High-Throughput 3D Tumor Spheroid Array Platform for Evaluating Sensitivity of Proton-Drug Combinations

Proton beam therapy (PBT) is a critical treatment modality for head and neck squamous cell carcinoma (HNSCC). However, not much is known about drug combinations that may improve the efficacy of PBT. This study aimed to test the feasibility of a three-dimensional (3D) tumor-spheroid-based high-throughput screening platform that could assess cellular sensitivity against PBT. Spheroids of two HNSCC cell lines—Fadu and Cal27—cultured with a mixture of Matrigel were arrayed on a 384-pillar/well plate, followed by exposure to graded doses of protons or targeted drugs including olaparib at various concentrations. Calcein staining of HNSCC spheroids revealed a dose-dependent decrease in cell viability for proton irradiation or multiple targeted drugs, and provided quantitative data that discriminated the sensitivity between the two HNSCC cell lines. The combined effect of protons and olaparib was assessed by calculating the combination index from the survival rates of 4 × 4 matrices, showing that Cal27 spheroids had greater synergy with olaparib than Fadu spheroids. In contrast, adavosertib did not synergize with protons in both spheroids. Taken together, we demonstrated that the 3D pillar/well array platform was a useful tool that provided rapid, quantitative data for evaluating sensitivity to PBT and drug combinations. Our results further supported that administration of the combination of PBT and olaparib may be an effective treatment strategy for HNSCC patients.

RNA N6-methyladenosine reader IGF2BP2 promotes lymphatic metastasis and epithelial-mesenchymal transition of head and neck squamous carcinoma cells via stabilizing slug mRNA in an m6A-dependent manner

Background Lymph node metastasis is the main cause of poor prognosis of head and neck squamous carcinoma (HNSCC) patients. N6-methyladenosine (m6A) RNA modification is an emerging epigenetic regulatory mechanism for gene expression, and as a novel m6A reader protein, IGF2BP2 has been implicated in tumor progression and metastasis. However, not much is currently known about the functional roles of IGF2BP2 in HNSCC, and whether IGF2BP2 regulates lymphatic metastasis through m6A modification in HNSCC remains to be determined. Methods The expression and overall survival (OS) probability of m6A-related regulators in HNSCC were analyzed with The Cancer Genome Atlas (TCGA) dataset and GEPIA website tool, respectively. The expression levels of IGF2BP2 were measured in HNSCC tissues and normal adjacent tissues. To study the effects of IGF2BP2 on HNSCC cell metastasis in vitro and in vivo, gain- and loss- of function methods were employed. RIP, MeRIP, luciferase reporter and mRNA stability assays were performed to explore the epigenetic mechanism of IGF2BP2 in HNSCC. Results We investigated 20 m6A-related regulators in HNSCC and discovered that only the overexpression of IGF2BP2 was associated with a poor OS probability and an independent prognostic factor for HNSCC patients. Additionally, we demonstrated that IGF2BP2 was overexpressed in HNSCC tissues, and significantly correlated to lymphatic metastasis and poor prognosis. Functional studies have shown that IGF2BP2 promotes both HNSCC cell migration as well as invasion via the epithelial-mesenchymal transition (EMT) process in vitro, and IGF2BP2 knockdown significantly inhibited lymphatic metastasis and lymphangiogenesis in vivo. Mechanistic investigations revealed that Slug, a key EMT-related transcriptional factor, is the direct target of IGF2BP2, and essential for IGF2BP2-regulated EMT and metastasis in HNSCC. Furthermore, we demonstrated that IGF2BP2 recognizes and binds the m6A site in the coding sequence (CDS) region of Slug and promotes its mRNA stability. Conclusions Collectively, our study uncovers the oncogenic role and potential mechanism of IGF2BP2, which serves as a m6A reader, in controlling lymphatic metastasis and EMT in HNSCC, suggesting that IGF2BP2 may act as a therapeutic target and prognostic biomarker for HNSCC patients with metastasis.

