Xiujie Xie

Lipid-based Nanoparticle Delivery of Pre-miR-107 Inhibits the Tumorigenicity of Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent cancer worldwide with about 600,000 new cases diagnosed in the last year. Our laboratory showed that miR-107 expression is reduced and functions as a tumor suppressor gene in HNSCC suggesting the potential application of miR-107 as a novel anticancer therapeutic. In this study, we determined the efficiency and efficacy of cationic lipid nanoparticles to deliver pre-miR-107 (NP/pre-miR-107) in HNSCC cells in vitro and in vivo. NP/pre-miR-107 increased delivery of miR-107 into HNSCC cells by greater than 80,000-fold compared to free pre-miR-107. Levels of known miR-107 targets, protein kinase Cε (PKCε), cyclin-dependent kinase 6 (CDK6), and hypoxia-inducible factor 1-β (HIF1-β), decreased following NP/pre-miR-107 treatment. Clonogenic survival, cell invasion, and cell migration of HNSCC cells was inhibited with NP/pre-miR-107. Moreover, NP/pre-miR-107 reduced the cancer-initiating cell (CIC) population and dampened the expression of the core embryonic stem cell transcription factors, Nanog, Oct3/4, and Sox2. In a preclinical mouse model of HNSCC, systemic administration of NP/pre-miR-107 significantly retarded tumor growth by 45.2% compared to NP/pre-miR-control (P < 0.005, n = 7). Kaplan-Meier analysis showed a survival advantage for the NP/pre-miR-107 treatment group (P = 0.017). Our results demonstrate that cationic lipid nanoparticles are an effective carrier approach to deliver therapeutic miRs to HNSCC.

Targeting HPV16 E6-p300 interaction reactivates p53 and inhibits the tumorigenicity of HPV-positive head and neck squamous cell carcinoma.

The incidence of human papillomavirus (HPV)-positive head and neck squamous cell carcinoma (HNSCC) has rapidly increased over the past 30 years, prompting the suggestion that an epidemic maybe on the horizon. Therefore, there is a clinical need to develop alternate therapeutic strategies to manage the growing number of HPV-positive HNSCC patients. High-risk HPV E6 inactivates p53 through two distinct mechanisms; association with E6AP to degrade p53 and association with p300 to block p300-mediated p53 acetylation and activation. In this study, we determined if targeting the E6-p300 interaction is an effective approach to reactivate p53 in HPV-positive HNSCC. Ectopic expression of the CH1 domain of p300 in HPV-positive HNSCC blocks the association between E6 and p300, increases total and acetylated p53 levels and enhances p53 transcriptional activity. Moreover, expression of p21, miR-34a and miR-200c are increased, demonstrating functional p53 reactivation. CH1 overexpression in HPV-positive HNSCC has a global anticancer effect resulting in a decrease in cell proliferation and clonogenic survival and an increase in apoptosis. The in vivo tumor-initiating ability of HPV-positive HNSCC is severely compromised with CH1 overexpression, in part through a reduction in the cancer-initiating cell population. A novel small-molecule CH1 inhibitor, CH1iB, reactivates p53 and potentiates the anticancer activity of cis-platinum in HPV-positive HNSCC cells. Our work shows that CH1-domain inhibitors represent a novel class of p53-reactivation therapeutics for managing HPV-positive HNSCC patients.

Emerging role of nanog in tumorigenesis and cancer stem cells

Nanog is a transcription factor that is well‐established as a key regulator of embryonic stem cell (ESC) maintenance. Recent evidence demonstrates that Nanog is dysregulated and intimately involved in promoting tumorigenesis in part through regulation of the cancer stem cell (CSC) population. Elevated Nanog is associated with poorer outcome in numerous epithelial malignancies. Nanog is enriched in CSCs and ablation of Nanog is sufficient to reduce the CSC pool. Nanog has also been implicated to promote chemoresistance and epithelial‐mesenchymal transition (EMT). Insight into the Nanog signaling cascade, upstream regulators and downstream effectors, is beginning to emerge but remains to be fully elucidated. This review highlights the current literature on the emerging role of Nanog in tumorigenesis and CSCs.

Phosphorylation of Nanog is essential to regulate Bmi1 and promote tumorigenesis.

