Head And Neck Cancer Cell Lines Research Articles

Human papillomavirus type 16 E7 oncoprotein causes a delay in repair of DNA damage

Background and purposePatients with human papillomavirus related (HPV+) head and neck cancers (HNCs) demonstrate improved clinical outcomes compared to traditional HPV negative (HPV−) HNC patients. We have recently shown that HPV+ HNC cells are more sensitive to radiation than HPV− HNC cells. However, roles of HPV oncogenes in regulating the response of DNA damage repair remain unknown. Material and methodsUsing immortalized normal oral epithelial cell lines, HPV+ HNC derived cell lines, and HPV16 E7-transgenic mice we assessed the repair of DNA damage using γ-H2AX foci, single and split dose clonogenic survival assays, and immunoblot. The ability of E7 to modulate expression of proteins associated with DNA repair pathways was assessed by immunoblot. ResultsHPV16 E7 increased retention of γ-H2AX nuclear foci and significantly decreased sublethal DNA damage repair. While phospho-ATM, phospho-ATR, Ku70, and Ku80 expressions were not altered by E7, Rad51 was induced by E7. Correspondingly, HPV+ HNC cell lines showed retention of Rad51 after γ-radiation. ConclusionsOur findings provide further understanding as to how HPV16 E7 manipulates cellular DNA damage responses that may underlie its oncogenic potential and influence the altered sensitivity to radiation seen in HPV+ HNC as compared to HPV− HNC.

XI-011 enhances cisplatin-induced apoptosis by functional restoration of p53 in head and neck cancer.

Head and neck cancer (HNC), one of the most common cancers worldwide, frequently involves mutation of the TP53 gene and dysregulation of the p53 pathway. Overexpression of MDM2 or MDM4 inactivates the tumor-suppressive function of p53. Restoration of p53 function that counteracts these p53 repressors can lead to in vivo tumor regression. Therefore, the present study assessed the ability of the small molecule p53 activator XI-011 (NSC146109) to induce apoptosis in HNC by restoring p53 function. We tested the effects of XI-011 treatment in HNC cell lines, either individually or in combination with cisplatin and assessed growth suppression, cell cycle arrest, and apoptosis. The drug effects on in vivo growth of HNC cells were examined in mice xenograft model. XI-011 exerted the highest growth suppression in tumor cells that overexpress MDM4, in which p53 is degraded. XI-011 treatment downregulated MDM4 mRNA and protein levels, and upregulated expression of proapoptotic genes and promoted apoptosis, in a dose-dependent manner. The apoptotic response was blocked by inhibition of p53 or expression of MDM4, demonstrating that the effects of XI-011 depend on p53 and MDM4. In combination treatments, XI-011 acted synergistically with cisplatin to inhibit growth of HNC cells in vitro and in vivo. MDM4 inhibition and functional restoration of p53 by XI-011 effectively enhanced cisplatin-induced cytotoxicity in HNC cells, an activity that suggests a promising strategy for treating HNC.

Poly (ADP-ribose) polymerase inhibitor efficacy in head and neck cancer

Poly (ADP-ribose) polymerase inhibitors (PARPi) have shown single agent activity against tumors with deficiencies in the DNA repair mechanism homologous recombination including, but not limited to those harboring BRCA mutations. We hypothesized that, in the context of homologous recombination deficiency (HRD), PARPi could have an effect in head and neck cancer (HNC). We evaluated TCGA data for evidence of HRD using a copy number data signature established for breast cancer. The comparative potency of three PARPi was evaluated using cell viability assays in a panel of HNC cell lines and response was compared to BRCA-deficient breast cancer cell lines. The change in foci formation of γH2AX and RAD51 was assessed with immunofluorescent staining after exposure to a PARPi. Baseline gene expression was analyzed using microarray data. We found a subgroup in the TCGA HNC cohort harboring genomic aberrations consistent with HRD in breast cancer. Rucaparib activity was superior to olaparib and veliparib and showed single agent activity in a subset of HNC cell lines that was comparable to BRCA-deficient breast cancer cell lines. Rucaparib-sensitive and rucaparib-resistant groups showed significant differences in γH2AX and RAD51 foci formation after rucaparib exposure. Expression of genes involved in chromosome structure was strongly associated with rucaparib resistance. We demonstrate that PARPi are effective in a subset of HNC cell lines and propose that HRD may be present in HNC in vivo suggesting that these compounds could play a role in the treatment of HNC.

Gelsolin regulates cisplatin sensitivity in human head-and-neck cancer.

