HPIP promotes epithelial-mesenchymal transition and cisplatin resistance in ovarian cancer cells through PI3K/AKT pathway activation

Purpose

Hematopoietic PBX interacting protein (HPIP), a scaffold protein, is known to regulate the proliferation, migration and invasion in different cancer cell types. The aim of this study was to assess the role of HPIP in ovarian cancer cell migration, invasion and epithelial-mesenchymal transition (EMT), and to unravel the mechanism by which it regulates these processes.

Methods

HPIP expression was assessed by immunohistochemistry of tissue microarrays containing primary ovarian tumor samples of different grades. OAW42, an ovarian carcinoma-derived cell line exhibiting a high HPIP expression, was used to study the role of HPIP in cell migration, invasion and EMT. HPIP knockdown in these cells was achieved using a small hairpin RNA (shRNA) approach. Cell migration and invasion were assessed using scratch wound and transwell invasion assays, respectively. The extent of EMT was assessed by determining the expression levels of Snail, Vimentin and E-cadherin using Western blotting. The effect of HPIP expression on AKT and MAPK activation was also investigated by Western blotting. Cell viabilities in response to cisplatin treatment were assessed using a MTT assay, whereas apoptosis was assessed by determining caspase-3 and PARP cleavage in ovarian carcinoma-derived SKOV3 cells.

Results

We found that HPIP is highly expressed in high-grade primary ovarian tumors. In addition, we found that HPIP promotes the migration, invasion and EMT in OAW42 cells and induces EMT in these cells via activation of the PI3K/AKT pathway. The latter was found to lead to stabilization of the Snail protein and to repression of E-cadherin expression through inactivation of GSK-3β. We also found that HPIP expression confers cisplatin resistance to SKOV3 cells after prolonged exposure and that its subsequent knockdown decreases the viability of these cells and increases caspase-3 activation and PARP proteolysis in these cells following cisplatin treatment.

Conclusions

From these results we conclude that HPIP expression is associated with high-grade ovarian tumors and may promote their migration, invasion and EMT, a process that is associated with metastasis. In addition, we conclude that HPIP may serve as a potential therapeutic target for cisplatin resistant ovarian tumors.

     

沉默泛素结合酶E2O对人非小细胞肺癌细胞增殖和侵袭的影响

  目的  研究泛素结合酶E2O（ubiquitin-conjugating enzyme E2O,UBE2O）蛋白在非小细胞肺癌（non-small cell lung cancer,NSCLC）细胞增殖、细胞周期、迁移、侵袭中的作用。  方法  通过慢病毒介导的shRNA靶向抑制人NSCLC细胞株A549中UBE2O基因的表达,应用CCK-8法、流式细胞术分别检测UBE2O对A549细胞增殖、细胞周期和凋亡的影响,应用Transwell实验检测下调UBE2O表达后对A549细胞迁移、侵袭能力的影响,应用Western blot检测细胞上皮间质转化（epithelial-mesenchymal transition,EMT）两种标志分子E-cadherin蛋白、N-cadherin蛋白和PI3K-Akt信号通路相关蛋白表达量的变化。  结果  下调UBE2O表达后,A549细胞UBE2O mRNA和蛋白表达均下调（均P < 0.01）,CCK-8实验结果显示沉默UBE2O可以抑制A549的增殖（P < 0.001）,Transwell实验显示下调UBE2O的表达能够抑制A549细胞的迁移、侵袭（均P < 0.001）。Western blot结果表明下调UBE2O的表达可使A549细胞中的E-cadherin蛋白表达水平升高、p-Akt蛋白表达水平下降。  结论  UBE2O蛋白能够促进NSCLC细胞侵袭和迁移,作用机制可能是通过诱导肺癌细胞发生EMT和促进pI3K-Akt信号通路的激活。      

