miR-214通过PTEN调控AKT信号通路抑制鼻咽癌细胞凋亡CSCD

目的探讨miR-214通过PTEN调控下游AKT信号通路激活对鼻咽癌细胞凋亡的影响。方法miR-214抑制剂转染鼻咽癌5-8F和6-10B细胞。MTT法评估细胞增殖情况。Annexin-V/PI染色法检测两种鼻咽癌细胞凋亡情况。Western blot和real-time PCR检测miR-214抑制剂对PTEN基因转录和蛋白表达以及对AKT信号通路和凋亡相关蛋白表达水平的影响。检测shRNA沉默PTEN基因转录和蛋白表达后,miR-214抑制剂对鼻咽癌细胞凋亡影响。结果miR-214抑制剂可抑制鼻咽癌细胞生长,诱导5-8F和6-10B细胞凋亡。miR-214通过靶向3'-UTR区域调控PTEN基因转录和蛋白表达。抑制miR-214可促进PTEN的表达,抑制AKT信号通路激活,进而调控下游细胞周期和凋亡相关蛋白表达。沉默PTEN基因转录和蛋白表达可逆转miR-214抑制剂对鼻咽癌细胞AKT信号通路活性和凋亡的影响。结论miR-214可通过直接靶向PTEN基因转录促进AKT信号通路激活抑制鼻咽癌细胞凋亡。     

TMCC3的异常表达通过激活AKT活性介导非小细胞肺癌对吉非替尼耐药

目的:探讨TMCC3的异常表达在介导非小细胞肺癌（non-small cell lung cancer,NSCLC）耐药中的作用。方法:通过免疫组化方法检测NSCLC中TMCC3的表达模式,并分析其与患者吉非替尼疗效的相关性。应用TMCC3-siRNA下调耐药细胞系中TMCC3的表达后,通过Western blot和细胞功能学实验等方法,检测肺癌细胞系的增殖能力。结果:肺癌组织中呈现TMCC3高表达的患者更容易在短期内出现吉非替尼耐药;在肺癌细胞系中,TMCC3的高表达能够显著激活PI3K/AKT信号通路的活性,促进肺癌细胞的增殖能力,减弱肺癌细胞对吉非替尼的敏感性。结论:TMCC3的异常表达在介导NSCLC耐药中发挥着重要作用,有望为寻求预测肺癌TKI疗效的组织学标记物,更好地实现NSCLC的个体化治疗提供科学依据。     

Acquired resistance to cetuximab is mediated by increased PTEN instability and leads cross-resistance to gefitinib in HCC827 NSCLC cells

EGFR inhibitors, including the small-molecule tyrosine kinase inhibitors such as gefitinib, and the monoclonal antibodies directed at the receptor such as cetuximab, have demonstrated promising effects in non-small cell lung cancer (NSCLC). In this study, we generated cetuximab-resistant cell lines (HCC827-CR) from HCC827 NSCLC cells to investigate acquired resistance mechanisms to cetuximab. In HCC827-CR cells, Akt was hyperactivated and its activity was persistent upon cetuximab treatment. Blockade of PI3K/Akt activity restored cetuximab sensitivity in HCC827-CR cells. Further investigation revealed that increased PTEN instability mediates constitutive Akt activation. By 1 μM proteosomal inhibitor, MG-132, PTEN protein levels were restored and Akt activity was dramatically reduced. Overexpression of PTEN by transfection could not restore cetuximab sensitivity in HCC827-CR because overexpressed PTEN was degraded rapidly (∼72 h). The increased PTEN instability was confirmed by the treatment of HCC827-CR with a protein synthesis inhibitor, cycloheximide. In the presence of cycloheximide, overexpressed PTEN was degraded more rapidly (∼12 h) in HCC827-CR cells. Interestingly, HCC827-CR cells also revealed de novo resistance to gefitinib. Inhibition of PI3K/Akt signaling pathway restored sensitivity to gefitinib in HCC827-CR cells. Taken together, these data show that PTEN instability-mediated constitutive Akt activation is involved in acquired resistance mechanisms to cetuximab and also induces de novo resistance to gefitinib. Importantly, these findings suggest emergence of cross-resistance between two agents as a potential serious problem in the clinical setting.     

