Genetic alterations of lung adenocarcinoma in relation to smoking and ethnicity

Clinical Applications of Aneuploidies in Evolution of NSCLC Patients: Current Status and Application Prospect

As one of the first characteristics of cancer cells, chromosomal aberrations during cell division have been well documented. Aneuploidy is a feature of most cancer cells accompanied by an elevated rate of mis-segregation of chromosomes, called chromosome instability (CIN). Aneuploidy causes ongoing karyotypic changes that contribute to tumor heterogeneity, drug resistance, and treatment failure, which are considered predictors of poor prognosis. Lung cancer (LC) is the leading cause of cancer-related deaths worldwide, and its genome map shows extensive aneuploid changes. Elucidating the role of aneuploidy in the pathogenesis of LC will reveal information about the key factors of tumor occurrence and development, help to predict the prognosis of cancer, clarify tumor evolution, metastasis, and drug response, and may promote the development of precision oncology. In this review, we describe many possible causes of aneuploidy and provide evidence of the role of aneuploidy in the evolution of LC, providing a basis for future biological and clinical research.

Multi-scale representation of proteomic data exhibits distinct microRNA regulatory modules in non-smoking female patients with lung adenocarcinoma

Adenocarcinoma in female non-smokers is an under-explored subgroup of non-small cell lung cancer (NSCLC), in which the molecular mechanism and genetic risk factors remain unclear. We analyzed the protein profiles of plasma samples of 45 patients in this subgroup and 60 non-cancer subjects using surface-enhanced laser desorption/ionization time-of- flight mass spectrometry. Among 85 peaks of mass spectra, the differential expression analysis identified 15 markers based on False Discovery Rate control and the Discrete Wavelet Transforms further selected a cluster of 6 markers that were consistently observed at multiple scales of mass-charge ratios. This marker cluster, corresponding to 7 unique proteins, was able to distinguish the female non-smokers with adenocarcinoma from non-cancer subjects with a value of accuracy of 87.6%. We also predicted the role of competing endogenous RNAs (ceRNAs) in 3 out of these 7 proteins. Other studies reported that these ceRNAs and their targeting microRNAs, miR-206 and miR-613, were significantly associated with NSCLC. This study paves a crucial path for further investigating the genetic markers and molecular mechanism of this special NSCLC subgroup.

Sex-related differences in DNA copy number alterations in hepatitis B virus-associated hepatocellular carcinoma

BACKGROUND

Males have a higher prevalence of hepatocellular carcinoma (HCC) than females in general, but the reasons for the sex disparity are still obscure. DNA copy number alteration (CNA) is a major feature of solid tumors including HCC, but whether CNA plays a role in sex-related differences in HCC development has never been evaluated.

METHODS

High-resolution array comparative genomic hybridization (CGH) was used to examine 17 female and 46 male HCC patients with chronic hepatitis B virus (HBV) infection in Shanghai, China. Two-tailed Fisher's exact or chi2 tests was used to compare CNAs between females and males.

RESULTS

The overall frequencies and patterns of CNAs in female and male cases were similar. However, female HCC tumors presented more copy number gains compared to those in males on 1q21.3-q22 (76.5% vs. 37.0%, P = 0.009), 11q11 (35.3% vs. 0.0%, P = 0.0002) and 19q13.31-q13.32 (23.5% vs. 0.0%, P = 0.004), and loss on 16p11.2 (35.3% vs. 6.5%, P = 0.009). Relative to females, male cases had greater copy number loss on 11q11 (63.0% vs. 17.6%, P = 0.002). Further analyses showed that 11q11 gain correlated with 19q13.31-q13.32 gain (P = 0.042), 11q11 loss (P = 0.011) and 16p11.2 loss (P = 0.033), while 1q21.3-q22 gain correlated with 19q13.31-q13.32 gain (P = 0.046).

CONCLUSIONS

These findings suggest that CNAs may play a role in sex-related differences in HBV-associated HCC development.

Safety and efficacy of first-line bevacizumab with chemotherapy in Asian patients with advanced nonsquamous NSCLC: results from the phase IV MO19390 (SAiL) study

INTRODUCTION

First-line treatment with bevacizumab combined with chemotherapy has been shown to improve outcomes in patients with advanced, nonsquamous non-small cell lung cancer (NSNSCLC) in phase III clinical trials. SAiL (MO19390), an open-label, multicenter, single-arm study, evaluated the safety and efficacy of first-line bevacizumab-based treatment in clinical practice. This report presents the results of a preplanned subanalysis of Asian patients enrolled in SAiL.