PTTG1促进结肠癌SW480细胞侵袭和迁移的作用机制

目的 研究垂体肿瘤转化基因 1（pituitary tumor transforming gene 1, PTTG1）过表达促进人结肠癌细胞SW480侵袭和迁移作用及其可能机制。方法 采用脂质体转染法将pcDNA3.1(+)-PTTG1及空载pcDNA3.1(+)转染人结肠癌SW480细胞,G418法筛选阳性克隆。Western blot和Real-time PCR法鉴定稳定过表达PTTG1细胞株建立。Transwell小室法检测细胞侵袭和迁移能力,Western blot检测MMP2、MMP9、E-cadherin、Vimentin和Snail的表达。结果 （1）成功获得稳定高表达PTTG1的SW480克隆细胞株PTTG1-SW480;（2）过表达PTTG1基因后,SW480细胞侵袭和迁移能力增强,MMP2和MMP9表达升高,上皮间质转化（epithelial-mesenchymal transition, EMT）标记分子E-cadherin表达降低,Vimentin和Snail的表达升高,差异均有统计学意义（P<0.01）;（3）过表达PTTG1基因后,SW480细胞中PI3K/AKT信号活化增强,使用LY29400干预后,抑制细胞侵袭、迁移和EMT,E-cadherin表达上调、Vimentin和Snail的表达下调,差异均有统计学意义（P<0.01）。结论 PTTG1基因过表达可能通过活化PI3K/AKT信号诱导SW480细胞EMT发生,发挥促进SW480侵袭和迁移作用;提示PTTG1蛋白可能成为结肠癌治疗的一个潜在靶点。     

阿托伐他汀调控上皮间质转化抑制结肠癌细胞生长的机制研究

目的:探讨阿托伐他汀调控上皮间质转化（EMT）对人结肠癌SW480细胞侵袭和迁移的影响。方法:0.1、1、10、100 μmol/L的阿托伐他汀处理SW480细胞24 h、48 h和72 h,MTT检测细胞活力。100 μmol/L的阿托伐他汀处理细胞48 h,Transwell小室检测细胞侵袭能力及迁移能力,Western blotting检测EMT相关蛋白E-cadherin、β-catenin和Twist及PI3K/AKT信号通路PI3K、AKT和p-AKT蛋白表达。结果:随着阿托伐他汀浓度升高,作用时间延长,对SW480细胞活力抑制越明显,各浓度阿托伐他汀组与对照组比较差异具有统计学意义（P<0.05）,同一实验组不同时间点间比较差异具有统计学意义（P<0.05）。与对照组比较,阿托伐他汀组细胞侵袭及迁移能力均明显降低,E-cadherin蛋白表达明显升高,β-catenin、Twist、PI3K和p-AKT蛋白表达明显降低（P<0.05）。结论:阿托伐他汀可抑制结肠癌细胞的侵袭和迁移能力,机制可能与抑制EMT及PI3K/AKT信号通路有关。     

CD44 enhances the epithelial-mesenchymal transition in association with colon cancer invasion

The metastatic process involves the migration and invasion of cancer cells throughout the body to produce secondary tumors at distant sites. Through of epithelial-mesenchymal transition (EMT), cancer cells employ developmental processes to gain migratory and invasive properties. CD44 is the transmembrane adhesion receptor for Hyaluronan (HA) and plays a central role in the remodeling and degradation of HA that leads to cell migration, as well as to cancer invasion and metastasis. CD44 is highly expressed in primary and metastatic colon cancer but lowly expressed in normal tissues. We evaluated the impact of CD44 on EMT and invasion of colon cancer cells. The functional role of CD44 in EMT was determined by the overexpression or knockdown of CD44. CD44 was overexpressed by transfection with plasmid-RT-PCR product and knockdown of CD44 by small hairpin RNA (shRNA)-mediated depletion of CD44 in SW480 colon cancer cells. Morphological changes were evaluated by confocal laser microscopy in the culture media. The expression of EMT markers (E-cadherin/N-cadherin/vimentin/fibronectin/actin/MMPs) and CD44/EGFR/PI3K-Akt signaling were evaluated using western blotting. The influence of EMT in tumor biology was assessed with proliferation, migration and invasion assays. EMT changes increased in CD44-overexpressing SW480 cells and decreased in CD44 knockdown cells. CD44 activation induced expression of EGFR and activation of phosphatidylinositol 3' kinase (PI3K)/Akt and expression of glycogen synthase kinase-3 β (GSK-3β). In terms of EMT markers, CD44 downregulated E-cadherin expression, upregulated N-cadherin, α-actin, vimentin, fibronectin and MT1-MMP, and inhibited the formation of the membrane-associated E-cadherin-β-catenin complex, which resulted in cell invasion and migration.     

