新穎HDAC抑制劑治療具Gefitinib抗藥性之非小細胞肺癌之研究

Abstract

亞洲區的非小細胞肺癌(NSCLC)病患，通常表現過度活化之epidermal growth factor receptor (EGFR)。小分子藥物EGFR-tyrosine kinase inhibitors (EGFR-TKIs) 如 gefitinib 和erlotinib ，能有效地抑制過度活化之EGFR，因而抑制癌細胞增生及轉移，然而治療數月後對TKI會產生抗藥性而導致腫瘤之復發，稱為acquired resistance (secondary resistance)，其機轉包含 EGFR產生 secondary T790M mutation 和c-Met gene的amplification，進一步探討acquired resistance之機轉可有不同治療策略來克服gefitinib之抗藥性。 本實驗中，對gefitinib產生抗藥性之NSCLC細胞株 (HCC827IR)，外觀俱mesenchymal form 伴隨著E-cadherin downregulation和vimentin upregulation，並具癌幹細胞(Cancer stem cells)性質。新穎HDAC 抑制劑 JMF 3086 可以增加E-cadherin以及減少vimentin 的表現，此為抑制Src 活性減少E-cadherin受phosphorylaion，並使Hakai 無法被recruit 到 E-cadherin complex，以減少E-cadherin之endocytosis；JMF 3086也會降低Hakai的生合成而抑制E-cadherin 之endocytosis。 JMF 3086恢復E-cadherin 的表現會減緩NSCLC細胞之生長及轉移和侵入。在動物模式中，JMF3086亦可以減緩NSCLC腫瘤的形成和轉移，並增加E-cadherin 的表現但減少vimentin 和Hakai的表現。因此，JMF 3086 具潛力應用於治療有secondary resistance 之NSCLC 病患。

Somatic activating mutation of epidermal growth factor receptor (EGFR) is found in NSCLC and occurs more frequent in East Asia countries. EGFR-tyrosine kinase inhibitors (EGFR-TKIs) such as gefitinib and erlotinib have exhibited superior outcomes against EGFR-mutant NSCLC. However, the patients develop acquired resistance to TKI treatment through T790M secondary mutation and c-Met gene amplification. To further explore the mechanism of acquired resistance provides the differential strategies to overcome gefitinib resistance. In our study, the acquired resistance of EGFR-mutant lung cancer cells HCC827/IR had mesenchymal phenotype accompanied with downregulation of E-cadherin and upregulation of vimentin expression and showed stem cell–like properties. A novel HDAC inhibitor, JMF 3086 could induce E-cadherin and decrease vimentin expression. It was associated with Src inhibition to reduce E-cadherin phosphorylation, leading to decrease in Hakai interacting with E-cadherin complex and reduce E-cadherin endocytosis. JMF3086 also inhibited the expression of Hakai to reduce E-cadherin endocytosis. Restoration of E-cadherin expression by JMF3086 could attenuate cell proliferation and migration in vitro, and retard the tumor growth and metastasis in orthotopic animal model. JMF 3086 also upregulated E-cadherin and downregulated vimentin and Hakai expression in orthotopic lungs. Thus, JMF 3086 was a potential lead compound to treat NSCLC with gefitinib resistance.