Proliferation rate but not mismatch repair affects the long-term response of colon carcinoma cells to 5FU treatment

Cisplatin (DDP) is widely used in lung cancer chemotherapy. However, cisplatin resistance represents a major obstacle in effective clinical treatment. This study aims to investigate whether Newcastle disease virus (NDV) exhibits an oncolytic effect on cisplatin-resistant A549 lung cancer cells. We found that NDV induced A549/DDP cell apoptosis via the caspase pathway, particularly involving caspase-9, while the mitogen-activated protein kinase (MAPK) and Akt pathways also contributed to apoptotic induction. Furthermore, NDV displayed oncolytic effects in a mouse A549/DDP lung cancer model. Collectively, our data indicate that NDV could overcome the cisplatin resistance in lung cancer cells in vitro and in vivo.     

Mitophagy promotes replication of oncolytic Newcastle disease virus by blocking intrinsic apoptosis in lung cancer cells

Apoptosis contributes to antitumor effect of Newcastle disease virus (NDV). Autophagy is a protective response under cellular stress including viral infection. How autophagy interferes with oncolysis of NDV remains unclear. In this study, we found that NDV La Sota strain induced autophagy and preserved autophagic flux in non-small cell lung cancer cells. NDV-induced autophagy promoted viral replication by blocking cancer cells from caspase-dependent apoptosis. Moreover, we found that NDV recruited SQSTM1-mediated mitophagy to control cytochrome c release, and thus blocked intrinsic pro-apoptotic signaling. Finally, we observed an enhanced oncolysis in NSCLC cells treated with NDV in the presence of an autophagy inhibitor 3-methyladenine (3-MA). Interestingly, a more profound antitumor effect could be achieved when administration of 3-MA was postponed to 24 h after NDV infection. Our findings unveil a novel way that NDV subverts mitophagy to favor its replication by blocking apoptosis, and provide rationale for systemic therapeutic cohort combining NDV with autophagy inhibitors in cancer therapy.     

miR-21调控非小细胞肺癌细胞增殖和凋亡的机制研究

目的 研究非小细胞肺癌(NSCLC)中高表达的miR-21对细胞增殖和凋亡的影响及其调控机制.方法 采用荧光定量聚合酶链反应检测miR-21在人NSCLC组织、癌旁组织和A549细胞系中的表达.通过序列分析预测被miR-21调控的抑癌基因,通过荧光素酶活性检测和Western blot 检测验证miR-21对靶基因表达调控的影响.采用RNA干扰技术抑制miR-21和程序性细胞死亡因子4(PDCD4),以台盼蓝染色和流式细胞术检测A549细胞增殖和凋亡的变化.结果 NSCLC组织和A549细胞中miR-21的表达水平分别为癌旁组织的2.24倍和3.06倍.序列预测和基因表达调控研究表明,miR-21可以在NSCLC中反向调控PDCD4的表达(P＜0.01).荧光素酶活性检测结果显示,共同转入Wt 3'UTR和miR-21会显著抑制A549细胞中的荧光素酶表达(P＜O.001).Western blot检测结果显示,导入反义寡核苷酸抑制miR-21的功能后,PDCD4的表达水平明显上升.抑制miR-21的作用可以显著抑制A549细胞的增殖,并使细胞凋亡率由2.6％上升到10.9％,而抑制PDCD4的表达可以在很大程度上消除miR-21介导的细胞增殖障碍,抑制细胞凋亡.结论 在NSCLC中,抑制抑癌基因PDCD4的表达可能是miR-21介导肿瘤细胞增殖、抵抗凋亡的重要途径之一.     

Oncolytic newcastle disease virus triggers cell death of lung cancer spheroids and is enhanced by pharmacological inhibition of autophagy

Lung cancer stem cells (CSCs) have recently been isolated from lung cancer patient samples and have been reported to be responsible for tumor initiation, treatment resistance and tumor recurrence. We have previously shown that oncolytic Newcastle disease virus (NDV), strain FMW (NDV/FMW) induces apoptosis in drug-resistant lung cancer cells. However, how NDV exerts its oncolytic effect on lung CSCs remains to be investigated. Here we show that NDV/FMW replicates in, and lyses CSC-enriched lung cancer spheroids and inhibits the 3D growth potential of lung cancer spheroid and agar colonies. We demonstrate that NDV/FMW triggers caspase-dependent apoptosis in lung cancer spheroids as shown by increased caspase-3 processing and Poly (ADP-ribose) polymerase (PARP) cleavage. Notably, NDV/FMW infection results in the degradation of microtubule-associated protein 1 light chain 3 (LC3) II and P62, two hallmarks of autophagy maturation, indicating that NDV/FMW promotes autophagy flux in lung cancer cell spheroids. This was further confirmed by the appearance of an increased number of double-membrane vesicles as detected by transmission electron microscopy. We also show that NDV/FMW promotes autophagy degradation in lung cancer spheroids via inhibition of the AKT/mTOR pathway. In addition, treatment of spheroids with the autophagy inhibitor, chloroquine increases NDV/FMW-induced cytotoxicity. Collectively, our data show that oncolytic NDV/FMW may be a potential strategy in targeting lung CSCs.     

