Musashi在乳腺發(fā)育和腫瘤發(fā)生中的功能與分子作用機(jī)制
發(fā)布時(shí)間：2018-08-26 14:00
【摘要】：癌細(xì)胞轉(zhuǎn)移是導(dǎo)致乳腺癌患者死亡的主要原因。上皮-間充質(zhì)轉(zhuǎn)化(EMT)是指細(xì)胞逐漸喪失正常上皮細(xì)胞特性,逐步獲得間充質(zhì)細(xì)胞特性的過(guò)程,在乳腺癌細(xì)胞轉(zhuǎn)移中發(fā)揮關(guān)鍵作用。闡明EMT分子調(diào)控機(jī)制將有利于深入認(rèn)識(shí)乳腺癌的轉(zhuǎn)移機(jī)理,而且有助于開(kāi)發(fā)新的藥物設(shè)計(jì)靶點(diǎn)。Musashi (Msi)是進(jìn)化上保守的RNA結(jié)合蛋白家族,在哺乳動(dòng)物中包括兩個(gè)同源蛋白：Msi1和Msi2。在機(jī)體正常發(fā)育過(guò)程中,Msi (Msi1和Msi2)主要在上皮組織表達(dá),尤其在干/祖細(xì)胞中特異性高表達(dá)。有研究發(fā)現(xiàn)Msi在多種上皮來(lái)源的癌組織中高表達(dá),并且在癌癥發(fā)生過(guò)程中發(fā)揮著重要作用。然而,Msi在乳腺發(fā)育和乳腺癌中的功能,尤其是否參與調(diào)控EMT過(guò)程,目前仍未揭示清楚。本研究利用Msi過(guò)表達(dá)轉(zhuǎn)基因小鼠、基因敲除小鼠和乳腺癌小鼠模型,結(jié)合體外細(xì)胞系培養(yǎng),系統(tǒng)探究了Msi在乳腺發(fā)育和乳腺癌中的功能。本研究發(fā)現(xiàn)Msi1和Msi2的表達(dá)水平與乳腺癌亞型的侵襲轉(zhuǎn)移能力密切相關(guān)。在轉(zhuǎn)移能力較弱的腺腔樣乳腺腫瘤中Msil和Msi2表現(xiàn)出更高的表達(dá),相反在浸潤(rùn)性、轉(zhuǎn)移能力較強(qiáng)的基底樣乳腺腫瘤中表達(dá)水平均較低。進(jìn)一步發(fā)現(xiàn)Msi與EMT分子標(biāo)記基因呈負(fù)相關(guān)。在細(xì)胞水平,當(dāng)敲減乳腺癌細(xì)胞中的Msil和Msi2基因時(shí),細(xì)胞退出上皮狀態(tài)轉(zhuǎn)而進(jìn)入間充質(zhì)狀態(tài)。為了驗(yàn)證Msi的體內(nèi)生理功能,本研究首先制備了可誘導(dǎo)Msi2在乳腺上皮特異性過(guò)表達(dá)的轉(zhuǎn)基因小鼠。過(guò)表達(dá)Msi2會(huì)導(dǎo)致乳腺導(dǎo)管延伸和分支受到顯著抑制,腔上皮細(xì)胞數(shù)量增加,并且抑制EMT過(guò)程。相反,在Msil和Msi2雙敲除小鼠中,乳腺上皮表現(xiàn)出促進(jìn)EMT和肌上皮細(xì)胞數(shù)量增加。以上體外和體內(nèi)實(shí)驗(yàn)結(jié)果表明,Msi在乳腺上皮中抑制EMT過(guò)程。為了進(jìn)一步探究Msi在乳腺癌中的體內(nèi)功能,本研究在MMTV-PyVT乳腺癌小鼠模型中過(guò)表達(dá)Msi2。發(fā)現(xiàn)Msi2過(guò)表達(dá)抑制乳腺腫瘤生長(zhǎng),同時(shí)通過(guò)抑制EMT過(guò)程顯著抑制乳腺癌細(xì)胞的肺轉(zhuǎn)移。因此,Msi是EMT的重要轉(zhuǎn)錄后調(diào)控因子,在乳腺癌轉(zhuǎn)移中發(fā)揮重要作用。在分子作用機(jī)制上,本研究證實(shí)Jagged1 (Jag1)是Msi2的直接功能靶基因。利用分子生物學(xué)和生物化學(xué)實(shí)驗(yàn)證實(shí)了Msi2通過(guò)結(jié)合Jagl的3'UTR來(lái)抑制Jag1 mRNA的翻譯。Jag1是Notch信號(hào)通路的配體,當(dāng)Jagl表達(dá)水平升高時(shí)會(huì)激活Notch信號(hào)通路,進(jìn)而促進(jìn)EMT。當(dāng)Jagl被Msi蛋白抑制后,細(xì)胞就被鎖定在一種上皮狀態(tài)。以上結(jié)果表明Msi2可以通過(guò)抑制Jag1-Notch信號(hào)通路來(lái)調(diào)控EMT過(guò)程。綜上所述,本研究表明Msi在乳腺發(fā)育和乳腺癌中,通過(guò)靶向抑制Jagl的翻譯和Notch信號(hào)通路的激活而抑制EMT過(guò)程和癌細(xì)胞轉(zhuǎn)移。本研究首次提出了EMT的轉(zhuǎn)錄后調(diào)控機(jī)制,豐富了EMT的調(diào)控網(wǎng)絡(luò),為乳腺癌治療藥物的設(shè)計(jì)和策略的制定提供了科學(xué)依據(jù)。
[Abstract]:Cancer cell metastasis is the leading cause of death in breast cancer patients. Epithelial-mesenchymal transformation (EMT) is a process in which cells gradually lose normal epithelial cell characteristics and gradually acquire mesenchymal characteristics, which play a key role in breast cancer cell metastasis. Elucidating the molecular regulatory mechanism of EMT will be helpful to further understand the metastasis mechanism of breast cancer, and to develop a new drug design target. Musashi (Msi) is an evolutionarily conserved family of RNA binding proteins, including two homologous proteins: Msi1 and Msi2. in mammals. MSI (Msi1 and Msi2) are mainly expressed in epithelial tissues during normal development, especially in stem / progenitor cells. Some studies have found that Msi is highly expressed in cancer tissues from various epithelial sources and