Molecular genetics of lung cancer

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.

Single nucleotide polymorphisms of MAGE-A3 gene and its clinical implications in Chinese patients with non-small cell lung cancer (NSCLC)

BACKGROUND

Available study revealed advanced tumors have a higher expression rate of MAGE-A3 gene which has a lot of single nucleotide polymorphism (SNP) loci with polymorphisms. This study aimed to analyze the allele frequency of SNP loci in MAGE-A3 gene and investigate the relationship between MAGE-A3 gene polymorphisms and clinical factors.

METHODS

Tumor samples of a cohort of 191 NSCLC patients were collected. EGFR mRNA expression were detected by qRT-PCR. SNPs in whole length of MAGE-A3 gene were detected by direct sequencing. Frequencies of the SNPs were correlated to gene expression, mutation status of EGFR and clinical factors.

RESULTS

Sequencing analysis confirmed that allele frequencies of genotypes on SNP loci rs5970360, rs5925210, rs5970361, rs5925211 and rs35123853 were CC (0.681)/CT (0.319), CC (0.660)/CG (0.340), CC (0.681)/CA (0.319), AA (0.984)/AT (0.016) and GG (1.000)/GA (0.000), respectively, which were different from the frequencies and genotypes of MAGE-A3 in SNP database. Chi-square tests showed the EGFR mRNA expression level had significant correlation with the genotypes of SNP loci rs5970360 and rs5925210. But all frequencies of each MAGE-A3 SNPs were not found significantly different between EGFR mutant and wild type patients. MAGE-A3 gene polymorphisms had no significant effects on survival of NSCLC patients.

CONCLUSIONS

Chinese patients with NSCLC had different SNP patterns of MAGE-A3 in comparison with those in international SNP database. These MAGE-A3 SNP loci might have not prognostic significance. MAGE-A3 SNP loci rs5970360 and rs5925210 might be predictive for EGFR mRNA expression levels and helpful to the selection of patients for epidermal growth factor receptor (EGFR) targeted immunotherapy.

Mining featured micro ribonucleic acids associated with lung cancer based on bioinformatics

Background

Few genetic markers useful for the screening of lung cancer risk exist. Although related research has shown that certain expression profiles of micro ribonucleic acids (miRNAs) are different in lung cancer versus the normal lung, such as miR-29a and miR-29s, the precise molecular mechanism of lung cancer remains obscure. In order to get a better understanding of the pathogenetic mechanism of lung cancer, we analyzed the differentially expressed genes (DEGs) and identified featured miRNAs in lung cancer tissues.

Methods

We used the gene expression profile GSE10072, including 49 gene chips of non-tumor tissues and 58 gene chips of lung tumor specimens. The DEGs between these two groups were identified by Limma package in R language. The TarBase database was used to construct the networks of miRNA regulating DEGs related to lung cancer. After ordering miRNAs regulating DEGs, we further screened featured miRNAs combined with the miR2Disease database.

Results

A total of 5572 DEGs were obtained between lung cancer and control specimens. After constructing a miRNA regulatory network, a total of 398 regulations between 57 miRNAs and 321 target genes existed. By intergrating the miR2Disease database and using a sorting algorithm, a total of six featured miRNAs related to lung cancer were identified, including miR-520h, miR-133a, miR-34, miR-103, miR-370, and miR-148. They might be involved in lung cancer progression by regulating ABCG2, PKM2, VAMP2, GPD1, MAP3K8, and DNMT3B, respectively.

Conclusion

The top 10 significant miRNAs, such as miR-520h, miR-133a, miR-34, and miR-103 may be potential therapeutic targets for lung cancer.

The comparison between dual inhibition of mTOR with MAPK and PI3K signaling pathways in KRAS mutant NSCLC cell lines

KRAS mutations are found in 15-25 % of patients with lung adenocarcinoma, and they lead to constitutive activation of KRAS signaling pathway that results in sustained cell proliferation. Currently, there are no direct anti-KRAS therapies available. Therefore, it is rational to target the downstream molecules of KRAS signaling pathway, which are mitogen-activated protein kinase (MAPK) signaling pathway (RAF-MEK-ERK) and PI3K pathway (PI3K-AKT-mTOR). Here, we examined the inhibition of both these pathways alone and in combination and analyzed the anti-proliferative and apoptotic events in KRAS mutant NSCLC cell lines, A549 and Calu-1. Cytotoxicity was determined by MTT assay after the cells were treated with LY294002 (PI3K inhibitor), U0126 (MEK inhibitor), and RAD001 (mTOR inhibitor) for 24 and 48 h. The expression levels of p-ERK, ERK, AKT, p-AKT, p53, cyclinD1, c-myc, p27(kip1), BAX, BIM, and GAPDH were detected by western blot after 6 and 24 h treatment. Although PI3K/mTOR inhibition is more effective in cytotoxicity in A549 and Calu-1 cells, MEK/mTOR inhibition markedly decreases cell proliferation protein marker expressions. Our data show that combined targeting of MEK and PI3K-AKT with mTOR is a better option than single agents alone for KRAS mutant NSCLC, thus opening the possibility of a beneficial treatment strategy in the future.

An in silico analytical study of lung cancer and smokers datasets from gene expression omnibus (GEO) for prediction of differentially expressed genes

Smoking is the leading cause of lung cancer development and several genes have been identified as potential biomarker for lungs cancer. Contributing to the present scientific knowledge of biomarkers for lung cancer two different data sets, i.e. GDS3257 and GDS3054 were downloaded from NCBI׳s GEO database and normalized by RMA and GRMA packages (Bioconductor). Diffrentially expressed genes were extracted by using and were R (3.1.2); DAVID online tool was used for gene annotation and GENE MANIA tool was used for construction of gene regulatory network. Nine smoking independent gene were found whereas average expressions of those genes were almost similar in both the datasets. Five genes among them were found to be associated with cancer subtypes. Thirty smoking specific genes were identified; among those genes eight were associated with cancer sub types. GPR110, IL1RN and HSP90AA1 were found directly associated with lung cancer. SEMA6A differentially expresses in only non-smoking lung cancer samples. FLG is differentially expressed smoking specific gene and is related to onset of various cancer subtypes. Functional annotation and network analysis revealed that FLG participates in various epidermal tissue developmental processes and is co-expressed with other genes. Lung tissues are epidermal tissues and thus it suggests that alteration in FLG may cause lung cancer. We conclude that smoking alters expression of several genes and associated biological pathways during development of lung cancers.