Down-regulation of c-Met and Bcl2 by microRNA-206, activates apoptosis,and inhibits tumor cell proliferation,migration and colony formation

Hsa-miRNA-206 (miR-206), highly expressed in skeletal muscle, has recently been discovered to have anticancer properties in different tissues. However, the role of miR-206 on lung cancer is still ambiguous. In this study, we investigated the role of miR-206 on the development of lung cancer. The results indicated that miR-206 expression was suppressed in lung cancer tissues and very low levels were found in non-small cell lung cancer (NSCLS) cell liness. Transient transfection of miR-206 into cultured A549 and SK-MES-1 cells led to significant decrease in cell growth, migration, invasion and colony formation, and promoted cell apoptosis. Using bioinformatics, we identified putative miR-206 binding sites within the 3′-untranslated region (3′-UTR) of the human c-Met and Bcl2 mRNA. The expression of c-Met and Bcl2 proteins were shown to be down-regulated after treated with miR-206 by subsequent Western blot and qRT-PCR analysis. Conversely, up-regulation of c-Met and Bcl2 were confirmed in tissue samples of human lung cancer, with its level inversely correlated with miR-206 expression. In addition, miR-206 also decreased the gene expression of MMP-9, CCND1 and CCND2 while increased the gene expression of p57 (Kip2) in A549 and SK-MES-1 cells. Taken together, our results demonstrated that miR-206 suppressed c-Met and Bcl2 expression in NSCLS and could function as a potent tumor suppressor in c-Met/Bcl2-over expressing tumors. Inhibition of miR-206 function could contribute to aberrant cell proliferation, migration, invasion and apoptosis, leading to NSCLS development.     

p53 Cooperates berberine-induced growth inhibition and apoptosis of non-small cell human lung cancer cells in vitro and tumor xenograft growth in vivo

Berberine has been shown to have anti-carcinogenic effects. Since p53 is the most commonly mutated tumor suppressor gene, and a lack of functional p53 is associated with an increased risk of cancer development, we examined the effects of berberine on p53-positive and p53-deficient non-small cell human lung cancer cells in vitro and in vivo. Treatment of A549, which express wild-type p53, and H1299, which are p53-deficient, human lung cancer cells with berberine resulted in inhibition of cell proliferation and an increase in apoptotic cell death; however, A549 cells were more sensitive to the berberine-induced cytotoxic effects than H1299 cells. Further, the treatment of A549 cells with pifithrin-alpha, a specific inhibitor of p53, or transfection of A549 cells with a p53 antisense oligodeoxynucleotide resulted in a reduction in the berberine-induced inhibition of cell proliferation and apoptosis. The berberine-induced apoptosis of both the A549 and H1299 human lung cancer cells was associated with the disruption of mitochondrial membrane potential, reduction in the levels of Bcl-2, Bcl-xl while increase in Bax, Bak, and activation of caspase-3. Treatment of the cells with pan-caspase inhibitor (z-VAD-fmk) or caspase-3 inhibitor (z-DEVD-fmk) inhibited berberine-induced apoptosis, thus suggesting the role of caspase-3. Further, the administration of berberine by oral gavage inhibited the growth of s.c. A549 and H1299 lung tumor xenografts in athymic nude mice, however, the growth of tumor xenograft of H1299 cells was faster than A549 cells in mice and the chemotherapeutic effect of berberine was more pronounced in the p53-positive-A549 tumor xenograft than p53-deficient-H1299 tumor xenograft.     

Tumor-suppressive microRNA-449a induces growth arrest and senescence by targeting E2F3 in human lung cancer cells

MicroRNA-449a (miR-449a) was significantly downregulated in 156 lung cancer tissues (p < 0.001). We found that the low expression of miR-449a was highly correlated with cancer recurrence and survival of lung cancer patients. The transient introduction of miR-449a caused cell cycle arrest and cell senescence in A549 and 95D cells. Further studies revealed that E2F3 was a direct target of miR-449a in lung cancer cells. miR-449a also suppressed tumor formation in vivo in nude mice. These results suggest that miR-449a plays an important role in lung cancer tumorigenesis and that miR-449a might predict cancer recurrence and survival of lung cancer patients.     