Chemoresistance is a major challenge in cancer therapy. Cisplatin is commonly used for chemotherapy in patients with head-and-neck cancer (HNC), but it increases control of the disease by only 10-15%. Downregulation of proapoptotic pathways is a key determinant for chemoresistance in which gelsolin (GSN) is critically involved. We analyzed the association between GSN expression and cisplatin resistance in HNC cell lines, animals with HNC and cancer tissue samples from 58 cisplatin-treated patients with HNC. GSN expression levels were positively associated with chemoresistance in vitro and in vivo. Cisplatin-induced GSN downregulation was associated with the cleavage of GSN and the promotion of apoptosis. GSN silencing facilitated cisplatin-induced apoptosis in chemoresistant cells. In contrast, intact gelsolin was prosurvival in the presence of cisplatin by interacting with X-linked inhibitor of apoptosis protein (XIAP). In chemosensitive cells, cisplatin suppressed GSN-XIAP interaction, promoted translocation of XIAP from the perinuclear region to the nucleus and induced apoptosis. In chemoresistant cells, GSN was highly expressed, and cisplatin had no significant effect on GSN-XIAP interaction and apoptosis. We conclude that GSN is important for chemoresistance in HNC and may be an appropriate therapeutic target in chemoresistant cancers.

TGM3, a candidate tumor suppressor gene, contributes to human head and neck cancer

BackgroundIn our previous study using oligonucleotide microarrays, we revealed that transglutaminase 3 (TGM3) was remarkably down-regulated in head and neck cancer (HNC). However, the potential of TGM3 as a useful biomarker or molecular target for HNC is unclear.MethodsThe transcriptional and post-translational status of TGM3 in HNC cell lines and specimens was detected using real-time PCR and western blot analysis. Bisulfate-treated DNA sequencing was used to analyze the molecular mechanism of TGM3 gene silencing. In addition, the effects of TGM3 on the proliferation, colony formation and induction of apoptosis in vitro and tumorigenicity in vivo were investigated through exogenous expression of TGM3 in HNC cells. Immunohistochemistry was used to evaluate TGM3 expression in large HNC samples.ResultsTGM3 was down-regulated in HNC samples and cell lines (P < 0.0001). The hypermethylation of a promoter CpG island was one of the mechanisms of silencing the TGM3 gene in HNC. Exogenous expression of TGM3 in HNC cells could inhibit the proliferation and enhance the apoptosis of HNC cells in vitro and suppress tumor growth in vivo. In addition, TGM3 protein levels were strongly associated with the pathological differentiation of HNC tissues (P = 0.0037). Survival analysis revealed that low TGM3 expression was associated with worse overall survival (P = 0.0002), and TGM3 expression level was an independent predictor in patients with HNC.ConclusionsThe studies prove that TGM3, as a candidate tumor suppressor, contributes to the carcinogenesis and development of HNC and may serve as a useful biomarker for patients with HNC.

Grp78 as a therapeutic target for refractory head–neck cancer with CD24−CD44+ stemness phenotype

Cancer stem cells are refractory to conventional therapy, which result to cancer metastasis and chemo-radioresistance. Grp78 is known to have important roles in cytoprotection and tumorigenesis in several cancers. We therefore examined whether Grp78 can serve as a therapeutic target for refractory stemness phenotype of head and neck cancer (HNC). Six HNC cell lines were used. Fluorescence-activated cell sorting (FACS) analysis was used to sort CD24(-)CD44(+) and Grp78(+) cells. The small interfering RNA (siRNA) knockdown and cDNA transfection were applied to examine the effects of Grp78 on cellular function. Western blot and confocol microscopy were used to determine the effects of downstream protein expressions. Xenografted mouse tumors and immunohistochemistry were used to validate the results. We found that Grp78 regulated the conversion of CD24(-)CD44(+) cells, a characteristic of HNC stem cells. The CD24(-)CD44(+)Grp78(+) cells showed superior chemo-radioresistance and invasion ability compared with CD24(-)CD44(+), Grp78(+) or the parental cells. Silencing Grp78 increased chemo-radiosensitivity, inhibited cell invasion, reverse epithelial-mesenchymal transition, suppressed cancer stemness, withdrew CD24(-)CD44(+) cell conversion and induced differentiated phenotype. Study in xenografted mice further showed that CD24(-)CD44(+)Grp78(+) cells exhibited highest tumorigenesis, compared with CD24(-)CD44(+) CD24(+)CD44(+) or the parental cells. Grp78 knockdown dramatically restrained tumor growth along with the inhibition of stem cell regulatory proteins Oct-4 and Slug. Grp78 may serve as a molecular target that can be further developed for eradication of refractory HNC with stemness phenotype.

Abstract B288: 17AAG enhances cisplatin-induced cytotoxicity to induce p53-mediated apoptosis in head and neck cancer.