Emerging evidence indicates that Nanog is intimately involved in tumorigenesis, in part, through regulation of the cancer-initiating cell (CIC) population. However, the regulation and role of Nanog in tumorigenesis are still poorly understood. In this study, human Nanog was identified to be phosphorylated by human protein kinase Cɛ at multiple residues, including T200 and T280. Our work indicated that phosphorylation at T200 and T280 modulates Nanog function through several regulatory mechanisms. Results with phosphorylation-insensitive and phosphorylation-mimetic mutant Nanog revealed that phosphorylation at T200 and T280 enhance Nanog protein stability. Moreover, phosphorylation-insensitive T200A and T280A mutant Nanog had a dominant-negative function to inhibit endogenous Nanog transcriptional activity. Inactivation of Nanog was due to impaired homodimerization, DNA binding, promoter occupancy and p300, a transcriptional co-activator, recruitment resulting in a defect in target gene-promoter activation. Ectopic expression of phosphorylation-insensitive T200A or T280A mutant Nanog reduced cell proliferation, colony formation, invasion, migration and the CIC population in head and neck squamous cell carcinoma (HNSCC) cells. The in vivo cancer-initiating ability was severely compromised in HNSCC cells expressing phosphorylation-insensitive T200A or T280A mutant Nanog; 87.5% (14/16), 12.5% (1/8), and 0% (0/8) for control, T200A, and T280A, respectively. Nanog occupied the Bmi1 promoter to directly transactivate and regulate Bmi1. Genetic ablation and rescue experiments demonstrated that Bmi1 is a critical downstream signaling node for the pleiotropic, pro-oncogenic effects of Nanog. Taken together, our study revealed, for the first time, that post-translational phosphorylation of Nanog is essential to regulate Bmi1 and promote tumorigenesis.

Elevated intrinsic cancer stem cell population in human papillomavirus-associated head and neck squamous cell carcinoma.

Human papillomavirus 16 (HPV16) is a major risk factor for the development of head and neck squamous cell carcinoma (HNSCC), particularly the development of oropharyngeal squamous cell carcinoma (OPSCC). Cancer stem cells (CSCs) are resistant to conventional therapies, and it is postulated that they are responsible for disease recurrence and/or progression. Because the prognoses of patients with HPV16‐positive and HPV‐negative HNSCC are distinct, the authors sought to determine whether differences in the number of CSCs could account for this clinical observation.

TriCurin, a novel formulation of curcumin, epicatechin gallate, and resveratrol, inhibits the tumorigenicity of human papillomavirus-positive head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent cancer worldwide with about 600,000 new cases diagnosed in the last year. The incidence of human papillomavirus-positive head and neck squamous cell carcinoma (HPV-positive HNSCC) has rapidly increased over the past 30 years prompting the suggestion that an epidemic may be on the horizon. Therefore, there is a clinical need to develop alternate therapeutic strategies to manage the growing number of HPV-positive HNSCC patients. TriCurin is a composition of three food-derived polyphenols in unique stoichiometric proportions consisting of curcumin from the spice turmeric, resveratrol from red grapes, and epicatechin gallate from green tea. Cell viability, clonogenic survival, and tumorsphere formation were inhibited and significant apoptosis was induced by TriCurin in UMSCC47 and UPCI:SCC090 HPV-positive HNSCC cells. Moreover, TriCurin decreased HPV16E6 and HPV16E7 and increased p53 levels. In a pre-clinical animal model of HPV-positive HNSCC, intra-tumoral injection of TriCurin significantly inhibited tumor growth by 85.5% compared to vehicle group (P < 0.05, n = 7). Our results demonstrate that TriCurin is a potent anti-tumor agent for HPV-positive HNSCC. Further development of TriCurin as a novel anti-cancer therapeutic to manage the HPV-positive HNSCC population is warranted.

Immunotherapy for head and neck cancer: the future of treatment?

ABSTRACT Introduction: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide with >500,000 cases diagnosed each year. HNSCC patients often present to the clinic with advanced disease and are managed with a multi-disciplinary approach consisting of surgery, chemotherapy, and/or radiation. Morbidity and quality of life issues are major challenges in this patient population due to the debilitating effects of standard of care treatment paradigms. There is a critical need for new therapeutic approaches to manage HNSCC with better anti-tumor activities and toxicity profiles. Immunotherapy has gained traction as a precision medicine initiative to manage solid malignancies. Areas covered: The authors review current knowledge of immune escape mechanisms and discuss key immunotherapies in HNSCC with an emphasis on clinical trials data. Expert opinion: The excitement over the potential of immunotherapy to manage solid malignancies, including HNSCC is high and warranted based on the impressive clinical data accrued to date. Research in immunity and immune modulation in cancer has been invigorated and offers the potential to reveal novel vulnerabilities that may be exploitable pharmacologically. The evolution of immunotherapy will continue and move toward rational combinations with other immunotherapies or molecularly-targeted agents in the first-line, adjuvant, and recurrent/metastatic settings in HNSCC.

