Silencing of Rac3 Inhibits Proliferation and Induces Apoptosis of Human Lung Cancer Cells

Background: Rac3, a member of the Rac family of small guanosine triphosphatases (GTPases), regulatesa variety of cell functions, including the organization of the cytoskeleton, cell migration, and invasion.Overexpression of Rac3 has been reported in several human cancers. However, the role of Rac3 in lung cancer(LC) has not been determined in detail. The purpose of this study was to investigate the effect of silencing of Rac3expression in human LC cells and the consequences for cell survival. Materials and Methods: Lentivirus smallhairpin RNA (shRNA) interference techniques were utilized to knock down the Rac3 gene. Gene and proteinexpression was quantified by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting.LC cell apoptosis was examined by annexin V-APC /propidium iodide staining. Results: Efficient silencing ofRac3 strongly inhibited A549 cell proliferation and colony formation ability, and significantly decreased tumorgrowth. Moreover, flow cytometry analysis showed that knockdown of Rac3 led to G2/M phase cell cycle arrestas well as an excess accumulation of cells in the G1 and S phase. Conclusions: Thus, functional analysis usingshRNAs revealed a critical role for Rac3 in the tumor growth of LC cells. shRNA silencing of Rac3 could providean effective strategy to treat LC.     

Suppression of Cellular Apoptosis Susceptibility (CSE1L)Inhibits Proliferation and Induces Apoptosis in ColorectalCancer Cells

The cellular apoptosis susceptibility (CSE1L) gene has been demonstrated to regulate multiple cellularmechanisms including the mitotic spindle check point as well as proliferation and apoptosis. However, theimportance of CSE1L in human colon cancer is largely unknown. In the present study, we examined expressionlevels of CSE1L mRNA by semiquantitative RT-PCR. A lentivirus-mediated small interfering RNA (siRNA)was used to knock down CSE1L expression in the human colon cancer cell line RKO. Changes in CSE1L targetgene expression were determined by RT-PCR. Cell proliferation was examined by a high content screeningassay. In vitro tumorigenesis was measured by colony-formation assay. Cell cycle distribution and apoptosiswere detected by flow cytometric analysis. We found CSE1L mRNA to be expressed in human colon cancer cells.Using a lentivirus based RNAi approach, CSE1L expression was significantly inhibited in RKO cells, causingcell cycle arrest in the G2/M and S phases and a delay in cell proliferation, as well as induction of apoptosisand an inhibition of colony growth capacity. Collectively, the results suggest that silencing of CSE1L may be apotential therapeutic approach for colon cancer.     

Inactivated Sendai Virus Strain Tianjin Induces Apoptosis in Human Breast Cancer MDA-MB-231 Cells

Sendai virus strain Tianjin is a novel genotype. Here, we investigate the antitumor and proapoptotic effects of ultraviolet-inactivated Sendai virus strain Tianjin (UV-Tianjin) on human breast cancer MDA-MB-231 cells in vitro, as well as the involvement of the apoptotic pathway in the mechanism of UV-Tianjin-induced antitumor effects. MTT assays showed that treatment with UV-Tianjin dose-dependently inhibited the proliferation of MDAMB-231 cells but not normal MCF 10A breast epithelium cells. Hoechst staining and flow cytometric analysis revealed that UV-Tianjin induced apoptosis of MDA-MB-231 cells in a dose-dependent manner. Moreover, UV-Tianjin treatment resulted in reduction in the mitochondria membrane potential (MMP) and release of cytochrome complex (cyt c) via regulation of Bax and Bcl-2, as well as activation of caspase-9, caspase-3, Fas, FasL and caspase-8 in MDA-MB-231 cells. In summary, our study suggests that UV-Tianjin exhibits anticancer activity in human breast cancer MDA-MB-231 cells through inducing apoptosis, which may involve both the endogenous mitochondrial and exogenous death receptor pathways.     