Abstract Purpose: Tumor suppressor p53 is often inactivated in head and neck cancer (HNC) because of TP53 mutations or the overexpression of MDM2 or MDMX. Restroation of p53 function through counteracting these p53 repressors is considered a promising strategy for cancer treatment. Therefore, we examined the role of a heat shock protein 90 inhibitor, 17-(Allylamino)-17-demethoxygeldanamycin (17AAG), in inducing apoptosis in HNC by restoring p53 function. Experimental Design: In five HNC cell lines, we tested the effects of 17AAG treatment, either individually or in combination with 17AAG or cisplatin and assessed growth suppression, cell cycle arrest, and apoptosis assay. Results: 17AAG activated and stabilized p53 in an HNC cell line bearing wild-type TP53 by disrupting the p53-MDMX interaction. 17AAG upregulated expression of p21 and proapoptotic genes and promoted apoptosis, in a dose-dependent manner. 17AAG exerted the highest growth suppression in tumor cells with MDMX overexpression. The apoptotic response was blocked by inhibition of p53 or MDMX expression, demonstrating that the effects of 17AAG depend on p53 and MDMX. In combination treatments, 17AAG acted synergistically with Nutlin-3a to inhibit growth of HNC cells. 17AAG also synergized the antitumor effect of cisplatin by inducing p53-mediated apoptosis. Conclusion: 17AAG effectively induced p53-mediated apoptosis in HNC cells by MDMX inhibition, suggesting a promising strategy for treating HNC. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B288. Citation Format: Minsu Kwon, Eun Hye Kim, Hyun Bae Park, Sang Yoon Kim, Jong-Lyel Roh. 17AAG enhances cisplatin-induced cytotoxicity to induce p53-mediated apoptosis in head and neck cancer. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B288.

Axl mediates acquired resistance of head and neck cancer cells to the epidermal growth factor receptor inhibitor erlotinib.

Elevated expression and activity of the epidermal growth factor receptor (EGFR) is associated with development and progression of head and neck cancer (HNC) and a poor prognosis. Clinical trials with EGFR tyrosine kinase inhibitors (e.g., erlotinib) have been disappointing in HNC. To investigate the mechanisms mediating resistance to these agents, we developed an HNC cell line (HN5-ER) with acquired erlotinib resistance. In contrast to parental HN5 HNC cells, HN5-ER cells exhibited an epithelial-mesenchymal (EMT) phenotype with increased migratory potential, reduced E-cadherin and epithelial-associated microRNAs (miRNA), and elevated vimentin expression. Phosphorylated receptor tyrosine kinase profiling identified Axl activation in HN5-ER cells. Growth and migration of HN5-ER cells were blocked with a specific Axl inhibitor, R428, and R428 resensitized HN5-ER cells to erlotinib. Microarray analysis of HN5-ER cells confirmed the EMT phenotype associated with acquired erlotinib resistance, and identified activation of gene expression associated with cell migration and inflammation pathways. Moreover, increased expression and secretion of interleukin (IL)-6 and IL-8 in HN5-ER cells suggested a role for inflammatory cytokine signaling in EMT and erlotinib resistance. Expression of the tumor suppressor miR-34a was reduced in HN5-ER cells and increasing its expression abrogated Axl expression and reversed erlotinib resistance. Finally, analysis of 302 HNC patients revealed that high tumor Axl mRNA expression was associated with poorer survival (HR = 1.66, P = 0.007). In summary, our results identify Axl as a key mediator of acquired erlotinib resistance in HNC and suggest that therapeutic inhibition of Axl by small molecule drugs or specific miRNAs might overcome anti-EGFR therapy resistance.

Curcumin Analogue May Be Used as Therapeutic Agent for Head and Neck Cancer

Objectives: Curcumin has shown anti-proliferative effects in multiple cancers and is an inhibitor of NF-kB. Downstream curcumin inhibits various genes which play an important role in tumor growth and metastasis. However, curcumin’s effects are greatly diminished due to its poor solubility. This study compared the effect of curcumin against more soluble curcumin analogues on the cell proliferation and gene expression in head and neck cancer (HNC) cell lines. Methods: Two novel curcumin analogues were synthesized, 1-flouro-curcumin (CF1) and 2-flouro-curcumin (CF2), which have shown increased solubility compared to curcumin. Our lab developed three HNC cell lines: 351GFP, 351GFP G1, and 351GFP G2. 351GFP G1 and 351GFP G2 are more metastatic HNC cell lines. The effect of CF1 and CF2 was tested in these three cell lines on the cell growth and the inhibition of genes (IL8, MMP7, COX2, and epidermal growth factor receptor [EGFR]) which are important in growth and metastasis of HNC. Results: The IC50s of curcumin, CF1, and CF2 in the 351GFP G1 cell line are 7.38microM, 0.33microM, and 0.1microM, respectively. Curcumin analogues were 20-80 times more potent than curcumin. Western Blot analysis showed that curcumin analogues blocked expression of IL8, MMP7, COX2, and EGFR. The analogues also showed several fold greater inhibition of these genes compared to curcumin in the HNC cell lines. Conclusions: Both curcumin analogues show greater anti-proliferative effect than curcumin, inhibiting cell proliferation and expression of genes involved in HNC growth and metastasis. Because of their increased activity, curcumin analogues may be of potential benefit in future HNC therapies.

