Expression Of PAK2 In Laryngeal Squamous Cell Carcinoma And Its Association With Chemotherapy Sensitivity

Objective:Laryngeal cancer（LC）is a primary malignant head and neck tumor with high morbidity and mortality and is susceptible to drug resistance^[1].PAK2 is a member of the p21 protein kinase family^[2],group A,and upregulation of PAK2 can lead to anchored non-dependent survival and growth of cells,thereby enabling tumor cells to resist chemotherapy-induced cell death^[2].This study aimed to investigate the expression of PAK2 in laryngeal squamous cell carcinoma and its potential biological functions.Through experiments,we verified the relationship between PAK2 expression,clinicopathological features,and its sensitivity to chemotherapy.And also initially clarified the mechanism of PAK2 in laryngeal squamous cell carcinoma and its effect on chemotherapy sensitivity.Methods:Gene expression data of laryngeal cancer screened from the TCGA database were processed using R software.The differential expression of PAK2 in laryngeal cancer tissues and normal tissues was analyzed.According to the KEGG signaling pathway database to investigate functional enrichment of PAK2 in laryngeal cancer.We collected fresh laryngeal cancer tissues from 34 patients with primary laryngeal squamous cell carcinoma in the Department of Otolaryngology,Chaoyang Downtown Hospital,from April 2016 to June 2021.And the adjacent paracancerous tissues（at least 0.5cm from the tumor）were also collected from each case.We used the normal mucosal tissues of the larynx from 20 non-laryngeal cancer surgery patients as controls.We cut the samples from the in vitro tissues after surgical tumor resection.All samples were then fixed in diluted formalin and embedded in liquid paraffin.The expression levels of PAK2 in cancer,paraneoplastic,and normal mucosal tissue were detected separately using immunohistochemical techniques.Clinical data were collected to analyze the association between the expression of PAK2 in laryngeal squamous cell carcinoma and the clinicopathological factors of laryngeal carcinoma patients and to explore the molecular mechanism of PAK2 in laryngeal squamous cell carcinoma.In the same period,we collected specimens of 35 primary laryngeal squamous cell carcinoma patients attending our hospital for induction chemotherapy.The fresh tumor specimens from before TPF（paclitaxel+cisplatin+5-fluorouracil）chemotherapy.The patients were divided into chemotherapy-sensitive（20 cases）and tolerant（15 cases）groups according to imaging scoring criteria after two standardized TPF treatments.qRT-PCR verified the PAK2 expression levels in the chemotherapy-sensitive and resistant groups according to the statistical verification（P<0.05 was considered significant）to detect the correlation with chemotherapy sensitivity.Results:1.PAK2 expression was significantly higher in laryngeal cancer tissues than in the TCGA database normal tissues.And based on the analysis of the KEGG signaling pathway,we found that the high PAK2 expression was more related to tumor-related signaling pathways,cell adhesion,and cell cycle.2.The positive expression rate of PAK2 was significantly higher in laryngeal squamous carcinoma tissues compared to paraneoplastic and normal laryngeal mucosa tissues（P<0.05）.The positive expression rate was lower in paraneoplastic tissues and no positive expression in normal laryngeal mucosa tissues,and the difference between the two groups was insignificant（P>0.05）.It confirmed the existence of upregulated expression of PAK2 in laryngeal cancer.3.The high expression of PAK2 in laryngeal cancer tissues correlated with pathological grade,lymph node metastasis,and clinical stage of patients（P<0.05）,and there was no significant correlation between age,history of smoking,and drinking,tumor size,and clinical staging（P>0.05）.4.The expression of PAK2 in laryngeal squamous carcinoma tissues in the sensitive group was significantly lower than that in patients with drug-resistant laryngeal squamous cell carcinoma,and the difference between the groups was statistically significant（P<0.05）.Conclusion:1.TCGA microarray data predicted that PAK2 expression upregulated in laryngeal carcinoma.KEGG analysis indicated that PAK2 upregulation might affect the development of laryngeal squamous carcinoma through regulating various tumor signaling pathways such as cell cycle,cytoskeleton remodeling and cell adhesion,Wnt,and MAPK,suggesting that PAK2 may be a potential molecular marker in the diagnosis and treatment of laryngeal carcinoma.2.PAK2 upregulation is associated with the development of laryngeal carcinoma.3.The upregulation of PAK2 expression was significantly associated with clinical stage,pathological grade,and lymph node metastasis of squamous laryngeal carcinoma,suggesting that PAK2 may promote tumor proliferation and metastasis.4.The expression level of PAK2 was up-regulated in the resistance group of induction chemotherapy for laryngeal squamous cell carcinoma,suggesting that PAK2 may promote the development of drug resistance in laryngeal cancer cells and it may be a potential biomarker to predict the sensitivity of laryngeal cancer induced chemoresistance.