MicroRNA-148b and microRNA-152 reactivate tumor suppressor genes through suppression of DNA methyltransferase-1 gene in pancreatic cancer cell lines

Overexpression of DNA methyltransferase 1 (DNMT-1) is observed mostly in pancreatic cancer and it can cause tumor suppressor genes silencing in this disease. Recent studies suggest that abnormal expressions of microRNAs (miRs) are involved in pathogenesis of different types of human cancers including pancreatic cancer. In this study we aimed to investigate the effect of miR-148b and -152 on reverting the tumorigenic phenotype of pancreatic cancer cell lines. In order to investigate whether miR-148b and -152 are involved in the regulation of DNMT-1, luciferase reporter assay was used and confirmed that the DNMT-1 mRNA could be a target for miR-148b and miR-152. Furthermore, overexpression of miR-148b and -152 in pancreatic cancer cell lines (MIA PaCa-2 and AsPC-1) decreased DNMT-1 expression (53% and 59% respectively), returned DNA methylation to normal patterns and induced re-expression of tumor suppressor genes, like BNIP3 (4.7- and 3.8-fold) and SPARC (5.3- and 2.9-fold) for miR-148b and -152 respectively. Moreover, the introduced miR-148b and -152 could inhibit the proliferation of MIA PaCa-2 (35% and 37% respectively) and AsPC-1 (39% and 40% respectively) cell lines. The apoptosis rates of MIA PaCa-1 after treatment with miR-148b and -152 were 10% and 8% respectively; while these rates in AsPC-1 were 16% and 11% respectively. Conclusively these findings mean that miRs that are targeting DNMT-1 and modifying methylation status of tumor suppressor genes such as BNIP3 and SPARC can be applied in killing the pancreatic cancer cells and decreasing the tumorigenicity of these cells.     

microRNA-145 suppresses lung adenocarcinoma-initiating cell proliferation by targeting OCT4

Recent studies demonstrated that microRNA-145 is downregulated in human cancer cells and may function as a tumor suppressor. However, its role in lung cancer tumorigenesis remains unclear. Here, we demonstrated that upregulation of miR-145 reduced the proliferation and invasion as well as the ratio of CD133-positive initiating cells and the tumorosphere growth capacity of the human lung adenocarcinoma A549 cell line. The direct targeting of miR-145 to OCT4 mRNA was predicted by bioinformatic analysis and validated by a luciferase reporter system. We, therefore, confirmed that miR-145 can impair the proliferation of human lung adenocarcinoma-initiating cells by targeting OCT4 and leads to inhibition of lung cancer development.     

MiRNA-1469 promotes lung cancer cells apoptosis through targeting STAT5a

MicroRNAs play key roles in cell growth, differentiation, and apoptosis. In this study, we described the regulation and function of miR-1469 in apoptosis of lung cancer cells (A549 and NCI-H1650). Expression analysis verified that miR-1469 expression significantly increased in apoptotic cells. Overexpression of miR-1469 in lung cancer cells increased cell apoptosis induced by etoposide. Additionally, we identified that Stat5a is a downstream target of miR-1469, which can bind directly to the 3’-untranslated region of the Stat5a, subsequently reducing both the mRNA and protein levels of Stat5a. Finally, co-expression of miR-1469 and Stat5a in A549 and NCI-H1650 cells partially abrogated the effect of miR-1469 on cell apoptosis. Our results show that miR-1469 functions as an apoptosis enhancer to regulate lung cancer apoptosis through targeting Stat5a and may become a critical therapeutic target in lung cancer.     

Antiproliferative effect of newcastle disease virus strain D90 on human lung cancer cell line A549

Newcastle disease virus (NDV) and variants of this virus have oncolytic properties and are potential anticancer agents. The objective of this study was to compare the effect of NDV strain D90 and strain D93 isolated from natural sources on human non-small cell lung cancer (NSCLC) cell line A549. We determined the 50% embryo infective dose (EID50) and 50% tissue culture infective dose (TCID50) of the NDV strains. The MTT assay was used to evaluate the effects of NDV strains on cell viability. We determined the expression of Annexin V and Bcl-2 proteins in NDV-infected cells. Light microscopy and electron microscopy indicated that the D90 strain significantly altered cell morphology and reduced cell viability, while strain D93 had negligible effects. Neither strain had a significant effect on normal cultured fetal liver cells. We used acridine orange staining to show that strain D90 (but not strain D93) induced nuclear fragmentation of A549 cells. An Annexin V-based apoptosis assay indicated that strain D90 (but not strain D93) caused significant apoptosis of A549 cells. Moreover, strain D90 (but not strain D93) significantly repressed the expression of Bcl-2 (an antiapoptotic protein) in A549 cells. Taken together, our results indicate that NDV strain D90 (but not strain D93) had no significant effect on normal cultured cells, but induced apoptosis of cultured NSCLC cells via a caspase-dependent pathway. These results suggest that NDV strain D90 has potential as an anticancer agent.     