miR-124 Regulates the Epithelial-Restricted with Serine Box/Epidermal Growth Factor Receptor Signaling Axis in Head and Neck Squamous Cell Carcinoma

Epithelial-restricted with serine box (ESX), a member of the ETS transcription factor family, is elevated and regulates EGFR in head and neck squamous cell carcinoma (HNSCC). However, the molecular mechanisms that contribute to ESX dysregulation remain to be elucidated. In this study, in silico analysis of the 3′-untranslated region (UTR) of ESX predicted two miR-124–binding sites. Delivery of miR-124 inhibited the 3′UTR ESX-driven reporter activity by 50% (P < 0.05) confirming ESX as a direct target of miR-124. Loss of miR-124 was found to be a frequent event in HNSCC. miR-124 expression was significantly depleted in the primary tumor compared with matched normal tissue in 100% (12/12) of HNSCC patients; relative mean miR-124 expression of 0.01197 and 0.00118 (P < 0.001, n = 12) in matched normal adjacent tissue and primary HNSCC tumor, respectively. Overexpression of miR-124 decreased ESX and EGFR levels in miR-124low/ESXhigh/EGFRhigh SCC15 HNSCC cells and reduced cell invasion, migration, proliferation, and colony formation. SCC15 cells with miR-124 restoration were less tumorigenic in vivo than miR-control SCC15 cells (70% inhibition, P < 0.01). Restoration of miR-124 in SCC15 cells enhanced the antiproliferative efficacy of the EGFR/Her2 tyrosine kinase inhibitors. Furthermore, recapitulation of EGFR in miR-124–overexpressing SCC15 cells was sufficient to completely block the antiproliferative effects of lapatinib and afatinib. Taken together, our work provides intriguing evidence that miR-124 is a novel therapeutic approach to reduce ESX/EGFR, and may be a tractable strategy to enhance the response rate of HNSCC patients to current anti-EGFR/Her2 therapies. Mol Cancer Ther; 14(10); 2313–20. ©2015 AACR.

Genetic and Chemical Targeting of Epithelial-Restricted with Serine Box Reduces EGF Receptor and Potentiates the Efficacy of Afatinib

EGF receptor (EGFR) is elevated in more than 90% of head and neck squamous cell carcinoma (HNSCC). However, a majority of patients with HNSCC do not respond to anti-EGFR therapeutics. Insensitivity to EGFR inhibitors may be due to kinase-independent actions of EGFR and/or activation of Her2. Strategies to reduce EGFR and Her2 protein levels in concert may be an optimal approach to enhance the efficacy of current anti-EGFR molecules. In this study, knockdown of epithelial-restricted with serine box (ESX) decreased EGFR and Her2 promoter activity, expression, and levels. ESX was elevated in primary HNSCC tumors and associated with increased EGFR and Her2. Genetic ablation of ESX decreased EGFR and Her2 levels and enhanced the antiproliferative effects of EGFR/Her2 tyrosine kinase inhibitors (TKI), lapatinib and afatinib. Biphenyl isoxazolidine, a novel small-molecule ESX inhibitor, reduced EGFR and Her2 levels and potentiated the antiproliferative efficacy of afatinib. Single-agent biphenyl isoxazolidine retarded the in vivo tumorigenicity of CAL27 cells. Importantly, the combination of biphenyl isoxazolidine and afatinib was significantly superior in vivo and resulted in a 100% response rate with a 94% reduction in tumor volume. Targeting EGFR/Her2 levels with an ESX inhibitor and EGFR/Her2 kinase activity with a TKI simultaneously is a highly active therapeutic approach to manage HNSCC. Our work provides evidence to support the further development of ESX inhibitors as an adjuvant to enhance the response rate of patients with HNSCC to current anti-EGFR/Her2 therapeutics. Mol Cancer Ther; 12(8); 1515–25. ©2013 AACR.

Are All Cancer Stem Cells Created Equal

Numerous solid malignancies have been reported to contain cancer stem cells (CSCs). Distinct functional characteristics have been attributed to CSCs, and thus it is widely believed that these unique cells may have genetic and phenotypic homogeneity. Recent exciting but limited evidence, however, contradicts this tenet and supports the intriguing concept of genetic and phenotypic diversity in the CSC population. We propose that CSC heterogeneity at the inter‐ and intrapatient levels may be due to the cell of origin, to environmental cues, and/or to human papillomavirus infection. Additional insight into CSC heterogeneity is needed to identify actionable targets for optimal eradication of the diverse CSC subpopulations within a tumor.