Chalcone-3 Inhibits the Proliferation of Human Breast Cancer MDA-MB-231 Cell Line

Objective: Chalcone-3 has been shown to be cytotoxic and selective against luminal subtype breast cancer cell lines, which are suspected to occur through the mechanism of epidermal growth factor receptors (EGFR) inhibition. However, the cytotoxic effect has never been tested on cell strains from patients with triple negative breast cancer (TNBC), where EGFR expression is known to increase. This study aimed to identify the role of chalcone-3 in one of the downstream targets of EGFR as an antiproliferative agent. Methods: Chalcone-3 was examined for its effect on proliferation in human breast cancer MDA-MB-231 cell lines. The percentage of proliferation inhibition was analyzed using methyl-thiazol tetrazolium assay. Flow cytometry was used to analyze the population of cell cycle distribution and the expression of cyclin-D1 and pEGFR. Results: Chalcone-3 inhibited the proliferation of MDA-MB-231 cells in a dose and time-dependent manner with an IC50 value of 17.98±6.36 µg/mL by inducing cell cycle arrest at the G2/M phase. Flow cytometry assays showed that chalcone-3 significantly reduced the expression of pEGFR and cyclin-D1, contributing to cell cycle arrest. Conclusion: Chalcone-3 might have potential as an anti-proliferative drug to treat TNBC.     

PRKAA1 Promotes Proliferation and Inhibits Apoptosis of Gastric Cancer Cells Through Activating JNK1 and Akt Pathways

PRKAA1 (protein kinase AMP-activated catalytic subunit 1) is a catalytic subunit of AMP-activated protein kinase (AMPK), which plays a key role in regulating cellular energy metabolism through phosphorylation, and genetic variations in the PRKAA1 have been found to be associated with gastric cancer risk. However, the effect and underlying molecular mechanism of PRKAA1 on gastric cancer tumorigenesis, especially the proliferation and apoptosis, are not fully understood. Our data showed that PRKAA1 is highly expressed in BGC- 823 and MKN45 cells and is expressed low in SGC-7901 and MGC-803 cells in comparison with the other gastric cancer cells. PRKAA1 downregulation by shRNA or treatment of AMPK inhibitor compound C significantly inhibited proliferation as well as promoted cell cycle arrest and apoptosis of BGC-823 and MKN45 cells. Moreover, the expression of PCNA and Bcl-2 and the activity of JNK1 and Akt signaling were also reduced in BGC-823 and MKN45 cells after PRKAA1 downregulation. In vivo experiments demonstrated that tumor growth in nude mice was significantly inhibited after PRKAA1 silencing. Importantly, inactivation of JNK1 or Akt signaling pathway significantly inhibited PRKAA1 overexpression-induced increased cell proliferation and decreased cell apoptosis in MGC-803 cells. In conclusion, our findings suggest that PRKAA1 increases proliferation and restrains apoptosis of gastric cancer cells through activating JNK1 and Akt pathways.     

Silibinin Inhibits Proliferation,Induces Apoptosis and Causes Cell Cycle Arrest in Human Gastric Cancer MGC803 Cells Via STAT3 Pathway Inhibition

Background: To investigate the effect of silibinin on proliferation and apoptosis in human gastric cancer cell line MGC803 and its possible mechanisms. Materials and Methods: Human gastric cancer cell line MGC803 cells were treated with various concentration of silibinin. Cellular viability was assessed by CCK-8 assayandapoptosis and cell cycle distribution by flow cytometry. Protein expression and mRNA of STAT3, and cell cycle and apoptosis regulated genes were detected by Western blotting and real-time polymerase chain reaction, respectively. Results: Silibinin inhibits growth of MGC803 cells in a dose- and time-dependent manner. Silibinin effectively induces apoptosis of MGC803 cells and arrests MGC803 cells in the G2/M phase of the cell cycle, while decreasing the protein expression of p-STAT3, and of STAT3 downstream target genes including Mcl-1, Bcl-xL, survivin at both protein and mRNA levels. In addition, silibinin caused an increase in caspase 3 and caspase 9 protein as well as mRNA levels. Silibinin caused G2/M phage arrest accompanied by a decrease inCDK1 and Cyclin B1 at protein and mRNA levels.. Conclusions: These results suggest that silibinin inhibits the proliferation of MGC803 cells, and it induces apoptosis and causes cell cycle arrest by down-regulating CDK1, cyclinB1, survivin, Bcl-xl, Mcl-1 and activating caspase 3 and caspase 9, potentially via the STAT3 pathway.     

