Head and neck squamous cell carcinoma

Most head and neck cancers are derived from the mucosal epithelium in the oral cavity, pharynx and larynx and are known collectively as head and neck squamous cell carcinoma (HNSCC). Oral cavity and larynx cancers are generally associated with tobacco consumption, alcohol abuse or both, whereas pharynx cancers are increasingly attributed to infection with human papillomavirus (HPV), primarily HPV-16. Thus, HNSCC can be separated into HPV-negative and HPV-positive HNSCC. Despite evidence of histological progression from cellular atypia through various degrees of dysplasia, ultimately leading to invasive HNSCC, most patients are diagnosed with late-stage HNSCC without a clinically evident antecedent pre-malignant lesion. Traditional staging of HNSCC using the tumour-node-metastasis system has been supplemented by the 2017 AJCC/UICC staging system, which incorporates additional information relevant to HPV-positive disease. Treatment is generally multimodal, consisting of surgery followed by chemoradiotherapy (CRT) for oral cavity cancers and primary CRT for pharynx and larynx cancers. The EGFR monoclonal antibody cetuximab is generally used in combination with radiation in HPV-negative HNSCC where comorbidities prevent the use of cytotoxic chemotherapy. The FDA approved the immune checkpoint inhibitors pembrolizumab and nivolumab for treatment of recurrent or metastatic HNSCC and pembrolizumab as primary treatment for unresectable disease. Elucidation of the molecular genetic landscape of HNSCC over the past decade has revealed new opportunities for therapeutic intervention. Ongoing efforts aim to integrate our understanding of HNSCC biology and immunobiology to identify predictive biomarkers that will enable delivery of the most effective, least-toxic therapies.

STAT3 as a therapeutic target in head and neck cancer

The signal transducer and activator of transcription (STAT) proteins relay signals from cytokine receptors and receptor tyrosine kinases on the cell surface to the nucleus, where they affect the transcription of genes involved in normal cell functions, including growth, apoptosis and differentiation. STAT3 has been found to be constitutively active in head and neck squamous cell carcinoma (HNSCC) as well as in other epithelial malignancies. In HNSCC, STAT3 alters the cell cycle, prevents apoptosis, and mediates the proliferation and survival of tumour cells. Several therapeutic approaches are being developed to target STAT3, including molecules that block either dimerisation or DNA binding by STAT3, strategies to decrease STAT3 expression and drugs that inhibit STAT3 function. Strategies that block STAT3 may prove efficacious for cancer treatment.

Phosphorylation of TNF-alpha converting enzyme by gastrin-releasing peptide induces amphiregulin release and EGF receptor activation

G protein-coupled receptors induce EGF receptor (EGFR) signaling, leading to the proliferation and invasion of cancer cells. Elucidation of the mechanism of EGFR activation by G protein-coupled receptors may identify new signaling paradigms. A gastrin-releasing peptide (GRP)/GRP receptor-mediated autocrine pathway was previously described in squamous cell carcinoma of head and neck. In the present study, we demonstrate that TNF-alpha converting enzyme (TACE), a disintegrin and metalloproteinse-17, undergoes a Src-dependent phosphorylation that regulates release of the EGFR ligand amphiregulin upon GRP treatment. Further investigation reveals the phosphatidylinositol 3-kinase (PI3-K) as the intermediate of c-Src and TACE, contributing to their association and TACE phosphorylation. Phosphoinositide-dependent kinase 1 (PDK1), a downstream target of PI3-K, has been identified as the previously undescribed kinase to directly phosphorylate TACE upon GRP treatment. These findings suggest a signaling cascade of GRP-Src-PI3-K-PDK1-TACE-amphiregulin-EGFR with multiple points of interaction, translocation, and phosphorylation. Furthermore, knockdown of PDK1 augmented the antitumor effects of the EGFR inhibitor erlotinib, indicating PDK1 as a therapeutic target to improve the clinical response to EGFR inhibitors.

Prognostic significance of tumor infiltrating immune cells in oral squamous cell carcinoma

Background

Prognostic factors aid in the stratification and treatment of cancer. This study evaluated prognostic importance of tumor infiltrating immune cell in patients with oral squamous cell carcinoma.