过表达 PTEN 增强肝癌 HepG2细胞对吉非替尼的敏感性

目的：探索过表达 PTEN 增强 HepG2细胞对吉非替尼敏感性的分子机制。方法：脂质体法转染获得稳定表达野生型 PTEN、磷酸酶缺失 PTEN 和空质粒 pcDNA3.1的肝癌 HepG2细胞株,MTT 法检测各组转染细胞对吉非替尼的药物敏感性,流式细胞仪检测吉非替尼诱导各组转染细胞的凋亡情况,Western blot 分析各组转染细胞 PTEN、Akt、pAkt 和 Caspase -3表达情况。结果：与转染 pcDNA3.1的对照组细胞相比,稳定转染PTEN 的 HepG2细胞对吉非替尼的敏感性显著增加（ P <0.05）。吉非替尼作用48h 后,稳定转染 PTEN 的HepG2细胞凋亡率明显高于对照组（P <0.05）。过表达 PTEN 可以抑制 Akt 磷酸化,促进 Caspase -3表达。而转染磷酸酶缺失 PTEN 的 HepG2细胞丧失上述生物学行为。结论：PTEN 可能通过抑制 Akt 信号通路、诱导细胞凋亡来增强细胞对吉非替尼的敏感性。     

EGFR genetic heterogeneity of nonsmall cell lung cancers contributing to acquired gefitinib resistance

Gefitinib is dramatically effective for nonsmall cell lung cancers (NSCLCs) with activating mutations of the epidermal growth factor receptor (EGFR) gene, but these tumors eventually develop drug resistance, attributable to a secondary T790M mutation or acquired MET amplification in some relapsed tumors. We analyzed EGFR mutations in matched pre- and post-therapeutic tumors of 6 gefitinib-responding lung cancers. With conventional PCR-based sequencing, classic mutations were detected in pretreatment samples of each case. The same mutations were readily confirmed in treated lesions of 4 cases, but were absent in those of Cases 1 and 2. Subsequent mutant-enriched peptide-nucleic-acid-mediated PCR clamping and subcloning assays detected the mutation in minor cells of treated lesions of Case 1, but still failed to detect a mutation in Case 2. We thus performed microdissection-based cell cluster mutation analysis of pretreatment tumors, and found that 3, including the first 2, concurrently contained tumor cells with either mutant or wild-type EGFR, although the latter was only a minor fraction. These findings suggest that some NSCLCs are genetically heterogeneous with regard to EGFR mutations; gefitinib-sensitive mutants decrease or vanish while wild clones selectively survive with gefitinib treatment. In addition, T790M was detected in a small fraction of treated lesions of 3 cases, and MET amplification was revealed in 3 treated tumors of Case 2. Thus, our results suggest that multiple mechanisms underlie acquired gefitinib resistance, and selection on a background of EGFR genetic heterogeneity also contributes to acquisition of resistance in a proportion of NSCLCs.     

Long non-coding RNA UCA1 induces non-T790M acquired resistance to EGFR-TKIs by activating the AKT/mTOR pathway in EGFR-mutant non-small cell lung cancer

The aim of this study was to explore the role of long non-coding RNA UCA1 (urothelial cancer-associated 1) in acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in EGFR-mutant non-small cell lung cancer (NSCLC). In our study, UCA1 expression was significantly increased in lung cancer cells and patients with acquired resistance to EGFR-TKIs. Over-expression of UCA1 was significantly associated with a shorter progression-free survival (PFS) [13.0 vs. 8.5 months, P < 0.01] in tumors with respond to EGFR-TKIs. The significant relationship was not observed in patients with T790M mutation (10.5 vs. 12.0 months, P = 0.778), but in patients with non-T790M (19.0 vs. 9.0 months, P = 0.023). UCA1 knockdown restored gefitinib sensitivity in acquired resistant cells with non-T790M and inhibited the activation of the AKT/mTOR pathway and epithelial-mesenchymal transition (EMT). The mTOR inhibitor was effective in UCA1-expressing cell PC9/R. Inhibiting mTOR could change the expression of UCA1, although there was no significant difference. In conclusion, the influence of over-expression of UCA1 on PFS for patients with acquired resistance to EGFR-TKIs was from the subgroup with non-T790M mutation. UCA1 may induce non-T790M acquired resistance to EGFR-TKIs by activating the AKT/mTOR pathway and EMT.     