Elucidation of changes in molecular signalling leading to increased cellular transformation in oncogenically progressed human bronchial epithelial cells exposed to radiations of increasing LET

The early transcriptional response and subsequent induction of anchorage-independent growth after exposure to particles of high Z and energy (HZE) as well as γ-rays were examined in human bronchial epithelial cells (HBEC3KT) immortalised without viral oncogenes and an isogenic variant cell line whose p53 expression was suppressed but that expressed an active mutant K-RAS(V12) (HBEC3KT-P53KRAS). Cell survival following irradiation showed that HBEC3KT-P53KRAS cells were more radioresistant than HBEC3KT cells irrespective of the radiation species. In addition, radiation enhanced the ability of the surviving HBEC3KT-P53RAS cells but not the surviving HBEC3KT cells to grow in anchorage-independent fashion (soft agar colony formation). HZE particle irradiation was far more efficient than γ-rays at rendering HBEC3KT-P53RAS cells permissive for soft agar growth. Gene expression profiles after radiation showed that the molecular response to radiation for HBEC3KT-P53RAS, similar to that for HBEC3KT cells, varies with radiation quality. Several pathways associated with anchorage independent growth, including the HIF-1α, mTOR, IGF-1, RhoA and ERK/MAPK pathways, were over-represented in the irradiated HBEC3KT-P53RAS cells compared to parental HBEC3KT cells. These results suggest that oncogenically progressed human lung epithelial cells are at greater risk for cellular transformation and carcinogenic risk after ionising radiation, but particularly so after HZE radiations. These results have implication for: (i) terrestrial radiation and suggests the possibility of enhanced carcinogenic risk from diagnostic CT screens used for early lung cancer detection; (ii) enhanced carcinogenic risk from heavy particles used in radiotherapy; and (iii) for space radiation, raising the possibility that astronauts harbouring epithelial regions of dysplasia or hyperplasia within the lung that contain oncogenic changes, may have a greater risk for lung cancers based upon their exposure to heavy particles present in the deep space environment.

Pathway crosstalk analysis of high-metastasis lung cancer cells

BACKGROUND

The aim of this study was to investigate the important role of pathway crosstalk and pathway dysfunction in the high-metastasis process of lung cancer cells, by using the microarray expression profiles of lung cancer cells at different metastasis levels.

METHODS

The gene expression profile GSE10096 was downloaded from the Gene Expression Omnibus database, including 4 nonmetastasis samples, 3 low-metastasis samples (M1) and 3 high-metastasis samples (M5) of lung cancer cells. After the conversion from probe level to expression values using Jetset, the data were identified by limma package in R language to screen differentially expressed genes (DEGs). The pathways of DEGs were further enriched by the Kyoto Encyclopedia of Genes and Genomes (KEGG). A protein-protein interaction (PPI) network of genes related to the core pathway (pathway in cancer) and its neighbor pathways was constructed. Based on the PPI network, significantly changed pathway crosstalk and pathways were analyzed.

RESULTS

Compared with those in the M1 lung cancer cells, the pathways hsa00564 (glycerophospholipid metabolism) and hsa0098 (metabolism of xenobiotics by cytochrome P450) of the M5 lung cancer cells showed significant functional changes. The dysfunction of pathway crosstalk mainly occurred between pathways hsa0098 and hsa04916 (melanogenesis pathway) and other pathways.

CONCLUSIONS

The results of our analysis indicate the significance of pathway crosstalk dysfunction and pathway dysfunction of M1 and M5 lung cancer cells as shown by bioinformatics methods. The present findings have the potential to lead to the study of the mechanisms of lung cancer in future.

Nuciferine, extracted from Nelumbo nucifera Gaertn, inhibits tumor-promoting effect of nicotine involving Wnt/β-catenin signaling in non-small cell lung cancer

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Nelumbo nucifera Gaertn are recorded in the earliest written documentation of traditional Chinese medicinal as "Ben Cao Gang Mu", a medicinal herb for blood clotting, dysentery and dizziness. Recently, nuciferine (NF), one of N. nucifera Gaertn leaf extracts has been shown to possess several pharmacological properties, including anti-viral and anti-cancer. The aim of this study is to investigate the underlying molecular mechanism of the anti-cancer activity of NF in NSCLC progression induced by nicotine

MATERIALS AND METHODS

The effect of NF on proliferation of A549 (human lung adenocarcinoma epithelial cell line) pretreated with or without nicotine was detected by tumor cell proliferation assay. TOP-Flash reporter assay was applied to investigate the activity of Wnt/β-catenin signaling in tumor cells in the presence of NF and/or nicotine. Apoptosis was measured using a FITC-Annexin V and PI detection kit by flow cytometry. In addition, mRNA or protein expression levels were respectively tested by quantitative RT-PCR or western blot. In vivo experiments, tumor samples were fixed in formalin and embedded in paraffin for additional analyses by immunohistochemistry and TUNEL staining.

RESULTS

NF significantly inhibited the proliferation of NSCLC cells in the presence of nicotine, suppressed the activity of Wnt/β-catenin signaling, enhanced the stabilization of Axin, and induced apoptosis. NF down-regulated the expression levels of β-catenin and its downstream targets including c-myc, cyclin D and VEGF-A. NF also decreased the ratio of Bcl-2/Bax, which may explain the pro-apoptosis effect of NF. In tumor xenograft nude mice, NF not only inhibited the growth of non-small cell lung cancer (NSCLC) cells, but also remarkably alleviated the injury induced by nicotine in liver function.

CONCLUSIONS

NF has the remarkable effect to inhibit nicotine-induced NSCLC progression, which was due to its ability to reduce the activity of Wnt/β-catenin signaling. Thus, the work stated here emphasizes the importance of this traditional medicine and presents a potential novel alternative to NSCLC prevention and therapy.

Combinatorial Action of MicroRNAs let-7 and miR-34 Effectively Synergizes with Erlotinib to Suppress Non-small Cell Lung Cancer Cell Proliferation

Lung cancer represents the leading cause of cancer-related deaths in men and women worldwide. Targeted therapeutics, including the epidermal growth factor receptor (EGFR) inhibitor erlotinib, have recently emerged as clinical alternatives for the treatment of non-small cell lung cancer (NSCLC). However, the development of therapeutic resistance is a major challenge, resulting in low 5-year survival rates. Due to their ability to act as tumor suppressors, microRNAs (miRNAs) are attractive candidates as adjuvant therapeutics for the treatment of NSCLC. In this study, we examine the ability of 2 tumor suppressor miRNAs, let-7b and miR-34a to sensitize KRAS;TP53 mutant non-small cell lung cancer cells to the action of erlotinib. Treatment with these miRNAs, individually or in combination, resulted in synergistic potentiation of the anti-proliferative effects of erlotinib. This effect was observed over a wide range of miRNA and erlotinib interactions, suggesting that let-7b and miR-34a target oncogenic pathways beyond those inhibited by EGFR. Combinatorial treatment with let-7b and miR-34a resulted in the strongest synergy with erlotinib, indicating that these miRNAs can effectively target multiple cellular pathways involved in cancer cell proliferation and resistance to erlotinib. Together, our findings indicate that NSCLC cells can be effectively sensitized to erlotinib by supplementation with tumor suppressor miRNAs, and suggest that the use of combinations of miRNAs as adjuvant therapeutics for the treatment of lung cancer is a viable clinical strategy.

Cell Free EGFR mRNA Expression and Implications for Survival and Metastasis in Non-Small Cell Lung Cancer Cases

BACKGROUND

NSCLC is a disease involving uncontrolled cell growth, which could result in metastases into nearby tissues beyond the lungs.

MATERIALS AND METHODS

The aim of the present study was to analyze the influence of epidermal growth factor receptor (EGFR) gene expression on metastasis and survival in NSCLC patients. The present case-control study included 100 cases of NSCLC patients and 100 age and sex matched controls. EGFR gene expression was analyzed by quantitative real time PCR using serum RNA. Association with NSCLC patient survival was analyzed by the Kaplan-Meier method.