阿帕替尼通过抑制糖酵解途径对乳腺癌MDA-MB-231细胞增殖抑制及凋亡的作用

 目的 探讨阿帕替尼体外水平抗乳腺癌作用及其机制。方法 采用CCK-8法检测阿帕替尼对乳腺癌MDA-MB-231细胞的增殖抑制作用；采用Annexin V-FITC/PI凋亡检测试剂盒检测阿帕替尼对乳腺癌MDA-MB-231细胞凋亡的影响；采用乳酸含量检测试剂盒检测阿帕替尼对乳腺癌MDA-MB-231细胞内乳酸产量的影响；采用糖酵解压力试剂盒检测阿帕替尼对乳腺癌细胞MDA-MB-231细胞外酸化速率的影响。结果 阿帕替尼可浓度依赖性地抑制乳腺癌MDA-MB-231细胞体外增殖（P<0.05），作用48 h的半数抑制浓度IC₅₀为1.56 μmol/L；阿帕替尼可浓度依赖性地诱导MDA-MB-231细胞凋亡（P<0.05）；阿帕替尼可浓度依赖性地抑制MDA-MB-231细胞内乳酸产量（P<0.05）；阿帕替尼干预可抑制MDA-MB-231细胞的糖酵解能力值及糖酵解保留值，降低MDA-MB-231细胞外酸化速率（P<0.05）。结论 阿帕替尼可能通过抑制乳腺癌MDA-MB-231细胞的有氧糖酵解效应，进而诱导其凋亡。     

ALEX1 Regulates Proliferation and Apoptosis in Breast Cancer Cells

Background: Arm protein lost in epithelial cancers, on chromosome X (ALEX) is a novel subgroup withinthe armadillo (ARM) family, which has one or two ARM repeat domains as opposed to more than six-thirteenrepeats in the classical Armadillo family members. Materials and Methods: In the study, we explore the biologicalfunctions of ALEX1 in breast cancer cells. Overexpression of ALEX1 and silencing of ALEX1 were performedwith SK-BR3 and MCF-7 cell lines. Cell proliferation and colony formation assays, along with flow cytometry,were carried out to evaluate the roles of ALEX1. Results: ALEX1 overexpression in SK-BR3 breast cancer cellsinhibited proliferation and induced apoptosis. Furthermore, depletion of ALEX1 in MCF-7 breast cancer cellsincreased proliferation and inhibited apoptosis. Additional analyses demonstrated that the overexpression ofALEX1 activated the intrinsic apoptosis cascades through up-regulating the expression of Bax, cytosol cytochromec, active caspase-9 and active caspase-3 and down-regulating the levels of Bcl-2 and mitochondria cytochrome c.Simultaneouly, silencing of ALEX1 inhibited intrinsic apoptosis cascades through down-regulating the expressionof Bax, cytosol cytochrome c, active caspase-9, and active caspase-3 and up-regulating the level of Bcl-2 andmitochondria cytochrome c. Conclusions: Our data suggest that ALEX1 as a crucial tumor suppressor genehas been involved in cell proliferation and apoptosis in breast cancer, which may serve as a novel candidatetherapeutic target.     

A Novel All-trans Retinoid Acid Derivative Induces Apoptosis in MDA-MB-231 Breast Cancer Cells