METHODS

Patients with untreated, locally advanced, metastatic or recurrent NSNSCLC received bevacizumab 7.5 or 15 mg/kg every 3 weeks plus chemotherapy for up to six cycles, followed by single-agent bevacizumab until disease progression. Eligibility criteria for SAiL permitted enrolment of a broad patient population. The primary end point was safety; secondary end points included time to disease progression and overall survival.

RESULTS

The Asian intent-to-treat population comprised 314 of the 2212 patients enrolled in the SAiL trial. In the Asian subanalysis, patients received a median of nine cycles of bevacizumab, and the median follow-up was 16.4 months. The incidence of clinically significant adverse events (grade ≥3) of special interest was relatively low in this population (15.6% overall); proteinuria (7.6%), hypertension (4.8%), and bleeding (2.5%) were the most common. A total of five adverse events related to bevacizumab were reported as grade 5. Disease control rate was 94.1%, median time to disease progression was 8.3 months, and median overall survival was 18.9 months.

CONCLUSIONS

The safety and efficacy of first-line bevacizumab-based treatment in Asian patients with advanced NSNSCLC is consistent with that demonstrated in phase III studies and in the overall SAiL population. There were no new safety signals.

Adenylosuccinate synthetase 1 gene is a novel target of deletion in lung adenocarcinoma

Tobacco smoke consists of numerous carcinogens whose effect on lung tumor development includes the induction of mutations in key genes as well as the induction of chromosome instability (CIN). Consequently, carcinogen-induced mouse lung adenocarcinomas (LAC) display many more recurrent site- and chromosome-specific changes in DNA copy number compared with noninduced LAC. Here we identified the Adenylosuccinate synthetase 1 (Adss1) gene located on distal chromosome 12q as a focus of bi-allelic or homozygous deletion (HD) in LAC. HDs of Adss1 were detected in 10 out of 84 carcinogen-induced mouse primary LAC and mouse LAC cell lines. In only four of these cases did the deletions affect either Siva1 or Inverted-formin 2 (Inf2), which immediately flank the Adss1 locus, indicating that Adss1 is a selective target of deletion in LAC. Losses of Adss1 not meeting the quantitative threshold of HD were detected in 36 out of 84 (42.9%) of the mouse tumors and cell lines. A similar frequency of ADSS1 deletion was observed in human LAC cell lines, suggesting relevance in human lung cancer. Adss1 losses were also found to be significantly associated with a more extensive CIN phenotype in the primary mouse tumors. These results implicate ADSS1 inactivation as a novel somatic alteration in lung carcinogenesis, and suggest that its selective deletion in LAC may be triggered by CIN.

Epigenetic effects of lung cancer predisposing factors impact on clinical diagnosis and prognosis

Lung carcinogenesis is a complex process requiring the acquisition of genetic mutations that confer the malignant phenotype as well as epigenetic alterations that may be both manipulated in the course of therapy. Aberrant gene function and transcriptional silencing by CpG island hypermethylation has become a critical component in the initiation and progression of lung cancer. Growing evidence shows that acquired epigenetic abnormalities participate with genetic alterations to cause this dysregulation. Human and animal studies have fostered significant advances in elucidating the role of gene-specific methylation in cancer initiation and progression, the modulation of DNA methylation by carcinogen exposure and the ability of pharmacologic agents to reverse promoter hypermethylation, making it an attractive target to pursue for prevention of lung cancer. This review focuses on how lung cancer predisposing factors participate in epigenetic alterations of lung neoplasia, and discusses the growing implications of these alterations for strategies to control cancer.

Computed Tomography–Diagnosed Emphysema, Not Airway Obstruction, Is Associated with the Prognostic Outcome of Early-Stage Lung Cancer

PURPOSE

Because both emphysema and lung cancer can arise from biological damage caused by cigarette smoking, we investigated if the development of emphysema is associated with the clinical features of smoker's lung cancer.

EXPERIMENTAL DESIGN

The subjects were a consecutive series of 100 smokers who underwent lobectomy with hilar and mediastinal dissection for clinical stage I non-small cell lung cancer. We studied the relationship between the presence or absence of emphysema at the onset of the lung cancer and clinicopathologic features. Emphysema was diagnosed by measuring the low-attenuation area using computed tomography densitometry.

RESULTS

There were no differences in clinicopathologic variables, including the degree of smoking exposure between the patients with (n=58) and those without (n=42) emphysema, although male gender and airflow limitation were predominant in the patients with emphysema. The presence of emphysema, but neither male gender nor airflow limitation, adversely affected both overall and disease-specific survival. According to Cox regression analysis, emphysema was an independent prognosticator among age, gender, degree of smoking exposure, tumor size, nodal status, histologic subtype, histologic grade, and microvessel invasion. These results were stabilized by a bootstrap sampling model.