A Novel Aldehyde Dehydrogenase-3 Activator (Alda-89) Protects Submandibular Gland Function from Irradiation without Accelerating Tumor Growth

To determine the effect of Alda-89 (an ALDH3 activitor) on (i) the function of irradiated (radiotherapy) submandibular gland (SMG) in mice, (ii) its toxicity profile, and (iii) its effect on the growth of head and neck cancer (HNC) in vitro and in vivo. Adult mice were infused with Alda-89 or vehicle before, during, and after radiotherapy. Saliva secretion was monitored weekly. Hematology, metabolic profile, and postmortem evaluation for toxicity were examined at the time of sacrifice. Alda-89 or vehicle was applied to HNC cell lines in vitro, and severe combined immunodeficient (SCID) mice transplanted with HNC in vivo with or without radiation; HNC growth was monitored. The ALDH3A1 and ALDH3A2 protein expression was evaluated in 89 patients with HNC and correlated to freedom from relapse (FFR) and overall survival (OS). Alda-89 infusion significantly resulted in more whole saliva production and a higher percentage of preserved acini after radiotherapy compared with vehicle control. There was no difference in the complete blood count, metabolic profile, and major organ morphology between the Alda-89 and vehicle groups. Compared with vehicle control, Alda-89 treatment neither accelerated HNC cell proliferation in vitro, nor did it affect tumor growth in vivo with or without radiotherapy. Higher expression of ALDH3A1 or ALDH3A2 was not significantly associated with worse FFR or OS in either human papillomavirus (HPV)-positive or HPV-negative group. Alda-89 preserves salivary function after radiotherapy without affecting HNC growth or causing measurable toxicity in mice. It is a promising candidate to mitigate radiotherapy-related xerostomia.

Enhanced Radiation Sensitivity in HPV-Positive Head and Neck Cancer

Patients with human papillomavirus (HPV+)-associated head and neck cancer (HNC) show significantly improved survival outcome compared with those with HPV-negative (HPV-) tumors. Published data examining this difference offers conflicting results to date. We systematically investigated the radiation sensitivity of all available validated HPV+ HNC cell lines and a series of HPV- HNC cell lines using in vitro and in vivo techniques. HPV+ HNCs exhibited greater intrinsic radiation sensitivity (average SF2 HPV-: 0.59 vs. HPV+: 0.22; P < 0.0001), corresponding with a prolonged G2-M cell-cycle arrest and increased apoptosis following radiation exposure (percent change 0% vs. 85%; P = 0.002). A genome-wide microarray was used to compare gene expression 24 hours following radiation between HPV+ and HPV- cell lines. Multiple genes in TP53 pathway were upregulated in HPV+ cells (Z score 4.90), including a 4.6-fold increase in TP53 (P < 0.0001). Using immortalized human tonsillar epithelial (HTE) cells, increased radiation sensitivity was seen in cell expressing HPV-16 E6 despite the effect of E6 to degrade p53. This suggested that low levels of normally functioning p53 in HPV+ HNC cells could be activated by radiation, leading to cell death. Consistent with this, more complete knockdown of TP53 by siRNA resulted in radiation resistance. These results provide clear evidence, and a supporting mechanism, for increased radiation sensitivity in HPV+ HNC relative to HPV- HNC. This issue is under active investigation in a series of clinical trials attempting to de-escalate radiation (and chemotherapy) in selected patients with HPV+ HNC in light of their favorable overall survival outcome.

Abstract 589: NQO1-dependent anticancer action with combination β-lapachone and ionizing radiation in the head and neck cancer.

