Marisa Shiina

Hyaluronan-CD44 interaction promotes oncogenic signaling, microRNA functions, chemoresistance, and radiation resistance in cancer stem cells leading to tumor progression.

Hyaluronan (HA), a major component of the extracellular matrix (ECM), is enriched in many types of tumors. There is good evidence linking high levels of HA production in human carcinomas to an aggressive phenotype and tumor metastasis. HA is generally bound to CD44 isoforms (so-called CD44s and CD44v3) which are ubiquitous, abundant, and functionally important cell surface receptors. This chapter describes the evidence for HA/CD44v3-mediated activation of the cytoskeleton (e.g., ankyrin and GTPases) and matrix metalloproteinase (MMP) signaling during tumor progression. A special focus is placed on the role of HA-CD44v3 interaction in cancer stem cells (CSCs). Matrix HA is known to be present in CSC niches. Since CD44v3 serves as a CSC marker, it provides an important physical linkage between matrix HA and various transcription factors that regulate tumor cell functions through distinct signaling pathways. CSCs are known to be chemoresistant and/or radiation resistant and to cause cancer relapse. The purpose of this chapter is to review the most current research on the cellular and molecular biology of CSCs. The emphasis will be placed on both CSC niche and matrix HA-induced microRNA signaling plus various CSC functions (e.g., self-renewal, differentiation, and chemoresistance) during cancer progression. Understanding the regulation of CSCs is critically important for designing CSC-specific therapeutic targets to prevent cancer development and progression.

A Dynamical Systems Model for Combinatorial Cancer Therapy Enhances Oncolytic Adenovirus Efficacy by MEK-Inhibition

Oncolytic adenoviruses, such as ONYX-015, have been tested in clinical trials for currently untreatable tumors, but have yet to demonstrate adequate therapeutic efficacy. The extent to which viruses infect targeted cells determines the efficacy of this approach but many tumors down-regulate the Coxsackievirus and Adenovirus Receptor (CAR), rendering them less susceptible to infection. Disrupting MAPK pathway signaling by pharmacological inhibition of MEK up-regulates CAR expression, offering possible enhanced adenovirus infection. MEK inhibition, however, interferes with adenovirus replication due to resulting G1-phase cell cycle arrest. Therefore, enhanced efficacy will depend on treatment protocols that productively balance these competing effects. Predictive understanding of how to attain and enhance therapeutic efficacy of combinatorial treatment is difficult since the effects of MEK inhibitors, in conjunction with adenovirus/cell interactions, are complex nonlinear dynamic processes. We investigated combinatorial treatment strategies using a mathematical model that predicts the impact of MEK inhibition on tumor cell proliferation, ONYX-015 infection, and oncolysis. Specifically, we fit a nonlinear differential equation system to dedicated experimental data and analyzed the resulting simulations for favorable treatment strategies. Simulations predicted enhanced combinatorial therapy when both treatments were applied simultaneously; we successfully validated these predictions in an ensuing explicit test study. Further analysis revealed that a CAR-independent mechanism may be responsible for amplified virus production and cell death. We conclude that integrated computational and experimental analysis of combinatorial therapy provides a useful means to identify treatment/infection protocols that yield clinically significant oncolysis. Enhanced oncolytic therapy has the potential to dramatically improve non-surgical cancer treatment, especially in locally advanced or metastatic cases where treatment options remain limited.

Oncogenic microRNA-4534 regulates PTEN pathway in prostate cancer

Prostate carcinogenesis involves alterations in several signaling pathways, the most prominent being the PI3K/AKT pathway. This pathway is constitutively active and drives prostate cancer (PCa) progression to advanced metastatic disease. PTEN, a critical tumor and metastasis suppressor gene negatively regulates cell survival, proliferation, migration and angiogenesis via the PI3K/Akt pathway. PTEN is mutated, downregulated/dysfunctional in many cancers and its dysregulation correlates with poor prognosis in PCa. Here, we demonstrate that microRNA-4534 (miR-4534) is overexpressed in PCa and show that miR-4534 is hypermethylated in normal tissues and cell lines compared to PCa tissues/cells. miR-4534 exerts its oncogenic effects partly by downregulating the tumor suppressor PTEN gene. Knockdown of miR-4534 impaired cell proliferation, migration/invasion and induced G0/G1 cell cycle arrest and apoptosis in PCa. Suppression of miR-4534 and its effects on tumor growth was confirmed in a xenograft mouse model. We performed parallel experiments in non-cancer RWPE1 cells by overexpessing miR-4534 followed by functional assays. Overexpression of miR-4534 induced pro-cancerous characteristics in this non-cancer cell line. Statistical analyses revealed that miR-4534 has potential to independently distinguish malignant from normal tissues and positively correlated with poor overall and PSA recurrence free survival. Taken together, our results show that depletion of miR-4534 in PCa induces a tumor suppressor phenotype partly through induction of PTEN. These results have important implications for identifying and defining the role of new PTEN regulators such as microRNAs in prostate tumorigenesis. Understanding aberrantly overexpressed miR-4534 and its downregulation of PTEN will provide mechanistic insight and therapeutic targets for PCa therapy.

