POLO-LIKE KINASE1 GENE EXPRESSION AND ITS CLINICOPATHOLOGICAL SIGNIFICANCE IN GASTRIC CARCINOMA

Objective To clarify the polo-like kinasel （PLK1） expression in human gastric cancer tissue and its clinicopathological significance in gastric carcinoma. Methods PLK1 expression in 60 cancer tissues and their corresponding noncancerous tissues from gastric cancer patients was measured by both real-time quantitative RT-PCR and western blot assay, lmmunohistochemistry was used to detect PLK1 protein expression in eighty-nine paraffin-embedded samples. Results The PLK1 mRNA and protein expression level in the 60 fresh cancer tissues was significantly higher than that in noncancerous tissues （ P 〈 0. 0001, P = 0. 031 respectively）. In paraffin-embedded samples, apart from its increased expression level, PLK1 was found to be in both cytoplasm and nucleus, double-site location only occurred in poor-differentiated cancer, PLKI expression intensity was associated with tumor dif- ferentiation （ P = 0. 03）, invasion （ P = 0. 032 ）, TNM stage （ P = 0. 019） , ki67 expression （ P = 0. 011 ）. The patients with negative PLK1 expression had better survival rate than that with positive PLK1 expression （ P =0. 0292 ）. Conclusion PLK1 may have clinicopathological value in tumor diagnosis, and may become another new biomarker and therapeutic target for gastric cancer.     

过氧化氢对PC12细胞plk1基因表达的影响

目的 观察过氧化氢对体外培养的PC12细胞plk1基因表达的影响.方法 采用MTT法观察不同浓度过氧化氢对体外培养的PC12细胞作用6h后,对PC12细胞存活率的影响;Western-blot检测不同浓度过氧化氢作用后,PC12细胞plk1基因蛋白表达水平的变化.结果 与对照组比较,过氧化氢剂量依赖性降低PC12细胞的存活率,增强PC12细胞plk1基因蛋白的表达水平.结论 过氧化氢降低PC12细胞的增殖活力,其机制可能是通过增强Plk1蛋白表达水平来实现.     

Dual-target inhibitors of bromodomain-containing protein 4 (BRD4) in cancer therapy: Current situation and future directions

Bromodomain-containing protein 4 (BRD4) is emerging as a therapeutic target that acts synergistically with other targets of small-molecule drugs in cancer. Therefore, the discovery of potential new dual-target inhibitors of BRD4 may be a promising strategy for cancer therapy. In this review, we highlight a series of strategies to design therapeutic dual-target inhibitors of BRD4 that focus on the synergistic functions of this protein. Drug combinations that exploit synthetic lethality, protein–protein interactions, functional complementarity, and blocking of resistance mechanisms could ultimately overcome the barriers inherent to the development of BRD4 inhibitors as future cancer drugs.     

miR-183及MAPK1蛋白在非小细胞肺癌中的表达及其意义

目的探讨miR-183及丝裂原激活的蛋白激酶1（MAPKl）mRNA与蛋白在非小细胞肺癌（NSCLC）组织中的表达及意义。方法实时定量PCR方法检测NSCLC组织miR-183及MAPKlmRNA的表达水平,Westernblot方法检测NSCLC组织MAPKl蛋白表达;统计分析miR-183与MAPKl蛋白的相关性。结果miR-183在非小细胞肺癌组织中的表达量较癌旁组织明显降低（P〈0．01）,MAPKlmRNA与蛋白在癌组织中较癌旁组织表达明显增高（P〈0．05）;统计分析显示,miR-183表达与MAPKl表达呈显著地负相关关系。结论miR-183在NSCLC组织中低表达,与MAPKl表达呈显著负相关关系。     

Impaired up-regulation of polo-like kinase 2 in B-cell chronic lymphocytic leukaemia lymphocytes resistant to fludarabine and 2-chlorodeoxyadenosine: a potential marker of defective damage response

The functional evaluation of ataxia telangiectasia mutated (ATM) and p53 was recently developed in B-cell chronic lymphocytic leukaemia (B-CLL), a disease in which the response to DNA damage is frequently altered. We identified a novel biomarker of chemosensitivity based on the induction of DNA damage by the purine nucleoside analogues (PNA) fludarabine and 2-chlorodeoxyadenosine (CdA). Using genome-wide expression profiling, it was observed that, in chemosensitive samples, PNA predominantly increased the expression of p53-dependent genes, among which PLK2 was the most highly activated at early time points. Conversely, in chemoresistant samples, p53-dependent and PLK2 responses were abolished. Using a quantitative real time polymerase chain reaction, we confirmed that PNA dose- and time-dependently increased PLK2 expression in chemosensitive but not chemoresistant B-CLL samples. Analysis of a larger cohort of B-CLL patients showed that cytotoxicity induced by PNA correlated well with PLK2 mRNA induction. Interestingly, we observed that failure to up-regulate PLK2 following PNA and chemoresistance were not strictly correlated with structural alterations in the TP53 gene. In conclusion, we propose that testing PLK2 activation after a 24-h incubation with PNA could be used to investigate the functional integrity of DNA damage-response pathways in B-CLL cells, and predict clinical sensitivity to these drugs.     