Abstract The number of new cases of oral cavity, pharynx and larynx cancers is estimated be 52,610 in 2012 with an expected 11,500 deaths. Despite progressive improvements in outcome, current treatment approaches still result in an overall survival rate of approximately 50% at five years for locally advanced head and neck cancer (HNC). Additional therapeutic approaches are needed to further enhance outcomes. NAD(P)H:quinone oxidoreductase 1 (NQO1) is a two-electron oxidoreductase that reduces quinones to hydroquinones and has been shown to be overexpressed in a number of solid tumors. For the first time, our studies in 45 HNC cell lines identified NQO1 overexpression in more than 70% of HNC cell lines. Furthermore over-expression of NQO1 has been shown to be a critical determinant for tumor-selective therapy using β-lapachone (β-lap), a substrate of NQO1 that undergoes partial reduction and spontaneous reversion, creating a futile cycle that produces very high levels of reactive oxygen species. HNC cell lines that overexpress NQO1 are significantly killed by treatment with β-lap. The anti-cancer action of β-lap in HNC cells is initiated and processed through five essential downstream mediators: (i) reactive oxygen species (ROS), particularly hydrogen peroxide (H2O2); (ii) DNA single strand breaks (SSBs) induced by ROS; (iii) hyperactivation of poly(ADP-ribose)polymerase-1 (PARP1) and accompanying poly(ADP-ribose)-PARP1 (PAR) formation; (iv) dramatic NAD+/ATP depletion; and (v) programmed necrosis (necroptosis). In combination with ionizing radiation (IR), β-Lap radiosensitized NQO1(+) HNC cells under conditions where nontoxic doses of either agent alone did not achieve threshold levels of DNA lesions and /or SSBs required for PARP-1 hyper-activation. Furthermore, combination therapy with β-lap and IR significantly enhanced γ-H2AX and 53BP1 foci formation and PARP-1 hyper-activation which was associated with ATP loss and induction of programmed cell death. Furthermore, the anticancer effects of combination β-Lap and IR were blocked by the NQO1 inhibitor dicoumarol. Our findings offer a strategy for the clinical utilization of β-lap as a radiosensitizer in HNC. Citation Format: Long Shan Li, Srilakshmi Reddy, Jinming Gao, David A. Boothman, Baran Sumer, John S. Yordy. NQO1-dependent anticancer action with combination β-lapachone and ionizing radiation in the head and neck 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 589. doi:10.1158/1538-7445.AM2013-589

Abstract 73: Preclinical evaluation of chemoradiation with cetuximab HPV-positive head and neck cancer suggests significant radiosensitization.

Abstract PURPOSE: Whether cetuximab, a monoclonal antibody to the epidermal growth factor receptor, should be combined with radiation in patients with human papillomavirus (HPV) positive locally advanced head and neck cancer (HNC) is not known. Currently available data are inadequate to address this important therapeutic question. We sought to examine the ability of cetuximab to act as a radiosensitizer and to examine the mechanism of action of this combination in a model system of HPV+ HNC. METHODS: Four cell lines (UD-SCC2, UM-SCC47, UPCI-SCC90, 93-VU-147T) validated for HPV expression were used for all assays. Subcutaneous flank xenografts were performed in Hsd:athymic Nude-Foxn1nu female mice treated with intraperitoneal cetuximab (0.2mg/mouse) or flank radiation (2 Gy/fraction) delivered twice weekly for 2 weeks. Time to tumor quadrupling from baseline was assessed by Kaplan-Meier method. Flow cytometry was used to assess apoptosis by Annexin V staining and cell cycle distribution by propidium iodide staining. RESULTS: While there was minimal in vitro radiosensitization after treatment with cetuximab (similar to that seen in HPV-negative HNC), cetuximab + radiation resulted in a significant increase in time to tumor quadrupling compared to cetuximab alone (p=0.001) or radiation alone (p&amp;lt;0.0001) in HPV+ HNC xenografts. Increased apoptosis was seen in cetuximab and radiation treated cells. Analysis of cell cycle distribution 24 hours after drug treatment showed that cetuximab induced a modest G1 cell cycle arrest when given prior to radiation, but that 24 hours after combined therapy, a significant G2 arrest was present. CONCLUSIONS: Using HPV+ HNC cell lines, radiation and cetuximab appear to be beneficial compared to either treatment alone. This combination, currently undergoing study in randomized clinical trial is being further evaluated in a direct from patient tumorgraft model of HPV+ HNC to further understand predictors of response. Citation Format: Molly A. Smith, Grace C. Blitzer, Alexandra D. Torres, Eric A. Armstrong, Paul F. Lambert, Paul M. Harari, Randall J. Kimple. Preclinical evaluation of chemoradiation with cetuximab HPV-positive head and neck cancer suggests significant radiosensitization. [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 73. doi:10.1158/1538-7445.AM2013-73

Abstract 3348: Inhibition of MDMX by XI-011 induces p53-mediated apoptosis in head and neck cancer.