Identification of the molecular function of tripartite motif containing 58 in human lung cancer

Lung cancer is a major public health problem worldwide, with a high associated incidence and mortality. In the present study, novel epigenetic signatures were identified through genome-wide DNA methylation microarrays. The results revealed that tripartite motif containing 58 (TRIM58), a potential tumor suppressor gene exhibited high methylation and low expression in lung cancer tissue samples compared with normal tissues. Receiver operating characteristic curve analysis demonstrated that TRIM58 may be a promising early diagnostic indicator of lung cancer. In addition, the present study analyzed the role of TRIM58 in tumorigenesis and development in lung cancer A549 cells. Wound healing assay and transwell migration assay were used to investigate cell migration, and flow cytometry analysis was used to detect apoptosis. Silencing TRIM58 accelerated the proliferation and migration of lung cancer cells. In contrast, the overexpression of TRIM58 significantly inhibited the proliferation and migration of lung cancer cells and promoted apoptosis. Gene set enrichment analysis revealed that TRIM58 expression was negatively correlated with MYC targets, G₂M checkpoints and the mTORC1 signaling pathway. These results of the present study suggested that TRIM58, a potential tumor suppressor gene may serve as a novel diagnostic biomarker and therapeutic target in human lung cancer.     

Upregulation of microRNA-451 increases cisplatin sensitivity of non-small cell lung cancer cell line (A549)

Background

Recently, miR-451 as a tumor suppressor has been reported in other studies. However, whether miR-451 can affect the sensitivity of non-small cell lung cancer (NSCLC) cells to cisplatin (DDP) remains unclear. The aim of this study is to evaluate the roles of miR-451 in the sensitivity of NSCLC cells to DDP.

Methods

Quantitative RT-PCR assay was performed to detect the expression of miR-451 in 10 pairs of NSCLC and noncancerous tissue samples. pcDNA-GW/EmGFP-miR-451 was stably transfected into NSCLC cell line (A549). Then, the effects of miR-451 upregulation on growth, colony formation and apoptosis of A549 cells were investigated. Finally, the effects of miR-451 upregulation on in vitro and in vivo sensitivity of A549 cells of DDP were also determined.

Results

The level of miR-451 expression in NSCLC tissues was significantly higher than that in corresponding noncancerous tissues. Ectopic overexpression of miR-451 could significantly inhibit growth and induce apoptosis of A549 cells. Moreover, ectopic overexpression of miR-451 could sensitize A549 cells to DDP possibly by increasing DDP-induced apoptosis which might be associated with the inactivation of Akt signaling pathway.

Conclusions

This study demonstrated for the first time that combination of DDP application with miR-451 upregulation might be a potential strategy for the treatment of human NSCLC.     

microRNA-130a在非小细胞肺癌中的表达和功能

目的:探讨microRNA-130a（miR-130a）在非小细胞肺癌中的表达情况,并对其功能和分子机制进行研究。方法:收集50例非小细胞肺癌肿瘤组织和相对应的正常肺组织,采用RT-PCR方法检测miR-130a的相对表达量,并分析其与临床病理资料的相关性。采用体外转染法将miR-130a抑制剂瞬时转染到A549细胞后,应用real-time PCR检测A549细胞中miR-130a的表达情况。CCK8实验检测细胞转染后的增殖变化。Western blot检测转染后细胞中Smad4的表达变化。结果:肺癌组织中miR-130a的表达水平明显高于正常肺组织（P<0.05）;miR-130a的表达水平与肿瘤大小、淋巴结转移和临床分期明显相关（P<0.05）。与对照组比较,A549细胞转染miR-130a抑制剂后miR-130a表达水平明显下调,细胞增殖率明显下降,差异具有统计学意义(P<0.05);转染miR-130a抑制剂后,肺癌细胞中Smad4的表达水平明显上调。结论:miR-130a在NSCLC组织中表达上调,可能部分通过下调Smad4的表达来促进肺癌细胞的增殖和转移。