Molecular Subtypes Based on Cell Differentiation Trajectories in Head and Neck Squamous Cell Carcinoma: Differential Prognosis and Immunotherapeutic Responses

ObjectiveHead and neck squamous cell carcinoma (HNSCC) is one of the most common and lethal malignant tumors. We aimed to investigate the HNSCC cell differentiation trajectories and the corresponding clinical relevance.MethodsBased on HNSCC cell differentiation-related genes (HDRGs) identified by single-cell sequencing analysis, the molecular subtypes and corresponding immunity, metabolism, and stemness characteristics of 866 HNSCC cases were comprehensively analyzed. Machine-learning strategies were used to develop a HNSCC cell differentiation score (HCDscore) in order to quantify the unique heterogeneity of individual samples. We also assessed the prognostic value and biological characteristics of HCDscore using the multi-omics data.ResultsHNSCCs were stratified into three distinct molecular subtypes based on HDRGs: active stroma (Cluster-A), active metabolism (Cluster-B), and active immune (Cluster-C) types. The three molecular subtypes had different characteristics in terms of biological phenotype, genome and epigenetics, prognosis, immunotherapy and chemotherapy responses. We then demonstrated the correlations between HCDscore and the immune microenvironment, subtypes, carcinogenic biological processes, genetic variation, and prognosis. The low-HCDscore group was characterized by activation of immunity, enhanced response to anti-PD-1/PD-L1 immunotherapy, and better survival compared to the high-HCDscore group. Finally, by integrating the HCDscore with prognostic clinicopathological characteristics, a nomogram with strong predictive performance and high accuracy was constructed.ConclusionsThis study revealed that the cell differentiation trajectories in HNSCC played a nonnegligible role in patient prognosis, biological characteristics, and immune responses. Evaluating cancer cell differentiation will help to develop more effective immunotherapy, metabolic therapy, and chemotherapy strategies.

Early senescence and production of senescence-associated cytokines are major determinants of radioresistance in head-and-neck squamous cell carcinoma

Resistance against radio(chemo)therapy-induced cell death is a major determinant of oncological treatment failure and remains a perpetual clinical challenge. The underlying mechanisms are manifold and demand for comprehensive, cancer entity- and subtype-specific examination. In the present study, resistance against radiotherapy was systematically assessed in a panel of human head-and-neck squamous cell carcinoma (HNSCC) cell lines and xenotransplants derived thereof with the overarching aim to extract master regulators and potential candidates for mechanism-based pharmacological targeting. Clonogenic survival data were integrated with molecular and functional data on DNA damage repair and different cell fate decisions. A positive correlation between radioresistance and early induction of HNSCC cell senescence accompanied by NF-κB-dependent production of distinct senescence-associated cytokines, particularly ligands of the CXCR2 chemokine receptor, was identified. Time-lapse microscopy and medium transfer experiments disclosed the non-cell autonomous, paracrine nature of these mechanisms, and pharmacological interference with senescence-associated cytokine production by the NF-κB inhibitor metformin significantly improved radiotherapeutic performance in vitro and in vivo. With regard to clinical relevance, retrospective analyses of TCGA HNSCC data and an in-house HNSCC cohort revealed that elevated expression of CXCR2 and/or its ligands are associated with impaired treatment outcome. Collectively, our study identifies radiation-induced tumor cell senescence and the NF-κB-dependent production of distinct senescence-associated cytokines as critical drivers of radioresistance in HNSCC whose therapeutic targeting in the context of multi-modality treatment approaches should be further examined and may be of particular interest for the subgroup of patients with elevated expression of the CXCR2/ligand axis.