Abstract Overexpression of MDM2 or MDMX inactivates the tumor-suppressive function of p53. Restoration of p53 function counteracting these p53 repressors can lead to in vivo tumor regression. Therefore, we evaluated whether the restoration of p53 function by a small-molecule p53 activator XI-011, a pseudouria derivative NSC146109, induce apoptosis in head-and-neck cancer (HNC). The effects of XI-011 treatment in four HNC cell lines were tested, individually or in combination with nutlin-3a, an inhibitor of MDM2-p53 interactions, and its growth suppression, cell-cycle arrest, and apoptosis were assessed. XI-011 induced accumulation and reactivation of p53 in a wild-type TP53-bearing HNC cell line. XI-011 showed maximal growth suppression in tumor cells with overexpression of MDMX and MDMX-dependent p53 degradation. With down-regulation of MDMX mRNA and protein levels, XI-011 upregulated expression of p21 and proapoptotic genes and promoted apoptosis in a dose-dependent manner. Notably, the apoptotic response was blocked by inhibition of p53 or MDMX gene expression, demonstrating the p53 and MDMX dependence of XI-011 effects. XI-011 decreased the viability of HNC cells expression low levels of MDMX in a less-efficient manner. Interestingly, in combination therapy, XI-011 synergistically acted with nutlin-3a to inhibit growth of HNC cells. Our data suggest that the MDMX inhibition and p53 functional restoration by XI-011 effectively induced cytotoxicity and apoptosis in cancer cells, an action that may offer a promising strategy for treating HNC. Citation Format: In Sun Ryu, Chang Hwan Ryu, Hyun Bae Park, Eunhye Kim, Jong-Lyel Roh. Inhibition of MDMX by XI-011 induces p53-mediated apoptosis in head and neck 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 3348. doi:10.1158/1538-7445.AM2013-3348

Regulation of epidermal growth factor receptor signaling and erlotinib sensitivity in head and neck cancer cells by miR-7.

Elevated expression and activity of the epidermal growth factor receptor (EGFR)/protein kinase B (Akt) signaling pathway is associated with development, progression and treatment resistance of head and neck cancer (HNC). Several studies have demonstrated that microRNA-7 (miR-7) regulates EGFR expression and Akt activity in a range of cancer cell types via its specific interaction with the EGFR mRNA 3′-untranslated region (3′-UTR). In the present study, we found that miR-7 regulated EGFR expression and Akt activity in HNC cell lines, and that this was associated with reduced growth in vitro and in vivo of cells (HN5) that were sensitive to the EGFR tyrosine kinase inhibitor (TKI) erlotinib (Tarceva). miR-7 acted synergistically with erlotinib to inhibit growth of erlotinib-resistant FaDu cells, an effect associated with increased inhibition of Akt activity. Microarray analysis of HN5 and FaDu cell lines transfected with miR-7 identified a common set of downregulated miR-7 target genes, providing insight into the tumor suppressor function of miR-7. Furthermore, we identified several target miR-7 mRNAs with a putative role in the sensitization of FaDu cells to erlotinib. Together, these data support the coordinate regulation of Akt signaling by miR-7 in HNC cells and suggest the therapeutic potential of miR-7 alone or in combination with EGFR TKIs in this disease.

The p53-reactivating small-molecule RITA enhances cisplatin-induced cytotoxicity and apoptosis in head and neck cancer

We evaluated whether the restoration of p53 function by the p53-reactivating small molecule RITA (reactivation of p53 and induction of tumor cell apoptosis enhances cisplatin-induced cytotoxicity and apoptosis in head-and-neck cancer (HNC). RITA induced prominent accumulation and reactivation of p53 in a wild-type TP53-bearing HNC cell line. RITA showed maximal growth suppression in tumor cells showing MDM2-dependent p53 degradation. RITA promoted apoptosis in association with upregulation of p21, BAX, and cleaved caspase-3; notably, the apoptotic response was blocked by pifithrin-α, demonstrating its p53 dependence. With increasing concentrations, RITA strongly induced apoptosis rather than G2-phase arrest. In combination therapy, RITA enhanced cisplatin-induced growth inhibition and apoptosis of HNC cells invitro and in vivo. Our data suggest that the restoration of p53 tumor-suppressive function by RITA enhances the cytotoxicity and apoptosis of cisplatin, an action that may offer an attractive strategy for treating HNC.

