肺癌是全球癌症死亡率首位的腫瘤，主要原因是癌轉移和治療的抗藥性。腫瘤內的癌症幹細胞(CSC) 在驅動這些過程中發揮著至關重要的作用。已知長鏈非編碼 RNA (lncRNA) 可以調節癌症的發生和進展，我們先前的研究透過分析TCGA資料庫在肺腺癌 (LUAD) 中發現一新的 lncRNA，即 MIR924HG，在肺腺癌中高量表現並與肺癌幹細胞特性相關。我們並進一步發現 Myb 結合蛋白 1A (MYBBP1A) 可與 MIR924HG 結合。因此，本研究我們的假說是 MYBBP1A 蛋白質和 MIR924HG 的交互作用會影響肺癌幹細胞特性。我們從 Western Blot 結果發現在H1299細胞中，過量表現 MIR924HG 後MYBBP1A 的表現會受到抑制，然而，RT-qPCR分析顯示在相同條件下 MYBBP1A mRNA 水平升高。因此我們想釐清 MIR924HG 是否會調控MYBBP1A 的蛋白質降解以及機制路徑。經 MG132 處理後，我們發現MIR924HG 似乎不透過蛋白酶體介導的降解來調節 MYBBP1A 的蛋白質穩定性。使用 CHX (Cycloheximide) 處理後，也顯示其對 MYBBP1A 穩定性的影響不一致或微弱，這表明 MIR924HG 可能不影響MYBBP1A蛋白質的穩定性而是藉由其他調控機制減少MYBBP1A蛋白質的表現量 。此外，探討MYBBP1A 在 LUAD 中的作用也至關重要。我們利用shRNA的靜默降低了MYBBP1A 的表達。在幹細胞球形成試驗中，發現下調 MYBBP1A 會增加 H1299 細胞球體形成。此外， RT-qPCR 分析發現幹性標誌基因 Nanog 與 Oct4 表現增加，支持 MYBBP1A 可能參與幹細胞自我更新的抑制。為了探討其他促腫瘤特性，我們進一步研究靜默 MYBBP1A 的表現是否會影響細胞增殖和遷移。透過 WST-1 實驗，我們發現靜默 MYBBP1A 後在24、48和72小時降低了細胞增殖。此外，傷口癒合實驗表明，在 4 小時和 16 小時的遷移能力均受到了抑制。這些結果表明 MYBBP1A 調節幹細胞特性，並在控制肺腺癌細胞增殖和遷移能力中發揮作用。在本研究，我們揭示了 MIR924HG 透過下調 MYBBP1A 蛋白來促進肺癌幹細胞特性和致瘤行為。此外，我們的數據支持 MYBBP1A 在 LUAD 中作為癌症幹細胞特性、增殖和遷移能力的潛在負調控因子發揮作用。這些發現揭示了一個新的 lncRNA -蛋白質調控軸，並強調 MYBBP1A 是肺癌治療的潛在治療靶點，並有望找到改善肺癌預後和治療的新分子標靶。

Lung cancer is the leading cause of cancer death worldwide, mainly due to metastasis and drug resistance. Cancer stem cells (CSCs) within tumors play a crucial role in driving these processes. Long non-coding RNAs (lncRNAs) are known to regulate cancer development and progression. Our previous study found a new lncRNA, MIR924HG, in lung adenocarcinoma (LUAD) by analyzing the TCGA database, which is highly expressed in LUAD and related to lung cancer stem cell properties. We further found that Myb-binding protein 1A (MYBBP1A) can bind to MIR924HG. Therefore, our hypothesis is that the interaction between MYBBP1A protein and MIR924HG affects lung cancer stemness. We found that overexpression of MIR924HG leads to the suppression of MYBBP1A protein expression levels in H1299 cells. However, RT-qPCR analysis revealed increased MYBBP1A mRNA levels under the same conditions. Therefore, we wanted to clarify whether MIR924HG regulates the degradation of MYBBP1A protein and the underlying mechanism. After treatment with MG132, we found that MIR924HG did not influence the protein stability of MYBBP1A via proteasome-mediated degradation. Cycloheximide (CHX) chase assays, showed minimal effects on MYBBP1A stability, suggesting that MIR924HG may regulate MYBBP1A through alternative, proteasome-independent mechanisms. In addition, it is also crucial to clarify the role of MYBBP1A in LUAD. RT-qPCR and Western Blot results confirmed that the expression of MYBBP1A was reduced by shRNAs silencing. By using sphere formation assays, we found that down-regulation of MYBBP1A increased spheroid formation in H1299 cells. RT-qPCR analysis of stemness markers showed increased expression of Nanog and Oct4 in MYBBP1A-silenced cells, supporting its possible involvement in self-renewal regulation. To investigate other tumorigenic properties, we further examined whether MYBBP1A knockdown affects cell proliferation and migration. Using WST-1 assays, we found that MYBBP1A knockdown reduced proliferation at 24, 48, and 72 hours. Additionally, wound healing assays demonstrated impaired migration ability in knockdown cells at both 4 and 16 hours. These results indicate that MYBBP1A modulates stemness and plays a role in controlling lung adenocarcinoma cell proliferation and motility. Through this study, we reveal that MIR924HG promotes lung cancer stemness and tumorigenic behaviors by downregulating MYBBP1A protein. Moreover, our data support the role of MYBBP1A functions as a potential negative regulator of cancer stemness, proliferation, and motility in LUAD. These findings provide insight into a novel lncRNA–protein regulatory axis and highlight MYBBP1A as a potential therapeutic target for lung cancer treatment, and hope to find new molecular targets for improving the prognosis and treatment of lung cancer.

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