Methods

Profiles of infiltrating immune cells and clinicopathological data were available for 78 OSCC patients with a median follow-up of 48 months. The infiltrating intensity of CD8, CD4, T-bet, CD68 and CD57 positive cells were assessed by immunohistochemistry. Chi-square test was used to compare immune markers expression and clinicopathological parameters. Univariate and multivariate COX proportional hazard models were used to assess the prognostic discriminator power of immune cells. The predictive potential of immune cells for survival of OSCC patients was determined using ROC and AUC.

Results

The mean value of CD8, CD4, T-bet, CD68 and CD57 expression were 28.99, 62.06, 8.97, 21.25 and 15.75 cells per high-power field respectively. The patient cohort was separated into low and high expression groups by the mean value. Higher CD8 expression was associated with no regional lymph node metastasis (p = 0.033). Patients with more abundant stroma CD57⁺ cells showed no metastasis into regional lymph node (p = 0.005), and early clinical stage (p = 0.016). The univariate COX regression analyses showed that no lymph node involvement (p < 0.001), early clinical stage (TNM staging I/II vs III/IV, p = 0.007), higher CD8 and CD57 expression (p < 0.001) were all positively correlated with longer overall survival. Multivariate COX regression analysis showed that no lymph node involvement (p = 0.008), higher CD8 (p = 0.03) and CD57 (p < 0.001) expression could be independent prognostic indicators of better survival. None of CD4, T-bet or CD68 was associated with survival in ether univariate or multivariate analysis. ROC and AUC showed that the predictive accuracy of CD8 and CD57 were all superior compared with TNM staging. CD57 (AUC = 0.868; 95% CI, 0.785–0.950) and CD8 (AUC = 0.784; 95% CI, 0.680–0.889) both provided high predictive accuracy, of which, CD57 was the best predictor.

Conclusion

Tumor stroma CD57 and CD8 expression was associated with lymphnode status and independently predicts survival of OSCC patients. Our results suggest an active immune microenvironment in OSCC that may be targetable by immune drugs.

Microneedle-Mediated Delivery of Lipid-Coated Cisplatin Nanoparticles for Efficient and Safe Cancer Therapy

Cisplatin is the first-line chemotherapeutic agent, but its systemic toxicity and side effects severely limit its clinical use. We report a microneedle technique to mediate the transdermal delivery of lipid-coated cisplatin nanoparticles (LCC-NPs) for efficient and safe cancer therapy. Cisplatin was encapsulated by tumor-targeting pH-responsive lipid nanoparticles with a high loading rate of 80%, and the encapsulation substantially increased the solubility of cisplatin and enhanced its antitumor efficiency in vitro. The LCC-NPs were embedded in dissolvable microneedles, and released from the microneedles after inserting into the skin. This enabled the nanoparticles to pass the stratum corneum for safe local delivery. An in vivo study with a xenograft tumor animal model demonstrated that microneedle arrays loaded with cisplatin nanoparticles significantly increased cytotoxicity and apoptosis in cancer cells with an apoptotic index of 58.6%, resulting in significantly reduced tumor volume and weight. Moreover, serum platinum, pulmonary toxicity, hepatotoxicity, and nephrotoxicity were not detected in vivo, indicating that this technique is biosafe. The cisplatin-nanoparticle microneedle system developed in this study may offer promising opportunities in cancer therapy for enhancing antitumor effects and reducing systemic toxicity and side effects.

Inactivation of ATP citrate lyase by Cucurbitacin B: A bioactive compound from cucumber, inhibits prostate cancer growth

Prostate cancer, a leading cause of cancer-related deaths in males, is well recognized as having late disease on-set (mostly at age 60-70) and showing slow/latent disease development, and strategies to prevent cancer formation in late manhood may have significant health impacts. Cucurbitacin B (CuB) is a naturally occurring compound that is found abundantly in cucumbers and other vegetables, and it is known to exert anti-cancer activities (primarily via apoptosis-induction) in several human cancers. However, its chemopreventive potential for prostate cancer has not yet been investigated. Here, we reported that CuB significantly and specifically inhibited prostate cancer cell growth with low IC50 (~0.3 μM; PC-3 and LNCaP), accompanied by marked apoptosis (Caspase 3/7 activation, PARP cleavage, increase of Annexin V-Alexa Fluor 488 (Alexa488)+ cells and accumulation of Sub-G0/G1 population), whereas normal human prostate epithelial cells (PrEC) were CuB-insensitive. Using a chemopreventive model, pre-treatment of mice with CuB (2 weeks before PC-3 prostate cancer cell implantation) significantly reduced the rate of in vivo tumor-formation. A 79% reduction in tumor size (accompanied by marked in situ apoptosis) was observed in the CuB-treated group (with no noticeable toxicity) vs. controls at day 31. Strikingly, mechanistic investigations demonstrated that CuB drove dose-dependent inhibition of ATP citrate lyase phosphorylation (ACLY; an important enzyme for cancer metabolism) both in vitro and in the CuB-chemopreventive mouse model. Importantly, ACLY over-expression abrogated CuB's apoptotic effects in prostate cancer cells, confirming ACLY as a direct target of CuB. Thus, CuB harbors potent chemopreventive activity for prostate cancer, and we revealed a novel anti-tumor mechanism of CuB via inhibition of ACYL signaling in human cancer.