plays an important role in carcinogenesis. However, the role of MSI in breast development and breast cancer, especially whether or not it is involved in the regulation of EMT, remains unclear. In this study, Msi overexpression transgenic mice, gene knockout mice and breast cancer mice were used to investigate the function of Msi in breast development and breast cancer. In this study, we found that the expression of Msi1 and Msi2 was closely related to the invasion and metastasis ability of breast cancer subtypes. The expression of Msil and Msi2 was higher in adenoid breast tumors with weak metastatic ability, but lower in invasive and metastatic basal breast tumors. Further, negative correlation was found between Msi and EMT molecular marker gene. At the cellular level, when the Msil and Msi2 genes in breast cancer cells are knocked down, the cells withdraw from the epithelial state and enter the mesenchymal state. In order to verify the physiological function of Msi in vivo, transgenic mice which can induce the overexpression of Msi2 in breast epithelium were first prepared. Overexpression of Msi2 resulted in significant inhibition of breast ductal extension and branching, increased number of luminal epithelial cells, and inhibition of EMT process. In contrast, breast epithelium increased the number of EMT and myoepithelial cells in Msil and Msi2 double knockout mice. The results in vitro and in vivo indicate that Msi inhibits the EMT process in breast epithelium. In order to further explore the function of Msi in breast cancer, Msi2. was overexpressed in the mouse model of MMTV-PyVT breast cancer. It was found that the overexpression of Msi2 inhibited the growth of breast cancer and inhibited the lung metastasis of breast cancer cells by inhibiting the process of EMT. Therefore, Msi is an important posttranscriptional regulator of EMT and plays an important role in breast cancer metastasis. In molecular mechanism, Jagged1 (Jag1) is a direct functional target gene of Msi2. Molecular biology and biochemical experiments have confirmed that Msi2 inhibits the translation of Jag1 mRNA by binding 3'UTR of Jagl. Jag1 is the ligand of Notch signaling pathway, which activates Notch signaling pathway when Jagl expression level increases, thus promoting EMT.. When Jagl is inhibited by the Msi protein, the cells are locked in an epithelial state. These results suggest that Msi2 can regulate the EMT process by inhibiting the Jag1-Notch signaling pathway. In conclusion, this study suggests that Msi inhibits the EMT process and cancer cell metastasis by targeting the translation of Jagl and activation of the Notch signaling pathway in breast development and breast cancer. In this study, the posttranscriptional regulation mechanism of EMT is proposed for the first time, which enriches the regulatory network of EMT and provides a scientific basis for the design of breast cancer treatment drugs and the formulation of strategies.