Gab2通过GSK-3β/Snail信号通路促进乳腺癌的上皮-间质转化

背景与目的：越来越多的证据显示,Grb2协同结合蛋白2(Grb2 binding protein-2,Gab2)与肿瘤的侵袭转移相关,但Gab2与乳腺癌上皮-间质转化(epithelial-mesenchymal transition,EMT)的关系尚不清楚。本研究旨在探讨Gab2对乳腺癌EMT标志物的影响,明确Gab2在乳腺癌侵袭和转移中的作用机制。方法：采用免疫组织化学染色法检测80例乳腺癌组织中Gab2及EMT标记物上皮性钙黏着蛋白(E-cadherin)、波形蛋白(vimentin)的表达情况并分析其相关性,用蛋白[质]印迹法(Western blot)检测乳腺组织Gab2的表达情况,采用小干扰RNA(siRNA)技术降低乳腺癌细胞系MDA-MB-231中Gab2的表达,采用划痕实验检测表皮生长因子(epithelial growth factor,EGF)刺激后转染细胞的侵袭能力变化,用Western blot检测敲低Gab2后MDA-MB-231细胞中E-cadherin及vimentin的表达情况,同时检测p-GSK-3β的表达情况、转录因子Snail转核情况。结果：Gab2在乳腺癌组织中的表达与E-cadherin的表达呈负相关,而与vimentin的表达呈正相关(P<0.05);乳腺癌组织中Gab2的表达量明显高于正常乳腺组织;siRNA质粒转染后,SiGab2/MDA-MB-231细胞组中Gab2蛋白的表达量明显降低,结果显示转染成功,划痕实验显示细胞的侵袭能力减弱,表明Gab2影响乳腺癌细胞系的侵袭能力;敲低Gab2后,MDA-MB-231细胞中的E-cadherin的表达明显升高,而vimentin的表达明显降低;GSK-3β的磷酸化受到抑制,而Snail在敲低Gab2的细胞核中的表达明显下调。结论：Gab2可以通过GSK-3β/Snail信号通路促进乳腺癌的EMT,从而促进乳腺癌的侵袭和转移。     

Fzd2诱导ER阴性乳腺癌细胞上皮-间质转化

目的:分析Frizzled 2（Fzd2）在雌激素受体阴性（ER-）乳腺癌中的表达及其对ER-乳腺癌细胞上皮-间质转换（epithelial-mesenchymal transition,EMT）的影响。方法:采用免疫组化方法检测Fzd2在乳腺癌组织中的表达;采用Western blot检测Fzd2、E-cadherin、Vimentin、Slug、Zeb1在乳腺癌细胞中的表达;采用伤口愈合试验和Transwell试验检测细胞迁移和侵袭。结果:Fzd2在ER-乳腺癌组织及细胞系中过表达;Fzd2敲减促进Hs578T细胞表达E-cadherin,减少Hs578T细胞表达Vimentin、Slug和Zeb1;Fzd2敲减抑制Hs578T细胞迁移和侵袭。结论:Fzd2诱导ER-乳腺癌细胞发生EMT;Fzd2可能作为ER-乳腺癌防治的一个潜在靶向分子。     

黏蛋白13在肺腺癌组织中的表达及其对A549细胞恶性生物学行为的影响与可能的机制

目的：探讨黏蛋白13(MUC13)在肺腺癌组织中的表达及其对A549细胞增殖、凋亡、迁移、侵袭及EMT的影响与可能的机制。方法：通过癌症基因组图谱（TCGA）和高通量基因表达（GEO）数据库分析MUC13在肺腺癌组织与正常肺组织、癌旁组织中的差异表达。qPCR法和WB法检测人肺腺癌细胞NCI-H1395、NCI-H1975、H1299、A549和人正常肺上皮细胞BEAS-2B中MUC13 mRNA和蛋白的表达水平。利用si RNA技术敲低A549细胞中MUC13表达,实验分为si-MUC13组、NC组和si-MUC13+IGF-1组。通过克隆形成实验、流式细胞术和Transwell实验分别检测敲低MUC13对A549细胞增殖、细胞周期、凋亡、迁移和侵袭的影响,WB法检测敲低MUC13对A549细胞上皮钙黏素（E-cadherin）、神经钙黏素（N-cadherin）、波形蛋白（vimentin）、EGFR、p-EGFR、PI3K、p-PI3K、AKT、p-AKT等蛋白表达的影响。结果：MUC13 mRNA和蛋白在肺腺癌组织和细胞中均呈高表达（均P<0.01）,选取表达水平较高的A...     