Up-regulation of Histone Methyltransferase, DOT1L, by Matrix Hyaluronan Promotes MicroRNA-10 Expression Leading to Tumor Cell Invasion and Chemoresistance in Cancer Stem Cells from Head and Neck Squamous Cell Carcinoma

Human head and neck squamous cell carcinoma is a solid tumor malignancy associated with major morbidity and mortality. In this study, we determined that human head and neck squamous cell carcinoma-derived HSC-3 cells contain a subpopulation of cancer stem cells (CSCs) characterized by a high level of CD44v3 and aldehyde dehydrogenase-1 (ALDH1) expression. Importantly, matrix hyaluronan (HA) induces the up-regulation of stem cell markers that display the hallmark CSC properties. Histone methyltransferase, DOT1L, is also up-regulated by HA in CSCs (isolated from HSC-3 cells). Further analyses indicate that the stimulation of microRNA-10b (miR-10b) expression is DOT1L-specific and HA/CD44-dependent in CSCs. This process subsequently results in the overexpression of RhoGTPases and survival proteins leading to tumor cell invasion and cisplatin resistance. Treatment of CSCs with DOT1L-specific small interfering RNAs (siRNAs) effectively blocks HA/CD44-mediated expression of DOT1L, miR-10b production, and RhoGTPase/survival protein up-regulation as well as reduces tumor cell invasion and enhances chemosensitivity. CSCs were also transfected with a specific anti-miR-10b inhibitor to silence miR-10b expression and block its target functions. Our results demonstrate that the anti-miR-10 inhibitor not only decreases RhoGTPase/survival protein expression and tumor cell invasion, but also increases chemosensitivity in HA-treated CSCs. Taken together, these findings strongly support the contention that histone methyltransferase, DOT1L-associated epigenetic changes induced by HA play pivotal roles in miR-10 production leading to up-regulation of RhoGTPase and survival proteins. All of these events are critically important for the acquisition of cancer stem cell properties, including self-renewal, tumor cell invasion, and chemotherapy resistance in HA/CD44-activated head and neck cancer.

ZEB1 limits adenoviral infectability by transcriptionally repressing the Coxsackie virus and Adenovirus Receptor

BackgroundWe have previously reported that RAS-MEK (Cancer Res. 2003 May 1;63(9):2088-95) and TGF-β (Cancer Res. 2006 Feb 1;66(3):1648-57) signaling negatively regulate coxsackie virus and adenovirus receptor (CAR) cell-surface expression and adenovirus uptake. In the case of TGF-β, down-regulation of CAR occurred in context of epithelial-to-mesenchymal transition (EMT), a process associated with transcriptional repression of E-cadherin by, for instance, the E2 box-binding factors Snail, Slug, SIP1 or ZEB1. While EMT is crucial in embryonic development, it has been proposed to contribute to the formation of invasive and metastatic carcinomas by reducing cell-cell contacts and increasing cell migration.ResultsHere, we show that ZEB1 represses CAR expression in both PANC-1 (pancreatic) and MDA-MB-231 (breast) human cancer cells. We demonstrate that ZEB1 physically associates with at least one of two closely spaced and conserved E2 boxes within the minimal CAR promoter here defined as genomic region -291 to -1 relative to the translational start ATG. In agreement with ZEB1s established role as a negative regulator of the epithelial phenotype, silencing its expression in MDA-MB-231 cells induced a partial Mesenchymal-to-Epithelial Transition (MET) characterized by increased levels of E-cadherin and CAR, and decreased expression of fibronectin. Conversely, knockdown of ZEB1 in PANC-1 cells antagonized both the TGF-β-induced down-regulation of E-cadherin and CAR and the reduction of adenovirus uptake. Interestingly, even though ZEB1 clearly contributes to the TGF-β-induced mesenchymal phenotype of PANC-1 cells, TGF-β did not seem to affect ZEB1s protein levels or subcellular localization. These findings suggest that TGF-β may inhibit CAR expression by regulating factor(s) that cooperate with ZEB1 to repress the CAR promoter, rather than by regulating ZEB1 expression levels. In addition to the negative E2 box-mediated regulation the minimal CAR promoter is positively regulated through conserved ETS and CRE elements.ConclusionsThis report provides evidence that inhibition of ZEB1 may improve adenovirus uptake of cancer cells that have undergone EMT and for which ZEB1 is necessary to maintain the mesenchymal phenotype. Targeting of ZEB1 may reverse some aspects of EMT including the down-regulation of CAR.