【學(xué)位授予單位】：中國(guó)農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：R737.9
，
本文編號(hào)：2205083
[Abstract]:Cancer cell metastasis is the leading cause of death in breast cancer patients. Epithelial-mesenchymal transformation (EMT) is a process in which cells gradually lose normal epithelial cell characteristics and gradually acquire mesenchymal characteristics, which play a key role in breast cancer cell metastasis. Elucidating the molecular regulatory mechanism of EMT will be helpful to further understand the metastasis mechanism of breast cancer, and to develop a new drug design target. Musashi (Msi) is an evolutionarily conserved family of RNA binding proteins, including two homologous proteins: Msi1 and Msi2. in mammals. MSI (Msi1 and Msi2) are mainly expressed in epithelial tissues during normal development, especially in stem / progenitor cells. Some studies have found that Msi is highly expressed in cancer tissues from various epithelial sources and plays an important role in carcinogenesis. However, the role of MSI in breast development and breast cancer, especially whether or not it is involved in the regulation of EMT, remains unclear. In this study, Msi overexpression transgenic mice, gene knockout mice and breast cancer mice were used to investigate the function of Msi in breast development and breast cancer. In this study, we found that the expression of Msi1 and Msi2 was closely related to the invasion and metastasis ability of breast cancer subtypes. The expression of Msil and Msi2 was higher in adenoid breast tumors with weak metastatic ability, but lower in invasive and metastatic basal breast tumors. Further, negative correlation was found between Msi and EMT molecular marker gene. At the cellular level, when the Msil and Msi2 genes in breast cancer cells are knocked down, the cells withdraw from the epithelial state and enter the mesenchymal state. In order to verify the physiological function of Msi in vivo, transgenic mice which can induce the overexpression of Msi2 in breast epithelium were first prepared. Overexpression of Msi2 resulted in significant inhibition of breast ductal extension and branching, increased number of luminal epithelial cells, and inhibition of EMT process. In contrast, breast epithelium increased the number of EMT and myoepithelial cells in Msil and Msi2 double knockout mice. The results in vitro and in vivo indicate that Msi inhibits the EMT process in breast epithelium. In order to further explore the function of Msi in breast cancer, Msi2. was overexpressed in the mouse model of MMTV-PyVT breast cancer. It was found that the overexpression of Msi2 inhibited the growth of breast cancer and inhibited the lung metastasis of breast cancer cells by inhibiting the process of EMT. Therefore, Msi is an important posttranscriptional regulator of EMT and plays an important role in breast cancer metastasis. In molecular mechanism, Jagged1 (Jag1) is a direct functional target gene of Msi2. Molecular biology and biochemical experiments have confirmed that Msi2 inhibits the translation of Jag1 mRNA by binding 3'UTR of Jagl. Jag1 is the ligand of Notch signaling pathway, which activates Notch signaling pathway when Jagl expression level increases, thus promoting EMT.. When Jagl is inhibited by the Msi protein, the cells are locked in an epithelial state. These results suggest that Msi2 can regulate the EMT process by inhibiting the Jag1-Notch signaling pathway. In conclusion, this study suggests that Msi inhibits the EMT process and cancer cell metastasis by targeting the translation of Jagl and activation of the Notch signaling pathway in breast development and breast cancer. In this study, the posttranscriptional regulation mechanism of EMT is proposed for the first time, which enriches the regulatory network of EMT and provides a scientific basis for the design of breast cancer treatment drugs and the formulation of strategies.
【學(xué)位授予單位】：中國(guó)農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：R737.9
，
本文編號(hào)：2205083
本文鏈接：http://www.lk138.cn/yixuelunwen/zlx/2205083.html
最近更新
教材專(zhuān)著