Genomic analysis of head and neck squamous cell carcinoma cell lines and human tumors: a rational approach to preclinical model selection

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common type of cancer worldwide. The increasing amount of genomic information on human tumors and cell lines provides more biologic data to design preclinical studies. We and others previously reported whole-exome sequencing data of 106 HNSCC primary tumors. In 2012, high-throughput genomic data and pharmacologic profiling of anticancer drugs of hundreds of cancer cell lines were reported. Here, we compared the genomic data of 39 HNSCC cell lines with the genomic findings in 106 HNSCC tumors. Amplification of eight genes (PIK3CA, EGFR, CCND2, KDM5A, ERBB2, PMS1, FGFR1, and WHSCIL1) and deletion of five genes (CDKN2A, SMAD4, NOTCH2, NRAS, and TRIM33) were found in both HNSCC cell lines and tumors. Seventeen genes were only mutated in HNSCC cell lines (>10%), suggesting that these mutations may arise through immortalization in tissue culture. Conversely, 11 genes were only mutated in >10% of human HNSCC tumors. Several mutant genes in the EGF receptor (EGFR) pathway are shared both in cell lines and in tumors. Pharmacologic profiling of eight anticancer agents in six HNSCC cell lines suggested that PIK3CA mutation may serve as a predictive biomarker for the drugs targeting the EGFR/PI3K pathway. These findings suggest that a correlation of gene mutations between HNSCC cell lines and human tumors may be used to guide the selection of preclinical models for translational research.

IMPLICATIONS

These findings suggest that a correlation of gene mutations between HNSCC cell lines and human tumors may be used to guide the selection of preclinical models for translational research.

Translational genomics of nasopharyngeal cancer

Nasopharyngeal carcinoma (NPC), also named the Cantonese cancer, is a unique cancer with strong etiological association with infection of the Epstein-Barr virus (EBV). With particularly high prevalence in Southeast Asia, the involvement of EBV and genetic aberrations contributive to NPC tumorigenesis have remained unclear for decades. Recently, genomic analysis of NPC has defined it as a genetically homogeneous cancer, driven largely by NF-κB signaling caused by either somatic aberrations of NF-κB negative regulators or by overexpression of the latent membrane protein 1 (LMP1), an EBV viral oncoprotein. This represents a landmark finding of the NPC genome. Exome and RNA sequencing data from new EBV-positive NPC models also highlight the importance of PI3K pathway aberrations in NPC. We also realize for the first time that NPC mutational burden, mutational signatures, MAPK/PI3K aberrations, and MHC Class I gene aberrations, are prognostic for patient outcome. Together, these multiple genomic discoveries begin to shape the focus of NPC therapy development. Given the challenge of NF-κB targeting in human cancers, more innovative drug discovery approaches should be explored to target the unique atypical NF-κB activation feature of NPC. Our next decade of NPC research should focus on further identification of the -omic landscapes of recurrent and metastatic NPC, development of gene-based precision medicines, as well as large-scale drug screening with the newly developed and well-characterized EBV-positive NPC models. Focused preclinical and clinical investigations on these major directions may identify new and effective targeting strategies to further improve survival of NPC patients.

c-Src activation mediates erlotinib resistance in head and neck cancer by stimulating c-Met

PURPOSE

Strategies to inhibit the EGF receptor (EGFR) using the tyrosine kinase inhibitor erlotinib have been associated with limited clinical efficacy in head and neck squamous cell carcinoma (HNSCC). Co-activation of alternative kinases may contribute to erlotinib resistance.