细胞角蛋白13通过PTEN抑制PI3K/AKT/mTOR通路增强鼻咽癌HNE1细胞放疗敏感性

目的:探讨细胞角蛋白13(cytokeratin13,CK13)对鼻咽癌HNE1细胞放疗敏感性的影响及其作用机制.方法:将HNE1细胞分为对照组、anti-CK13#a组及anti-CK13#b组(敲减CK13)、对照组+西罗莫司处理组(100nmol/L的西罗莫司处理1 h)、anti-CK13#a+西罗莫司处理组(...     

吉非替尼获得性耐药细胞株对不同化疗药物的敏感性分析

目的 探讨吉非替尼获得性耐药细胞株对不同化疗药物的敏感性,为分子靶向治疗失败的患者选择化疗方案提供临床前的依据.方法 体外培养人肺腺癌细胞株PC9和吉非替尼获得性耐药株PC9/G,采用二苯基溴化四氮唑蓝(MTT)法测定PC9和PCg/G细胞对不同药物的敏感性以及细胞的增殖抑制率;采用流式细胞仪检测药物对PC9和PCg/G细胞凋亡的影响及P-170蛋白的表达;采用基因芯片技术分析PC9和PC9/G细胞的表达基因谱差异;采用Western blot法检测PC9和PC9/G细胞中总Akt、磷酸化Akt和整合素β1的表达.结果 MTT和凋亡检测的结果 表明,与PC9细胞相比,吉非替尼获得性耐药细胞株PC9/G对顺铂的耐药指数为5.4,细胞凋亡减少,联合LY294002后对顺铂的敏感性显著增加(P＜0.05).PC9/G细胞对多西紫杉醇较PC9细胞更为敏感,培美曲塞对两株细胞的IC50及凋亡影响的差异无统计学意义(P＞0.05).PC9/G细胞中P-170蛋白的表达水平为5.32,与PC9细胞(7.18)比较,差异无统计学意义(P＞0.05).基因芯片分析显示,PC9/G细胞中,整合素β1及DNA修复基因的表达上调,有丝分裂期基因表达下调.PC9/G细胞中总Akt、磷酸化Akt及整合素β1的蛋白表达水平分别为1.32、1.82和1.59,PC9细胞巾总Akt、磷酸化Akt及整合素β1的蛋白表达水平分别为0.83、0.87和0.57.结论 在吉非替尼获得件耐药细胞株中存在P13K的表达上调及激活、整合素β1及DNA修复基因的表达上调,其表达土调与顺铂耐药相关;表皮生长因子受体-酪氨酸激酶抑制剂(EGFR-TKI)治疗失败的患者在选择化疗方案时应避免使用铂类药物,可选择给予多西紫杉醇或培美曲塞治疗.     

Molecular basis for sensitivity and acquired resistance to gefitinib in HER2-overexpressing human gastric cancer cell lines derived from liver metastasis

Gastric cancer metastasised to the liver was found to overexpress HER2 at a significantly higher incidence than primary gastric cancers. The purpose of the present study was to investigate the possibility of molecular therapy targeting HER2 overexpression in gastric cancer liver metastasis. We developed three new HER2-overexpressing gastric cancer cell lines (GLM-1, GLM-2, GLM-4) without epidermal growth factor receptor (EGFR) mutations derived from such liver metastasis, two of which had HER2 gene amplifications. All these GLM series of cell lines were highly sensitive to gefitinib in vitro, a specific inhibitor of EGFR tyrosine kinase (Iressa) rather than anti-HER2 antibody trastuzumab (Herceptin), whereas most of the HER2 low-expressing counterparts were not. In these HER2-overexpressing GLM series, protein kinase B (Akt), but not extracellular signal-regulated kinase 1/2 (ERK1/2), was constitutively phosphorylated, and gefitinib efficiently inhibited this Akt phosphorylation, induced strong apoptosis in vitro and exhibited antitumour activity in tumour xenografts in nude mice. This gefitinib-mediated antitumour effect in xenograft was significantly potentiated by trastuzumab treatment. On the other hand, gefitinib-resistant cells (GLM-1R) exhibited increased EGFR expression, followed by constitutive activation of mitogen-activated protein kinase (MAPK) pathway. These results suggest that the antitumour effect of gefitinib is due to the effective inhibition of HER2-driven constitutive activation of phosphatidylinositol-3-kinase (PI3K)/Akt pathway, and that the acquired resistance to gefitinib is due to the constitutive activation of Ras/MAPK pathway in compensation for PI3K/Akt pathway. Gastric cancer liver metastasis with HER2 overexpression would be a potential molecular target for gefitinib and trastuzumab.     

