Aage Haugen

KIF5B-RET fusions in lung adenocarcinoma

We identified in-frame fusion transcripts of KIF5B (the kinesin family 5B gene) and the RET oncogene, which are present in 1–2% of lung adenocarcinomas (LADCs) from people from Japan and the United States, using whole-transcriptome sequencing. The KIF5B-RET fusion leads to aberrant activation of RET kinase and is considered to be a new driver mutation of LADC because it segregates from mutations or fusions in EGFR, KRAS, HER2 and ALK, and a RET tyrosine kinase inhibitor, vandetanib, suppresses the fusion-induced anchorage-independent growth activity of NIH3T3 cells.

Expression of estrogen receptors α and β in human lung tissue and cell lines

Epidemiological studies have indicated that females may be at greater risk of smoking associated lung cancer compared with males. Several lines of biochemical evidence support these observations. A possible role of circulating steroid hormones in the etiology of lung cancer has been hypothesized. In the present paper, we have studied the expression of the estrogen receptors (ER)-alpha and ER beta in histologically normal human lung tissue and lung tumor cell lines. Relative ER mRNA levels were measured by reverse transcriptase-PCR and normalized to the level of expression of the glyceraldehyde 3-phosphate dehydrogenase gene (GAPDH). In lung tissue, an ER alpha transcript was found at various levels in 38 out of 46 cases (83%). ER beta was expressed in all cases. The ERs were expressed at similar levels in females and males, and the levels of ER alpha and ER beta mRNA were significantly related (P<0.0001). Compared with the lung tissue, ER expression levels were lower in 16 human lung tumor cell lines and two immortalized human bronchial epithelial cell lines. Five of the tumor cell lines (31%) expressed detectable levels of ER alpha and both of the immortalized cell lines showed a weak ER alpha expression level. All cell lines expressed the ER beta. The lung cell lines BEAS-2B and DB354 showed significantly reduced cell proliferation in response to tamoxifen and a minor increased growth in response to 17 beta-estradiol. In conclusion, ER genes are abundantly expressed in both histologically normal human lung and lung tumor cell lines. This indicates a possible role of ERs in lung carcinogenesis.

Replication of Lung Cancer Susceptibility Loci at Chromosomes 15q25, 5p15, and 6p21: A Pooled Analysis From the International Lung Cancer Consortium

BACKGROUND Genome-wide association studies have identified three chromosomal regions at 15q25, 5p15, and 6p21 as being associated with the risk of lung cancer. To confirm these associations in independent studies and investigate heterogeneity of these associations within specific subgroups, we conducted a coordinated genotyping study within the International Lung Cancer Consortium based on independent studies that were not included in previous genome-wide association studies. METHODS Genotype data for single-nucleotide polymorphisms at chromosomes 15q25 (rs16969968, rs8034191), 5p15 (rs2736100, rs402710), and 6p21 (rs2256543, rs4324798) from 21 case-control studies for 11 645 lung cancer case patients and 14 954 control subjects, of whom 85% were white and 15% were Asian, were pooled. Associations between the variants and the risk of lung cancer were estimated by logistic regression models. All statistical tests were two-sided. RESULTS Associations between 15q25 and the risk of lung cancer were replicated in white ever-smokers (rs16969968: odds ratio [OR] = 1.26, 95% confidence interval [CI] = 1.21 to 1.32, P(trend) = 2 x 10(-26)), and this association was stronger for those diagnosed at younger ages. There was no association in never-smokers or in Asians between either of the 15q25 variants and the risk of lung cancer. For the chromosome 5p15 region, we confirmed statistically significant associations in whites for both rs2736100 (OR = 1.15, 95% CI = 1.10 to 1.20, P(trend) = 1 x 10(-10)) and rs402710 (OR = 1.14, 95% CI = 1.09 to 1.19, P(trend) = 5 x 10(-8)) and identified similar associations in Asians (rs2736100: OR = 1.23, 95% CI = 1.12 to 1.35, P(trend) = 2 x 10(-5); rs402710: OR = 1.15, 95% CI = 1.04 to 1.27, P(trend) = .007). The associations between the 5p15 variants and lung cancer differed by histology; odds ratios for rs2736100 were highest in adenocarcinoma and for rs402710 were highest in adenocarcinoma and squamous cell carcinomas. This pattern was observed in both ethnic groups. Neither of the two variants on chromosome 6p21 was associated with the risk of lung cancer. CONCLUSIONS In this international genetic association study of lung cancer, previous associations found in white populations were replicated and new associations were identified in Asian populations. Future genetic studies of lung cancer should include detailed stratification by histology.

