Vidar Skaug

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.

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).

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.

The TERT-CLPTM1L lung cancer susceptibility variant associates with higher DNA adduct formation in the lung

Genome-wide association studies have provided evidence that common variation at 5p15.33 [telomerase reverse transcriptase (TERT)-cleft lip and palate transmembrane 1-like (CLPTM1L)], 6p21.33 and 15q25.1 (CHRNA5-CHRNA3) influences lung cancer risk and cancer types with strong environmental risk factors. To independently validate these associations, we compared 5p15.33 (rs402710, rs401681), 6p21.33 (rs4324798) and 15q25.1 (rs1051730, rs16969968 and rs8034191) genotypes in 365 non-small cell lung cancer cases and 440 controls. Consistent with published data, variant genotypes of 5p15 (rs402710), 6p21 and 15q25 showed dose-dependent associations with lung cancer risk. To examine if variants influence the impact of environmental risk factors on lung carcinogenesis, we studied the relationship between genotype and levels of bulky aromatic/hydrophobic DNA adducts in lung tissue adjacent to tumor from 204 lung cancer cases. The risk allele of rs402710 (TERT-CLPTM1L locus) was associated with significantly higher levels of bulky aromatic/hydrophobic DNA adducts (P = 0.02). These data demonstrate a potential association between the TERT-CLPTM1L variant and levels of bulky DNA adducts measured by (32)P-postlabeling and hence a basis for susceptibility to the development of lung cancer.

Sex differences in risk of lung cancer: Expression of genes in the PAH bioactivation pathway in relation to smoking and bulky DNA adducts

It is controversial whether women have a higher lung cancer susceptibility compared to men. We previously reported higher levels of smoking‐related bulky DNA adducts in female lungs. In a pilot study (27 cases), we also found a higher level of female lung cytochrome P4501A1 (CYP1A1) gene expression. In the present extended study we report on the pulmonary expression of several genes involved in polycyclic aromatic hydrocarbon bioactivation in relation to sex, smoking and DNA adducts. CYP1A1, CYP1B1, aryl hydrocarbon receptor and microsomal epoxide hydrolase gene expression was measured by quantitative real‐time reverse transcriptase‐PCR in 121 normal lung tissue samples. The expression of CYP1A1 and CYP1B1 was significantly higher among current smokers compared to ex‐smokers and never‐smokers. Among current smokers, females had a 3.9‐fold higher median level of CYP1A1 compared to males (p = 0.011). CYP1B1 expression was not related to sex. Lung DNA adducts (measured by 32P‐postlabeling) were highly significantly related to CYP1A1 (p < 0.0001) irrespective of smoking‐status. Our results are consistent with the hypothesis that CYP1A1 plays a significant role in lung DNA adduct formation and support a higher susceptibility to lung cancer among females.

Genome-Wide Analysis of Survival in Early-Stage Non–Small-Cell Lung Cancer

PURPOSE Lung cancer, of which 85% is non-small-cell (NSCLC), is the leading cause of cancer-related death in the United States. We used genome-wide analysis of tumor tissue to investigate whether single nucleotide polymorphisms (SNPs) in tumors are prognostic factors in early-stage NSCLC. PATIENTS AND METHODS One hundred early-stage NSCLC patients from Massachusetts General Hospital (MGH) were used as a discovery set and 89 NSCLC patients collected by the National Institute of Occupational Health, Norway, were used as a validation set. DNA was extracted from flash-frozen lung tissue with at least 70% tumor cellularity. Genome-wide genotyping was done using the high-density SNP chip. Copy numbers were inferred using median smoothing after intensity normalization. Cox models were used to screen and validate significant SNPs associated with the overall survival. RESULTS Copy number gains in chromosomes 3q, 5p, and 8q were observed in both MGH and Norwegian cohorts. The top 50 SNPs associated with overall survival in the MGH cohort (P < or = 2.5 x 10(-4)) were selected and examined using the Norwegian cohort. Five of the top 50 SNPs were validated in the Norwegian cohort with false discovery rate lower than 0.05 (P < .016) and all five were located in known genes: STK39, PCDH7, A2BP1, and EYA2. The numbers of risk alleles of the five SNPs showed a cumulative effect on overall survival (P(trend) = 3.80 x 10(-12) and 2.48 x 10(-7) for MGH and Norwegian cohorts, respectively). CONCLUSION Five SNPs were identified that may be prognostic of overall survival in early-stage NSCLC.

A specific interleukin-1B haplotype correlates with high levels of IL1B mRNA in the lung and increased risk of non-small cell lung cancer

Epidemiological evidence suggests a relationship between chronic inflammation and lung cancer. Inflammation in the lung may be modulated by host genetic factors such as polymorphisms in inflammatory genes. Identification of polymorphisms in inflammatory genes may help understanding interindividual differences in susceptibility to lung cancer. We have investigated single-nucleotide polymorphisms (SNPs) and their haplotypes in the regulatory region of the IL1B gene in association to non-small cell lung cancer (NSCLC) risk. Our previous work showed that two promoter SNPs C-511T and T-31C modulated NSCLC risk. In the present study, we show that G-3893A and G-1464C located in the enhancer region of the IL1B gene may also affect this risk, with odds for developing NSCLC being 0.69 [95% confidence interval (CI), 0.52-0.92] for -3893 A-allele and 0.63 (95% CI, 0.47 - 0.83) for -1464 C-allele. The associations were particularly prominent in patients with TP53 mutations in the tumor. Inference of the haplotype structures showed that -3893 G, -1464 G, -511 C and -31 T formed a specific haplotype (GGCT) with near complete linkage disequilibrium in lung cancer patients but not in controls. Furthermore, the risk haplotype (GGCT) was present in 65% of cases compared with 36% of controls. Quantitative analysis of RNA in normal lung tissue of the patients showed that the risk haplotype was correlated with significantly higher IL1B messenger RNA (mRNA) levels compared with the non-risk haplotype (ACTC). These data suggest that a specific IL1B haplotype associated with increased IL1B gene expression increases the risk of NSCLC.