MicroRNA-203 inhibits long noncoding RNA HOTAIR and regulates tumorigenesis through epithelial-to-mesenchymal transition pathway in renal cell carcinoma

This study aims to investigate the role of miR-203–HOTAIR interaction in the suppression of renal cell carcinoma (RCC). We employed series of in vitro assays such as proliferation, invasion, migration, and colony formation along with in vivo tumor xenograft model. Profiling of miR-203 and HOTAIR expression revealed that miR-203 was significantly underexpressed, whereas HOTAIR was overexpressed in RCC cell lines and clinical specimens compared with normal cell line and tissue. Both miR-203 and HOTAIR expression significantly distinguished malignant from normal tissues and significantly correlated with clinicopathologic characteristics of patients. Overexpression of miR-203 significantly inhibited proliferation, migration, and invasion with an induction of apoptosis and cell-cycle arrest. However, HOTAIR suppression resulted in the similar functional effects in the same RCC cell lines. In silico, RNA-22 algorithm showed a binding site for miR-203 in HOTAIR. We observed a direct interaction between miR-203 and HOTAIR by RNA-immunoprecipitation (RIP) and luciferase reporter assays. We show that miR-203–HOTAIR interaction resulted in the inhibition of epithelial-to-mesenchymal transition (EMT) and metastatic genes as indicated by induction of key metastasis-suppressing proteins E-cadherin, claudin (epithelial markers), and PTEN along with induction of tumor suppressor genes p21 and p27. A significant decrease in vimentin (mesenchymal marker), KLF4, and Nanog (stemness markers) was also observed. This is the first report demonstrating miR-203–mediated regulation of HOTAIR induces tumor suppressor effects in RCC by regulating EMT and metastatic pathway genes. Thus, the study suggests that therapeutic regulation of HOTAIR by miR-203 overexpression may provide an opportunity to regulate RCC growth and metastasis. Mol Cancer Ther; 17(5); 1061–9. ©2018 AACR.

Versican Promotes Tumor Progression, Metastasis and Predicts Poor Prognosis in Renal Carcinoma

The proteoglycan versican (VCAN) promotes tumor progression and enhances metastasis in several cancers; however, its role in clear cell renal cell carcinoma (ccRCC) remains unknown. Recent evidence suggests that VCAN is an important target of chromosomal 5q gain, one of the most prevalent genetic abnormalities in ccRCC. Thus, we investigated whether VCAN expression is associated with the pathogenesis of ccRCC. VCAN expression was analyzed using three RCC and normal kidney cell lines as well as a clinical cohort of 84 matched ccRCC and normal renal tissues. Functional analyses on growth and progression properties were performed using VCAN-depleted ccRCC cells. Microarray expression profiling was employed to investigate the target genes and biologic pathways involved in VCAN-mediated ccRCC carcinogenesis. ccRCC had elevated VCAN expression in comparison with normal kidney in both cell lines and clinical specimens. The elevated expression of VCAN was significantly correlated with metastasis (P < 0.001) and worse 5-year overall survival after radical nephrectomy (P = 0.014). In vitro, VCAN knockdown significantly decreased cell proliferation and increased apoptosis in Caki-2 and 786-O cells, and this was associated with alteration of several TNF signaling–related genes such as TNFα, BID, and BAK. Furthermore, VCAN depletion markedly decreased cell migration and invasion which correlated with reduction of MMP7 and CXCR4. These results demonstrate that VCAN promotes ccRCC tumorigenesis and metastasis and thus is an attractive target for novel diagnostic, prognostic, and therapeutic strategies. Implications: This study highlights the oncogenic role of VCAN in renal cell carcinogenesis and suggests that this gene has therapeutic and/or biomarker potential for renal cell cancer. Mol Cancer Res; 15(7); 884–95. ©2017 AACR.

