Therapeutic Approaches For Human Cancers Research Articles

Exploring the Biological Activity and Mechanism of Xenoestrogens and Phytoestrogens in Cancers: Emerging Methods and Concepts.

Xenoestrogens and phytoestrogens are referred to as “foreign estrogens” that are produced outside of the human body and have been shown to exert estrogen-like activity. Xenoestrogens are synthetic industrial chemicals, whereas phytoestrogens are chemicals present in the plant. Considering that these environmental estrogen mimics potentially promote hormone-related cancers, an understanding of how they interact with estrogenic pathways in human cells is crucial to resolve their possible impacts in cancer. Here, we conducted an extensive literature evaluation on the origins of these chemicals, emerging research techniques, updated molecular mechanisms, and ongoing clinical studies of estrogen mimics in human cancers. In this review, we describe new applications of patient-derived xenograft (PDX) models and single-cell RNA sequencing (scRNA-seq) techniques in shaping the current knowledge. At the molecular and cellular levels, we provide comprehensive and up-to-date insights into the mechanism of xenoestrogens and phytoestrogens in modulating the hallmarks of cancer. At the systemic level, we bring the emerging concept of window of susceptibility (WOS) into focus. WOS is the critical timing during the female lifespan that includes the prenatal, pubertal, pregnancy, and menopausal transition periods, during which the mammary glands are more sensitive to environmental exposures. Lastly, we reviewed 18 clinical trials on the application of phytoestrogens in the prevention or treatment of different cancers, conducted from 2002 to the present, and provide evidence-based perspectives on the clinical applications of phytoestrogens in cancers. Further research with carefully thought-through concepts and advanced methods on environmental estrogens will help to improve understanding for the identification of environmental influences, as well as provide novel mechanisms to guide the development of prevention and therapeutic approaches for human cancers.

Epigenetic Restoration of Fetal-like IGF1 Signaling Inhibits Leukemia Stem Cell Activity

Acute leukemias are aggressive malignancies of developmentally arrested hematopoietic progenitors. We sought here to explore the possibility that changes in hematopoietic stem/progenitor cells during development might alter the biology of leukemias arising from this tissue compartment. Using a mouse model of acute Tcell leukemia, we found that leukemias generated from fetal liver (FL) and adult bone marrow (BM) differed dramatically in their leukemia stem cell activity with FL leukemias showing markedly reduced serial transplantability as compared to BM leukemias. We present evidence that this difference is due to NOTCH1-driven autocrine IGF1 signaling, which is active in FL cells but restrained in BM cells by EZH2-dependent H3K27 trimethylation. Further, we confirmed this mechanism is operative in human disease and show that enforced IGF1 signaling effectively limits leukemia stem cell activity.These findings demonstrate that resurrecting dormant fetal programs in adult cells may represent an alternate therapeutic approach in human cancer.

678. Neural Stem Cell-Based Gene Therapy for Malignant Brain Tumor by Doubl-Stranded Adeno-Associated Viral Vectors

Despite intensive efforts exploring gene therapeutic approaches for human cancers, the clinical results in treating of malignant brain tumors are still poor. We demonstrated that the combined therapeutic strategy by using an adenoviral vector carrying the thymidine kinase (suicidal) gene and an adeno-associated viral vector carrying the angiostatin gene achieved better therapeutic results. However, the malignant brain tumor could not be completely eradicated. Therefore, novel vectors and strategies are urgently needed. Neural stem cells (NSCs) may be used either for cell replacement or for gene delivery vehicles in neurodegenerative diseases. The expression of therapeutic proteins by NSCs can be enhanced by viral-mediated gene transfer, though the effects of several common recombinant viruses on primary progenitor cell populations have not been widely tested. The goal of this study is to identify and develop a safe and effective NSCs-based gene therapy protocol to treat malignant glioma. We examined what seral type of the novel double-stranded recombinant adeno-associated viral (AAV) vector can efficiently deliver anti-angiogenic genes and suicidal gene into the rat NSCs. Meanwhile, we investigated the gene product delivered by the genetically engineered NSCs in the adult normal brain. Then, we injected genetically engineered NSCs into different sites of the animal model of human malignant glioma. Flowcytometry data showed that AAV2 had higher transduction efficiency in neural stem cells. The NSCs were engineered to express Decorin and Angiostatin by AAV2, and then injected into the hemisphere contralateral to tumor cell implantation. We demonstrated that genetically-modified NSCs have the capacity to migrate into brain tumors. The therapeutic efficacy of genetically-modified NSCs is remaining explored.