Aims: To explore the effect and probable mechanism of a synthetic retinoid 4-amino-2-tri-fluoromethylphenylester (ATPR) on apoptosis of MDA-MB-231 breast cancer cells. Materials and Methods: MTT assayswere performed to measure the proliferation of MDA-MB-231 cells treated with different concentrations of alltransretinoic acid (ATRA) and ATPR. Morphologic changes were observed by microscopy. The apoptosis ratesand cell cycling of MDA-MB-231 cells treated with ATRA or ATPR were assessed using flow cytometry analysis.Expression of retinoic acid receptor and phosphorylation of ERK, JNK, p38 proteins were detected by Westernblotting. Results: Treatment of the cells with the addition of 15 μmol/L ATPR for 48 h clearly demonstratedreduced cell numbers and deformed cells, whereas no changes in the number and morphology were observedafter treatment with ATRA. The apoptosis rate was 33.2% after breast cancer MDA-MB-231 cells were treatedby ATPR (15 μmol/L) whereas ATRA (15 μmol/L) had no apoptotic effect. ATPR inhibited the phosphorylationof ERK, JNK, and p38 while ATRA had no significant effect. ATPR inhibited the expression of BiP and increasedthe expression of Chop at the protein level compared with control groups, ATRA and ATPR both decreasedthe protein expression of RXR α, ATPR reduced the protein expression of RARβ and RXRβ while ATRA didnot decrease RARβ or RXRβ. Conclusions: ATPR could induce apoptosis of breast cancer MDA-MB-231 cells,possible mechanisms being binding to RARβ/RXRβ heterodimers, then activation of ER stress involving theMAPK pathway.     

小檗碱通过调控IGF-1R信号通路抑制食管癌细胞增殖和诱导细胞凋亡的实验

目的 检测小檗碱对食管癌细胞增殖、周期和凋亡的影响,并探讨其作用机制。 方法 MTT法检测细胞的增殖抑制作用;碘化丙啶（Propidium iodide, PI）染色法检测细胞周期进程;Annexin V-FITC和PI双染法结合流式细胞技术检测小檗碱的凋亡诱导作用;Western blot技术检测小檗碱对胰岛素样生长因子1受体（IGF-1R）的活化及下游主要信号分子AKT和p44/42MAPK（ERK）磷酸化水平的影响。结果 小檗碱在体外可浓度依赖性地抑制四种食管癌细胞系的增殖,且其IC50值与细胞表面IGF-1R的表达水平呈负相关。小檗碱可使细胞阻滞在G₂/M期。细胞凋亡实验结果显示,小檗碱可浓度依赖性地诱导食管癌细胞发生凋亡,并且在相同浓度下KYSE450细胞（IGF-1R高表达）的凋亡率显著高于KYSE150细胞（IGF-1R低表达）。Western blot结果显示,小檗碱处理可显著抑制IGF-1R的磷酸化,并抑制AKT和ERK的活化,且抑制作用随着小檗碱浓度的增加而增强。结论 小檗碱可通过对IGF-1R及其介导的下游信号通路的调控来发挥抑制食管癌细胞增殖、阻断细胞周期进程以及诱导食管癌细胞凋亡的作用。     

SCD1抑制剂对乳腺癌细胞增殖凋亡的影响及其机制

目的 检测硬脂酰辅酶A去饱和酶1（stearoyl-CoA desaturase 1, SCD1）在乳腺癌组织中的表达,分析抑制SCD1的活性对乳腺癌MCF-7细胞增殖凋亡的影响及其机制。方法 采用免疫组织化学法检测乳腺癌及癌旁正常组织中SCD1蛋白的表达。应用MTS法测定SCD1抑制剂MF-438对MCF-7细胞增殖的抑制率。应用Hoechst33342染色荧光显微镜观察细胞形态并计算凋亡指数,PI染色流式细胞术检测细胞凋亡率。蛋白质印迹法检测凋亡相关蛋白Bcl-2和Bax的表达。结果 乳腺癌组织中SCD1阳性表达率显著高于正常乳腺组织（P<0.05）,并且三阴性乳腺癌中的SCD1表达水平低于其他亚型（P<0.05）。MF-438在0.1~100 μmol/L浓度范围内,对MCF-7细胞显示出显著的剂量依赖性的增殖抑制作用,并在低血清条件下更为敏感。MCF-7细胞在5 μmol/L MF-438作用48 h后,表现出典型的细胞凋亡特征性变化,细胞凋亡指数及细胞凋亡率显著高于对照组（P<0.05）;同时,MF-438下调MCF-7细胞抑凋亡蛋白Bcl-2的表达,并上调促凋亡蛋白Bax的表达。结论 抑制SCD1能抑制乳腺癌细胞增殖并诱导凋亡,对SCD1的深入研究将有望为乳腺癌的分子靶向治疗提供一个新的靶标。     