RESULTS

We analyzed EGFR gene expression and observed mean increased gene expression of 13.5 fold in NSCLC patients. Values reflected overall survival of patients with a median of 15.8 months in the cases of <13 fold increased gene expression vs 6.7 months with >13 fold increased EGFR gene expression (p=0.005). Distant metastatic patients with <13 fold increased EGFR gene expression had 7.9 months of median survival time while>13 fold increased EGFR gene expression had only 5 months of median survival time (p=0.03). Non metastatic patients with <13 fold increased EGFR gene expression had 18 months of median survival time as compared to only 7.1 months with >13 fold increased expression.

CONCLUSIONS

Higher cell free EGFR mRNA expression may play an important role in causing distant metastases and reducing overall survival of NSCLC patients in the Indian population.

Functions of lncRNA HOTAIR in lung cancer

Long non-coding RNAs (lncRNAs) govern fundamental biochemical and cellular processes. lncRNA HOX transcript antisense RNA (HOTAIR) represses gene expression through recruitment of chromatin modifiers. The expression of HOTAIR is elevated in lung cancer and correlates with metastasis and poor prognosis. Moreover, HOTAIR promotes proliferation, survival, invasion, metastasis, and drug resistance in lung cancer cells. Here we review the molecular mechanisms underlying HOTAIR-mediated aggressive phenotypes of lung cancer. We also discuss HOTAIR’s potential in diagnosis and treatment of lung cancer, as well as the challenges of exploiting HOTAIR for intervention of lung cancer.

Arl4c expression in colorectal and lung cancers promotes tumorigenesis and may represent a novel therapeutic target

We recently demonstrated that expression of ADP-ribosylation factor (ARF)-like 4c (Arl4c) induced by a combination of Wnt/β-catenin and epidermal growth factor/Ras signaling in normal epithelial cells grown in three-dimensional culture promotes cellular migration and proliferation, resulting in formation of tube-like structures, suggesting the involvement of Arl4c in epithelial morphogenesis. It is conceivable that there could be a common mechanism between epithelial morphogenesis and carcinogenesis. Therefore the current study was conducted to investigate whether Arl4c might be involved in tumorigenesis. Immunohistochemical analyses of tissue specimens obtained from colorectal and lung cancer patients revealed that Arl4c was not observed in non-tumor regions but was strongly expressed at high frequencies in tumor lesions. Inhibition of Wnt/β-catenin or Ras/mitogen-activated protein kinase signaling reduced Arl4c mRNA levels in HCT116 colorectal cancer cells and A549 lung cancer cells. Knockdown of Arl4c inhibited Rac activity and also prevented nuclear localization of yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) in these cancer cells. Arl4c-depleted cancer cells consistently showed decreased migration, invasion and proliferation capabilities both in vitro and in vivo. Furthermore, direct injection of Arl4c small interfering RNA (siRNA) into HCT116 cell-derived tumors (in vivo treatment with siRNA) inhibited tumor growth in immunodeficient mice. These results suggest that Arl4c is involved in tumorigenesis and might represent a novel therapeutic target for suppressing proliferation and invasion of colorectal and lung cancer cells.

Serum starvation regulates E-cadherin upregulation via activation of c-Src in non-small-cell lung cancer A549 cells

E-cadherin is essential for the integrity of adherens junctions between lung epithelial cells, and the loss of E-cadherin allows cell motility and is thought to promote lung cancer metastasis. While the downregulation of E-cadherin expression has been well characterized and is seen with transforming growth factor-β1 (TGF-β1) exposure, few studies have focused on E-cadherin upregulation. Here, we show that serum starvation causes increased E-cadherin expression via the activation of c-Src kinase in non-small-cell lung cancer A549 cells. Serum starvation increased E-cadherin protein levels in a time- and dose-dependent manner. E-cadherin mRNA transcripts were unchanged with starvation, while protein translation inhibition with cycloheximide attenuated E-cadherin protein induction by starvation, suggesting that E-cadherin is regulated at the translational level by serum starvation. c-Src is a nonreceptor tyrosine kinase known to regulate protein translation machinery; serum starvation caused early and sustained activation of c-Src in A549 cells followed by E-cadherin upregulation. Furthermore, overexpression of a dominant negative c-Src attenuated the induction of E-cadherin by serum deprivation. Finally, we observed that TGF-β1 treatment attenuated the serum activation of c-Src as well as E-cadherin expression when cells were deprived of serum. In conclusion, our data demonstrate that the c-Src kinase is activated by serum starvation to increase E-cadherin expression in A549 cells, and these phenomena are antagonized by TGF-β1. These novel observations implicate the c-Src kinase as an upstream inducer of E-cadherin protein translation with serum starvation and TGF-β1 diametrically regulating c-Src kinase activity and thus E-cadherin abundance in A549 cells.

Ras transformation uncouples the kinesin-coordinated cellular nutrient response

The kinesin family members (KIFs) KIF2A and KIF2C depolymerize microtubules, unlike the majority of other kinesins, which transport cargo along microtubules. KIF2A regulates the localization of lysosomes in the cytoplasm, which assists in activation of the mechanistic target of rapamycin complex 1 (mTORC1) on the lysosomal surface. We find that the closely related kinesin KIF2C also influences lysosomal organization in immortalized human bronchial epithelial cells (HBECs). Expression of KIF2C and, to a lesser extent, KIF2A in untransformed and mutant K-Ras-transformed cells is regulated by ERK1/2. Prolonged inhibition of ERK1/2 activation with PD0325901 mimics nutrient deprivation by disrupting lysosome organization and decreasing mTORC1 activity in HBEC, suggesting a long-term mechanism for optimization of mTORC1 activity by ERK1/2. We tested the hypothesis that up-regulation of KIF2C and KIF2A by ERK1/2 caused aberrant lysosomal positioning and mTORC1 activity in a mutant K-Ras-dependent cancer and cancer model. In Ras-transformed cells, however, mTORC1 activity and lysosome organization appear independent of ERK1/2 and these kinesins although ERK1/2 activity and the kinesins are required for Ras-dependent proliferation and migration. We conclude that mutant K-Ras repurposes these signaling and regulatory proteins to support the transformed phenotype.

Molecular markers to predict clinical outcome and radiation induced toxicity in lung cancer

The elucidation of driver mutations involved in the molecular pathogenesis of cancer has led to a surge in the application of novel targeted therapeutics in lung cancer. Novel oncologic research continues to lead investigators towards targeting personalized tumor characteristics rather than applying targeted therapy to broad patient populations. Several driver genes, in particular epidermal growth factor receptor (EGFR) and ALK fusions, are the earliest to have made their way into clinical trials. The avant-garde role of genomic profiling has led to important clinical challenges when adapting current standard treatments to personalized oncologic care. This new frontier of medicine requires newer biomarkers for toxicity that will identify patients at risk, as well as, new molecular markers to predict and assess clinical outcomes. Thus far, several signature genes have been developed to predict outcome as well as genetic factors related to inflammation to predict toxicity.