935 Attraction of immune cells by head and neck cancer cell lines and primary tumor-conditioned supernatants

BackgroundHead and neck squamous cell carcinomas (HNSCC) are classified in human papillomavirus (HPV)-positive and HPV-negative tumors. In general, HPV-negative HNSCC are genetically characterized by many chromosomal gains and losses.1 Previously, we and others identified a HPV-negative subgroup with few or absent copy number alterations (CNA-silent), and a more favorable prognosis.2 3 Tumors with low copy number changes have generally been associated with high immune infiltration scores,4 but for CNA-silent versus CNA-high HPV-negative HNSCC such data are lacking.In this study we aim to unravel by functional assays immunological differences between HPV-negative and HPV-positive HNSCC, as well as between CNA-silent and CNA-high HPV-negative HNSCC. We analyzed the immune cell subsets attracted by HNSCC cell lines and by tumor-conditioned supernatants.MethodsEight HNSCC cell lines (3 HPV-positive, 3 HPV-negative CNA-high, 2 HPV-negative CNA-silent) and 24-hour supernatants of thirteen HNSCC biopsies were used to characterize their ability to attract immune cells in a transwell migration system. A chemokine mixture was used as a positive control, while medium alone was used to determine spontaneous migration. Peripheral blood mononuclear cells (PBMCs) of various healthy donors were plated in the upper compartment and after six hours the transwell migration was quantified by flow cytometry.ResultsMost HNSCC cell lines induced migration of monocytes, B cells and CD4+ T-cells up to maximal 12%, whereas CD8+ T-cells and conventional dendritic cells (cDCs) were not attracted, irrespective of the donor. Notably, one HPV-negative CNA-silent cell line induced significantly more migration compared to the negative control and other cell lines. Tumor-conditioned supernatants promoted immune cell migration with no apparent differences between tumor sites or HPV-status. Remarkably, up to 31% of monocytes migrated to these supernatants, 9x more than the chemokine control. Also cDC migration was induced, whereas lymphocytes were not attracted.ConclusionsHNSCC cell lines induced monocyte, B-lymphocyte and CD4+ T-lymphocyte migration, whereas tumor-conditioned supernatants attracted monocytes and cDCs only. No difference in immune cell attraction between HPV-positive and -negative HNSCC was observed. Interestingly, one HPV-negative CNA-silent cell line induced robust immune cell migration. Currently we perform a comprehensive chemokine analysis to explain the observed migration. The noted lack of CD8+ T-cell attraction may explain why current treatments with PD-1 inhibitors are effective in only a minority of HNSCC patients. Our data could provide a means to identify patients who might most likely respond to immune checkpoint blockade and to find clues to improve CD8+ T-cell attraction.ReferencesLeemans CR, Snijders PJF, Brakenhoff RH. The molecular landscape of head and neck cancer. Nat Rev Cancer 2018;18:269–82.Smeets SJ, Brakenhoff RH, Ylstra B, van Wieringen WN, van de Wiel MA, Leemans CR, et al. Genetic classification of oral and oropharyngeal carcinomas identifies subgroups with a different prognosis. Cell Oncol 2009;31:291–300.Cancer Genome Atlas N. Comprehensive genomic characterization of head and neck squamous cell carcinomas. Nature 2015;517:576–82.Davoli T, Uno H, Wooten EC, Elledge SJ. Tumor aneuploidy correlates with markers of immune evasion and with reduced response to immunotherapy. Science 2017;355.Ethics ApprovalWritten informed consent was obtained from all patients from whom fresh tumor biopsies were used for research, as part of the HNcol protocol at the Department of Otolaryngology|Head and Neck Surgery of Amsterdam UMC (VUmc) as approved by the Institutional Review Board (2008.071|A2016.035). Buffy coats, with written consent from the donors, were purchased from the Dutch blood bank (Sanquin) and used to isolate PBMC.

889 DuoBody®-CD3x5T4 induces efficient T-cell activation and killing of patient-derived head and neck cancer cells in vitro and ex vivo

Background5T4, also known as trophoblast glycoprotein, is expressed in many solid cancers, including non-small cell lung cancer, triple-negative breast cancer, bladder, esophageal, prostate, uterine and head and neck squamous cell carcinomas (HNSCCs). DuoBody-CD3x5T4 is a CD3 bispecific antibody that efficiently induces T-cell mediated cytotoxicity of 5T4-positive tumor cells. Currently, DuoBody-CD3x5T4 is being evaluated in a first-in-human clinical trial (NCT04424641) in solid cancers in partnership between Genmab and AbbVie. In this study we explored the preclinical mechanism-of-action of DuoBody-CD3x5T4 in vitro and ex vivo, using HNSCC as a case study.Methods5T4 protein expression in HNSCC tumor specimens was determined by immunohistochemistry (IHC) and flow cytometry. T-cell mediated cytotoxicity and T-cell activation induced by DuoBody-CD3x5T4 were studied in co-cultures of healthy donor T cells and patient-derived HNSCC cell lines in vitro. Lastly, the capacity of DuoBody-CD3x5T4 to activate tumor-infiltrating lymphocytes (TILs) was analyzed in freshly dissociated 5T4-expressing HNSCC tumor specimens ex vivo.ResultsIHC analysis confirmed expression of 5T4 in HNSCC oral biopsies, including specimens from primary tumors, recurrent tumors and lymph node metastases. Patient-derived HNSCC cell lines (n=22) demonstrated 5T4 expression on the plasma membrane, ranging from 10,000 - 61,000 5T4 molecules per cell. Moreover, 5T4 expression was evident on EGFR+CD45- tumor cells in single-cell suspensions from freshly dissociated HNSCC biopsies, independent of the tumor site. DuoBody-CD3x5T4 demonstrated potent, target-dependent cytotoxicity in vitro in co-cultures of healthy donor T cells and patient-derived HNSCC cell lines across the range of 5T4 expression levels tested. Tumor cell kill was associated with CD4+ and CD8+ T-cell activation and granzyme B secretion. Importantly, DuoBody-CD3x5T4 induced potent activation of autologous TILs in single-cell suspensions from freshly dissociated HNSCC biopsies. Notably, T-cell activation (as assessed by expression of CD69, CD25 and CD137) was also observed in PD-1+ TILs, suggesting that DuoBody-CD3x5T4 was able to engage antigen-experienced T cells in the tumor microenvironment. In this autologous assay, preliminary data showed that 5T4-expressing HNSCC tumor cells were specifically eradicated.Conclusions5T4 was broadly expressed in HNSCC cell lines, tumor biopsies and primary tumor cell suspensions. DuoBody-CD3x5T4 activated healthy donor T cells in co-cultures with patient-derived HNSCC cell lines, resulting in secretion of granzyme B and efficient tumor cell kill. In single-cell suspensions from freshly dissociated 5T4+ HNSCC biopsies, DuoBody-CD3x5T4 activated autologous CD4+ and CD8+ TILs, including PD-1+ TILs. This dataset adds to the preclinical evidence for targeting 5T4-expressing solid cancers with DuoBody-CD3x5T4.Ethics ApprovalWritten informed consent was obtained from all patients from whom fresh tumor biopsies were used for research, as part of the HNcol protocol at the Department of Otolaryngology|Head and Neck Surgery of Amsterdam UMC (VUmc) as approved by the Institutional Review Board (2008.071|A2016.035). Archival FFPE specimens were used for scientific research in agreement with the medical ethical guidelines described in the Code of Conduct for Proper Secondary Use of Human Tissue of the Dutch Federation of Biomedical Scientific Societies (Federa) in accordance with the Declaration of Helsinki and after Biobank approval (BUP2019-74).