Overexpression of CMET is associated with signal transducer and activator of transcription 3 activation and diminished prognosis in oesophageal adenocarcinoma but not in squamous cell carcinoma

BackgroundInhibition of cMet is a promising therapeutic approach in human cancer, but few data in oesophageal cancer exist. MethodsExpression of mesenchymal-epithelial transition factor (cMet), epidermal growth factor receptor (EGFR) and phosphatase and tensin homologue (PTEN) were investigated immunohistochemically in 246 oesophageal carcinomas (128 adenocarcinomas (AC); 118 squamous cell carcinomas (SCC)) and corresponding metastases in a subset of AC (n=42). Data on phosphorylated signal transducer and activator of transcription 3 (pSTAT3) and HER2 expression and on lymphovascular invasion (LVI) of tumour cells were available from previous studies. ResultsOverexpression of cMet was seen in 44 (34.4%) of AC, and nine (7.6%) of SCC (p<0.001, Chi square test). In AC but not in SCC, cMet expression correlated with EGFR expression (p<0.001, Chi square test), pSTAT3 expression (p=0.01, Chi square tests) and LVI of tumour cells (p<0.001, Chi square test).Overexpression of cMet was associated with shorter disease free, disease specific and overall survival of AC patients (p<0.05, Cox regression, respectively). All cMet positive ACs in which metastases were investigated had also cMet positive lymph node and distant metastases, but 25% of cMet negative primary tumours showed cMet positive lymph node and 33% distant metastases. ConclusionsCMet plays no relevant role in most oesophageal SCC. In contrast, cMet overexpression seems to be a key oncogene in about 35% of oesophageal AC, representing a highly promising therapeutic target and prognostic factor.

Mitochondrial UQCRB regulates VEGFR2 signaling in endothelial cells

Vascular endothelial growth factor (VEGF) signal transduction is involved in tumor angiogenesis, and the inhibition of this pathway is considered to be a powerful strategy for cancer therapy. We previously showed that small molecules targeting the ubiquinol-cytochrome c reductase binding protein (UQCRB), a subunit of mitochondrial complex III, in tumor cells suppress hypoxia-induced tumor angiogenesis. However, the mechanism by which UQCRB functioned remained unknown. In the present study, we demonstrate in endothelial cells (ECs) that UQCRB enhances VEGF receptor type 2 (VEGFR2) signaling by increasing the levels of mitochondrial reactive oxygen species (ROS). By contrast, terpestacin, a UQCRB targeting small molecule, blocked mitochondrial ROS-mediated VEGFR2 signaling pathways in ECs, thereby suppressing VEGF-dependent angiogenesis in vitro and in vivo. Furthermore, treatment with both terpestacin and bevacizumab, a VEGF signaling inhibitor, resulted in additive inhibition of tumor-induced angiogenesis both in vitro and in vivo. These data demonstrate that mitochondrial UQCRB positively regulates VEGFR2 signaling in ECs and the UQCRB targeting agent could be applied in new therapeutic approaches for human cancer. Inhibiting angiogenesis has been a focus for anti-cancer strategies. Mitochondrial UQCRB enhances VEGFR2 signaling by increasing ROS in endothelial cells. UQCRB inhibitor blocks angiogenesis by suppressing mitochondrial ROS. Findings may provide a new therapeutic approach for human cancer.

Abstract 3723: Tangeretin enhances sensitivity of human pancreatic cancer cells to gemcitabine through targeting the reprogramming of stemness.