Inhibition of breast cancer metastasis suppressor 1 promotes a mesenchymal phenotype in lung epithelial cells that express oncogenic K-RasV12 and loss of p53

Expression of the breast cancer metastasis suppressor 1 (BRMS1) protein is dramatically reduced in non-small cell lung cancer (NSCLC) cells and in primary human tumors. Although BRMS1 is a known suppressor of metastasis, the mechanisms through which BRMS1 functions to regulate cell migration and invasion in response to specific NSCLC driver mutations are poorly understood. To experimentally address this, we utilized immortalized human bronchial epithelial cells in which p53 was knocked down in the presence of oncogenic K-Ras^V12 (HBEC3-p53KD-K-Ras^V12). These genetic alterations are commonly found in NSCLC and are associated with a poor prognosis. To determine the importance of BRMS1 for cytoskeletal function, cell migration and invasion in our model system we stably knocked down BRMS1. Here, we report that loss of BRMS1 in HBEC3-p53KD-K-Ras^V12 cells results in a dramatic increase in cell migration and invasion compared to controls that expressed BRMS1. Moreover, the loss of BRMS1 resulted in additional morphological changes including F-actin re-distribution, paxillin accumulation at the leading edge of the lamellapodium, and cellular shape changes resembling mesenchymal phenotypes. Importantly, re-expression of BRMS1 restores, in part, cell migration and invasion; however it does not fully reestablish the epithelial phenotype. These finding suggests that loss of BRMS1 results in a permanent, largely irreversible, mesenchymal phenotype associated with increased cell migration and invasion. Collectively, in NSCLC cells without p53 and expression of oncogenic K-Ras our study identifies BRMS1 as a key regulator required to maintain a cellular morphology and cytoskeletal architecture consistent with an epithelial phenotype.

SV40 TAg mouse models of cancer

The discovery of a number of viruses with the ability to induce tumours in animals and transform human cells has vastly impacted cancer research. Much of what is known about tumorigenesis today regarding tumour drivers and tumour suppressors has been discovered through experiments using viruses. The SV40 virus has proven extremely successful in generating transgenic models of many human cancer types and this review provides an overview of these models and seeks to give evidence as to their relevance in this modern era of personalised medicine and technological advancements.

Polymorphisms of EpCAM gene and prognosis for non-small-cell lung cancer in Han Chinese

The epithelial cell adhesion molecule (EpCAM) is overexpressed in a wide variety of human cancers and is associated with patient prognosis, including those with lung cancer. However, the association of single nucleotide polymorphisms (SNPs) in the EpCAM gene with the prognosis for non-small-cell lung cancer (NSCLC) patients has never been investigated. We evaluated the association between two SNPs, rs1126497 and rs1421, in the EpCAM gene and clinical outcomes in a Chinese cohort of 506 NSCLC patients. The SNPs were genotyped using the Sequenom iPLEX genotyping system. Multivariate Cox proportional hazards model and Kaplan-Meier curves were used to assess the association of EpCAM gene genotypes with the prognosis of NSCLC. We found that the non-synonymous SNP rs1126497 was significantly associated with survival. Compared with the CC genotype, the CT+TT genotype was a risk factor for both death (hazard ratio, 1.40; 95% confidence interval [CI], 1.02-1.94; P = 0.040) and recurrence (hazard ratio, 1.34; 95% CI, 1.02-1.77; P = 0.039). However, the SNP rs1421 did not show any significant effect on patient prognosis. Instead, the AG+GG genotype in rs1421 was significantly associated with early T stages (T1/T2) when compared with the AA genotype (odds ratio for late stage = 0.65; 95% CI, 0.44-0.96, P = 0.029). Further stratified analysis showed notable modulating effects of clinical characteristics on the associations between variant genotypes of rs1126497 and NSCLC outcomes. In conclusion, our study indicated that the non-synonymous SNP rs1126497 may be a potential prognostic marker for NSCLC patients.

Ras regulates kinesin 13 family members to control cell migration pathways in transformed human bronchial epithelial cells

We show that expression of the microtubule depolymerizing kinesin KIF2C is induced by transformation of immortalized human bronchial epithelial cells by expression of K-Ras^G12V and knockdown of p53. Further investigation demonstrates that this is due to the K-Ras/ERK1/2 MAPK pathway, as loss of p53 had little effect on KIF2C expression. In addition to KIF2C, we also found that the related kinesin KIF2A is modestly upregulated in this model system; both proteins are expressed more highly in many lung cancer cell lines compared to normal tissue. As a consequence of their depolymerizing activity, these kinesins increase dynamic instability of microtubules. Depletion of either of these kinesins impairs the ability of cells transformed with mutant K-Ras to migrate and invade matrigel. However, depletion of these kinesins does not reverse the epithelial-mesenchymal transition caused by mutant K-Ras. Our studies indicate that increased expression of microtubule destabilizing factors can occur during oncogenesis to support enhanced migration and invasion of tumor cells.

PRC2 overexpression and PRC2-target gene repression relating to poorer prognosis in small cell lung cancer

Small cell lung cancer (SCLC) is a subtype of lung cancer with poor prognosis. Expression array analysis of 23 SCLC cases and 42 normal tissues revealed that EZH2 and other PRC2 members were highly expressed in SCLC. ChIP-seq for H3K27me3 suggested that genes with H3K27me3(+) in SCLC were extended not only to PRC2-target genes in ES cells but also to other target genes such as cellular adhesion-related genes. These H3K27me3(+) genes in SCLC were repressed significantly, and introduction of the most repressed gene JUB into SCLC cell line lead to growth inhibition. Shorter overall survival of clinical SCLC cases correlated to repression of JUB alone, or a set of four genes including H3K27me3(+) genes. Treatment with EZH2 inhibitors, DZNep and GSK126, resulted in growth repression of SCLC cell lines. High PRC2 expression was suggested to contribute to gene repression in SCLC, and may play a role in genesis of SCLC.

The influence of TP53 mutations on the prognosis of patients with early stage non-small cell lung cancer may depend on the intratumor heterogeneity of the mutations

A large number of studies have evaluated the impact of TP53 mutations on the prognosis of patients with non-small cell lung cancer (NSCLC); however, the results of these studies are still controversial. Recently, considerable intratumor heterogeneity for genetic alterations has been demonstrated in various human cancers, including lung cancer. In the present study, we evaluated TP53 mutations in NSCLCs by direct sequencing and observed remarkable variation in the values of relative intensity (RI, the height of the peak of mutated allele/the height of the peak of non-mutated allele) of the mutations. We also examined whether the RI values were associated with intratumor heterogeneity of TP53 mutations. In addition, we evaluated the relationship between TP53 mutations and survival outcome. The patients with a TP53 mutation did not have significantly worse survival compared to those without the mutation. However, when tumors with a TP53 mutation were categorized into two groups, those with a low and those with a high RI, the latter group had significantly worse survival compared to those with wild-type TP53 (adjusted hazard ratio = 2.58, 95% confidence interval = 1.21-5.48, P = 0.01), whereas the former group did not. These results suggest that intratumor genetic heterogeneity may be an important factor in determining the role of TP53 mutations on the prognosis of NSCLC patients.