Human cyp1a1 (Cytochrome p1 450) gene: Lack of association between the msp i restriction fragment length polymorphism and incidence of lung cancer in a norwegian population

In this study of 221 lung cancer patients and 212 controls, no association between a Msp I polymorphism in the CYP1A1 gene and an increased risk of lung cancer was found. Histological type, smoking habits and family history were also examined. No associations between the Msp I restriction fragment length polymorphism in the CYP1A1 gene and any of these parameters were found. These results are in contrast to a previous report by a Japanese group (Kawajiri et al., 1990) who found an association between the less common allele and an increased susceptibility to lung cancer in their population. The frequency of the less common Msp I 1.9 kb fragment allele (C2) appears to be three times greater in the Japanese population than in the Norwegian population and a Caucasian population of North America. It is possible that in the Asian population this Msp I polymorphism is in linkage disequilibrium with another mutation important for CYP1A1 gene expression, whereas in the Caucasian population these mutations are in equilibrium.

The Association of MicroRNA Expression with Prognosis and Progression in Early-Stage, Non–Small Cell Lung Adenocarcinoma: A Retrospective Analysis of Three Cohorts

Purpose: There is increasing evidence that altered microRNA expression is associated with tumor progression and survival in cancer patients. We tested if the expression of specific microRNAs was associated with prognosis and disease progression in early-stage lung adenocarcinoma. Experimental Design: The expression of miR-21, miR-17, and miR-155 was measured by quantitative RT-PCR in tissues from 317 non–small cell lung cancer (NSCLC) patients that originated from Maryland, Norway, and Japan. Kaplan-Meier and Cox regression analysis evaluated associations of microRNA expression with cancer-specific mortality and disease-free survival. Results: Elevated miR-21 (HR 2.06, 1.13–3.75), miR-17 (HR 2.00, 1.10–3.61), and miR-155 (HR 2.37, 1.27–4.42) was associated with worse cancer-specific mortality in the Maryland cohort. These were evaluated in two additional cohorts and only miR-21 was associated with worse cancer-specific mortality in the Norwegian cohort (HR 2.78, 1.22–6.31) and worse relapse-free survival in the Japanese cohort (HR 2.82, 1.57–5.07). More advanced stage tumors expressed significantly higher levels of miR-21 compared with TNM stage I tumors. TNM stage I patients were evaluated separately and high levels of miR-21 was associated with worse cancer-specific mortality (HR 2.16, 1.11–4.21) and relapse-free survival (3.40, 1.57–7.36) independent of other clinical factors. Conclusions: This is the first study to report that increased miR-21 expression is associated with disease progression and survival in stage I lung cancer. This suggests that expression of miR-21 may contribute to lung carcinogenesis and serve as a therapeutic target or early-stage prognostic biomarker for lung adenocarcinoma. Clin Cancer Res; 17(7); 1875–82. ©2011 AACR.

