Introduction: The immune system plays a pivotal role in identification and clearance of tumor cells, but can also be counterproductive and enhance tumor progression. Presence of neutrophils in solid tumors, including the sixth most common cancer globally - head and neck squamous cell carcinomas (HNSCC), is associated with poor prognosis. IL-8 and GM-CSF, whose secretion is regulated by NF-κB, are pro-inflammatory cytokines that promote extravasation of neutrophils into tissue and play an important role in the proliferation, invasion, and metastasis of HNSCC. The onset and progression of HNSCC is also associated with genetic alterations that affect several cellular signaling pathways such as transforming growth factor-β (TGFβ) pathway. TGF-β is responsible for polarization of neutrophils towards anti-tumor (N1) versus pro-tumor (N2) phenotype. Objective: The role of neutrophils in HNSCC and the possible molecular mechanisms of pro-tumor neutrophil recruitment is being investigated. Methods and Results: IL-8 and GM-CSF released at various time points by FaDu (ATCC® HTB-43™), SCC-9 (ATCC® CRL-1629™) and Cal-27 (ATCC® CRL-2095™) was measured by ELISA. Conditioned media from FaDu and Cal-27 cells exhibited consistent expression of IL-8 (115 - 117pg/mL and 103 - 110pg/ml, respectively) at 6 - 72 hours. SCC-9 conditioned media exhibited sustained levels of IL-8 expression (103 - 110pg/ml) at 6 - 24 hours that then declined at 48 - 72 hours. GM-CSF was not significantly expressed in the FaDu conditioned media; even with increasing cell density, the mean expression remained 0.142pg/ml. SCC-9 and Cal-27 expressed GM-CSF at 6 - 72 hours (16 - 20pg/mL and ~15pg/ml, respectively). In all cell lines, IL-8 expression decreased in a dose and time dependent manner after treatment with the NF-κB inhibitor, BAY 11-7082, while effect on GM-CSF expression was negligible. Expression of phosphorylated IκBα in FaDu and SCC-9 cell lysates decreased in a time and dose dependent manner, indicating inhibition of the NF-κB pathway by BAY11-7082. Expression of phosphorylated NF-κB also decreased as compared to control in these cells. In nuclear extracts, BAY 11-7082 dose-dependent alteration in NF-κB expression was observed in FaDu and Cal-27 cells at earlier time points. Conditioned media from SCC-9 and Cal-27 cells also exhibited sustained baseline expression of TGF- β (~30pg/ml) over 6 - 72 hours. Conclusion: HNSCC cells derived from tongue and hypopharyngeal squamous cell carcinoma release pro-inflammatory cytokines. The NF-κB signaling pathway appears to be involved in the release of IL-8, a cytokine that is in turn likely to be involved in recruitment of neutrophils to the cancer site that may be polarized towards the N2 pro-tumor phenotype by TGF-β secreted by HNSCC cells. Citation Format: Hina Shakeel, Fareena Bilwani, Kiran Iqbal, Kulsoom Ghias. NF-κB-mediated pro-inflammatory cytokine release and neutrophil recruitment in head and neck squamous cell carcinoma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3152.
The immune system plays a pivotal role in identification and clearance of tumor cells, but can also be counterproductive and enhance tumor progression. Presence of neutrophils in solid tumors, including the sixth most common cancer globally - head and neck squamous cell carcinomas (HNSCC), is associated with poor prognosis. Pro-inflammatory cytokines regulated by NF-κB promote extravasation of neutrophils into tissue; neutrophils are polarized to anti-tumor (N1) or pro-tumor (N2) phenotype through the action of various pathways, including TGF-β. The mechanism and role of neutrophil recruitment in HNSCC were explored this study. Neutrophils isolated from adult donors were co-cultured for 5 hours with conditioned media (CM) from HNSCC cells SCC-9 and Cal-27, and stained with TNF-α, ICAM-1, CCL2, CCL5 for analysis of neutrophil phenotype by flow cytometry. TGF-β blocking antibody was used to explore the role of TGF-β in polarization of neutrophils. Canonical and non-canonical TGF-β signaling pathway activation was also investigated in these neutrophils through western blots. Using HNSCC patient samples, qPCR was performed for expression of genes involved in apoptosis, epithelial-to-mesenchymal transition, metastasis, and neutrophil function. Following co-culture with 24-hour HNSCC CM, neutrophils begin to exhibit cell surface markers indicative of N2 phenotype, which is impacted by TGF-β blocking antibody. Neutrophils co-cultured with HNSCC CM exhibited altered expression of TGF-β mediators Smad2/3, p38 and Akt, which was abrogated with the addition of TGF-β blocking antibody indicating specificity of a TGF-β induced signaling. Gene expression analysis exhibited significantly higher expression of anti-apoptotic BCL2 and neutrophil function marker alpha defensin 1 in HNSCC patient samples with greater neutrophil infiltration, while caspase 3 was expressed at significantly higher levels in HNSCC patient samples with low neutrophil infiltration. HNSCC cells recruit neutrophils; evidence suggests that TGF-β pathway, which typically promotes N2 phenotype in neutrophils, is involved via canonical and non-canonical mediators including p38 and Akt. Further, HNSCC patient samples have varying levels of neutrophil infiltration and differentially express genes involved in apoptosis, EMT, metastasis and invasion, inflammation. Citation Format: Kulsoom Ghias, Hina Shakeel, Alisalman Sheikh, Syed Hani Abidi, Kiran I. Masood, Saira Fatima, Fareena Bilwani. Mechanism and role of neutrophil recruitment in head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5942.
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