Elham Rahimy

EGFR Kinase Promotes Acquisition of Stem Cell-Like Properties: A Potential Therapeutic Target in Head and Neck Squamous Cell Carcinoma Stem Cells

Members of the EGFR/ErbB family of tyrosine kinases are found to be highly expressed and deregulated in many cancers, including head and neck squamous cell carcinoma (HNSCC). The ErbB family, including EGFR, has been demonstrated to play key roles in metastasis, tumorigenesis, cell proliferation, and drug resistance. Recently, these characteristics have been linked to a small subpopulation of cells classified as cancer stem cells (CSCs) which are believed to be responsible for tumor initiation and maintenance. In this study, we investigated the possible role of EGFR as a regulator of “stemness” in HNSCC cells. Activation of EGFR by the addition of EGF ligand or ectopic expression of EGFR in two established HNSCC cell lines (UMSCC-22B and HN-1) resulted in the induction of CD44, BMI-1, Oct-4, NANOG, CXCR4, and SDF-1. Activation of EGFR also resulted in increased tumorsphere formation, a characteristic ability of cancer stem cells. Conversely, treatment with the EGFR kinase inhibitor, Gefinitib (Iressa), resulted in decreased expression of the aforementioned genes, and loss of tumorsphere-forming ability. Similar trends were observed in a 99.9% CD44 positive stem cell culture derived from a fresh HNSCC tumor, confirming our findings for the cell lines. Additionally, we found that these putative cancer stem cells, when treated with Gefitinib, possessed a lower capacity to invade and became more sensitive to cisplatin-induced death in vitro. These results suggest that EGFR plays critical roles in the survival, maintenance, and function of cancer stem cells. Drugs that target EGFR, perhaps administered in combination with conventional chemotherapy, might be an effective treatment for HNSCC.

Salinomycin induces cell death and differentiation in head and neck squamous cell carcinoma stem cells despite activation of epithelial-mesenchymal transition and Akt

BackgroundCancer stem cells (CSC) are believed to play a crucial role in cancer recurrence due to their resistance to conventional chemotherapy and capacity for self-renewal. Recent studies have reported that salinomycin, a livestock antibiotic, selectively targets breast cancer stem cells 100-fold more effectively than paclitaxel. In our study we sought to determine the effects of salinomycin on head and neck squamous cell carcinoma (HNSCC) stem cells.MethodsMTS and TUNEL assays were used to study cell proliferation and apoptosis as a function of salinomycin exposure in JLO-1, a putative HNSCC stem cell culture. MTS and trypan blue dye exclusion assays were performed to investigate potential drug interactions between salinomycin and cisplatin or paclitaxel. Stem cell-like phenotype was measured by mRNA expression of stem cell markers, sphere-forming capacity, and matrigel invasion assays. Immunoblotting was also used to determine expression of epithelial-mesenchymal transition (EMT) markers and Akt phosphorylation. Arrays by Illumina, Inc. were used to profile microRNA expression as a function of salinomycin dose.ResultsIn putative HNSCC stem cells, salinomycin was found to significantly inhibit cell viability, induce a 71.5% increase in levels of apoptosis, elevate the Bax/Bcl-2 ratio, and work synergistically with cisplatin and paclitaxel in inducing cell death. It was observed that salinomycin significantly inhibited sphere forming-capability and repressed the expression of CD44 and BMI-1 by 3.2-fold and 6.2-fold, respectively. Furthermore, salinomycin reduced invasion of HNSCC stem cells by 2.1 fold. Contrary to expectations, salinomycin induced the expression of EMT markers Snail, vimentin, and Zeb-1, decreased expression of E-cadherin, and also induced phosphorylation of Akt and its downstream targets GSK3-β and mTOR.ConclusionsThese results demonstrate that in HNSCC cancer stem cells, salinomycin can cause cell death and decrease stem cell properties despite activation of both EMT and Akt.