乳腺癌组织和细胞中低表达的LZTS2 通过PI3K/AKT信号通路抑制癌细胞增殖、迁移和EMT

[摘要] 目的：探讨亮氨酸拉链肿瘤抑制因子2（leucine zipper tumor suppressor 2, LZTS2）基因在人乳腺癌组织和细胞系中的表达及其对乳腺癌细胞增殖、迁移和EMT的影响及其作用机制。方法：收集2016 年1 月至2016 年12 月开封中心医院乳腺外科收治的50 例女性乳腺癌患者的癌及癌旁组织标本和乳腺癌细胞系MCF-7、MDA-MB-231、MDA-MB-468 以及正常人乳腺上皮细胞株HBL-100,用qPCR 和Western blotting 检测乳腺癌组织和细胞中LZTS2 mRNA和蛋白表达水平。构建pcDNA-LZTS2 真核表达载体并采用脂质体转染MCF-7 细胞,同时转染pcDNA3.1 作为阴性对照。用Western blotting 检测转染48~72 h 后MCF-7 细胞中LZTS2 蛋白表达水平;用MTT法、Transwell 小室法检测LZTS2 过表达对细胞增殖、迁移和侵袭的影响,同时用Western blotting检测细胞中EMT相关蛋白Cyclin D1、波形蛋白、神经钙黏蛋白、上皮钙黏蛋白以及PI3K/AKT信号通路中相关蛋白的表达。结果：人乳腺癌组织中LZTS2 mRNA和蛋白表达水平均明显低于癌旁组织（P<0.05 或P<0.01）;乳腺癌MCF-7、MDA-MB-231 和MDA-MB-468 细胞中LZTS2 mRNA和蛋白表达水平显著低于乳腺上皮细胞HBL-100（P<0.05 或P<0.01）。与空白对照组和pcDNA3.1组相比,pcDNA-LZTS2 组MCF-7 细胞中LZTS2 蛋白表达水平明显上调（P<0.01）,细胞增殖、迁移和侵袭能力显著受到抑制（P<0.05 或P<0.01）,同时过表达LZTS2 细胞中Cyclin D1、波形蛋白和神经钙黏蛋白表达水平均明显降低（P<0.05 或P<0.01）、上皮钙黏蛋白表达水平明显升高（均P<0.01）,显示LZTS2 过表达通过降低p-PI3K和p-AKT 表达而抑制PI3K/AKT信号通路。结论：LZTS2 在乳腺癌中低表达,过表达LZTS2 能够抑制乳腺癌细胞的增殖、迁移和侵袭能力,可能与抑制细胞EMT过程的PI3K/AKT信号通路有关。     

Gab2 and Src co-operate in human mammary epithelial cells to promote growth factor independence and disruption of acinar morphogenesis

The Gab2 docking protein is a target of several oncogenic protein tyrosine kinases and potentiates activation of the Ras/extracellular signal regulated kinase and phosphatidylinositol 3-kinase (PI3-kinase) pathways. Since Gab2 is phosphorylated by c-Src, and both proteins are overexpressed in breast cancers, we have determined the biological consequences of their co-expression in the immortalized human mammary epithelial cell line MCF-10A. While overexpression of c-Src did not affect acinar morphogenesis or growth factor dependence in three-dimensional culture, c-Src co-operated with Gab2 to promote epidermal growth factor (EGF)-independent acinar growth. In contrast, expression of v-Src or the activated mutant c-SrcY527F led to a spectrum of aberrant phenotypes ranging from spheroids with incomplete luminal clearance to highly disrupted, dispersed structures. Gab2 co-expression shifted the phenotypic distribution towards the dispersed phenotype, an effect not observed with a Gab2 mutant unable to bind the p85 subunit of PI3-kinase (Gab2Deltap85). In v-Src-expressing cells, Gab2, but not Gab2Deltap85, significantly decreased E-cadherin adhesive strength without altering its surface expression. Gab2 associated with E-cadherin in the presence and absence of v-Src, indicating that the ability of Gab2 to weaken the strength of cell-cell contacts may reflect enhanced activation of PI3-kinase at adherens junctions. Gab2 also increased migration and invasion of these cells in transwell assays, but these effects were p85-independent. Overall, these findings demonstrate a novel mechanism whereby Gab2 may promote metastatic spread and indicate that Gab2 may play several roles during breast cancer progression.     