EXPERIMENTAL DESIGN

We generated HNSCC cells expressing dominant-active c-Src (DA-Src) to determine the contribution of c-Src activation to erlotinib response.

RESULTS

Expression of DA-Src conferred resistance to erlotinib in vitro and in vivo compared with vector-transfected control cells. Phospho-Met was strongly upregulated by DA-Src, and DA-Src cells did not produce hepatocyte growth factor (HGF). Knockdown of c-Met enhanced sensitivity to erlotinib in DA-Src cells in vitro, as did combining a c-Met or c-Src inhibitor with erlotinib. Inhibiting EGFR resulted in minimal reduction of phospho-Met in DA-Src cells, whereas complete phospho-Met inhibition was achieved by inhibiting c-Src. A c-Met inhibitor significantly sensitized DA-Src tumors to erlotinib in vivo, resulting in reduced Ki67 labeling and increased apoptosis. In parental cells, knockdown of endogenous c-Src enhanced sensitivity to erlotinib, whereas treatment with HGF to directly induce phospho-Met resulted in erlotinib resistance. The level of endogenous phospho-c-Src in HNSCC cell lines was also significantly correlated with erlotinib resistance.

CONCLUSIONS

Ligand-independent activation of c-Met contributes specifically to erlotinib resistance, not cetuximab resistance, in HNSCC with activated c-Src, where c-Met activation is more dependent on c-Src than on EGFR, providing an alternate survival pathway. Addition of a c-Met or c-Src inhibitor to erlotinib may increase efficacy of EGFR inhibition in patients with activated c-Src.

Frequent mutation of receptor protein tyrosine phosphatases provides a mechanism for STAT3 hyperactivation in head and neck cancer

The underpinnings of STAT3 hyperphosphorylation resulting in enhanced signaling and cancer progression are incompletely understood. Loss-of-function mutations of enzymes that dephosphorylate STAT3, such as receptor protein tyrosine phosphatases, which are encoded by the PTPR gene family, represent a plausible mechanism of STAT3 hyperactivation. We analyzed whole exome sequencing (n = 374) and reverse-phase protein array data (n = 212) from head and neck squamous cell carcinomas (HNSCCs). PTPR mutations are most common and are associated with significantly increased phospho-STAT3 expression in HNSCC tumors. Expression of receptor-like protein tyrosine phosphatase T (PTPRT) mutant proteins induces STAT3 phosphorylation and cell survival, consistent with a "driver" phenotype. Computational modeling reveals functional consequences of PTPRT mutations on phospho-tyrosine-substrate interactions. A high mutation rate (30%) of PTPRs was found in HNSCC and 14 other solid tumors, suggesting that PTPR alterations, in particular PTPRT mutations, may define a subset of patients where STAT3 pathway inhibitors hold particular promise as effective therapeutic agents.

Mitogenic effects of gastrin-releasing peptide in head and neck squamous cancer cells are mediated by activation of the epidermal growth factor receptor

Head and neck squamous cell carcinomas (HNSCC) are characterized by upregulation of the epidermal growth factor receptor (EGFR), where EGFR serves as a potential therapeutic target. We previously reported that a gastrin-releasing peptide/gastrin-releasing peptide receptor (GRP/GRPR) autocrine growth pathway is activated early in HNSCC carcinogenesis. In the present study, we examined the mechanism of EGFR activation by GRP/GRPR in HNSCC proliferation. In HNSCC cells that express elevated levels of both GRPR and EGFR, we found that GRP induced rapid phosphorylation of EGFR as well as p44/42-MAPK activation. Using several EGFR-specific tyrosine kinase inhibitors and cells derived from EGFR knockout mice, we demonstrated that GRP-induced p44/42-MAPK activation was dependent upon EGFR activation. Further investigation demonstrated that cleavage of transforming growth factor-alpha (TGF-alpha) by matrix metalloproteinases mediated GRP-induced MAPK activation. In addition, HNSCC proliferation stimulated by GRP was eliminated upon specific inhibition of EGFR or MEK, and GRP failed to stimulate proliferation in EGFR-deficient cells. These results imply that the mitogenic effects of GRP in HNSCC are mediated by extracellular release of TGF-alpha and require the activation of an EGFR-dependent MEK/MAPK-dependent pathway.