Abstract 5136: Identification of sensitizers of platinum-based therapy in head and neck cancer using a functional genomics approach

Abstract Objective The prevalence and mortality for head and neck cancer (HNC) has not improved significantly in the last several decades. It is the sixth most common cancer with an estimated 600,000 new cases diagnosed worldwide every year and has ∼50% 5-year survival rate. Of these, 47000 new cases are diagnosed in the US annually. The most common risk factors for HNC are tobacco and alcohol use but a growing subset is also attributed to human papillomavirus (HPV) infection. Late stage HNCs are treated with a combination of surgery, radiation, and chemotherapy (often platinum-based), but the cancers treated with platinum-based chemotherapy often develop drug resistance. Identification of target genes using high-throughput RNAi (HT-RNAi) gene-silencing technology has become an increasingly popular method in the field of cancer research. The objective of our study is to use this functional genomics based approach to identify genes that, when silenced, increase the sensitivity of the platinum drugs. This would possibly help us in identifying potentiators of platinum-based drugs to more effectively treat HNC patients. Methods We performed drug dose response (DDR) experiments on nine HNC cell lines; including two are HPV-positive lines, to identify cisplatin-resistant and -sensitive cancer cell lines. To identify sensitizers of cisplatin response, we used a siRNA library targeting 572 kinases. Each kinase is represented by two different siRNA sequences in the library. Based on the data mined from published literature on head and neck cancer as well as genes thought to confer a functional relationship between HPV infection and HNC, a more focused siRNA library was also designed and included in the screening. Cell lines were reverse transfected with the siRNAs in a 384 well format, dosed with cisplatin after 24 hours and the plates were read 72 hours later. Results We calculated the inhibitory concentrations using DDR experiments for all the nine HNC cell lines and identified cisplatin-resistant (UMSCC47 and SCC9) and -sensitive (Cal27, UMSCC14C, and SCC090) HNC cell lines. HT-RNAi experiments have been performed on the cisplatin-resistant cell lines, one of which is HPV-positive. After data analysis, confirmation of silencing and validation of drug modulation will be done on a subset of candidate genes. Conclusions HNC patients with surgically non-resectable tumors could have improved treatment with chemotherapeutic drugs; however, acquired drug resistance often inhibits a successful treatment. Identification of sensitizing targets may provide hope for a better outcome, but may also allow for use of smaller doses of more toxic drugs, such as cisplatin. In addition, this study may also identify alternate genes that can be targeted in the subset of HPV-positive HNC. 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 5136. doi:1538-7445.AM2012-5136

Abstract 669: Disparities in head and neck cancer: A case for chemoprevention with vitamin D

Abstract Worldwide head and neck cancer (HNC) is the sixth most frequently diagnosed cancer in men and is associated with significant morbidity, mortality and economic loss. African Americans (AA) experience significantly more HNC compared to Caucasian Americans (CA) and they have markedly reduced 5-year survival rates, 40% compared to 61% among CA. AA bear a disproportionate burden of HNC for reasons that are incompletely understood, but likely due to the complex interplay of environmental, genetic and health care access issues. An inverse association for vitamin (vit) D status and HNC cancer has been reported and hypovitaminosis D in AA is well documented; yet, vit D status has not been assessed in HNC patients stratified by race. Thus, objective of this prospective pilot study is to access vit D status in newly diagnosed AA and CA HNC patients by measuring the circulating metabolite of vit D, vit-D 25-OH and by assessing dietary levels utilizing the Block vit D/Calcium screener. Circulating calcium, parathyroid, and 1,25-Dihydroxy vit D are also being measured. In addition, to improve our understanding of mechanisms associated with the potential cancer protective effects of vit D in the context of HNC two HNC cell lines were treated with 2 µM cholecalciferol for 6 hours and protein harvested for proteome profiling. To date, 18 HNC patients have been evaluated, 8 AA and 10 CA. Mean circulating vit D 25-OH levels were 27.3 (+ 9.9) and 20.0 (+ 5.9) ng/mL in CA and AA, respectively supporting that vit D levels are suppressed to a greater extent in AA compared to CA HNC patients, even in sunny Florida. Dietary vit D estimates were non-significantly higher in AA HNC patients compared to CA who had higher total vit D levels, supporting differences in metabolism or potentially supplement use. None of the AA patients had vit D 25-OH levels &amp;gt; 30 ng/mL, a level suggested for optimum regulation of PTH, calcium absorption and bone density; 30% of CA patients expressed levels above 30 ng/mL. Proteome profiling of CAL27 and SSC25 HNC cell lines following vit D treatment revealed inverse modulation of proteins linked to HNC. Proteins down-regulated by vit D treatment included nucleophosmin (NPM), lactoylglutathione, heat shock protein beta-1 (HSPB1) Peroxiredoxin-1 (PRDX1) and Ras-related protein Rap-2b. Recent reports have linked NPM with the regulation of the oncogene FOXM1, also a potential biomarker for early detection. Disease-free survival rate is improved in HNC patients with low NPM expression. Similarly, HSPB1 has been shown to be over expressed in HNC and silencing of HSPB1 has been shown to decrease metastatic behavior in HSNCC. PRDX1 displays upregulation in oral premalignancy and is an indicator for local recurrence. Histone H2A type was up-regulated by Vitamin D. Study results support that newly diagnosed AA HNC patients have depressed vit D levels compared to CA cases and that vit D treatment inversely targets select proteins dysregulated in HNC. 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 669. doi:1538-7445.AM2012-669