Polymorphisms in DNA repair and apoptosis-related genes and clinical outcomes of patients with non-small cell lung cancer treated with first-line paclitaxel-cisplatin chemotherapy

This study was conducted to analyze a comprehensive panel of single nucleotide polymorphisms (SNPs) in genes in DNA repair and apoptosis pathways and determine the relationship between polymorphisms and treatment outcomes of patients with non-small cell lung cancer (NSCLC) treated with first-line paclitaxel-cisplatin chemotherapy. Three hundred eighty two patients with NSCLC were enrolled. Seventy-four SNPs in 48 genes (42 SNPs in 27 DNA repair pathway genes and 32 SNPs in 21 apoptotic pathway genes) were genotyped and their associations with chemotherapy response and overall survival (OS) were analyzed. Among SNPs in DNA repair genes, BRCA1 rs799917 was significantly associated with both chemotherapy response and OS. XRCC1 rs25487 exhibited a significant association with chemotherapy response and ERCC2 rs1052555 with OS. Four SNPs in apoptotic genes (TNFRSF1B rs1061624, BCL2 rs2279115, BIRC5 rs9904341, and CASP8 rs3769818) were significantly associated with OS, but not with response to chemotherapy. When the six SNPs which were associated with OS in individual analysis were combined, OS decreased as the number of bad genotypes increased (P(trend) = 2 × 10(-6)). Patients with 3, and 4-6 bad genotypes had significantly worse OS compared with those carrying 0-2 bad genotypes (adjusted hazard ratio [aHR] = 1.54, 95% CI = 1.14-2.08, P = 0.005; aHR = 2.10, 95% CI = 1.55-2.85, P = 2 × 10(-6), respectively). In conclusion, these findings suggest that the six SNPs identified, particularly their combined genotypes, could be used as biomarkers predicting chemotherapy response and survival of NSCLC patients treated with first-line paclitaxel-cisplatin chemotherapy.

Genetic and epigenetic alterations of the LKB1 gene and their associations with mutations in TP53 and EGFR pathway genes in Korean non-small cell lung cancers

INTRODUCTION

Liver kinase 1 (LKB1) plays a critical barrier role in lung tumorigenesis by controlling initiation, differentiation and metastasis. We searched for genetic and epigenetic alterations of the LKB1 gene in Korean non-small cell lung cancers (NSCLCs) and correlated the results with clinicopathological features. We also investigated the relationship between genetic and epigenetic alterations of LKB1 and mutations in the TP53 gene and epidermal growth factor receptor (EGFR) pathway genes.

METHODS

A total of 159 NSCLCs were analyzed for loss of heterozygosity (LOH) at microsatellite loci D19S886, and D19S878. Mutations and methylation status of LKB1 were examined by direct sequencing and a methylation-specific polymerase chain reaction, respectively.

RESULTS

A somatic mutation was found in one of the 159 tumors. LOH and promoter methylation was detected in 19.5% (31/159) and 13.2% (21/159) of the tumors, respectively. Four of the 159 tumors had concomitant LOH and methylation of LKB1. In total, 30.2% of the 159 NSCLCs harbored LKB1 LOH or promoter methylation, which were correlated with down-regulation of gene expression. LKB1 LOH was more frequent in males, smokers, and tumors with a TP53 mutation than in females, never-smokers, and tumors without a TP53 mutation, respectively. However, no significant correlation between LKB1 alterations and mutations in EGFR pathway genes was found.

CONCLUSION

These results suggest that the prevalence of LKB1 genetic and epigenetic alterations in NSCLCs vary depending on patient ethnicity. Our results show that LKB1 alterations often occur simultaneously with mutations in EGFR pathway genes.

Independent of ErbB1 gene copy number, EGF stimulates migration but is not associated with cell proliferation in non-small cell lung cancer

Background

Lung cancer often exhibits molecular changes, such as the overexpression of the ErbB1 gene. ErbB1 encodes epidermal growth factor receptor (EGFR), a tyrosine kinase receptor, involved mainly in cell proliferation and survival. EGFR overexpression has been associated with more aggressive disease, poor prognosis, low survival rate and low response to therapy. ErbB1 amplification and mutation are associated with tumor development and are implicated in ineffective treatment. The aim of the present study was to investigate whether the ErbB1 copy number affects EGFR expression, cell proliferation or cell migration by comparing two different cell lines.

Methods

The copies of ErbB1 gene was evaluated by FISH. Immunofluorescence and Western blotting were performed to determine location and expression of proteins mentioned in the present study. Proliferation was studied by flow cytometry and cell migration by wound healing assay and time lapse.

Results

We investigated the activation and function of EGFR in the A549 and HK2 lung cancer cell lines, which contain 3 and 6 copies of ErbB1, respectively. The expression of EGFR was lower in the HK2 cell line. EGFR was activated after stimulation with EGF in both cell lines, but this activation did not promote differences in cellular proliferation when compared to control cells. Inhibiting EGFR with AG1478 did not modify cellular proliferation, confirming previous data. However, we observed morphological alterations, changes in microfilament organization and increased cell migration upon EGF stimulation. However, these effects did not seem to be consequence of an epithelial-mesenchymal transition.

Conclusion

EGFR expression did not appear to be associated to the ErbB1 gene copy number, and neither of these aspects appeared to affect cell proliferation. However, EGFR activation by EGF resulted in cell migration stimulation in both cell lines.

Effects of common polymorphism rs11614913 in Hsa-miR-196a2 on lung cancer risk

Background

Emerging evidence suggests that single nucleotide polymorphisms (SNPs) in microRNA-coding genes may participate in the pathogenesis of lung cancer by altering the expression of tumor-related microRNAs. Several studies were investigated in recent years to evaluate the association between hsa-miR-196a2 rs11614913 polymorphism and increased/decreased lung cancer risk. In the present study, we performed a meta-analysis to systematically summarize the possible association.

Methodology/Principal Findings

We performed a meta-analysis of 4 case-control studies that included 2219 lung-cancer cases and 2232 cancer-free controls. We evaluated the strength of the association using odds ratios (ORs) with 95% confidence intervals (CIs). In the overall analysis, it was found that the rs11614913 polymorphism significantly elevated the risk of lung cancer (CC versus (vs.) TT OR = 1.26, 95% CI 1.07–1.49, P = 0.007; CC/CT vs. TT: OR = 1.13, 95% CI 0.98–1.29, P = 0.007; C vs. T: OR = 1.12, 95% CI 1.03–1.22, P = 0.008). In the subgroup analysis by ethnicity, statistically significantly increased cancer risk was found among Asians (CC vs. TT: OR = 1.30, 95% CI 1.10–1.54, P = 0.003; CT vs. TT: OR = 1.16, 95% CI 1.01–1.34, P = 0.039; CC vs. CT/TT: OR = 1.21, 95% CI 1.04–1.41, P = 0.012; C vs. T: OR = 1.14, 95% CI 1.05–1.25, P = 0.002). For Europeans, a significant association with lung cancer risk was found in recessive model (CC vs. CT/TT: OR = 0.63, 95% CI 0.40–0.98, P = 0.040). No publication bias was found in this study.

Conclusions/Significance

Our meta-analysis suggests that the rs11614913 polymorphism is significant associated with the increased risk of lung cancer, especially in Asians. Besides, the C allele of rs11614913 polymorphism may contribute to increased lung cancer risk.

The EGFR family members sustain the neoplastic phenotype of ALK+ lung adenocarcinoma via EGR1

In non-small cell lung cancer (NSCLC), receptor tyrosine kinases (RTKs) stand out among causal dominant oncogenes, and the ablation of RTK signaling has emerged as a novel tailored therapeutic strategy. Nonetheless, long-term RTK inhibition leads invariably to acquired resistance, tumor recurrence and metastatic dissemination. In ALK+ cell lines, inhibition of ALK signaling was associated with coactivation of several RTKs, whose pharmacological suppression reverted the partial resistance to ALK blockade. Remarkably, ERBB2 signaling synergized with ALK and contributed to the neoplastic phenotype. Moreover, the engagement of wild-type epidermal growth factor receptor or MET receptors could sustain cell viability through early growth response 1 (EGR1) and/or Erk1/2; Akt activation and EGR1 overexpression prevented cell death induced by combined ALK/RTK inhibition. Membrane expression of ERBB2 in a subset of primary naive ALK+ NSCLC could be relevant in the clinical arena. Our data demonstrate that the neoplastic phenotype of ALK-driven NSCLC relays ‘ab initio' on the concomitant activation of multiple RTK signals via autocrine/paracrine regulatory loops. These findings suggest that molecular and functional signatures are required in de novo lung cancer patients for the design of efficacious and multi-targeted ‘patient-specific' therapies.