Antitumor mechanisms of combined gastrin-releasing peptide receptor and epidermal growth factor receptor targeting in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is characterized by epidermal growth factor receptor (EGFR) overexpression, where EGFR levels correlate with survival. To date, EGFR targeting has shown limited antitumor effects in head and neck cancer when administrated as monotherapy. We previously identified a gastrin-releasing peptide/gastrin-releasing peptide receptor (GRP/GRPR) aurocrine regulatory pathway in HNSCC, where GRP stimulates Src-dependent cleavage of EGFR proligands with subsequent EGFR phosphorylation and mitogen-activated protein kinase (MAPK) activation. To determine whether GRPR targeting can enhance the antitumor efficacy of EGFR inhibition, we investigated the effects of a GRPR antagonist (PD176252) in conjunction with an EGFR tyrosine kinase inhibitor (erlotinib). Combined blockade of GRPR and EGFR pathways significantly inhibited HNSCC, but not immortalized mucosal epithelial cell, proliferation, invasion, and colony formation. In addition, the percentage of apoptotic cells increased upon combined inhibition. The enhanced antitumor efficacy was accompanied by increased expression of cleaved poly(ADP-ribose) polymerase (PARP) and decreased phospho-EGFR, phospho-MAPK, and proliferating cell nuclear antigen (PCNA). Using reverse-phase protein microarray (RPPA), we further detected decreased expression of phospho-c-Jun, phospho-p70S6K, and phospho-p38 with combined targeting. Cumulatively, these results suggest that GRPR targeting can enhance the antitumor effects of EGFR inhibitors in head and neck cancer.

Gastrin-releasing peptide receptor-mediated autocrine growth in squamous cell carcinoma of the head and neck

BACKGROUND

Gastrin-releasing peptide receptor (GRPR)-mediated autocrine growth appears to be an early marker of susceptibility to tobacco-related lung cancers. Because expression of GRPR, however, has not been reported in squamous cell carcinoma of the head and neck (SCCHN), we investigated its expression and that of its ligand GRP in normal mucosa and SCCHN tissues and the involvement of these proteins in the proliferation of SCCHN cells.

METHODS

We assessed GRPR messenger RNA (mRNA) expression in specimens from 25 patients with SCCHN, six control noncancer patients, and 14 SCCHN cell lines by use of quantitative reverse transcriptase-polymerase chain reaction. We used neutralizing GRP monoclonal antibody 2A11 to block the GRP-GRPR interaction in SCCHN cell lines and xenografts and assessed the antibody's effect on proliferation by counting cultured cells or measuring xenograft tumor volume in vivo. All statistical tests were two-sided.

RESULTS

Tumor and mucosa tissues, respectively, from SCCHN patients expressed sixfold and fourfold higher levels of GRPR mRNA than normal mucosa tissue from noncancer patients (P<.001). The levels of GRPR expression in the tumor and adjacent normal epithelium of individual patients with SCCHN were correlated (r =.652; P =.001), suggesting that increased GRPR expression is an early event in SCCHN formation. SCCHN cells expressed fivefold higher levels of GRPR mRNA than did cultured normal mucosal epithelial cells (P =.005). GRP stimulated proliferation of SCCHN cells in a dose-dependent fashion (P =.006). Neutralizing GRP monoclonal antibody 2A11 inhibited SCCHN cell proliferation in vitro and in vivo. Median survival was 54 months in patients with higher levels of GRPR mRNA and was not reached in those with lower levels.

CONCLUSIONS

GRP and GRPR appear to participate in an autocrine regulatory pathway in SCCHN. Thus, strategies that specifically target GRP and/or GRPR may be effective therapeutic approaches for this disease.

Antiproliferative mechanisms of a transcription factor decoy targeting signal transducer and activator of transcription (STAT) 3: the role of STAT1