Genetic modelling of the PTEN/AKT pathway in cancer research

The focus on targeted therapies has been fuelled by extensive research on molecular pathways and their role in tumorigenesis. Novel models of human cancer have been created to evaluate the role of specific genes in the different stages of cancer. Currently, mouse modelling of human cancer is possible through the expression of oncogenes, specific genetic mutations or the inactivation of tumour suppressor genes, and these models have begun to provide us with an understanding of the molecular pathways involved in tumour initiation and progression at the physiological level. Additionally, these mouse models serve as an excellent system to evaluate the efficacy of currently developed molecular targeted therapies and identify new potential targets for future therapies. The PTEN/AKT pathway is implicated in signal transduction through tyrosine kinase receptors and heterotrimeric G protein-linked receptors. Deregulation of the PTEN/AKT pathway is a common event in human cancer. Despite the abundant literature, the physiological role of each element of the pathway has begun to be uncovered thanks to genetically engineered mice. This review will summarise some of the key animal models which have helped us to understand this signalling network and its contribution to tumorigenesis. Supported by an unrestricted educational grant from Pfizer.     

PTEN and PIK3CA gene copy numbers and poor outcomes in non-small cell lung cancer patients with gefitinib therapy

Background:

Preclinical studies in non-small cell lung cancer (NSCLC) suggest the interaction of PTEN and PI3K affects sensitivity to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). We investigated outcomes in relation to PTEN, PIK3CA and EGFR gene copy number, and chromosome 7 (CEN7) polysomy in NSCLC patients treated with gefitinib.

Methods:

Fluorescent in situ hybridisation analyses of PTEN, PIK3CA, EGFR and CEN7 were performed on tumour specimens from patients treated on the expanded access gefitinib trial. Progression-free survival (PFS) and overall survival (OS) were correlated with outcomes in all patients and EGFR wild-type patients.

Results:

Progression-free survival (hazard ratio=2.54, P<0.001) and OS (hazard ratio=4.04, P<0.001) were significantly shorter in patients whose tumours had all of the following molecular patterns: CEN7 <4 copies per cell, PTEN loss (<2 copies in at least 20% of cells), and PIK3CA gain (>2 copies in at least 40% of cells) both in all and EGFR wild-type only patients.

Conclusion:

The combination of low CEN7 copy number, PTEN loss, and PI3KCA gain may be useful for identifying NSCLC patients unlikely to benefit from treatment with EGFR (TKIs), specifically in wild-type EGFR cases.     