Overexpression of FYN suppresses the epithelial-to-mesenchymal transition through down-regulating PI3K/AKT pathway in lung adenocarcinoma

BackgroundTyrosine-protein kinase Fyn (FYN) plays a crucial role in Src family, which participates in the signal transduction of brain nerves and the development and activation of T lymphocytes in physiological conditions. We probed into the roles and mechanisms of FYN in lung adenocarcinoma (LUAD).MethodsCell activity, apoptosis, invasion, and migration were detected by CCK-8, FCM, transwell, and wound-healing assays, respectively. The angiogenesis capacity was evaluated by in vitro angiogenesis test. Relative mRNA and protein expressions were determined by qRT-PCR, Western blot, and immunohistochemistry assays, respectively. Insulin-like growth factors-I (IGF-I) was used as an agonist of PI3K/AKT pathway.ResultsWe demonstrated that FYN expression correlated with LUAD prognosis and was down-regulated in LUAD tissues and LUAD cells. Overexpression of FYN suppressed the cell viability, together with invasion and migration abilities of A549 cells. FYN overexpression accelerated the cell apoptosis and reduced the angiogenesis capacity of A549 cells. Overexpression of FYN suppressed E-cadherin, Vimentin, Snail, and PI3K/AKT expressions in A549 cells. High expression level of FYN reduced the migration and invasion capacities of A549 cells via down-regulating the PI3K/AKT pathway.ConclusionCollectively, our findings reveal that overexpression of FYN inhibits the epithelial-to-mesenchymal transition (EMT) through down-regulating the PI3K/AKT pathway in A549 cells.     

下调MYEOV抑制胰腺癌细胞PaTu8988增殖、迁移、侵袭

目的:研究骨髓瘤过表达基因（MYEOV）对胰腺癌细胞增殖、迁移、侵袭的影响,以及对上皮间质转化（EMT）相关蛋白和STAT3信号通路相关蛋白的调控作用。方法:利用UCSC Xena数据库分析MYEOV在胰腺癌及正常组织中的表达水平,利用ICGC数据库分析MYEOV与胰腺癌患者预后的关系。使用慢病毒重组构建稳定低表达MYEOV的胰腺癌PaTu8988细胞系,运用实时定量聚合酶链反应（qRT-PCR）和蛋白质印迹法（Western blot）检测胰腺癌细胞系中MYEOV mRNA和蛋白的表达情况,采用CCK-8、划痕实验、Transwell迁移及侵袭实验分析细胞的增殖、迁移、侵袭能力。利用Western blot方法检测E-cadherin、Vimentin、MMP2、MMP9、STAT3、p-STAT3的表达情况。结果:经生物信息学分析发现,MYEOV在胰腺癌组织中高表达,且与胰腺癌预后不良有关。与对照组比较,下调MYEOV后胰腺癌细胞株PaTu8988的增殖、迁移和侵袭能力降低;与对照组比较,下调MYEOV后胰腺癌PaTu8988细胞系中E-cadherin蛋白表达水平升高,Vimentin、MMP2、MMP9、p-STAT3蛋白表达水平下降。结论:下调MYEOV的表达抑制胰腺癌细胞的增殖、迁移、侵袭,其机制可能与抑制EMT过程有关,而STAT3通路蛋白在EMT发生过程中出现改变,提示STAT3通路可能参与了该表型的调控。     

Phosphatidylinositol 3-kinase activity in epidermal growth factor-stimulated matrix metalloproteinase-9 production and cell surface association

