纖維母細胞生長因子受器與上皮細胞生長因子受器的訊息交互作用對頭頸癌細胞中細胞遷移的影響

Abstract

頭頸部鱗狀上皮細胞癌在台灣有相當高的發病率及致死率，且容易復發及轉移，然而目前在頭頸癌的治療上並沒有很有效的治療方式。因此，我們希望找到新的治療標的來阻止腫瘤的轉移。纖維母細胞生長因子受器(fibroblast growth factor receptor, FGFR)參與了胚胎發育、血管新生、傷口癒合等重要的生理功能，且在細胞增生、分化以及移動上都扮演了重要的角色。除此之外，近年來有研究顯示異常的FGFR和許多癌症的發生及其病程發展相關，但FGFR在頭頸癌病程上所扮演的角色目前仍沒有詳盡的探討。因此，我們利用FGFRs的抑制劑AZD4547來觀察對口腔鱗狀上皮癌細胞遷移的影響。我們發現，在沒有FBS並加入FGF1作刺激的環境下給予AZD4547，細胞移動速度會顯著的下降；然而在有FBS的環境下給予AZD4547，卻無法達到抑制細胞遷移的效果。進一步釐清FBS中的何種物質導致此現象的發生，發現到在沒有胎牛血清(fetal bovine serum, FBS)並加入表皮生長因子(epidermal growth factor, EGF)的環境下再給予AZD4547，能夠看到類似在FBS中的結果。藉此，我們推論表皮細胞生長因子受器(epidermal growth factor, EGFR)和FGFR 訊息之間可能存在交互作用。 為了進一步探討EGFR與FGFR 訊息之間的交互作用，我們透過單細胞追蹤的技術去探討其中一個受器訊息的存在與否，對另一個受器在細胞遷移上造成何種影響。從實驗結果我們觀察到EGF可以回復FGFRs抑制劑的抑制效果，卻無法回復敲減FGFR2的抑制效果。在加EGFR抑制劑及敲減EGFR的實驗中也觀察到相似的情形。藉此推論EGFR和FGFR要在彼此都存在之下才會產生交互作用。 我們進一步提出三個可能的機轉模型：receptor level model、transactivation model以及internalization competition model。我們目前的實驗結果指出：當FGFR的adaptor protein FGFR substrate 2a (FRS2)被敲減時可以輕微減弱EGF在抑制劑上的回復效果，且從western blot結果發現到敲減FRS2時可以讓細胞中的phospho-ERK (pErk)表現量減少。因此，我們推論EGFR和FGFR 訊息之間很可能是透過transactivation的方式來產生交互作用。我們仍需透過其他實驗來釐清並加強此部分的推論，期望能有更充分的瞭解後，對頭頸癌的治療提供指引與方向。

Head and neck squamous cell carcinoma (HNSCC) causes high metastatic rate, recurrence rate and mortality in Taiwan, but there is still no effective treatment. We therefore aimed at finding new therapeutic targets for HNSCC and focused on the fibroblast growth factor receptor (FGFR), which is important in cancer cell proliferation, differentiation and migration. When we used FGFR inhibitor AZD4547 to treat HNSCC cells in cell migration assays, it inhibited fibroblast growth factor (FGF1)-stimulated SAS migration. However, AZD4547 did not inhibit SAS migration when FBS (fetal bovine serum) was present. Furthermore, the presence of EGF (epidermal growth factor) also abrogated the inhibitory effect of AZD4547 on SAS migration. Thus, we proposed that EGFR (epidermal growth factor receptor) and FGFR signalling interacted with each other during cell migration. To elucidate the crosstalk between EGFR and FGFR signalling, we used single-cell tracking to analyze how FGFR/EGFR inhibition alters migration behavior in the presence or absence of the other i.e. EGFR/FGFR signalling. We found out that EGF rescued the inhibition of HNSCC cell migration by FGFR inhibitors, but EGF could not rescue FGFR2 knockdown effect. Likewise, FGF1 rescued the inhibition of HNSCC cell migration by EGFR inhibitors, but could not rescue EGFR knockdown effect. To explain how EGFR interacts with FGFR signaling, we proposed three hypothetical models: receptor level model, transactivation model and internalization competition model. Because FGFR substrate 2a (FRS2) knockdown showed modest inhibition on EGF stimulation and western blot showed that knockdown FRS2 decreased phospho-ERK (pErk) expression, we favor transactivation model. Further investigations are underway to verify our speculations, with the hope to benefit current HNSCC treatments.