藥物抗藥性仍然是癌症治療期間非常重要的一個問題。有許多的原因導致藥物的抗藥性發生包括藥物泵出細胞、基因異質性等等。一些蛋白質：E1/E2/E3 和去泛素蛋白酶們皆有參與在各種生理疾病理條件下蛋白質的泛素化來調控目標蛋白的功能及目標蛋白的降解。我們實驗室之前的研究裡已經發現了 USP24 可以透過調降 Rad51 的表現來誘導基因的不穩定性，從而提高腫瘤突變負荷和癌幹特性。更進一步地，我們也發現USP24 可以穩定 ABCG2 轉運蛋白、P-gp 和 ABCG2 的表現導致化療藥物有更高的機會泵出癌細胞外。此研究當中，首先，我們透過基於結構的策略篩選出特定的 USP24 抑制劑。有幾種 USP24 抑制劑已經被測試並驗證了他們對於肺腺癌細胞 A549 和經由紫杉醇所誘導的已產生抗藥性的A549 細胞：A549-T24 細胞的作用，在這些抑制劑之中發現 USP24i-397和其類似物 USP24i-A 被證實為目前為止阻斷藥物抗性最有效果的化合物。接著我們研究了 USP24 抑制劑阻斷藥物抗性的分子機制從而發現了USP24 抑制劑能夠降低 ABCG2 的表現量，也發現這抑制劑能調降與癌幹特性相關的蛋白標記物表現量。最後我們也使用 RNA-NGS 大數據分析 USP24-i-a 影響基因表現的狀況。其中和代謝級固醇類合成的相關基因備高度誘發。以上這些綜觀來看，USP24 抑制劑確實能夠阻斷藥物抗性。
尚有一些實驗像是動物實驗還有化合物優化的實驗在未來還需要再進行。
希望我們的化合物 USP24-i 能在未來發展成為臨床用藥，阻斷或延緩癌症治療過程中抗藥性的發生。



關鍵字：USP24、藥物抗藥性、USP24 抑制劑、ABC 轉運蛋白

Drug resistance has remained an important issue during cancer therapy.
Various reasons including drug pump out and heterogeneity contribute to drug resistance during cancer therapy. Several proteins including E1/E2/E3 and deubiquitinases are involved in protein ubiquitination to regulate the function and degradation of target proteins in various physiological and pathological conditions. Our previous studies revealed that USP24 can induce genomic instability through a decrease in Rad51 expression, thereby enhance the tumor mutation burden (TMB) and cancer stemness. Furthermore, we also found that USP24 can stabilize ABCs transporters, P-gp and ABCG2, resulted in the chemotherapeutic drug, paclitaxel, pump out cancer cells. In this study, at first, we tried to screen specific USP24 inhibitors by structure-based strategy.
Several USP24 inhibitors have been probed and then validated their effects on A549, and Taxol-induced drug-resistant A549-T24 cell, USP24i-397, and its analog, USP24i-A, were proved to be the most efficacy in blocking drug resistance. To study the molecular mechanism of how USP24 inhibitors block drug resistance, we found that USP24 inhibitors decreased the level of ABC transporters and cancer stemness-related markers, subsequently inhibited drug resistance. Finally, we also used RNA-NGS to study the global gene expression profile under USP24-i-a treated A549-T24 lung cancer cells. Many metabolisms and steroid synthesis-related genes were upregulated. Taken together, USP24i is indeed working on blocking drug resistance. Several experiments such as animal experiments and compound optimization need to be performed in the future. Hope our compound, USP24-i, can be developed as a clinical-used drug to block or delay the occurrence of drug resistance during cancer therapy in the future.

Key words: lung cancer, drug resistance, USP24 inhibitor, ABC transporter.

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