Abstract Background: As a single agent, gemcitabine (2′,2′-difluorodeoxycytidine) has shown only a modest improvement in survival in patients with pancreatic ductal adenocarcinoma (PDAC). Our recent studies found CCN1 (a member of CCN family of growth factor) as an important factor in determining PDAC aggressiveness as it promotes epithelial to mesenchymal transition, tumor stemness, migration and tumorigenicity in xenograft model, possibly through the regulation of multiple miRNAs that are known to link with the progression of cancers and survival and the maintenance of cancer stem cells. Targeting CCN1 may lead to the development of novel therapeutic approaches for human cancers. Here, we examined the effects of tangeretin, a polymethoxylated flavonoid compound produced by citrus fruits in combination of gemcitabine on CCN1-sonic hedgehog (SHh) signaling in pancreatic cancer cells, and assessed the therapeutic potential of tangeretin with gemcitabine for the treatment and/or prevention of pancreatic cancer. Methodology/Principal Findings: Cell viability and apoptosis were measured by crystal violet staining assay and annexinV/PI staining assay, respectively. Gene and protein expressions were measured by Western blot analysis, respectively. We found that tangeretin in combination with gemcitabine significantly decreased cell survival, clonogenicity, wound-healing capacity, sphere-forming capacity (pancreatospheres) in pancreatic cell lines. Tangeretin also decreased the expression of cancer stem cells (CSC) markers, CD44, Notch-1, Nanog, Oct-4, ABCG2, SHh and CCN1. Conclusions: Collectively, these studies clearly suggest that tangeretin helps in sensitizing pancreatic cancer cells to gemcitabine by reprogramming the CSC-specific markers. Thus tangeretin could be useful for overcoming therapeutic resistance of pancreatic cancer cells. Citation Format: Inamul Haque, Sushanta K. Banerjee, Snigdha Banerjee. Tangeretin enhances sensitivity of human pancreatic cancer cells to gemcitabine through targeting the reprogramming of stemness. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3723. doi:10.1158/1538-7445.AM2013-3723

PI3K/AKT/mTOR Signaling is Involved in (-)-Epigallocatechin-3-Gallate-Induced Apoptosis of Human Pancreatic Carcinoma Cells

PI3K/AKT/mTOR signaling promotes cell survival, proliferation and progression in cancer cells. Targeting this pathway may lead to the development of novel therapeutic approaches for human cancers. Here, we examined the effects of (-)-epigallocatechin-3-gallate (EGCG) on the PI3K/AKT/mTOR pathway in pancreatic cancer cells, and assessed its therapeutic potential. In this study, the proliferation and apoptosis of PANC-1 cells were examined by MTT assay and flow cytometry, respectively. The expression of genes and proteins involved in the PI3K/AKT/mTOR pathway were measured by RT-PCR and western blotting, respectively. Our results revealed that EGCG dramatically inhibited the proliferation of PANC-1 cells and induced apoptosis simultaneously. Furthermore, it upregulated PTEN mRNA and protein expression levels, as well as downregulating the expression of phospho-AKT and phospho-mTOR. In conclusion, these results suggest that EGCG can suppress proliferation and induce apoptosis of PANC-1 cells in a time- and dose-dependent manner; moreover, EGCG also can upregulate PTEN expression and downregulate the expression of pAKT and p-mTOR to modulate the PI3K/AKT/mTOR signaling pathway.

Promises and Challenges of MicroRNA-based Treatment of Multiple Myeloma

MicroRNAs (miRNAs) recently emerged with a key role in multiple myeloma (MM) pathophysiology and are considered important regulators of MM cell growth and survival. Since miRNAs can act either as oncogenes or tumour suppressors, the potential of targeting the miRNA network arises as a novel therapeutic approach for human cancer. Potential strategies based on miRNA therapeutics basically rely on miRNA inhibition or miRNA replacement approaches and take benefit respectively from the use of antagomirs or synthetic miRNAs as well as from lipid-based nanoparticles which allow an efficient miRNA-delivery. The availability of experimental in vivo platforms which recapitulate the growth of MM cells within the specific human bone marrow microenvironment in immunocompromised mice (SCID-hu and SCID-synth-hu) provides powerful systems for development of miRNA-based therapeutics in MM. Preliminary findings on the anti-MM activity of synthetic miRNAs in such experimental models offer a proof-of-principle that miRNA therapeutics is a promising opportunity for this still incurable disease representing the rationale for a new venue of investigation in this specific field.