miR-103 靶向PTEN并激活PI3K/AKT通路促进肺癌细胞A549 对达沙替尼耐药

[摘要] 目的：探讨miR-103 靶向PTEN并激活PI3K/AKT信号通路促进肺癌细胞对达沙替尼（dasatinib,DASA）耐药的机制。方法：收集2014 年4 月至2018 年1 月昆明医科大学第一附属医院胸外科收治的资料完整的肺癌DASA耐药组织和不耐药组织各35 例。采用qPCR实验检测miR-103 在肺癌DASA耐药组织和细胞中的表达水平,同时,采用CCK-8、Transwell 和Wb实验检测敲降miR-103 对A549/DASA细胞增殖、迁移和上皮间质转化（EMT）的影响,双荧光素酶报告基因验证miR-103 与PTEN的靶向关系。进一步采用CCK-8、Transwell 和Wb实验检测miR-103 通过PTEN-PI3K/AKT信号通路对A549/DASA细胞恶性生物学行为的影响。结果：miR-103 在肺癌DASA 耐药组织和A549/DASA 细胞中均高表达（均P<0.01）。敲降miR-103 可显著抑制A549/DASA细胞的增殖、迁移和EMT（P<0.05 或P<0.01）。此外,双荧光素酶报告基因证实miR-103 靶向作用PTEN并下调其表达水平（P<0.01）。进一步实验显示,过表达miR-103 通过靶向下调PTEN并激活PI3K/AKT信号通路进而显著促进A549/DASA细胞增殖、迁移和EMT（P<0.05 或P<0.01）,从而上调A549/DASA细胞对DASA的耐药性。结论：miR-103/PTEN/PI3K/AKT信号通路与肺癌DASA耐药性存在调控关系,敲降miR-103 可逆转A549/DASA对DASA耐药。     

Gankyrin plays an essential role in estrogen-driven and GPR30-mediated endometrial carcinoma cell proliferation via the PTEN/PI3K/AKT signaling pathway

Gankyrin has been implicated in the formation of multiple cancer types, although its roles in estrogen-driven endometrial carcinoma remain unclarified. We evaluated the expression of Gankyrin in endometrial tissues and further explored its roles in estrogen-driven and GPR30-mediated endometrial cancer cell proliferation. Gankyrin was overexpressed in endometrial carcinoma tissues and showed an inverse relationship with the pattern of PTEN expression. The depletion or overexpression of Gankyrin induced endometrial cancer cell proliferation inhibition or expansion, respectively, which was associated with estrogen-driven GPR30 signaling via the PTEN/PI3K/AKT pathway. This study suggests that Gankyrin is functional in endometrial cancer development.     

Targeting c-kit inhibits gefitinib resistant NSCLC cell growth and invasion through attenuations of stemness,EMT and acquired resistance

EGFR tyrosine kinase inhibitors (TKIs) are the first-line drugs for NSCLC. But, the acquired resistance limited their efficacy, so that the patients deteriorate eventually. Therefore, it is necessary to clarify the mechanism of the acquired resistance and overcome it for effective NSCLC therapy. In this experimental study, a stable gefitinib resistant lung adenocarcinoma cell line (PC9/GR) infected with shRNA-c-kit-homo-1386 were established; c-kit siRNA and c-kit inhibitors were used to block c-kit signaling; the acquired resistance of PC9/GR cells and the effects of c-kit siRNA and c-kit inhibitors on the growth and invasion of PC9/GR cells were investigated with CCK-8 assay, colony formation and cell invasion assays in vitro; the tumor growth inhibition effects of c-kit inhibitors on PC9/GR cell generated tumors were tested in vivo; the mechanisms involved in the acquired resistance reverse, growth and invasion inhibition effects of c-kit siRNA and c-kit inhibitors on PC9/GR cells were evaluated with qRT-PCR, Western blot and immunohistochemistry staining. The proliferation, colony formation, and invasion of PC9/GR cells were decreased by c-kit siRNA and inhibitors in vitro significantly; c-kit inhibitors suppressed the tumor growth of PC9/GR cell generated tumors in vivo. In the stable shRNA-c-kit transfected PC9/GR cells, the protein expressions of c-kit signaling and stemness phenotype related proteins, including ALDH1A1, Oct4, Sox2 and ABCG2 were decreased, and EMT phenotype related protein expressions including vimentin, N-cadherin, and Slug, were downregulated and with upregulation of E-cadherin; c-kit inhibitors reduced stemness phenotype related protein expressions, downregulated EMT phenotype related protein expressions including vimentin, N-cadherin, and Slug, with upregulation of E-cadherin, and the stemness related protein expressions of c-kit, ALDH1A1, ABCG2 and EMT-related proteins of vimentin and slug were decreased in the imatinib treated tumor tissues. The findings of this study indicated that c-kit signaling mediated the acquired gefitinib resistance, cell growth, invasion, stemness and EMT phenotype of PC9/GR cells. Targeting c-kit signaling with c-kit siRNA and small molecule c-kit inhibitors might overcome the acquired gefitinib resistance, and inhibit PC9/GR cell growth in vitro and in vivo.     