Efficacy of the polo-like kinase inhibitor rigosertib,alone or in combination with Abelson tyrosine kinase inhibitors,against break point cluster region-c-Abelson-positive leukemia cells

The potency of Abelson (ABL) tyrosine kinase inhibitors (TKIs) against chronic myeloid leukemia (CML) has been demonstrated. However, ABL TKI resistance can develop. In this study, we investigated the efficacy of a combination therapy including rigosertib (ON 01910.Na), a polo-like kinase (PLK) and phosphoinositide 3-kinase (PI3K) inhibitor, and ABL TKIs. A 72-h rigosertib treatment was found to inhibit cell growth, induce apoptosis, reduce phosphorylation of the breakpoint cluster region-c (BCR)-ABL and its substrate Crk-L, and increase the activities of caspase 3 and poly (ADP-ribose) polymerase (PARP). This combination therapy also exerted a synergistic inhibitory effect on Philadelphia chromosome (Ph)-positive cell proliferation and reduced the phosphorylation of BCR-ABL and Crk-L while increasing that of cleaved PARP and the H2A.X histone. Rigosertib also potently inhibited the growth of ABL TKI-resistant cells, and cotreatment with ABL TKIs and rigosertib induced higher cytotoxicity. These results indicate that rigosertib treatment may be a powerful strategy against ABL TKI-resistant cells and could enhance the cytotoxic effects of ABL TKIs.     

Survival of primary,but not of cancer cells after combined Plk1-HDAC inhibition

In the current study we examined the combination of SAHA and SBE13 in cancer and non-cancer cells. HeLa cells displayed a synergistically reduced cell proliferation, which was much weaker in hTERT-RPE1 or NIH-3T3 cells. Cell cycle distribution differed in HeLa, hTERT-RPE1 and NIH-3T3 cells. SAHA-treated HeLa cells showed slightly increasing cell numbers in G2/M phase, but after combination with SBE13 strongly elevated cell numbers in G2/M and S phase, accompanied by decreasing G0/G1 percentages. hTERT-RPE1 and NIH-3T3 cells showed strongly enriched cell numbers in G0/G1 phase. Western blot and quantitative real time analyses revealed reduced Plk1 mRNA and protein in all cells. p21 protein was strongly induced in cancer, but not in non-cancer cells, corresponding to a different localization in immunofluorescence studies. Additionally, these revealed an abundantly present pRb protein in HeLa cells after any treatment but almost completely vanished pRb staining in treated hTERT-RPE1 cells. These differences could be approved in Western blots against Parp and Caspase 3, which were activated in HeLa, but not in hTERT-RPE1 cells. Thus, we observed for the first time a differential effect of cancer versus non-cancer cells after treatment with SAHA and SBE13, which might be due to the dual role of p21.     

碱性成纤维细胞生长因子经ERK信号通路抑制卵巢癌CAOV3细胞凋亡

目的:研究卵巢癌CAOV3细胞中碱性成纤维细胞生长因子(bFGF)经MEK/ERK1/2信号转导通路对CREB、Bcl-2表达以及对细胞凋亡的影响作用。方法:无血清饥饿诱导细胞凋亡。分为对照组、bFGF组、bFGF PD98059组。Annexin-EGFP/PI荧光双染法检测细胞凋亡。Western印迹法检测ERK1/2、CREB以及Bcl-2蛋白表达。RT-PCR法检测Bcl-2的mRNA表达。结果:bFGF可抑制无血清饥饿诱导的细胞凋亡;时效依赖性地诱导ERK1/2活性增高、刺激CREB磷酸化、促进Bcl-2的mRNA及蛋白表达增加。bFGF作用CAOV3细胞15 min时ERK1/2活性达高峰;45 min时CREB磷酸化达峰值;Bcl-2的mREN表达高峰为6h,8h时蛋白表达最高。MEK1抑制剂PD98059可抑制bFGF的上述作用。结论:bFGF可能通过激活MEK/ERK1/2/CREB/Bcl-2信号转导途径抑制卵巢癌CAOV3细胞凋亡。     

细胞外信号调节激酶1/2传导通路在不同发育阶段皮肤组织内的变化

为研究磷酸化细胞外信号调节激酶1/2（p-ERK1/2）、Ras和C-fos在不同发育阶段皮肤中的表达特征及其可能的生物学意义,用免疫组化技术检测这3种蛋白在8例胎儿皮肤和8例成人皮肤中的表达变化规律。结果发现,在胎儿发育初期,p-ERK1/2、Ras和C-fos蛋白表达较低,随着胎儿生长发育,这3种蛋白的阳性细胞率逐渐增大,在妊娠后期胎儿和成人皮肤组织中,3种蛋白的阳性细胞率明显高于妊娠早期胎儿皮肤（P<0.01）。p-ERK1/2、Ras和C-fos蛋白在不同发育阶段皮肤组织内都有表达,显示它们可能对皮肤的发生、结构和功能的维持以及损伤后修复十分重要。