POLYMORPHISMS OF THE INTERLEUKIN-1 GENE ARE ASSOCIATED WITH INCREASED RISK OF NON-SMALL CELL LUNG CANCER

Lung cancer is one of the leading causes of cancer death worldwide. Tobacco smoking is the main risk factor for lung cancer. Less than 20% of smokers develop lung cancer in their lifetime, however, indicating individual variations in lung cancer risk. Pro‐inflammatory cytokines produced by inflammatory cells have been associated with inflammatory diseases and cancer. The IL1B gene, encoding IL‐1β cytokine, contains several single nucleotide polymorphisms (SNPs). Two of these are in the promoter region, at positions −511 (C‐T) and −31 (T‐C). These polymorphisms have been associated with increased risk of developing a number of inflammatory diseases and gastric carcinoma. We genotyped the 2 polymorphisms in 251 non‐small cell lung cancer patients from Norway and 272 healthy controls chosen from the general Norwegian population. The T allele at the −31 SNP (p = 0.01) and C allele at −511 SNP (p < 0.01) were over represented in lung cancer cases. The homozygote subjects were particularly at higher risk of lung cancer with odds ratio of 2.39 (95% CI = 1.29–4.44) for −31T/T and 2.51 (95% CI = 1.47–4.58) for −511C/C genotypes. In view of the significance of the p53 gene in lung carcinogenesis, we also analyzed the IL1B genotypes in relation to p53 mutations in the tumors. The results indicated that subjects having homozygote genotypes were more likely to have a mutation in the p53 gene (p = 0.05). This is the first study to provide evidence for an association of 1L1B gene polymorphisms with lung cancer risk.

Association of a functional polymorphism in the promoter of the MDM2 gene with risk of nonsmall cell lung cancer.

Lung cancer is the leading cause of cancer mortality in the world. Although exposure to carcinogens is considered to be the main cause, genetic variation may contribute to lung cancer risk. Murine double minute 2, MDM2, is a key regulator of p53 activity and recently a polymorphism in the promoter region of the MDM2 gene was characterized. This single nucleotide polymorphism, SNP309, was shown to influence MDM2 transcription, MDM2 protein levels and p53 activity. The aim of this study was to investigate whether this functionally important SNP is associated with risk of nonsmall cell lung cancer. The study consisted of 341 nonsmall cell lung cancer cases and 412 healthy controls of Norwegian origin. Our results indicate that the G/G genotype of SNP309 is associated with lung cancer risk with an odds ratio of 1.62 (95% CI: 1.06–2.50). Interestingly, the strongest effect of the polymorphism was seen among women. Females homozygous for SNP309 G/G had associated odds ratio 4.06 (1.29–12.8). We also explored the MDM2 SNP309 in relation to TP53 gene mutations and age at nonsmall cell lung cancer diagnosis. Our results indicate that the G/G genotype of SNP309 is associated with higher age at diagnosis in individuals with TP53 mutations (p = 0.037).

CYP1A1 T3801 C polymorphism and lung cancer: A pooled analysis of 2,451 cases and 3,358 controls

CYP1A1 is involved in the metabolism of benzopyrene, a suspected lung carcinogen; it is therefore conceivable that genetically determined variations in its activity modify individual susceptibility to lung cancer. The role of the CYP1A1 MspI polymorphism in lung cancer has been widely studied but has not been fully clarified. We have included 2,451 cases and 3,358 controls in a pooled analysis of 22 case‐control studies on CYP1A1 and lung cancer risk. We found a clear association between the CYP1A1 homozygous MspI restriction fragment length polymorphism (RFLP) and lung cancer risk in Caucasians (age‐ and gender‐adjusted odds ratio = 2.36; 95% confidence interval 1.16–4.81); other associations were weaker or not statistically significant. The association with the homozygous variant was equally strong for squamous cell carcinomas and adenocarcinomas among Caucasians. We analyzed the risk by duration of smoking: for Caucasian subjects with the MspI RFLP combined variants (homozygotes plus heterozygotes), the increase in the risk of lung cancer was steeper than among the individuals with the homozygous reference allele. Our analysis suggests that Caucasians with homozygous variant CYP1A1 polymorphism have a higher risk of lung cancer. The data were more consistent among Caucasians, with a strong association between the homozygous variant in both squamous cell carcinomas and adenocarcinomas, and a stronger association in men than in women. The analyses were more inconsistent and failed to reach statistical significance in Asians. This observation might be due to design specificities or unknown effect modifiers in the Asian studies.