Long-term smoking mediated down-regulation of Smad3 induces resistance to carboplatin in non-small cell lung cancer

While numerous cell signaling pathways are known to play decisive roles in chemotherapeutic response, relatively little is known about the impact of the Smad-dependent transforming growth factor β pathway on the therapeutic outcome. Previous reports suggested that patients with lung cancer who continue to smoke while receiving chemotherapy have a poorer outcome than their nonsmoking counterparts do. In our previous study, we showed that long-term cigarette smoke condensate (CSC)-mediated down-regulation of Smad3 induces tumorigenesis. The objective of this study was to determine the mechanism of function of Smad3 in chemoresistance induced by CSC in human lung cell lines, namely, A549 and HPL1A. Long-term CSC treatment increases the half-maximal inhibitory concentration (IC(50)) of carboplatin and makes cells resistant to carboplatin. The increase in IC(50) of long-term CSC-treated cells is due to the reduced induction in apoptosis by carboplatin. The increase in IC(50) and decrease in apoptosis in long-term CSC-treated cells is correlated with the expression of Bcl2. We have determined that Bcl2 is both necessary and sufficient to make the cells resistant to carboplatin. We have also shown that Smad3 acts upstream to regulate the expression of Bcl2 specifically and, thus, sensitivity of the cells to carboplatin. This is supported by the inverse correlation between the expressions of Smad3 and Bcl2 in human lung tumors. Collectively, these data suggest that loss of Smad3 expression in CSC-treated cells induces resistance to carboplatin by upregulating the expression of Bcl2. This study explains, at least in part, the higher chemoresistance rate observed in smokers.

Cell of origin of lung cancer

Lung cancer is the leading cause of cancer deaths worldwide, and current therapies are disappointing. Elucidation of the cell(s) of origin of lung cancer may lead to new therapeutics. In addition, the discovery of putative cancer-initiating cells with stem cell properties in solid tumors has emerged as an important area of cancer research that may explain the resistance of these tumors to currently available therapeutics. Progress in our understanding of normal tissue stem cells, tumor cell of origin, and cancer stem cells has been hampered by the heterogeneity of the disease, the lack of good in vivo transplantation models to assess stem cell behavior, and an overall incomplete understanding of the epithelial stem cell hierarchy. As such, a systematic computerized literature search of the MEDLINE database was used to identify articles discussing current knowledge about normal lung and lung cancer stem cells or progenitor cells. In this review, we discuss what is currently known about the role of cancer-initiating cells and normal stem cells in the development of lung tumors.

Association of CASP7 polymorphisms and survival of patients with non-small cell lung cancer with platinum-based chemotherapy treatment

BACKGROUND

CASP7 plays a crucial role in cancer development and chemotherapy efficacy. We, therefore, explored whether single nucleotide polymorphisms (SNPs) of the CASP7 gene can modulate outcomes of patients with advanced non-small cell lung cancer (NSCLC) treated with first-line platinum-based chemotherapy.

METHODS

We systematically genotyped 17 SNPs of CASP7 first in a discovery set of 279 patients with advanced NSCLC treated with platinum-based chemotherapy and then replicated the results in an independent set of 384 patients, in whom we evaluated associations with overall survival (OS) and progress-free survival (PFS) by Kaplan-Meier analysis and Cox hazards regression analysis.

RESULTS

In both discovery and validation sets as well as in the pooled analysis, heterozygotes of CASP7 rs2227310 and rs4353229 as well as rs12415607 variant allele were strongly associated with a better OS of NSCLC (in the pooled sample: adjusted hazard ratio [HR], 0.73; 95% CI = 0.59-0.90; P = .003; HR, 0.72; 95% CI = 0.59-0.89; P = .002; and HR, 0.76; 95% CI = 0.62-0.94; P = .009; respectively). In stratified analyses of the pooled data set, treated with paclitaxel, individuals carrying variant allele of rs2227310, rs4353229, and rs12415607 had significantly improved OS (HR, 0.60; 95% CI = 0.41-0.87; P = .008; HR, 0.58; 95% CI = 0.39-0.84; P = .004; and HR, 0.61; 95% CI = 0.42-0.89; P = .010; respectively).

CONCLUSIONS

This study provides evidence that genetic variations of CASP7 may modulate OS and PFS of patients with advanced NSCLC treated with platinum-based chemotherapy.

Molecular Markers with Predictive and Prognostic Relevance in Lung Cancer

Lung cancer accounts for the majority of cancer-related deaths worldwide of which non-small-cell lung carcinoma alone takes a toll of around 85%. Platinum-based therapy is the stronghold for lung cancer at present. The discovery of various molecular alterations that underlie lung cancer has contributed to the development of specifically targeted therapies employing specific mutation inhibitors. Targeted chemotherapy based on molecular profiling has shown great promise in lung cancer treatment. Various molecular markers with predictive and prognostic significance in lung cancer have evolved as a result of advanced research. Testing of EGFR and Kras mutations is now a common practice among community oncologists, and more recently, ALK rearrangements have been added to this group. This paper discusses various predictive and prognostic markers that are being investigated and have shown significant relevance which can be exploited for targeted treatment in lung cancer.

The DNA methylation landscape of small cell lung cancer suggests a differentiation defect of neuroendocrine cells

Small cell lung cancer (SCLC) is a disease characterized by aggressive clinical behavior and lack of effective therapy. Owing to its tendency for early dissemination, only a third of patients have limited-stage disease at the time of diagnosis. SCLC is thought to derive from pulmonary neuroendocrine cells. Although several molecular abnormalities in SCLC have been described, there are relatively few studies on epigenetic alterations in this type of tumor. Here, we have used methylation profiling with the methylated-CpG island recovery assay in combination with microarrays and conducted the first genome-scale analysis of methylation changes that occur in primary SCLC and SCLC cell lines. Among the hundreds of tumor-specifically methylated genes discovered, we identified 73 gene targets that are methylated in >77% of primary SCLC tumors, most of which have never been linked to aberrant methylation in tumors. These methylated targets have potential for biomarker development for early detection and therapeutic management of SCLC. SCLC cell lines had a greater number of hypermethylated genes than primary tumors. Gene ontology analysis indicated a significant enrichment of methylated genes functioning as transcription factors and in processes of neuronal differentiation. Motif analysis of tumor-specific methylated regions identified enrichment of binding sites for several neural cell fate-specifying transcription factors including NEUROD1, HAND1, ZNF423 and REST. We hypothesize that two potential mechanisms, loss of cell fate-determining transcription factors by methylation of their promoters and functional inactivation of their corresponding genomic-binding sites by DNA methylation, can promote a differentiation defect of neuroendocrine cells thus enhancing the ability of tumor progenitor cells to transition toward SCLC.