Nicotine Promotes Acquisition of Stem Cell and Epithelial-to-Mesenchymal Properties in Head and Neck Squamous Cell Carcinoma

The ability of nicotine to enhance the malignancy of cancer cells is known; however, the possibility that nicotine could regulate a cancer stem cell phenotype remains to be well-established. In this study we sought to determine whether long-term exposure to nicotine could promote cancer stem cell-like properties in two head and neck squamous cell carcinoma cell lines, UMSCC-10B and HN-1. Nicotine treatment induced epithelial-to-mesenchymal transition (EMT) in both cell lines by repressing E-cadherin expression, and led to the induction of stem cell markers Oct-4, Nanog, CD44 and BMI-1, which was reversed upon ectopic re-expression of E-cadherin. Nicotine-treated cells formed spheres at a higher efficiency than non-treated cells, formed larger tumors when injected into mice, and formed tumors with 4-fold greater efficiency compared to control cells when injected at limiting doses. Consistent with previous literature, nicotine-treated cells demonstrated a greater capacity for survival and also a higher tendency to invade. Comparison of microRNA profiles between nicotine and control cells revealed the upregulation of miR-9, a repressor of E-cadherin, and the downregulation of miR-101, a repressor of EZH2. Taken together, these results suggest that nicotine may play a critical role in the development of tobacco-induced cancers by regulating cancer stem cell characteristics, and that these effects are likely mediated through EMT-promoting, microRNA-mediated pathways. Further characterization of such pathways remains a promising avenue for the understanding and treatment of tobacco-related cancers.

Alcohol-dysregulated miR-30a and miR-934 in head and neck squamous cell carcinoma.

BackgroundAlcohol consumption is a well-established risk factor for head and neck squamous cell carcinoma (HNSCC); however, the molecular mechanisms by which alcohol promotes HNSCC pathogenesis and progression remain poorly understood. Our study sought to identify microRNAs that are dysregulated in alcohol-associated HNSCC and investigate their contribution to the malignant phenotype.MethodUsing RNA-sequencing data from 136 HNSCC patients, we compared the expression levels of 1,046 microRNAs between drinking and non-drinking cohorts. Dysregulated microRNAs were verified by qRT-PCR in normal oral keratinocytes treated with biologically relevant doses of ethanol and acetaldehyde. The most promising microRNA candidates were investigated for their effects on cellular proliferation and invasion, sensitivity to cisplatin, and expression of cancer stem cell genes. Finally, putative target genes were identified and evaluated in vitro to further establish roles for these miRNAs in alcohol-associated HNSCC.ResultsFrom RNA-sequencing analysis we identified 8 miRNAs to be significantly upregulated in alcohol-associated HNSCCs. qRT-PCR experiments determined that among these candidates, miR-30a and miR-934 were the most highly upregulated in vitro by alcohol and acetaldehyde. Overexpression of miR-30a and miR-934 in normal and HNSCC cell lines produced up to a 2-fold increase in cellular proliferation, as well as induction of the anti-apoptotic gene BCL-2. Upon inhibition of these miRNAs, HNSCC cell lines exhibited increased sensitivity to cisplatin and reduced matrigel invasion. miRNA knockdown also indicated direct targeting of several tumor suppressor genes by miR-30a and miR-934.ConclusionsAlcohol induces the dysregulation of miR-30a and miR-934, which may play crucial roles in HNSCC pathogenesis and progression. Future investigation of the alcohol-mediated pathways effecting these transformations will prove valuable for furthering the understanding and treatment of alcohol-associated HNSCC.

Parathyroid hormone related-protein promotes epithelial-to-mesenchymal transition in prostate cancer.