Abstract 4919: Pathway profiling of head and neck cancer cell lines

Abstract Introduction: Cell lines retain key genetic aberrations of the originating tumors, which frequently correlate with sensitivity to specific inhibitors. We performed genetic and pathway based profiling of 40 head and neck cancer (HNC) cell lines using three publicly available methods for pathway profiling based on expression and copy number data. Methods: 40 HNC cell lines were analyzed for expression using expression arrays (Agilent), and copy number using array comparative hybridization (aCGH) and/or Nanostring methodologies. Integrative genomic analysis was performed to determine pathway activity using pathway analysis techniques previously described by Gatza et al. (BFRM), Pe'er et al (CONEXIC), Vaske et al. (PARADIGM). Results: Frequent pathway activation was identified in &amp;gt;10 well established signalling pathways for HNC including TP53, PI3K-AKT, TP63/SOX2, Cyclin D1, MYC etc, as well as several - for HNC previously unknown - signalling pathways. Cell lines could be associated with expression-based biologic subtypes in HNC tissues suggesting that specific cell lines should be used preferentially for modelling and therapeutic evaluation for HNC subtypes (including HPV(+) cell lines with characteristics of HPV(+) tumors). The three pathway analysis platforms identified a large number of pathways with some overlap in particular between BFRM and CONEXIC, whereas PARADIGM profiled a much wider set of pathways. Both CONEXIC and PARADIGM employed copy number data, whereas BFRM relied solely on expression data. Conclusion: Pathway alterations characteristic of head and neck cancers were identified in virtually all HNC cell lines. Pathway based classification of cell lines was achieved and correlated with pathway activity in HNC tumor tissues. Three pathway-profiling approaches provided a large set of pathway activity with some significant overlap that may have translational relevance. Validation studies are currently on-going. 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 4919. doi:1538-7445.AM2012-4919

Abstract 1588: Synergistic apoptosis by combination of natural compound EGCG and resveratrol in head and neck cancer: Potential role for AKT-dependent signaling

Abstract Natural dietary agents have drawn great attention for cancer prevention because of their wide safety margin and ready availability. Green tea is one such agent that is widely used for chemoprevention (Amin et al. 2009, Kim et al., 2010). Recent clinical trials suggest that green tea alone might not be sufficient for chemoprevention of head and neck cancer (HNC) (Tsao et al., 2009). Therefore, identification of compounds which exhibit synergistic effects with green tea is warranted. In the current study, we investigated combination of green tea component EGCG and resveratrol (a major constituent of red wines and grapes), and found that their combination strongly induced apoptosis as measured by annexin-V staining and supported by cleavage of PARP and caspase 3. The combination of resveratrol (15 and 20 μM, which alone induce 10-15% apoptosis) with EGCG (30-80 μM, which also induce &amp;lt;10% apoptosis) strongly increased apoptosis (to 60-80%) in multiple HNC cell lines. Data analysis for the combination using CalcuSyn software suggests that the combination of EGCG and resveratrol has synergistic apoptotic effects with combination index between 0.4-0.7. Interestingly, a premalignant oral leukoplakia cell line was sensitive to relatively lower doses of the combination (5 and 10 μM resveratrol, 10 and 15 μM EGCG) than fully transformed cancer cell lines, suggesting that the combination of EGCG and resveratrol might be a suitable combination for prevention of HNC. To further elucidate the mechanism of synergistic apoptosis, we found that combination of EGCG and resveratrol strongly inhibited AKT and ERK phosphorylation along with its several downstream targets including p-mTOR, p-S6 and p-4EBP1. Retroviral transduction of constitutively active AKT significantly inhibited apoptosis induced by the combination (p=.003). We also found that the combination of EGCG and resveratrol strongly inhibited p-AMPK, a kinase that regulates autophagy, a protective mechanism during energy stress. The fact that inhibition of autophagy triggers apoptosis (Xu Y et al., 2011) suggests that inhibition of p-AMPK might also play a role in EGCG- and resveratrol-induced apoptosis. Furthermore, strong inhibition of anti-apoptotic Mcl-1 and survivin by the combination was observed as a consequence. Taken together, our studies identify a novel combination of two natural dietary agents, EGCG and resveratrol, which induces synergistic anti-tumor effects in both premalignant and fully transformed HNC cells by targeting multiple signal transduction pathways. The signaling pathways modulated by the combination of EGCG and resveratrol are critical for development of HNC, thus our study provides an important rationale for future preclinical and clinical development. (Supported by U01CA101244, R01CA112643, and P50CA128613 to DMS) 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 1588. doi:1538-7445.AM2012-1588