RNA N6-methyladenosine Reader IGF2BP2 Promotes Lymphatic Metastasis and Epithelial-mesenchymal Transition of Head and Neck Squamous Carcinoma Cells via Stabilizing Slug mRNA in an M6A-dependent Manner

Background: Lymph node metastasis is the main cause of poor prognosis of head and neck squamous carcinoma (HNSCC) patients. N6-methyladenosine (m6A) RNA modification is an emerging epigenetic regulatory mechanism for gene expression, and as a novel m6A reader protein, IGF2BP2 has been implicated in tumor progression and metastasis. However, not much is currently known about the functional roles of IGF2BP2 in HNSCC, and whether IGF2BP2 regulates lymphatic metastasis through m6A modification in HNSCC remains to be determined. Methods: The expression and overall survival (OS) probability of m6A-related regulators in HNSCC were analyzed with The Cancer Genome Atlas (TCGA) dataset and GEPIA website tool, respectively. The expression levels of IGF2BP2 were measured in HNSCC tissues and normal adjacent tissues. To study the effects of IGF2BP2 on HNSCC cell metastasis in vitro and in vivo, gain- and loss- of function methods were employed. RIP, MeRIP, and luciferase reporter and mRNA stability assays were performed to explore the epigenetic mechanism of IGF2BP2 in HNSCC. Results: We investigated 20 m6A-related regulators in HNSCC and discovered that only the overexpression of IGF2BP2 was associated with a poor OS probability and an independent prognostic factor for HNSCC patients. Additionally, we demonstrated that IGF2BP2 was overexpressed in HNSCC tissues, and significantly correlated to lymphatic metastasis and poor prognosis. Functional studies have shown that IGF2BP2 promotes both HNSCC cell migration as well as invasion via the epithelial-mesenchymal transition (EMT) process in vitro, and IGF2BP2 knockdown significantly inhibited lymphatic metastasis and lymphangiogenesis in vivo. Mechanistic investigations revealed that Slug, a key EMT-related transcriptional factor, is the direct target of IGF2BP2, and essential for IGF2BP2-regulated EMT and metastasis in HNSCC. Furthermore, we demonstrated that IGF2BP2 recognizes and binds the m6A site in the coding sequence (CDS) region of Slug and promotes its mRNA stability. Conclusions: Collectively, our study uncovers the oncogenic role and potential mechanism of IGF2BP2, which serves as a m6A reader, in controlling lymphatic metastasis and EMT in HNSCC, suggesting that IGF2BP2 may act as a therapeutic target and prognostic biomarker for HNSCC patients with metastasis.