We previously developed a transcription factor decoy targeting signal transducer and activator of transcription 3 (STAT3) and reported antitumor activity in both in vitro and in vivo models of squamous cell carcinoma of the head and neck (SCCHN). Based on the known existence of STAT1-STAT3 heterodimers, the high sequence homology between STAT1 and STAT3, as well as expression of both STAT1 and STAT3 in SCCHN, we examined whether the STAT3 decoy interferes with STAT1 signaling. SCCHN cell lines with different STAT1 expression levels (but similar STAT3 levels) were used. Both cell lines were sensitive to the growth-inhibitory effects of the STAT3 decoy compared with a mutant control decoy. Intact STAT1 signaling was demonstrated by interferon-gamma (IFN-gamma)-mediated induction of STAT1 phosphorylation (Tyr701) and interferon-regulatory factor-1 (IRF-1) expression. Treatment with the STAT3 decoy (but not a mutant control decoy) resulted in inhibition of IRF-1 protein expression in both cell lines, indicating specific inhibition of STAT1 signaling by the STAT3 decoy. Because STAT1 is a potential tumor suppressor, we also investigated whether STAT1 signaling mitigated the therapeutic efficacy of the STAT3 decoy. In both PCI-15B and UM-22B cells, STAT1 siRNA treatment resulted in decreased STAT1 expression, without altering the antitumor activity of the STAT3 decoy. Likewise, the antitumor effects of the STAT3 decoy were not altered by STAT1 activation upon IFN-gamma treatment. These results suggest that the therapeutic mechanisms of STAT3 blockade using a transcription factor decoy are independent of STAT1 activation.

Microneedles loaded with anti-PD-1-cisplatin nanoparticles for synergistic cancer immuno-chemotherapy

Programmed cell death protein-1 (PD-1) on T-cells combined with programmed cell death ligand-1 (PD-L1) critically accounts for tumor immune evasion. Anti-PD-1 (aPD-1) blocks the binding of PD-1 to PD-L1, thus allowing T-cell activation for tumor cell eradication. Currently, the major challenges for cancer immunotherapy are how to improve the response rate and overcome drug resistance. Dermal administration turns out to be a promising route for immunotherapy since skin is a highly active immune organ containing a large population of resident antigen-presenting cells. Microneedle arrays can pierce the immune-cell-rich epidermis, leading to a robust T-cell response in the microenvironment of tumor cells. Herein, we successfully developed a microneedle patch loaded with pH-responsive tumor-targeted lipid nanoparticles (NPs), which allows local delivery of aPD-1 and cisplatin (CDDP) precisely to cancer tissues for cancer therapy. For in vivo studies, aPD-1/CDDP@NPs delivered through microneedles effectively boosted the immune response, thereby a remarkable effect on tumor regression was realized. Synergistic anticancer mechanisms were therefore activated through robust microneedle-induced T-cell response, blockage of PD-1 in T-cells by aPD-1, and an increase in direct cytotoxicity of CDDP in tumor cells. Strikingly, transdermal delivery using MNs increased the response rate in the animal model unresponsive to aPD-1 systemic therapy. This exhibited promise in the treatment of immunotherapy-unresponsive cancers. Taken together, microneedle-mediated local delivery of nano-encapsulated chemotherapeutic and immunotherapeutic agents at tumor skin sites provides a novel treatment strategy and insights into cancer therapy.

Constitutive activation of signal transducer and activator of transcription 5 contributes to tumor growth, epithelial-mesenchymal transition, and resistance to epidermal growth factor receptor targeting

PURPOSE

Signal transducer and activator of transcription 5 (STAT5) is activated in squamous cell carcinoma of the head and neck (SCCHN), where targeting of STAT5 inhibits tumor growth in vitro and in vivo. The role of STAT5 activation in carcinogenesis, tumor progression, and response to therapy remains incompletely understood. In this study, we investigated the effects of STAT5 activation on squamous epithelial carcinogenesis and response to therapy.

EXPERIMENTAL DESIGN

The functional consequences of STAT5 activation in squamous epithelial carcinogenesis were examined using cells derived from normal (Het-1A) and transformed mucosal epithelial cells engineered to express constitutive-active mutants of STAT5.

RESULTS

The growth rate of stable clones derived from both normal and transformed squamous epithelial cells expressing the constitutive-active STAT5 was increased. In SCCHN xenografts, tumor volumes were increased in constitutive-active STAT5 mutant cells compared with vector-transfected controls. Constitutive activation of STAT5 significantly increased cell migration and invasion through Matrigel, as well as the transforming efficiency of SCCHN cells in vitro, as assessed by soft agar assays. The constitutive-active STAT5 clones derived from SCCHN cells showed changes consistent with an epithelial-mesenchymal transition including decreased expression of E-cadherin and increased vimentin in comparison with control transfectants. In these cells, STAT5 activation was associated with resistance to cisplatin-mediated apoptosis and growth inhibition induced by the epidermal growth factor receptor tyrosine kinase inhibitor, erlotinib.

