| 摘要: | 頭頸部鱗狀細胞癌(head and neck squamous cell carcinoma; HNSCC) 為最常見之頭頸部惡性腫瘤，而口腔鱗狀細胞癌(oral squamous cell carcinoma; OSCC)更是佔 HNSCC 之大宗，是台灣男性腫瘤第四常見癌種，更造成全世界每年超過 170,000 人死於此癌; 特別是已發生頸部淋巴轉移的病人。因此探討調控口腔鱗狀細胞癌病程發展之相關分子機制以及開發有潛力的治療策略是刻不容緩的。
Histamine receptor H1 (HRH1，第一型組織胺受體) 屬於 G 蛋白偶聯受體，主要媒介組織胺調控免疫發炎反應。近期研究指出組織胺和其不同亞型之受體結合後扮演著促進或抑制癌症發展之功能。到目前為止 histamine-HRH1 axis 在頭頸鱗狀細胞癌病程發展中的角色仍然不是十分清楚。透過等位基因鑑別分析法探討 HRH1 四種 genotypes (rs346074, rs346076, rs901865, and rs2606731)，我們發現帶有 HRH1 rs901865 SNP and rs346074 SNP 之病人其產生較大腫瘤 (>T2) 的機率較低。另外在具有嚼食檳榔的病人族群中發現帶有 HRH1 rs901865 SNP 的病人發展為臨床晚期（第三及四期）的機率也有下降趨勢。透過細胞實驗發現在口腔鱗狀細胞癌細胞株中帶有 T allele of rs90186 或 rs346074 之 genotype 的細胞其 HRH1 表現量有減少的趨勢。結果顯示 HRH1 之基因多型性 rs901865 和 rs346074 與環境致癌物之間具有一定交互作用進而參與口腔癌生成。透過 TCGA (The Cancer Genome Atlas; 癌症基因組圖譜)與 GEO (Gene Expression Omnibus; 基因表達數據庫) 臨床資料分析發現在臨床頭頸癌與口腔癌病人檢體中 HRH 的高表現量和病人不良預後有關。另外我們發現臨床上 HRH1 於頭頸部鱗狀細胞癌組織表現量高於正常組織，在有淋巴轉移的病人檢體中表現較高並且有較差的預後。在 12 株 HNSCC 細胞中也觀察到 HRH1 的蛋白表現量高於正常之口腔角質細胞HOK (human oral keratinocyte)。進一步在口腔癌細胞株剔除 HRH1 基因可以明顯抑制細胞之增生、群落形成及移動能力，而過度表現 HRH1 則會得到相反結果。我們的初步研究成果顯示 HRH1 在頭頸部鱗狀細胞癌為致癌基因的角色。在分子機制上我們利用剔除 HRH 之口腔癌細胞株進行 RNA sequencing 及 protease array 並配合基因集富集分析 (Gene Set Enrichment Analysis，GSEA) 後發現HRH1 可能是透過促進上皮-間質轉化 (epithelial–mesenchymal transition，EMT) 相關基因的表現進而調控癌細胞的惡化。
Head and neck squamous cell carcinoma (HNSCC) is the most encountered histological type of head and neck cancer, with oral squamous cell carcinoma (OSCC) being the predominant subtype within HNSCC. OSCC accounts for the fourth highest incidence of malignancy in males in Taiwan and causes more than 170,000 OSCCrelated deaths annually in worldwide. Therefore, it is crucial to investigate the underlying mechanisms involved in modulating the progression of OSCC and develop effective treatment strategies. Histamine receptor H1 (HRH1) is a G-protein-coupled receptor (GPCR) that plays a role in modulating immune system inflammation. Recent studies have indicated that the activation of different subtypes of histamine receptors by histamine in various cancer cells can result in different outcomes in terms of tumor progression or antitumor response. Histamine receptor H1 (HRH1) has been reported to play a significant role in the development of oral squamous cell carcinoma (OSCC). However, the effects of genetic variants of HRH1 on OSCC carcinogenesis remain unclear. Therefore, we conducted an investigation to explore the association between functional single-nucleotide polymorphisms (SNPs) of HRH1 and OSCC susceptibility, as well as clinicopathologic variables, using logistic regression models. We performed an analysis of HRH1 genotypes at four loci (rs346074, rs346076, rs901865, and rs2606731) using a TaqMan allelic discrimination assay. We observed that patients with OSCC who carried HRH1 rs901865 T and rs346074 T alleles had a significantly reduced risk of developing larger tumor sizes (>T2) under a dominant model. Based on the status of environmental carcinogen exposure, we discovered that HRH1 rs901865 polymorphic variants were also linked to a reduced risk of developing more advanced clinical stages (III or IV) in patients with a betel quid-chewing habit. In addition, genotype screening of rs901865 and rs346074 in OSCC cell lines was performed and revealed that cells respectively carrying the CT and TT genotypes of rs901865 and rs346074 showed lower HRH1 levels expression compared to cells carrying the CC genotype of rs901865 and rs346074. These results indicated the involvement of HRH1 SNPs rs901865 and rs346074 in OSCC development and support the interaction between HRH1 gene polymorphisms and an environmental carcinogen as a trigger factor for OSCC development. Moreover, we analyzed the databases of TCGA (The Cancer Genome Atlas) and GEO (Gene Expression Omnibus) and found that HRH1 expression levels were upregulated in HNSCC and OSCC tissues compared to normal tissues which were correlated with larger tumor sizes, lymph node metastasis, and poorer prognoses. Compared normal human oral keratinocyte, higher HRH1 level was also observed in 12 HNSCC cell lines. HRH1 depletion caused by shRNA dominantly inhibited proliferative, colony forming, and migratory capabilities in OSCC cell lines, while overexpression of HRH1 caused the opposite effects. In terms of mechanism, we conducted protease array and RNA sequencing analyses combined with Gene Set Enrichment Analysis (GSEA). Through this approach, we discovered that epithelial-mesenchymal transition (EMT) may act as a potential downstream effector of HRH1, promoting the progression of HNSCC. |