Genetic and biochemical alterations in non-small cell lung cancer

Despite significant advances in the detection and treatment of lung cancer, it causes the highest number of cancer-related mortality. Recent advances in the detection of genetic alterations in patient samples along with physiologically relevant animal models has yielded a new understanding of the molecular etiology of lung cancer. This has facilitated the development of potent and specific targeted therapies, based on the genetic and biochemical alterations present in the tumor, especially non-small-cell lung cancer (NSCLC). It is now clear that heterogeneous cell signaling pathways are disrupted to promote NSCLC, including mutations in critical growth regulatory proteins (K-Ras, EGFR, B-RAF, MEK-1, HER2, MET, EML-4-ALK, KIF5B-RET, and NKX2.1) and inactivation of growth inhibitory pathways (TP53, PTEN, p16, and LKB-1). How these pathways differ between smokers and non-smokers is also important for clinical treatment strategies and development of targeted therapies. This paper describes these molecular targets in NSCLC, and describes the biological significance of each mutation and their potential to act as a therapeutic target.

Non-small cell lung carcinoma cell motility, rac activation and metastatic dissemination are mediated by protein kinase C epsilon

Background

Protein kinase C (PKC) ε, a key signaling transducer implicated in mitogenesis, survival, and cancer progression, is overexpressed in human primary non-small cell lung cancer (NSCLC). The role of PKCε in lung cancer metastasis has not yet been established.

Principal Findings

Here we show that RNAi-mediated knockdown of PKCε in H358, H1299, H322, and A549 NSCLC impairs activation of the small GTPase Rac1 in response to phorbol 12-myristate 13-acetate (PMA), serum, or epidermal growth factor (EGF). PKCε depletion markedly impaired the ability of NSCLC cells to form membrane ruffles and migrate. Similar results were observed by pharmacological inhibition of PKCε with εV1-2, a specific PKCε inhibitor. PKCε was also required for invasiveness of NSCLC cells and modulated the secretion of extracellular matrix proteases and protease inhibitors. Finally, we found that PKCε-depleted NSCLC cells fail to disseminate to lungs in a mouse model of metastasis.

Conclusions

Our results implicate PKCε as a key mediator of Rac signaling and motility of lung cancer cells, highlighting its potential as a therapeutic target.

Biomarkers for small cell lung cancer: neuroendocrine, epithelial and circulating tumour cells

Small cell lung cancer (SCLC) is characterised by an aggressive clinical course with invariable resistance to chemotherapy despite initially high response rates. There has been little improvement in outcome over the past few decades, with no breakthrough yet in targeted therapies. Recent preclinical data and studies of circulating tumour cells (CTCs) highlight distinct cellular heterogeneity within SCLC. Better understanding of how these phenotypes contribute to metastasis and tumour progression might pave the way for development of more successful targeted therapies. Here we review these studies, their implications for future research and for the incorporation of biomarkers reflecting neuroendocrine, epithelial and mesenchymal phenotypes in clinical studies.

Intratumor heterogeneity and chemotherapy-induced changes in EGFR status in non-small cell lung cancer

INTRODUCTION

Biomarker expression is increasingly being used to customize treatment in non-small cell lung cancer (NSCLC). The choice of systemic treatment usually depends on biomarker expression in the initial diagnostic biopsy taken before initiation of first-line treatment. Chemotherapy induces DNA damages in the tumor cells, and thus, biomarker expression in the tumor after systemic treatment might not be identical to biomarker expression in the diagnostic biopsy. NSCLC is highly heterogeneous and biomarker expression may vary in different areas within the same tumor. This review explores the tumor heterogeneity and chemotherapy-induced changes in EGFR biomarker status in NSCLC.

METHODS

A literature search was performed in August 2011 using pubmed.

RESULTS

Fifteen trials explored EGFR status in primary tumor and subsequent resected primary tumor, lymph node metastases, or organ metastases. Four papers compared EGFR status in primary tumor or metastases before and after systemic treatment. All trials included relatively few patients and used different chemotherapy regimes, biopsy locations, or time intervals between biopsies.

CONCLUSIONS

Tumor heterogeneity and probably also previous systemic treatment may be an obstacle for correct interpretation of EGFR status in NSCLC. Heterogeneity regarding EGFR mutations is probably rare and previously reported intra and intertumor heterogeneity may be due to methodological issues. In the current and future clinical scenario with many different options for systemic treatment both as 2nd line and beyond, it is increasingly important to further elucidate the role extent of chemotherapy-induced changes in biomarker expression for proper use of biomarkers in order to customize treatment and thus improve prognosis.

Molecular biology of lung cancer: clinical implications

Lung cancer is a heterogeneous disease clinically, biologically, histologically, and molecularly. Understanding the molecular causes of this heterogeneity, which might reflect changes occurring in different classes of epithelial cells or different molecular changes occurring in the same target lung epithelial cells, is the focus of current research. Identifying the genes and pathways involved, determining how they relate to the biological behavior of lung cancer, and their utility as diagnostic and therapeutic targets are important basic and translational research issues. This article reviews current information on the key molecular steps in lung cancer pathogenesis, their timing, and clinical implications.

Polymorphisms in apoptosis-related genes and TP53 mutations in non-small cell lung cancer

Apoptosis plays an essential role in the elimination of mutated or transformed cells from the body. Therefore, polymorphisms of apoptosis-related genes may lead to an alteration in apoptotic capacity, thereby affecting the occurrence of TP53 mutations in lung cancer. We investigated the relationship between potentially functional polymorphisms of apoptosis-related genes and TP53 mutations in non-small cell lung cancer (NSCLC). Twenty-seven single nucleotide polymorphisms in 20 apoptosis-related genes were genotyped by a sequenome mass spectrometry-based genotyping assay in 173 NSCLCs and the associations with TP53 mutations in the entire coding exons (exons 2-11), including splicing sites of the gene, were analyzed. None of the 27 polymorphisms was significantly associated with the occurrence of TP53 mutations. This suggests that apoptosis-related genes may not play an important role in the occurrence of TP53 mutations in lung cancer.

Knockdown of oncogenic KRAS in non-small cell lung cancers suppresses tumor growth and sensitizes tumor cells to targeted therapy

Oncogenic KRAS is found in more than 25% of lung adenocarcinomas, the major histologic subtype of non-small cell lung cancer (NSCLC), and is an important target for drug development. To this end, we generated four NSCLC lines with stable knockdown selective for oncogenic KRAS. As expected, stable knockdown of oncogenic KRAS led to inhibition of in vitro and in vivo tumor growth in the KRAS-mutant NSCLC cells, but not in NSCLC cells that have wild-type KRAS (but mutant NRAS). Surprisingly, we did not see large-scale induction of cell death and the growth inhibitory effect was not complete. To further understand the ability of NSCLCs to grow despite selective removal of mutant KRAS expression, we conducted microarray expression profiling of NSCLC cell lines with or without mutant KRAS knockdown and isogenic human bronchial epithelial cell lines with and without oncogenic KRAS. We found that although the mitogen-activated protein kinase pathway is significantly downregulated after mutant KRAS knockdown, these NSCLCs showed increased levels of phospho-STAT3 and phospho-epidermal growth factor receptor, and variable changes in phospho-Akt. In addition, mutant KRAS knockdown sensitized the NSCLCs to p38 and EGFR inhibitors. Our findings suggest that targeting oncogenic KRAS by itself will not be sufficient treatment, but may offer possibilities of combining anti-KRAS strategies with other targeted drugs.