CONCLUSIONS

These results suggest that constitutive STAT5 signaling enhances tumor growth, invasion, and epithelial-to-mesenchymal transition in squamous epithelial carcinogenesis and may contribute to resistance to epidermal growth factor receptor tyrosine kinase inhibitor and chemotherapy.

Gastrin-releasing peptide receptor mediates activation of the epidermal growth factor receptor in lung cancer cells

Gastrin-releasing peptide receptor (GRPR) and the epidermal growth factor receptor (EGFR) are expressed in several cancers including non-small cell lung cancer (NSCLC). Here we demonstrate the activation of EGFR by the GRPR ligand, gastrin-releasing peptide (GRP), in NSCLC cells. GRP induced rapid activation of p44/42 MAPK in lung cancer cells through EGFR. GRP-mediated activation of MAPK in NSCLC cells was abrogated by pretreatment with the anti-EGFR-neutralizing antibody, C225. Pretreatment of NSCLC cells with neutralizing antibodies to the EGFR ligands, TGF-A or HB-EGF, also decreased GRP-mediated MAPK activation. On matrix metalloproteinase (MMP) inhibition, GRP failed to activate MAPK in NSCLC cells. EGF and GRP both stimulated NSCLC proliferation, and inhibition of either EGFR or GRPR resulted in cell death. Combining a GRPR antagonist with the EGFR tyrosine kinase inhibitor, gefitinib, resulted in additive cytotoxic effects. Additive effects were seen at gefitinib concentrations from 1 to 18 microM, encompassing the ID50 values of both gefitinib-sensitive and gefitinib-resistant NSCLC cell lines. Because a major effect of GRPR appears to be promoting the release of EGFR ligand, this study suggests that a greater inhibition of cell proliferation may occur by abrogating EGFR ligand release in consort with inhibition of EGFR.

Stromal interleukin-33 promotes regulatory T cell-mediated immunosuppression in head and neck squamous cell carcinoma and correlates with poor prognosis

Regulatory T cells (Tregs) mediate immunosuppressive signals that can contribute to the progression of head and neck squamous cell carcinoma (HNSCC). Interleukin-33 (IL-33) is defined as an 'alarmin', an endogenous factor that is expressed during tissue and cell damage, which has been shown to promote Treg proliferation in non-lymphoid organs. However, the interaction between IL-33 and Tregs in the HNSCC tumor microenvironment remains uncertain. In this study, we examined IL-33+ and Foxp3+ cells by immunohistochemistry in 68 laryngeal squamous cell cancer patients, followed by functional analysis of IL-33 in Tregs. In addition, the suppressive function of Tregs was assessed by cell proliferation assays. The level of stromal IL-33 was significantly upregulated in advanced versus early stage HNSCC patients and positively correlated with Foxp3+ Treg infiltration as well as a poor prognosis. ST2 is regarded as the only receptor of IL-33. Infiltrated ST2-expressing Tregs were responsive to IL-33, and the percentage of Tregs was increased upon IL-33 stimulation. Functional investigation demonstrated that IL-33 increased the proportion of Foxp3+GATA3+ Tregs and improved the suppressive functions of Tregs by inducing IL-10 and TGF-β1 as well as decreasing the proliferation of responder T cells. Blockade of ST2 abrogated the immunosuppression caused by IL-33. Our data demonstrate that stromal IL-33 both expands the Treg population and enhances their functions in the tumor microenvironment. Furthermore, stromal IL-33 has prognostic value for tumor progression. Thus, stromal IL-33 is a potential target for future HNSCC immunotherapy.

KIAA0495/PDAM is frequently downregulated in oligodendroglial tumors and its knockdown by siRNA induces cisplatin resistance in glioma cells

Co-deletion of chromosomes 1p and 19q is a common event in oligodendroglial tumors (OTs), suggesting the presence of OT-related genes. The aim of this study was to identify the target genes residing in the minimally deleted regions on chromosome 1p36.31-p36.32 that might be involved in OTs. A novel gene KIAA0495/p53-dependent apoptosis modulator (PDAM) was found frequently deregulated, with 37 of 58 (63.8%) OTs examined showing reduced expression compared with normal brain. Chromosome 1p loss and epigenetic modifications were the major mechanisms contributing to PDAM downregulation. The role of PDAM in chemosensitivity was also evaluated. PDAM knockdown had no effect on sensitivity to vincristine, lomustine, temozolomide and paclitaxel, but could induce cisplatin resistance in glioma cells harboring wild-type p53. B-cell CCL/lymphoma 2 (BCL2)-like 1 (BCL2L1) exhibited significant upregulation, while BCL2 showed partial derepression in PDAM-silenced cells after cisplatin treatment, suggesting that alteration of anti-apoptotic genes contributed in part to cisplatin resistance. Knockdown of BCL2L1 abrogated the induced cisplatin-resistant phenotype. Moreover, our data suggested that PDAM might function as a non-protein-coding RNA. Collectively, these findings suggest that PDAM deregulation may play a role in OT development and that PDAM may possess the capacity to modulate apoptosis via regulation of p53-dependent anti-apoptotic genes.

