Micro RNA-33a影響肺癌骨轉移之相關分子機制探討

The role of micro RNA-33a on bone metastasis in lung cancer

廖思慧(Szi-Hui Laio)

指導教授 ： 郭柏麟

高雄醫學大學/醫學院/醫學研究所/碩士(2012年)

摘要

肺癌是為最常發見的癌症之一，其中約30-40%肺癌病患容易發生骨轉移。MicroRNA (miR) 為長度約20~22個 nucleotide 小片段的 RNA。本研究探討乃 microRNA 與肺癌之骨轉移的機制，提供未來癌症一個有效治療方式。比較正常支氣管細胞和肺癌細胞，發現肺癌細胞的miR-33a表現明顯降低。相對的其標的分子 PTHrP 無論在mRNA或蛋白質的表現皆上升。利用基因轉殖方式使A549細胞大量表現miR-33a，發現 PTHrP的表現隨之下降。因對抑制 Beas-2B 的 miR-33a，會促進細胞大量表現 PTHrP，並且抑制 A549 細胞對蝕骨細胞分化的誘導作用，其抑制作用可被外加 PTHrP 蛋白而抵銷，因此肺癌細胞因 miR-33a表現降低而使 PTHrP 呈現過度表現。除此，miR-33a的表現也會降低A549對成骨細胞分泌兩種促進蝕骨細胞分化分子M-CSF (macrophage colony stimulating factor) 和 RANKL (Receptor activator of nuclear factor kappa-B ligand) 表現的誘導作用，但抑制OPG (Osteoprotegerin)。再者，阻斷 Beas-2B 之 miR-33a 表現後，會使 Beas-2B 對蝕骨細胞產生分化促進效果。同時對成骨細胞會產生刺激 M-CSF 表現。綜合以上，本研究證實肺癌細胞的表現較低而造成 miR-33a 表現進而促進 PTHrP 表現增加並促進骨溶蝕性轉移現象。因此，miR-33a 提供對於肺癌病患所造成的溶骨性骨轉移的重要治療標靶。

關鍵字

微小核醣核酸 ； 肺癌 ； 骨轉移 ； 副甲狀腺荷爾蒙相關蛋白

並列摘要

Lung cancer is the most common cancer in the world. Approximately 30-40% of patients with advanced lung cancer with develop bone metastasis, resulting in the decrease of life quality and survival rate. MicroRNAs (miRNA) are 20~22 nucleotides that are known to modulate cancer development and evolution. The role of miRNA on cancer bone metastasis reminds unknown. This study is to investigate the role of miRNA-33a a tumor suppressor on bone metastasis in lung cancer. Our data shows that
inverse correlation of miR-33a and PTHrP (parathyroid hormone-related protein) expression in breast cancer cells. Overexpression of miR-33a by a miR-33a plasmid transfection in A549 cells decreased the expression of bone resorption factor PTHrP. In addition, the upregulation of miR-33a not only reduced the induction effect of A549 on osteoclast differentiation, but also decreased the effect of A549 to on the production of M-CSF (macrophage colony stimulating factor) and RANKL (Receptor activator of nuclear factor kappa-B ligand) and decrease OPG production in osteoblast. In contrast, knockdown of miR-33a in Beas-2B cells increased the expression PTHrP which in turn stimulated osteoclast differentiation and increased the expression of M-CSF in osteoblast. Taken together, our data suggest that the miR-33a may play an important role for the developing ostolytic bone metastasis.

並列關鍵字

MicroRNA ； Lung cancer ； Bone metastasis ； PTHrP

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