, tumor recurrence and metastasis. Due to their potential clinical importance, many researchers have put their efforts over decades to unravel the molecular mechanisms that regulate CSCs functions. MicroRNAs (miRNAs) which are 21-23 nucleotide long, endogenous non-coding RNAs, regulate gene expression through gene silencing at post-transcriptional level by binding to the 3’-untranslated regions or the open reading frames of target genes, thereby result in target mRNA degradation or its translational repression and serve important role in several cellular, physiological and developmental processes. Aberrant miRNAs expression and their implication in CSCs regulation by controlling asymmetric cell division, drug/treatment resistance and metastasis make miRNAs a tool of great therapeutic potential against cancer. Recent advancements on the biological complexities of CSCs, modulation in CSCs properties by miRNA network and development of miRNA based treatment strategies specifically targeting the CSCs as an attractive therapeutic targets for clinical application are being critically analysed.

MicroRNA-21 coordinates human multipotent cardiovascular progenitors therapeutic potential

Published clinical trials in patients with ischemic diseases show limited benefit of adult stem cell-based therapy, likely due to their restricted plasticity and commitment toward vascular cell lineage. We aim to uncover the potent regenerative ability of MesP1/stage-specific embryonic antigen 1 (SSEA-1)-expressing cardiovascular progenitors enriched from human embryonic stem cells (hESCs). Injection of only 10(4) hESC-derived SSEA-1(+) /MesP1(+) cells, or their progeny obtained after treatment with VEGF-A or PDGF-BB, was effective enough to enhance postischemic revascularization in immunodeficient mice with critical limb ischemia (CLI). However, the rate of incorporation of hESC-derived SSEA-1(+) /MesP1(+) cells and their derivatives in ischemic tissues was modest. Alternatively, these cells possessed a unique miR-21 signature that inhibited phosphotase and tensin homolog (PTEN) thereby activating HIF-1α and the systemic release of VEGF-A. Targeting miR-21 limited cell survival and inhibited their proangiogenic capacities both in the Matrigel model and in mice with CLI. We next assessed the impact of mR-21 in adult angiogenesis-promoting cells. We observed an impaired postischemic angiogenesis in miR-21-deficient mice. Notably, miR-21 was highly expressed in circulating and infiltrated monocytes where it targeted PTEN/HIF-1α/VEGF-A signaling and cell survival. As a result, miR-21-deficient mice displayed an impaired number of infiltrated monocytes and a defective angiogenic phenotype that could be partially restored by retransplantation of bone marrow-derived cells from wild-type littermates. hESC-derived SSEA-1(+) /MesP1(+) cells progenitor cells are powerful key integrators of therapeutic angiogenesis in ischemic milieu and miR-21 is instrumental in this process as well as in the orchestration of the biological activity of adult angiogenesis-promoting cells.