Parathyroid hormone-related protein (PTHrP) possesses a variety of physiological and developmental functions and is also known to facilitate the progression of many common cancers, notably their skeletal invasion, primarily by increasing bone resorption. The purpose of this study was to determine whether PTHrP could promote epithelial-to-mesenchymal transition (EMT), a process implicated in cancer stem cells that is critically involved in cancer invasion and metastasis. EMT was observed in DU 145 prostate cancer cells stably overexpressing either the 1-141 or 1-173 isoform of PTHrP, where there was upregulation of Snail and vimentin and downregulation of E-cadherin relative to parental DU 145. By contrast, the opposite effect was observed in PC-3 prostate cancer cells where high levels of PTHrP were knocked-down via lentiviral siRNA transduction. Increased tumor progression was observed in PTHrP-overexpressing DU 145 cells while decreased progression was observed in PTHrP-knockdown PC-3 cells. PTHrP-overexpressing DU 145 formed larger tumors when implanted orthoptopically into nude mice and in one case resulted in spinal metastasis, an effect not observed among mice injected with parental DU 145 cells. PTHrP-overexpressing DU 145 cells also caused significant bone destruction when injected into the tibiae of nude mice, while parental DU 145 cells caused little to no destruction of bone. Together, these results suggest that PTHrP may work through EMT to promote an aggressive and metastatic phenotype in prostate cancer, a pathway of importance in cancer stem cells. Thus, continued efforts to elucidate the pathways involved in PTHrP-induced EMT as well as to develop ways to specifically target PTHrP signaling may lead to more effective therapies for prostate cancer.

Recombinant human erythropoietin promotes the acquisition of a malignant phenotype in head and neck squamous cell carcinoma cell lines in vitro

BackgroundRecent studies indicate an increase in tumor progression and recurrence in head and neck squamous cell carcinomas (HNSCC) of cancer patients taking recombinant human erythropoietin (rhEpo) for anemia. This study was undertaken to investigate the potential role of rhEpo in invasion, proliferation, and cisplatin-induced cell death in HNSCC cell lines.MethodsThe following experiments were performed with two HNSCC cell lines, UMSCC-10B and UMSCC-22B. Presence of EpoR in both cell lines was determined by western blot and quantitative PCR. Colorimetric MTS assays and clonogenic assays were used to study the effect of rhEpo at pharmacologically relevant doses on cell proliferation. Matrigel invasion assays were performed in order to determine effects of exogenous rhEpo on invasive abilities. Clonogenic assays were also used to study potential cytoprotective effects of rhEpo against cisplatin. Immunoblotting was done to analyze the effect of rhEpo on Akt phosphorylation. Finally, MTS and TUNEL assays were performed to test our hypothesis that Akt activation by PI3K was involved in rhEpo-mediated cisplatin resistance.ResultsHNSCC cell lines were shown to express Epo receptor (EpoR). RhEpo increased invasion 1.8-fold in UMSCC-10B and 2.6-fold in UMSCC-22B compared to control. RhEpo at 10 U/ml increased cell proliferation by 41% and 53% in UMSCC-10B and UMSCC-22B, respectively, and colony formation by 1.5-fold and 1.8-fold. UMSCC-10B treated with cisplatin and exposed to rhEpo at 1 and 10 U/ml resulted in a 1.7-fold and 3.0-fold increase in colony number compared to control, respectively. UMSCC-22B treated with cisplatin and rhEpo at 1 or 10 U/ml resulted in ~2.5-fold increase in colony number. A TUNEL assay demonstrated a 30.5% and 76.5% increase in survival in UMSCC-10B and UMSCC-22B cells, respectively, in cisplatin and rhEpo-treated cells compared to cisplatin alone. MTS assay showed similar cytoprotective effects. Western blot revealed increased phosphorylation of Akt upon exposure of HNSCC cell lines to rhEpo. MTS assay and TUNEL analyses implicate Akt as a likely contributor to regulation of rhEpo-mediated cytoprotection.ConclusionsThe results demonstrate that, in HNSCC cells expressing functional EpoR, rhEpo promotes invasion, cell proliferation, and induces resistance to cisplatin, which may contribute to tumor progression.