Selective Activation of Cancer Stem Cells by Size-Specific Hyaluronan in Head and Neck Cancer

We determined that human head and neck cancer cells (HSC-3 cell line) contain a subpopulation displaying cancer stem cell (CSC) properties and are very tumorigenic. Specifically, we investigated whether different sizes of hyaluronan (HA) (e.g., 5 kDa, 20 kDa, 200 kDa, or 700 kDa-HA-sizes) play a role in regulating these CSCs. First, we observed that 200 kDa-HA (but not other sizes of HA) preferentially induces certain stem cell marker expression resulting in self-renewal and clonal formation of these cells. Further analyses indicate that 200 kDa-HA selectively stimulates the expression of a panel of microRNAs (most noticeably miR-10b) in these CSCs. Survival protein (cIAP-1) expression was also stimulated by 200 kDa-HA in these CSCs leading to cisplatin resistance. Furthermore, our results indicate that the anti-miR-10 inhibitor not only decreases survival protein expression, but also increases chemosensitivity of the 200 kDa-HA-treated CSCs. These findings strongly support the contention that 200 kDa-HA plays a pivotal role in miR-10 production leading to survival protein upregulation and chemoresistance in CSCs. Together, our findings suggest that selective activation of oncogenic signaling by certain sizes of HA (e.g., 200 kDa-HA) may be instrumental in the formation of CSC functions leading to tumor cell survival and chemoresistance in head and neck cancer progression.

Activation of Matrix Hyaluronan-Mediated CD44 Signaling, Epigenetic Regulation and Chemoresistance in Head and Neck Cancer Stem Cells

Head and neck squamous cell carcinoma (HNSCC) is a solid tumor composed by a genotypically and phenotypically heterogeneous population of neoplastic cells types. High recurrence rate and regional metastases lead to major morbidity and mortality. Recently, many studies have focused on cellular and molecular mechanisms of tumor progression that can help to predict prognosis and to choose the best therapeutic approach for HNSCC patients. Hyaluronan (HA), an important glycosaminoglycan component of the extracellular matrix (ECM), and its major cell surface receptor, CD44, have been suggested to be important cellular mediators influencing tumor progression and treatment resistance in head and neck cancer. HNSCC contains a small subpopulation of cells that exhibit a hallmark of CD44-expressing cancer stem cell (CSC) properties with self-renewal, multipotency, and a unique potential for tumor initiation. HA has been shown to stimulate a variety of CSC functions including self-renewal, clone formation and differentiation. This review article will present current evidence for the existence of a unique small population of CD44v3highALDHhigh-expressing CSCs in HNSCC. A special focus will be placed on the role of HA/CD44-induced oncogenic signaling and histone methyltransferase, DOT1L activities in regulating histone modifications (via epigenetic changes) and miRNA activation. Many of these events are essential for the CSC properties such as Nanog/Oct4/Sox2 expression, spheroid/clone formation, self-renewal, tumor cell migration/invasion, survival and chemotherapeutic drug resistance in HA-activated head and neck cancer. These newly-discovered HA/CD44-mediated oncogenic signaling pathways delineate unique tumor dynamics with implications for defining the drivers of HNSCC progression processes. Most importantly, the important knowledge obtained from HA/CD44-regulated CSC signaling and functional activation could provide new information regarding the design of novel drug targets to overcome current therapeutic drug resistance which will have significant treatment implications for head and neck cancer patients.

A novel microRNA regulator of prostate cancer epithelial–mesenchymal transition

The most frequent alteration in the prostate oncogenome is loss of chromosome (chr) 8p21 that has been associated with loss of NKX3.1 homeobox gene. Chr8p21 deletions increase significantly with tumor grade and are associated with poor prognosis in prostate cancer (PCa), suggesting critical involvement of this region in tumor progression. Recent studies suggest that apart from NKX3.1, this region harbors alternative tumor suppressors that are yet undefined. We proposed a novel, paradigm shifting hypothesis that this locus is associated with a miRNA gene cluster-miR-3622a/b- that plays a crucial suppressive role in PCa. Here we demonstrate the crucial role of miR-3622a in prostate cancer epithelial-to-mesenchymal transition (EMT). MicroRNA expression profiling in microdissected human PCa clinical tissues showed that miR-3622a expression is widely downregulated and is significantly correlated with poor survival outcome and tumor progression. To understand the functional significance of miR-3622a, knockdown and overexpression was performed using non-transformed prostate epithelial and PCa cell lines, respectively, followed by functional assays. Our data demonstrate that endogenous miR-3622a expression is vital to maintain the epithelial state of normal and untransformed prostate cells. miR-3622a expression inhibits EMT, progression and metastasis of PCa in vitro and in vivo. Further, we found that miR-3622a directly targets EMT effectors ZEB1 and SNAI2. In view of these data, we propose that frequent loss of miR-3622a at chr8p21 region leads to induction of EMT states that in turn, promotes PCa progression and metastasis. This study has potentially significant implications in the field of prostate cancer as it identifies an important miRNA component of a frequently lost chromosomal region with critical roles in prostate carcinogenesis which is a highly significant step towards understanding the mechanistic involvement of this locus. Also, our study indicates that miR-3622a is a novel PCa biomarker and potential drug target for developing therapeutic regimens against advanced PCa.