PI3K/AKT/mTOR信号通路介导索拉非尼治疗原发性肝癌耐药机制的研究进展

索拉非尼（sorafenib）作为原发性肝癌（hepatocellular carcinoma,HCC）靶向治疗的一线药物已广泛应用于临床,然而部分HCC患者对索拉非尼治疗耐药导致临床疗效欠佳,联合其他靶向药物的临床实验仍未取得突破,故深入研究索拉非尼耐药机制,逆转索拉非尼耐药对于改善肝癌治疗的预后具有重要意义。最新研究发现,PI3K/AKT/mTOR信号通路在索拉非尼耐药机制中起重要作用,本文将从PI3K/AKT/mTOR信号通路促进肿瘤血管生成、参与细胞自噬、抑制肿瘤细胞凋亡并促进其增殖、与RAS/RAF/ERK/MEK信号通路交联及其促进上皮-间质转化等几个方面,概述其在索拉非尼治疗原发性肝癌时产生耐药的机制,为进一步开发治疗原发性肝癌的新型药物提供研究方向。     

Association of PTEN gene methylation with genetic alterations in the phosphatidylinositol 3-kinase/AKT signaling pathway in thyroid tumors

BACKGROUND: The phosphatidylinositol 3-kinase (PI3K)/AKT pathway plays an important role in thyroid tumorigenesis and progression. Genetic alterations, particularly PIK3CA amplification and mutations and ras mutations, are the major cause of aberrant activation of this pathway in thyroid tumors. Epigenetic silencing of the PTEN gene, a negative regulator of the PI3K/AKT pathway, also occurs in thyroid tumors, but its relationship with genetic alterations in this pathway is unclear. METHODS: By using quantitative methylation-specific polymerase chain reaction, the authors examined PTEN methylation and its relationship with genetic alterations in the PI3K/AKT pathway in various types of thyroid tumors. RESULTS: The authors found PTEN methylation to become progressively higher from benign thyroid adenoma to follicular thyroid cancer and to aggressive anaplastic thyroid cancer, which harbored activating genetic alterations in the PI3K/AKT pathway correspondingly with a progressively higher prevalence. The association of PTEN methylation was seen with both overall genetic alterations and individual genetic alterations, particularly PIK3CA alterations and ras mutations, in the PI3K/AKT pathway within each of the 3 types of thyroid tumors. In contrast, no such relationship was observed for the tumor suppressor gene RASSF1A. CONCLUSIONS: The authors found an interesting association of PTEN methylation with the activating genetic alterations in the PI3K/AKT pathway in thyroid tumors. This finding is consistent with a model in which aberrant methylation and hence silencing of the PTEN gene, which coexists with activating genetic alterations of the PI3K/AKT pathway, may enhance the signaling of this pathway aberrantly activated by genetic alterations and hence contribute to the progression of thyroid tumors. Cancer 2008.     

Sequential use of vinorelbine followed by gefitinib enhances the antitumor effect in NSCLC cell lines poorly responsive to reversible EGFR tyrosine kinase inhibitors

Preclinical studies have suggested that combining cytotoxic agents with epidermal growth factor receptor tyrosine kinase inhibitors (EGFR‐TKIs) to treat EGFR‐mutated tumors may increase their inhibitory effect depending on the order of drug administration. The antitumor efficacy of different treatment sequences using vinorelbine (VNB) and gefitinib (GEF) was investigated both in vitro and in vivo in non‐small cell lung cancer (NSCLC) cell lines with the rationale of potentially translating these findings into the clinical setting. The EGFR‐wild‐type A549 and the EGFR‐mutated (exon 21 L858R/exon 20 T790M) H1975 cell lines were treated as follows: GEF followed by VNB, VNB followed by GEF and the two drugs applied individually or concurrently. Results in vitro demonstrated that the sequence of VNB followed by GEF was significantly more active than single‐agent treatments. The expression of activated EGFR and its downstream pathway genes indicated that the increased cytotoxic effect of the VNB and GEF treatment sequence was accompanied by inhibition of EGFR, AKT and ERK1/2. Moreover, the increased inhibition of tumor growth after treatment with VNB followed by GEF was also confirmed in CD1‐nude mice that were xenotransplanted with H1975 cells (p < 0.0001). This effect was paralleled by a corresponding decrease in cancer glucose consumption, as assessed by micro‐positron emission tomography scans (p < 0.05). These preclinical findings in NSCLC cell lines, which are poorly responsive to EGFR‐TKIs, demonstrated that the sequential treatment of VNB followed by GEF induced a significant antitumor effect, which supports the translation of this treatment schedule into a clinical setting.     