Activation of the epidermal growth factor (EGF) receptor regulates many processes associated with metastasis, including modulation of cell:cell and cell:substrate interactions, production of matrix-degrading proteinases, and cellular migration. We have demonstrated previously that EGF stimulates migration and matrix metalloproteinase (MMP)-9-dependent invasion of ovarian cancer cells. In this study, we compare the roles of EGF-induced phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) activities in regulation of cellular responses associated with ovarian tumor cell metastasis. Inhibition of PI3K and MAPK activity impairs EGF-stimulated cell migration, in vitro invasion, and MMP-9 production. PI3K activity is not required for growth factor disruption of cell:cell junctions, whereas inhibitors of extracellular signal-regulated kinase (ERK)1/ERK2 activation and p38 MAPK activity block EGF-dependent junction dissolution. EGF promotes pro-MMP-9 binding to the cell surface through a mechanism that is independent of extracellular enzyme concentration. Interestingly, inhibition of PI3K activity abolishes EGF-induced cell surface association of pro-MMP-9, whereas inhibitors of MAPKs only partially block the response. These data suggest that EGF receptor activation promotes a PI3K-dependent induction of a cell surface pro-MMP-9 binding component that may facilitate gelatinase-mediated cellular invasion and supports an expanded role for elevated PI3K activity in cellular responses associated with ovarian tumor metastasis. In addition, our findings support the hypothesis that divergent kinase activities regulate distinct cellular events associated with growth factor-induced invasion of ovarian cancer cells.     

溶酶体组织蛋白酶L对人卵巢癌SKOV3细胞迁移及侵袭的作用

目的 探讨溶酶体组织蛋白酶L（Cathepsin L）是否通过上皮-间充质转化（EMT）影响卵巢癌细胞的侵袭及迁移能力。方法 荧光定量PCR法检测人卵巢癌细胞ES-2、SKOV3、OV1以及OV2中CathepsinL的表达水平;设计并合成靶向Cathepsin L的特异性shRNA,通过脂质体转染法转染Cathepsin L表达最高的卵巢癌细胞SKOV3以构建稳定低表达Cathepsin L细胞株,Western blot和定量PCR法验证shRNA的干扰效率;划痕实验及Transwell法检测干扰后细胞的迁移及侵袭能力,Western blot法检测EMT相关指标E-cadherin和N-cadherin以及其上游信号分子Snail、p-AKT的变化。结果 四株卵巢癌细胞中,SKOV3的Cathepsin L表达水平最高（以此为参照）,而ES-2、OV1以及OV2细胞的表达水平分别为0.72±0.04、0.34±0.03和0.55±0.05。Cathepsin L-shRNA转染SKOV3细胞后,SKOV3/shRNA中的Cathepsin L的表达水平较空白组和对照组显著下降;划痕12 h和24 h后, SKOV3/shRNA组的细胞迁移能力明显受到抑制;SKOV3、SKOV3/Con和SKOV3/shRNA组的穿膜细胞数分别为（93.67±8.62）、（90.33±12.22）、（35.67±4.73）,与对照组相比,SKOV3/shRNA组细胞侵袭能力受到显著抑制（P<0.01）;Cathepsin L干扰组细胞的E-cadherin表达增加,N-cadherin的表达降低;此外,Cathepsin L干扰组细胞的Snail、p-AKT表达较对照组显著下降。结论 Cathepsin L可以促进卵巢癌细胞的迁移和侵袭;其机制可能与调节EMT的上游信号分子Snail、p-AKT有关。提示Cathepsin L在卵巢癌的发生发展中起重要作用。     

Activation of PI3 kinase/Akt/HIF-1α pathway contributes to hypoxia-induced epithelial-mesenchymal transition and chemoresistance in hepatocellular carcinoma

Hypoxia is known to promote malignant progression and to induce chemoresistance in cancer. However, the exact mechanisms driving hypoxia induced malignance remain elusive. We found that with exposure to hypoxic condition, hepatocellular carcinoma (HCC) cells experienced epithelial-mesenchymal transition (EMT), with increased cell migration and invasion, and exhibited high resistance to chemotherapy. We demonstrated that hypoxia-induced EMT and chemoresistance were accompanied by increased HIF-1α expression and activation of Akt. HIF-1α could be blocked by PI3K inhibitor LY294002, indicating HIF-1α activation was regulated by PI3K/Akt pathway. Furthermore, we showed that inhibition of PI3K/Akt and HIF-1α enhanced the therapeutic efficacy of hypoxic chemotherapy in the HCC xenograft model. Our findings indicate that the activation of PI3K/Akt/HIF-1α pathway plays a critical role in mediating hypoxia-induced EMT and drug resistance leading to unfavorable treatment outcome. Our study provides novel insights into the malignant progression triggered by hypoxic microenvironment in HCC cells.