Abstract 171: EGCG enhances the therapeutic potential of gemcitabine and CP690550 (Tasocitinib) by inhibiting STAT3 signaling pathway in human pancreatic cancer cells

Abstract Signal Transducer and Activator of Transcription 3 (STAT3) is an oncogene, which promotes cell survival, proliferation, motility and progression in cancer cells. Targeting STAT3 signaling may lead to the development of novel therapeutic approaches for human cancers. Here, we examined the effects of epigallocathechin gallate (EGCG) on STAT3 signaling in pancreatic cancer cells, and assessed the therapeutic potential of EGCG with gemcitabine or JAK3 inhibitor CP690550 (Tasocitinib) for the treatment and/or prevention of pancreatic cancer. Cell viability and apoptosis were measured by XTT assay and TUNEL staining, respectively. Gene and protein expressions were measured by qRT-PCR and Western blot analysis, respectively. The results revealed that EGCG inhibited the expression of phospho and total JAK3 and STAT3, STAT3 transcription and activation, and the expression of STAT3-regulated genes, resulting in the inhibition of cell motility, migration and invasion, and the induction of caspase-3 and PARP cleavage. The inhibition of STAT3 enhanced the inhibitory effects of EGCG on cell motility and viability. Additionally, gemcitabine and CP690550 alone inhibited STAT3 target genes and synergized with EGCG to inhibit cell viability and induce apoptosis in pancreatic cancer cells. Overall, these results suggest that EGCG suppresses the growth, invasion and migration of pancreatic cancer cells, and induces apoptosis by interfering with the STAT3 signaling pathway. Moreover, it can be combined with other chemotherapeutic agents like gemcitabine and CP690550 for the treatment and/or prevention of pancreatic cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 171. doi:1538-7445.AM2012-171

EGCG Enhances the Therapeutic Potential of Gemcitabine and CP690550 by Inhibiting STAT3 Signaling Pathway in Human Pancreatic Cancer

BackgroundSignal Transducer and Activator of Transcription 3 (STAT3) is an oncogene, which promotes cell survival, proliferation, motility and progression in cancer cells. Targeting STAT3 signaling may lead to the development of novel therapeutic approaches for human cancers. Here, we examined the effects of epigallocathechin gallate (EGCG) on STAT3 signaling in pancreatic cancer cells, and assessed the therapeutic potential of EGCG with gemcitabine or JAK3 inhibitor CP690550 (Tasocitinib) for the treatment and/or prevention of pancreatic cancer.Methodology/Principal FindingsCell viability and apoptosis were measured by XTT assay and TUNEL staining, respectively. Gene and protein expressions were measured by qRT-PCR and Western blot analysis, respectively. The results revealed that EGCG inhibited the expression of phospho and total JAK3 and STAT3, STAT3 transcription and activation, and the expression of STAT3-regulated genes, resulting in the inhibition of cell motility, migration and invasion, and the induction of caspase-3 and PARP cleavage. The inhibition of STAT3 enhanced the inhibitory effects of EGCG on cell motility and viability. Additionally, gemcitabine and CP690550 alone inhibited STAT3 target genes and synergized with EGCG to inhibit cell viability and induce apoptosis in pancreatic cancer cells.Conclusions/SignificanceOverall, these results suggest that EGCG suppresses the growth, invasion and migration of pancreatic cancer cells, and induces apoptosis by interfering with the STAT3 signaling pathway. Moreover, EGCG further enhanced the therapeutic potential of gemcitabine and CP690550 against pancreatic cancer.