Evaluation of Non-Coding RNAs as Potential Targets in Head and Neck Squamous Cell Carcinoma Cancer Stem Cells

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer in the world and has not seen improved survival rates over the past few decades. Current treatment plans include surgery, radiation therapy, and chemotherapy, but these are relatively ineffective options for recurrent or metastatic tumors. Therefore, there is a high priority for new therapies that specifically target the resistant HNSCC cancer stem cells (CSCs), a subpopulation responsible for tumor initiation and metastasis. Given their vast effects on gene expression and biological processes, including stem cell capabilities, non-coding RNAs (ncRNAs) have become a promising new repertoire of genes to investigate as potential diagnostic or therapeutic targets. This review presents a comprehensive overview of current investigative studies that can contribute to our understanding of the still tentative link between ncRNA and the biology of HNSCC cancer stem cells. In doing so, we aim to analyze the potential role of stem cell-related ncRNAs in the development of molecularly targeted cancer therapy for HNSCC. Although the majority of updated knowledge on HNSCC and ncRNA focuses heavily on microRNA, we chose to give considerable attention to the promise of other classes of ncRNAs (lncRNA, piRNA, and snoRNA), many of which are not yet well characterized or are yet to be discovered, and thus represent a potentially exciting and untapped pool of molecular targets or biomarkers in HNSCC therapy.

Abstract 3767: Nicotine promotes acquisition of stem cell and epithelial-to-mesenchymal properties in head and neck squamous cell carcinoma.

The ability of nicotine to enhance the malignancy of cancer cells is known; however, the possibility that nicotine could regulate a cancer stem cell phenotype remains to be well-established. In this study we sought to determine whether long-term exposure to nicotine could promote cancer stem cell-like properties in two head and neck squamous cell carcinoma cell lines, UMSCC-10B and HN-1. Nicotine treatment induced epithelial-to-mesenchymal transition (EMT) in both cell lines by repressing E-cadherin expression, and led to the induction of stem cell markers Oct-4, Nanog, CD44 and BMI-1, which was reversed upon ectopic re-expression of E-cadherin. Nicotine-treated cells formed spheres at a higher efficiency than non-treated cells, formed larger tumors when injected into mice, and formed tumors with 4-fold greater efficiency compared to control cells when injected at limiting doses. Consistent with previous literature, nicotine-treated cells demonstrated a greater capacity for survival and also a higher tendency to invade. Comparison of microRNA profiles between nicotine and control cells revealed the upregulation of miR-9, a repressor of E-cadherin, and the downregulation of miR-101, a repressor of EZH2. Taken together, these results suggest that nicotine may play a critical role in the development of tobacco-induced cancers by regulating cancer stem cell characteristics, and that these effects are likely mediated through EMT-promoting, microRNA-mediated pathways. Further characterization of such pathways remains a promising avenue for the understanding and treatment of tobacco-related cancers. Citation Format: Michael A. Yu, Alan Kiang, Jessica Wang-Rodriguez, Elham Rahimy, Martin Haas, Vicky Yu, Lesley G. Ellies, Jian-Bing Fan, Kevin T. Brumund, Robert A. Weisman, Weg M. Ongkeko. Nicotine promotes acquisition of stem cell and epithelial-to-mesenchymal properties in head and neck squamous cell carcinoma. [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 3767. doi:10.1158/1538-7445.AM2013-3767

Abstract 1952: Deregulated microRNA expression in the progression of salivary gland cancer.