Zerumbone acts as a radiosensitizer in head and neck squamous cell carcinoma

SummaryIntroduction. Zerumbone is a phytochemical compound of the ginger plant Zingiber zerumbet with cytotoxic effects in various cancer cell lines. To date, zerumbone has shown an antiproliferative effect in oral squamous cell carcinoma cells lines. However, the effect of combination with radiation or cisplatin in head and neck squamous cell carcinoma (HNSCC) is unclear. The aim of this study was to investigate the effect of zerumbone alone, and in combination with irradiation and cisplatin on HNSCC cell lines. Methods. The three HNSCC cell lines SCC25, Cal27 and FaDu were treated with zerumbone, radiation and/or cisplatin. Cell viability and clonogenic assays were performed. The interaction between zerumbone and radiation or cisplatin was evaluated using the combination index. Apoptosis was measured by flow cytometry and cell migration was assessed using a wound healing assay. Results. Treatment with zerumbone resulted in a dose dependent induction of cytotoxicity and apoptosis in all three cell lines. The combination with cisplatin revealed a synergistic to additive effect in Cal27. The clonogenic assay showed a significant radiosensitizing effect in all three cell lines. The wound healing assay showed a reduction of cell migration in Cal27. Conclusion. The natural compound zerumbone shows a cytotoxic and proapoptotic effect on HNSCC cell lines. Furthermore, zerumbone enhances the radiation effect in all three cell lines and thus may be a suitable candidate for combination therapy in HNSCC.

The Role of Akt in Acquired Cetuximab Resistant Head and Neck Squamous Cell Carcinoma: An In Vitro Study on a Novel Combination Strategy

The epidermal growth factor receptor (EGFR) is a therapeutic target in head and neck squamous cell carcinoma (HNSCC). Resistance to EGFR-targeted therapies, such as cetuximab, poses a challenging problem. This study aims to characterize acquired cetuximab resistance mechanisms in HNSCC cell lines by protein phosphorylation profiling. Through this, promising combination treatments can be identified to possibly overcome acquired cetuximab resistance in HNSCC. Protein phosphorylation profiling showed increased phosphorylation of Akt1/2/3 after cetuximab treatment in acquired cetuximab resistant cells compared to cetuximab sensitive cells, which was confirmed by western blotting. Based on this protein phosphorylation profile, a novel combination treatment with cetuximab and the Akt1/2/3 inhibitor MK2206 was designed. Synergy between cetuximab and MK2206 was observed in two cetuximab sensitive HNSCC cell lines and one acquired cetuximab resistant variant in simultaneous treatment schedules. In conclusion, this study demonstrates that increased Akt1/2/3 phosphorylation seems to be characteristic for acquired cetuximab resistance in HNSCC cell lines. Our results also show an additive to synergistic interaction between cetuximab and MK2206 in simultaneous treatment schedules. These data support the hypothesis that the combination of cetuximab with PI3K/Akt pathway inhibition might be a promising novel therapeutic strategy to overcome acquired cetuximab resistance in HNSCC patients.

Identification of CCT3 as a prognostic factor and correlates with cell survival and invasion of head and neck squamous-cell carcinoma

Background: Recurrent locally advanced or metastatic head and neck squamous cell carcinoma (HNSCC) is associated with dismal prognosis because of its highly invasive behavior and resistance to conventional intensive chemotherapy. The identification of effective markers for early diagnosis and prognosis is important for reducing mortality and ensuring that therapy for HNSCC is effective. Chaperonin-containing TCP-1 3 (CCT3) folds cancer-related proteins to control carcinogenesis. The prognostic value and growth association of CCT3 and HNSCC remains unknown. Methods: The GEO, Oncomine and UALCAN databases were used to examine CCT3 expression in HNSCC. A few clinical HNSCC samples with normal tissues were used to detect CCT3 expression by using immunohistochemistry method. The TCGA-HNSC dataset was used to evaluate the association between expression of CCT3 and prognosis. The molecular mechanism was investigated with gene set enrichment analysis (GSEA). CCK-8 and wound healing assays were used to detect cell growth and invasion of HNSCC, respectively. Results: CCT3 expression was significantly upregulated in HNSCC in both mRNA and protein levels. In addition, upregulated CCT3 expression was associated with various clinicopathological parameters. High expression of CCT3 was significantly correlated with inferior survival of HNSCC patients. Knockdown of CCT3 significantly inhibited cell growth and invasion of HNSCC cell lines. GSEA analysis indicated that CCT3 was closely correlated with tumor-related signaling pathways and HNSCC cell survival. Conclusion: Our findings suggest that CCT3 is a biomarker of poor prognosis and related to the process of HNSCC.