芒柄花黄素对白血病HL-60细胞增殖、凋亡和miR-21/PTEN/AKT信号通路的影响

目的:探讨芒柄花黄素对白血病HL-60细胞增殖、凋亡的影响及其机制。方法:以不同浓度（0、12.5、25、50、100和200 μg/ml）芒柄花黄素处理HL-60细胞24、48和72 h后，采用MTT法检测细胞存活率，并计算出IC50以筛选出合适的作用浓度。采用流式细胞仪检测芒柄花黄素对HL-60细胞周期和凋亡的影响，实时荧光定量PCR检测芒柄花黄素对HL-60细胞中miR-21表达的影响，免疫印迹法检测芒柄花黄素对HL-60细胞中PTEN、AKT和p-AKT蛋白表达的影响。结果:与0 μg/ml处理组相比，25、50、100和200 μg/ml芒柄花黄素处理24 h后HL-60细胞的存活率明显降低（P<0.05）；同时，12.5、25、50、100和200 μg/ml芒柄花黄素分别处理48 h和72 h后HL-60细胞的存活率明显低于0 μg/ml处理组（P<0.05）；芒柄花黄素作用HL-60细胞24、48和72 h后的IC50值分别为146.50 μg/ml、120.10 μg/ml和89.00 μg/ml。50、100和150 μg/ml芒柄花黄素处理后HL-60细胞在G0/G1期的百分比、细胞凋亡率和PTEN蛋白的表达水平均逐渐升高，而细胞在S期和G2/M期的百分比、miR-21的表达水平以及p-AKT蛋白的表达水平均逐渐降低，且与0 μg/ml相比，差异均有统计学意义（P<0.05），但HL-60细胞中AKT蛋白的表达水平与0 μg/ml组比较差异无统计学意义（P>0.05）。结论:芒柄花黄素可抑制白血病HL-60细胞增殖并诱导细胞凋亡，其作用机制可能与调控miR-21/PTEN/AKT信号通路有关。     

Reduction of PTEN protein and loss of epidermal growth factor receptor gene mutation in lung cancer with natural resistance to gefitinib (IRESSA)

Gefitinib (IRESSA), an epidermal growth factor receptor (EGFR) tyrosine kinase (TK) inhibitor, has antitumour activity in the advanced non-small-cell lung cancer (NSCLC) setting. However, in chemotherapy-naïve patients with advanced NSCLC, the addition of gefitinib to standard chemotherapy regimens failed to increase survival. These results suggest the need for improved patient selection and combination rationales for targeted therapies. We have identified subpopulations of an adenocarcinoma cell line that are naturally resistant to gefitinib, and have analysed the cDNA expression profiles, genomic status of EGFR gene and the effect of gefitinib on signalling pathways in these cell lines in order to identify key mechanisms for naturally acquired resistance to gefitinib. Gefitinib-resistant subpopulations demonstrated increased Akt phosphorylation (not inhibited by gefitinib), reduced PTEN protein expression and loss of the EGFR gene mutation when compared with parental cell lines. These differences in Akt and PTEN protein expression were not evident from the cDNA array profiles. These data suggests that (1) the EGFR gene mutation may be possibly lost in some cancer cells with other additional mechanisms for activating Akt, (2) reintroduction of PTEN or pharmacological downregulation of the constitutive PI3K–Akt-pathway activity may be an attractive therapeutic strategy in cancers with gefitinib resistance.