CONCLUSIONS

Computed tomography-diagnosed emphysema, but not airway obstruction, is associated with poor prognosis in smokers with early-stage lung cancer. Thus, routine computed tomography densitometry in smokers with lung cancer should be mandatory.

High resolution analysis of genomic aberrations by metaphase and array comparative genomic hybridization identifies candidate tumour genes in lung cancer cell lines

Tumours develop from clonally expanded population of cells harbouring aberrations of oncogenes and tumour suppressor genes. In this study, metaphase and array comparative genomic hybridization showed good correlation of aberration profiles in lung adenocarcinoma cell lines from patients with different tobacco exposure. Recurrent DNA gains were found at chromosomes 1, 7, 8, 17, 20, and deletions at 1, 3, 8, 9, 10, 12, 17, 18, 19. Candidate tumour loci and encompassed genes at 7p21 (AGR2), 8q21(TPD52), 20q13 (ZNF217, WFDC2, EEF1A2) and 10p15 (KLF6) were analyzed by dual colour FISH for genomic changes and quantitative PCR for expression changes. Results indicated that EEF1A2 and KLF6 were strong candidates of oncogene and tumour suppressor genes, respectively. This study illustrates, a practical strategy for identifying candidate cancer genes from microarray data.

Array CGH analysis reveals chromosomal aberrations in mouse lung adenocarcinomas induced by the human lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone

Exposure to genotoxic carcinogens in tobacco smoke is a major cause of lung cancer. However, the effect this has on DNA copy number and genomic stability during lung carcinogenesis is unclear. Here we used bacterial artificial chromosome array-based comparative genomic hybridization to examine the effect of NNK, a potent human lung carcinogen present in tobacco smoke, on the major genomic changes occurring during mouse lung adenocarcinogenesis. Observed were significantly more gross chromosomal changes in NNK-induced tumors compared with the spontaneous tumors. An average of 5.6 chromosomes were affected by large-scale changes in DNA copy number per NNK-induced tumor compared with only 2.0 in spontaneous lung tumors (p = 0.017). Further analysis showed that gains on chromosomes 6 and 8, and losses on chromosomes 11 and 14 were more common in NNK-induced tumors (p <or= 0.002). The changes on chromosomes 8, 11, and 14 were positively (p <or= 0.001) associated with the degree of chromosome instability (CIN). This association was less significant for gains on chromosomes 6 and 12 (p = 0.035). In contrast, loss of distal chromosome 4 was very frequent (71%) in both NNK-induced and spontaneous tumors, and showed no association with CIN phenotype. Each of these chromosomes contains sites of orthology with those altered in human lung adenocarcinomas, suggesting similar roles in human lung cancer. We next investigated the mechanism of NNK-induced CIN and found that a genotoxic metabolite of this carcinogen causes numerous karyotypic changes in lung epithelial cells. With similar changes evident in NNK-induced tumors, this suggests that the persistence of such damage in exposed lung epithelia may initiate CIN during lung carcinogenesis. These results show for the first time that NNK potently induces gross chromosomal alterations in lung adenocarcinogenesis and modulates the evolutionary pathway of these tumors through the recruitment of genes with altered DNA copy number.

Chromosomal aberrations in squamous cell carcinomas of the upper aerodigestive tract: biologic insights and clinical opportunities

Oncogenesis results from a progressive accumulation of genetic aberrations consequent to a complex interplay between carcinogenic factors and innate infidelity of DNA surveillance mechanisms. Although the development of genetic aberrations is random, those conferring survival advantages are selected for in a Darwinian manner, thus allowing continuous adaptation to selection pressures. Chromosomal aberrations are a prominent manifestation of genetic damage, which can be closely linked with tumor behavior and outcome as exemplified by curative treatment of chronic myelogenous leukemia resulting from targeting the BCR-ABL translocation. In the case of head and neck squamous cell carcinomas (HNSCC), chromosomal changes are detectable at all stages of tumor development, providing excellent opportunities for genomic prognostication and therapy. Several studies have shown that the overall genomic profile of HNSCC is highly consistent, but individual tumors vary significantly in their complement of genetic alterations, thereby confounding clinical correlation. The application of modern genetic and bioinformatic analytic approaches has facilitated the identification of critical genomic changes in HNSCC, many of which have been linked to clinical outcome. These genetic aberrations represent excellent targets for novel therapeutics, but require validation. The initiation of phase III trials evaluating the therapeutic utility of genetic aberrations suggests a promising future for genome-based treatment of HNSCC.