Salivary gland cancer constitutes one of the five main subsets of cancer in the head and neck region. Nonresectable malignant tumors demonstrate a low 20-year survival rate due to radioresistance and a high propensity for metastasis. The molecular mechanisms underlying pathogenesis of salivary cancer remains poorly elucidated, and thus necessitates further investigation. MicroRNAs (miRNA) are small noncoding RNAs that are predicted to regulate up to 30% of protein-encoding genes. Signature miRNA expression profiles have been identified in various malignancies, implicating miRNAs in the progression of human cancer. In order to better understand the role of miRNAs in the progression of salivary cancer, we profiled the miRNA expression levels of normal salivary tissue, benign salivary tumor, and salivary cancer. A total of 17 formalin-fixed paraffin-embedded salivary tissues, including 4 normal, 4 pleomorphic adenoma (PA), 3 squamous cell carcinoma (SCC), 3 mucoepidermoid carcinoma (ME) and 3 adenocarcinoma (AC), were collected and the endogenous expression of 95 miRNAs was analyzed by microarray. A large number of miRNAs were observed to be aberrantly expressed and generally down-regulated in salivary cancer and salivary tumor tissues with respect to normal salivary gland tissues. An unsupervised clustering and a student t-test were performed with a threshold p-value less than 0.05, resulting in the identification of 22 miRNAs differentially expressed at a statistically significant level. Eight candidate miRNAs were selected and further validated by RT-qPCR. The results suggest three miRNAs in SCC (miR-200a, let-7-family, and miR-192) and three miRNAs in AC (miR-107, miR-15b and miR-200a) to be highly involved in the carcinogenetic process of salivary cancers. Furthermore, the up-regulated expression pattern of miR-203 is indicative of a tumorigenetic function in salivary tumors. Interestingly, miR-200b was found to be consistently and significantly down regulated (p=0.01, 19.03 fold decrease) in the three types of salivary cancer under investigation. Recent studies have implicated miR-200b in EMT and invasion in cancer cells by directly targeting E-cadherin transcriptional repressors. The miRNAs identified in this study may serve as potential biomarkers and targets for future miRNA based therapy. Citation Format: Hao Zheng, Alan Kiang, Selena Z. Kuo, Elham Rahimy, Jessica Wang-Rodriguez, Weg M. Ongkeko. Deregulated microRNA expression in the progression of salivary gland cancer. [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 1952. doi:10.1158/1538-7445.AM2013-1952

Abstract 422: Nanog promotes PI3K/Akt and mTOR-mediated invasion in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) affects nearly 40,000 new patients annually in the United States with approximately 50% of these patients having a poor prognosis. Frequent metastasis of the primary tumor to nearby cervical lymph nodes and local critical structures poses a major problem in the treatment of HNSCC. To date, several molecular mediators of invasion and metastasis in HNSCC have been studied; however, with the emergence of the cancer stem cell hypothesis, other genes normally associated with self-renewal and pluripotency in stem cells would also need to be evaluated for their role in tumor invasion and metastasis. In the present study, we used various functional assays to determine the role of Nanog in HNSCC invasion and metastasis as well as identify the underlying pathway through which Nanog acts to regulate invasion and metastasis. We observed that Nanog overexpression increased invasion and cell migration in two cell lines (UMSCC-10B and UMSCC-22B) while Nanog knockdown using siRNA decreased invasion and cell migration in both cell lines and in a putative HNSCC cancer stem cell culture which expressed high levels of Nanog. Treatment with LY294002 or Rapamycin using doses that did not significantly affect cell viability and proliferation dramatically reversed both invasion and migration conferred by Nanog overexpression, indicating the effect is most likely dependent upon the PI3K/Akt/mTOR pathway. By western blot, we found that Nanog-overexpressing cells expressed higher levels of p-Akt and p-mTOR compared to control cells or Nanog-knockdown cells, confirming regulation of Akt by Nanog. In addition, Nanog overexpression resulted in the induction of MMP-2/MMP-9 as well as EMT genes Snail, Vimentin, and Twist. This enhanced expression of EMT was consistent with the observed increased migration as demonstrated by a wound healing assay. Nanog regulation in a mouse model is currently under way to confirm our results in vivo. The results of our study support the possibility of screening for Nanog expression as a prognostic tool. Meanwhile, further efforts aimed at elucidating the signaling pathway between Nanog and Akt may reveal novel treatment targets. 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 422. doi:1538-7445.AM2012-422