Abstract 1641: Targeting developmental regulators of zebrafish exocrine pancreas as a therapeutic approach in human pancreatic cancer

Abstract We aim to test the hypothesis that histone deacetylases (HDACs) and RNA polymerase III (Polr3) cooperatively control exocrine pancreatic growth, and combined inhibition of HDACs and POLR3 produces enhanced growth suppression in pancreatic cancer. This hypothesis is based on the observations that HDACs and POLR3 play vital roles in fundamental cellular processes, and deregulation of these enzymes has been implicated in malignant transformation. Using chemical inhibitors of HDACs and POLR3, we examined the effect on exocrine pancreas during morphogenesis, and then translated the developmental findings to human pancreatic adenocarcinoma cultured cells. Hdacs and Polr3 are required for exocrine pancreatic epithelial proliferation during morphogenesis. In zebrafish larvae, combination of a Hdac inhibitor (Trichostatin A) and an inhibitor of Polr3 (ML-60218) synergistically prohibited expansion of exocrine pancreas. In human pancreatic adenocarcinoma cells, combination of the clinical HDAC inhibitor suberoyl-anilide hydroxamic acid (SAHA) and ML-60218 produced enhanced suppression of colony formation and proliferation, and induction of cell cycle arrest and apoptotic cell death. The enhanced cytotoxicity was associated with supra-additive induction of a pro-apoptotic regulator and the cyclin-dependent kinase inhibitors. tRNAs have been shown to have pro-proliferative and anti-apoptotic roles, and SAHA-stimulated expression of tRNAs was reversed by ML-60218. These findings demonstrate that chemically targeting developmental regulators in zebrafish can be translated into a potential therapeutic approach in human cancer, and suggest that counteracting the pro-malignant side effect of HDAC inhibitors can enhance their anti-tumor activity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1641. doi:10.1158/1538-7445.AM2011-1641

Growth hormone-releasing hormone antagonist induces apoptosis of human endometrial cancer cells through PKCδ-mediated activation of p53/p21

The growth hormone-releasing hormone (GHRH) antagonists have been shown to inhibit growth of human cancer cells, but the underlying molecular mechanisms and their actions have not been fully investigated. In this study, we first showed that GHRH-R splice variant 1 (SV1) was expressed in two human endometrial cancer cell lines, Ishikawa and ECC-1. By using MTT assay, immunoblotting for cleaved caspase-3 and TUNEL assays, we found that cell growth inhibition and apoptosis were induced in GHRH antagonist, JMR-132-treated cells by activating PKCδ and could be inhibited by treatment with PKC inhibitor, GF109203X. In addition, activation and protein expression of p53 as well as the expression of its downstream effector, p21, were increased by JMR-132 treatment. Moreover, JMR-132-induced p53 and p21 expression were diminished by treatment with PKC inhibitor. Knockdown of endogenous p53 and p21 by siRNAs abolished the JMR-132-induced cell growth inhibition and apoptosis. This study demonstrates a novel mechanism in which GHRH antagonist-induced cell growth inhibition and apoptosis through PKCδ-mediated activation of p53/p21 in human endometrial cancer cells. These findings may suggest the feasibility of GHRH antagonists as a therapeutic approach for human cancer.

The role of autocrine motility factor in tumor and tumor microenvironment

Autocrine motility factor (AMF) is a tumor-secreted cytokine and is abundant at tumor sites, where it may affect the process of tumor growth and metastasis. AMF is a multifunctional protein capable of affecting cell migration, invasion, proliferation, and survival, and possesses phosphoglucose isomerase activity and can catalyze the step in glycolysis and gluconeogenesis. Here, we review the role of AMF and tumor environment on malignant processes. The outcome of metastasis depends on multiple interactions between tumor cells and homeostatic mechanisms, therefore elucidation of the tumor/host interactions in the tumor microenvironment is essential in the development of new prevention and treatment strategies. Such knowledge might provide clues to develop new future therapeutic approaches for human cancers.

Highlights on endoglin (CD105): from basic findings towards clinical applications in human cancer

Antibody targeting of tumor-associated vasculature is a promising therapeutic approach in human cancer; however, a specific cell membrane marker for endothelial cells of tumor vasculature has not been discovered yet. Endoglin (CD105) is a cell-surface glycoprotein most recently identified as an optimal indicator of proliferation of human endothelial cells. The finding that CD105 is over-expressed on vascular endothelium in angiogenetic tissues has prompted several pre-clinical studies designed to get a deeper understanding on the role of CD105 in angiogenesis, and to evaluate the most appropriate clinical setting(s) to utilize CD105 as a therapeutic target. In this review, the foreseeable clinical applications of CD105 in human cancer are discussed.