A comprehensive analysis of phase I and phase II metabolism gene polymorphisms and risk of non-small cell lung cancer in smokers

Lung cancer is a leading cause of cancer mortality worldwide with smoking and occupational exposure to carcinogenic compounds as the major risk factors. Susceptibility to lung cancer is affected by existence of polymorphic genes controlling the levels of metabolic activation and detoxification of carcinogens. We have investigated 105 single nucleotide polymorphisms (SNPs) in 31 genes from the phase I and phase II metabolism genes and antioxidant defense genes for association with the risk of non-small cell lung cancer (NSCLC) in a Norwegian population-based study. Our results indicate that several SNPs in the phase I genes, CYP1B1, CYP2D6, CYP2E1 and CYP3A4, are associated with the risk of NSCLC. Moreover, significant associations with multiple SNPs in the phase II genes ALDH2, COMT, EPHX1, SOD2, NAT1, NAT2, GSTM3, GSTP1, GSTT2 and MPO were also found. We prioritized our findings by use of two different recently developed Bayesian statistical tools, employing conservative prior probabilities of association. When we corrected for multiple testing using these statistical tools, three novel associations of NSCLC risk with SNPs in the CYP1B1 (Arg48Gly), COMT (Val158Met) and GSTT2 (Met139Ile) genes were found noteworthy. However, only four of the previously reported associations with polymorphisms in the GSTP1 (Ala14Val), SOD2 (Val16Ala), EPHX1 (His139Arg) genes and the NAT1 fast acetylator phenotype remained significantly associated with lung cancer.

Obesity, metabolic factors and risk of different histological types of lung cancer: A Mendelian randomization study.

Background Assessing the relationship between lung cancer and metabolic conditions is challenging because of the confounding effect of tobacco. Mendelian randomization (MR), or the use of genetic instrumental variables to assess causality, may help to identify the metabolic drivers of lung cancer. Methods and findings We identified genetic instruments for potential metabolic risk factors and evaluated these in relation to risk using 29,266 lung cancer cases (including 11,273 adenocarcinomas, 7,426 squamous cell and 2,664 small cell cases) and 56,450 controls. The MR risk analysis suggested a causal effect of body mass index (BMI) on lung cancer risk for two of the three major histological subtypes, with evidence of a risk increase for squamous cell carcinoma (odds ratio (OR) [95% confidence interval (CI)] = 1.20 [1.01–1.43] and for small cell lung cancer (OR [95%CI] = 1.52 [1.15–2.00]) for each standard deviation (SD) increase in BMI [4.6 kg/m2]), but not for adenocarcinoma (OR [95%CI] = 0.93 [0.79–1.08]) (Pheterogeneity = 4.3x10-3). Additional analysis using a genetic instrument for BMI showed that each SD increase in BMI increased cigarette consumption by 1.27 cigarettes per day (P = 2.1x10-3), providing novel evidence that a genetic susceptibility to obesity influences smoking patterns. There was also evidence that low-density lipoprotein cholesterol was inversely associated with lung cancer overall risk (OR [95%CI] = 0.90 [0.84–0.97] per SD of 38 mg/dl), while fasting insulin was positively associated (OR [95%CI] = 1.63 [1.25–2.13] per SD of 44.4 pmol/l). Sensitivity analyses including a weighted-median approach and MR-Egger test did not detect other pleiotropic effects biasing the main results. Conclusions Our results are consistent with a causal role of fasting insulin and low-density lipoprotein cholesterol in lung cancer etiology, as well as for BMI in squamous cell and small cell carcinoma. The latter relation may be mediated by a previously unrecognized effect of obesity on smoking behavior.