Genomic Landscapes of EBV-Associated Nasopharyngeal Carcinoma vs. HPV-Associated Head and Neck Cancer

: Epstein-Barr virus-positive nasopharyngeal carcinoma (EBV(+) NPC), and human papillomavirus-positive head and neck squamous cell carcinoma (HPV(+) HNSCC) are two distinct types of aggressive head and neck cancers with early age onsets. Their recently identified genomic landscapes by whole-exome sequencing (WES) clearly reveal critical roles of: (1) inflammation via NF-kB activation, (2) survival via PI3K aberrations, and perhaps (3) immune evasion via MHC loss in these cancers as summarized in this review. Immediate outcomes of these WES studies include the identification of potential prognostic biomarkers, and druggable events for these cancers. The impact of these genomic findings on the development of precision medicine and immunotherapies will be discussed. For both of these cancers, the main lethality comes from metastases and disease recurrences which may represent therapy resistance. Thus, potential curing of these cancers still relies on future identification of key genomic drivers and likely druggable events in recurrent and metastatic forms of these intrinsically aggressive cancers of the head and neck.

Precision drugging of the MAPK pathway in head and neck cancer

The mitogen-activating protein kinase (MAPK) pathway is central for cell proliferation, differentiation, and senescence. In human, germline defects of the pathway contribute to developmental and congenital head and neck disorders. Nearly 1/5 of head and neck squamous cell carcinoma (HNSCC) harbors MAPK pathway mutations, which are largely activating mutations. Yet, previous approaches targeting the MAPK pathway in HNSCC were futile. Most recent clinical evidences reveal remarkable, or even exceptional pharmacologic vulnerabilities of MAPK1-mutated, HRAS-mutated, KRAS-germline altered, as well as BRAF-mutated HNSCC patients with various targeted therapies, uncovering diverse opportunities for precision drugging this pathway at multiple “genetically condemned” nodes. Further, recent patient tumor omics unveil novel effects of MAPK aberrations on direct induction of CD8⁺ T cell recruitment into the HNSCC microenvironment, providing evidences for future investigation of precision immunotherapy for this large subset of patients. MAPK pathway-mutated HNSCC should warrant precision therapy assessments in vigorous manners.

Systemic administration of naked DNA encoding interleukin 12 for the treatment of human papillomavirus DNA-positive tumor

Interleukin 12 (IL-12) is one of the most effective and promising cytokines for cancer therapy. Its therapeutic effects have been demonstrated in a variety of tumors in animal models when it is administrated locally or systemically. We describe here a systemic delivery of naked murine IL-12 (mIL-12) gene in vivo. Dose-dependent systemic production of mIL-12, with a serum level up to approximately 20 microg/ml, was observed 24 hr after systemic gene delivery. The apparent half-life in the circulation was about 5 hr. The result of a bioactivity assay (in vitro interferon gamma [IFN-gamma] release) indicated that the gene product in mice was as active as the purified recombinant murine IL-12 protein (rmIL-12). The circulating mIL-12 activated natural killer cells and stimulated IFN-gamma production in vivo. A single administration of mIL-12 gene resulted in prominent regression of established subcutaneous tumor in a human papillomavirus (HPV) DNA-positive tumor model (TC-1) in C57BL/6J mice. The antitumor effect of the single gene dose was comparable to repeated intraperitoneal administration of rmIL-12 (0.5 microg/day for consecutive 5 days). This systemic gene delivery is simple, economical, and highly efficient for the production of large amounts of cytokine in vivo. With this gene delivery method, we have demonstrated the therapeutic potential of IL-12 for the treatment of HPV DNA-positive tumor and the usefulness of the systemic gene delivery for assessing the therapeutic effect of a candidate gene.