Proteins kinase Cɛ is required for non-small cell lung carcinoma growth and regulates the expression of apoptotic genes

Protein kinase C (PKC)ɛ, a member of the novel PKC family, has key roles in mitogenesis and survival in normal and cancer cells. PKCɛ is frequently overexpressed in epithelial cancers, particularly in lung cancer. Using a short-hairpin RNA approach, here we established that PKCɛ is required for non-small cell lung carcinoma (NSCLC) growth in vitro as well as tumor growth when inoculated into athymic mice. Moreover, sustained delivery of a PKCɛ-selective inhibitor peptide, ɛV1-2, reduced xenograft growth in mice. Both RNA interference depletion and pharmacological inhibition of PKCɛ caused a marked elevation in the number of apoptotic cells in NSCLC tumors. PKCɛ-depleted NSCLC cells show elevated expression of pro-apoptotic proteins of the Bcl-2 family, caspase recruitment domain-containing proteins and tumor necrosis factor ligands/receptor superfamily members. Moreover, a Gene Set Enrichment Analysis revealed that a vast majority of the genes changed in PKCɛ-depleted cells were also deregulated in human NSCLC. Our results strongly suggest that PKCɛ is required for NSCLC cell survival and maintenance of NSCLC tumor growth. Therefore, PKCɛ may represent an attractive therapeutic target for NSCLC.

AKT1 polymorphisms and survival of early stage non-small cell lung cancer

BACKGROUND AND OBJECTIVES

This study was conducted to investigate the impact of polymorphisms in the AKT1 gene on the survival of early stage non-small cell lung cancer (NSCLC) patients.

METHODS

Three hundred and ten patients with surgically resected NSCLC were enrolled. The rs3803300, rs1130214, rs3730358, rs1130233, and rs2494732 single nucleotide polymorphisms (SNPs) in the AKT1 gene were investigated. The genotype and haplotype associations with overall survival (OS) and disease free survival (DFS) were analyzed.

RESULTS

The three SNPs (rs3803300, rs1130214, and rs2494732) were significantly associated with survival outcomes on multivariate analysis. When the three SNPs were combined, OS and DFS were decreased in a dose-dependent manner as the number of bad genotypes increased (P(trend)  = <1.0 × 10(-4) and 0.001, respectively). Patients with 2 bad genotypes had a significantly worse OS and DFS compared with those with 0 bad genotypes (adjusted hazard ratio (HR) = 3.08, 95% confidence interval (CI) = 1.61-5.89, P = 0.001; and adjusted HR = 2.04, 95% CI = 1.22-3.43, P = 0.01).

CONCLUSIONS

These results suggest that the AKT1 polymorphisms could be used as prognostic markers for the patients with early-stage NSCLC.

The causes and consequences of polyploidy in normal development and cancer

Although nearly all mammalian species are diploid, whole-genome duplications occur in select mammalian tissues as part of normal development. Such programmed polyploidization involves changes in the regulatory pathways that normally maintain the diploid state of the mammalian genome. Unscheduled whole-genome duplications, which lead primarily to tetraploid cells, also take place in a substantial fraction of human tumors and have been proposed to constitute an important step in the development of cancer aneuploidy. The origins of these polyploidization events and their consequences for tumor progression are explored in this review.

Cell of origin of small cell lung cancer: inactivation of Trp53 and Rb1 in distinct cell types of adult mouse lung

Small cell lung cancer (SCLC) is one of the most lethal human malignancies. To investigate the cellular origin(s) of this cancer, we assessed the effect of Trp53 and Rb1 inactivation in distinct cell types in the adult lung using adenoviral vectors that target Cre recombinase to Clara, neuroendocrine (NE), and alveolar type 2 (SPC-expressing) cells. Using these cell type-restricted Adeno-Cre viruses, we show that loss of Trp53 and Rb1 can efficiently transform NE and SPC-expressing cells leading to SCLC, albeit SPC-expressing cells at a lesser efficiency. In contrast, Clara cells were largely resistant to transformation. The results indicate that although NE cells serve as the predominant cell of origin of SCLC a subset of SPC-expressing cells are also endowed with this ability.

Pivotal role of epithelial cell adhesion molecule in the survival of lung cancer cells

Epithelial cell adhesion molecule (EpCAM) is overexpressed in a wide variety of human cancers including lung cancer, and its contribution to increased proliferation through upregulation of cell cycle accelerators such as cyclins A and E has been well established in breast and gastric cancers. Nevertheless, very little is known about its role in supporting the survival of cancer cells. In addition, the functional role of EpCAM in the pathogenesis of lung cancer remains to be explored. In this study, we show that RNAi-mediated knockdown of EpCAM suppresses proliferation and clonogenic growth of three EpCAM-expressing lung cancer cell lines (H3255, H358, and HCC827), but does not induce cell cycle arrest in any of these. In addition, EpCAM knockdown inhibits invasion in the highly invasive H358 but not in less invasive H3255 cells in a Transwell assay. Of note, the EpCAM knockdown induces massive apoptosis in the three cell lines as well as in another EpCAM-expressing lung cancer cell line, HCC2279, but to a much lesser extent in a cdk4/hTERT immortalized normal human bronchial epithelial cell line, HBEC4, suggesting that EpCAM could be a therapeutic target for lung cancer. Finally, EpCAM knockdown partially restores contact inhibition in HCC827, in association with p27(Kip1) upregulation. These results indicate that EpCAM could contribute substantially to the pathogenesis of lung cancer, especially cancer cell survival, and suggest that EpCAM targeted therapy for lung cancer may have potential.

DNA methylation profile during multistage progression of pulmonary adenocarcinomas

Multiple genetic and epigenetic alterations are known to be involved in the carcinogenesis of peripheral pulmonary adenocarcinoma (ADC). However, epigenetic abnormalities have not been extensively investigated in the following multistage progression sequence: atypical adenomatous hyperplasia (AAH) to adenocarcinoma in situ (AIS), to invasive ADC. To determine the potential role of promoter methylation during ADC development of the lung, we examined methylation status in 20 normal, 20 AAH, 30 AIS, and 60 ADC lung tissues and compared methylation status among the lesions. The MethyLight assay was used to determine the methylation status of 18 CpG island loci, which were hypermethylated in ADC compared to noncancerous lung tissues. The mean number of methylated CpG island loci was significantly higher in ADC than in AAH and AIS, (p < 0.003 between ADC and AAH, p < 0.005 between ADC and AIS). Aberrant methylation of HOXA1, TMEFF2, and RARB was frequently observed in preinvasive lesions, including AAH and AIS. Furthermore, methylation of PENK, BCL2, RUNX3, DLEC1, MT1G, GRIN2B, CDH13, CCND2, and HOXA10 was significantly more frequent in invasive ADC than AAH or AIS. Our results indicate that epigenetic alterations are involved in the multistep progression of pulmonary ADC development, and aberrant CpG island methylation accumulates during multistep carcinogenesis. In addition, aberrant methylation of HOXA1, TMEFF2, and RARB occurred in preinvasive lesions, which indicates that epigenetic alterations of these genes are involved in the early stages of pulmonary ADC development. In contrast, hypermethylation of PENK, BCL2, RUNX3, DLEC1, MT1G, GRIN2B, CDH13, CCND2, and HOXA10 was more frequent in invasive ADC than in preinvasive lesions, which indicates that methylation of these genes occurs later during tumor invasion in the AAH-AIS-ADC sequence.