MicroRNA 495 Inhibits Proliferation and Metastasis and Promotes Apoptosis by Targeting Twist1 in Gastric Cancer Cells

Recently, microRNAs (miRNAs) have been reported to participate in multiple biological processes. However, the effects of miR-495 on gastric cancer (GC) remain unclear. The purpose of this study was to explore the functions of miR-495 in GC cell proliferation, metastasis, and apoptosis. SGC-7901 and BGC-823 cell lines were transfected with miR-495 mimic, miR-495 inhibitor, and negative controls (mimic control and inhibitor control). The expressions of miR-495, cell viability, migration, apoptosis, and apoptosis-related factors were examined by qRT-PCR, trypan blue staining, Transwell, flow cytometry, and Western blot, respectively. Simultaneously, key factor expression levels of EMT were detected by qRT-PCR and Western blot. The direct target of miR-495 was confirmed by dual-luciferase assay. Additionally, sh-Twist1, pc-Twist1, and corresponding controls were transfected into SGC-7901 and BGC-823 cells, and the protein levels of EMTassociated factors were detected by Western blot. miR-495 was downregulated in GC cells. miR-495 expression level was effectively overexpressed or suppressed in SGC-7901 and BGC-823 cells. Overexpression of miR-495 significantly decreased cell viability and migration, increased apoptosis, and inhibited the EMT process. Suppression of miR-495 showed contrary results. Twist1 was clarified as a target gene of miR-495, and Twist1 silencing obviously reduced the promoting effect of miR-495 suppression on these biological processes. Twist1 silencing significantly blocked the EMT process in both SGC-7901 and BGC-823 cells. miR-495 inhibited proliferation and metastasis and promoted apoptosis by targeting Twist1 in GC cells. These data indicated that miR-495 might be a novel antitumor factor of GC and provide a new method for the treatment of GC.     

GRP78 Secreted by Colon Cancer Cells Facilitates Cell Proliferation via PI3K/Akt Signaling

Glucose regulated protein 78 (GRP78) is usually recognized as a chaperone in the endoplasmic reticulum. However, increasing evidence indicates that GRP78 can be translocated to the cell surface, acting as a signaling receptor for a variety of ligands. Since little is known about the secretion of GRP78 and its role in the progression of colon cancer we here focused on GRP78 from colon cancer cells, and purified GRP78 protein mimicking the secreted GRP78 was able to utilize cell surface GRP78 as its receptor, activating downstream PI3K/Akt and Wnt/β-catenin signaling and promote colon cancer cell proliferation. Our study revealed a new mode of action of autocrine GRP78 in cancer progression: secreted GRP78 binds to cell surface GRP78 as its receptor and activates intracellular proliferation signaling.     

川芎嗪对乳腺癌细胞株MDA-MB-231增殖及凋亡的影响

[目的]评价川芎嗪对MDA-MB-231细胞增殖和凋亡的影响。[方法]以体外培养的乳腺癌细胞株MDA-MB-231为研究对象,MTT法检测川芎嗪对MDA-MB-231细胞的增殖作用,流式细胞仪检测川芎嗪对MDA-MB-231细胞周期的影响,PI单染流式细胞仪检测川芎嗪对MDA-MB-231细胞凋亡的影响。[结果]不同浓度川芎嗪能有效地抑制MDA-MB-231细胞增殖,且随浓度增加和作用时间延长,细胞的增殖抑制率增加。0.50、1.00、1.50mg/ml的川芎嗪作用MDA-MB-231细胞48h,G0/G1期细胞所占细胞周期的比例分别为54.71%±3.83%、64.17%±4.01%和75.06%±4.32%;而对照组G0/G1期比例为40.95%±5.89%。0.50、1.00、1.50mg/ml川芎嗪处理48h后细胞的凋亡率分别为6.59%±2.90%、14.85%±3.41%和22.22%±2.98%。[结论]川芎嗪能抑制MDA-MB-231细胞的体外增殖,且抑制作用表现出时效和量效关系;并能通过阻滞细胞周期于G0/G1期,抑制乳腺癌细胞凋亡。