Curtis Harris

Abstract B35: The expression of four genes as a prognostic classifier for stage I lung adenocarcinoma in 12 independent cohorts.

We previously developed and validated a prognostic classifier using the mRNA expression levels of BRCA1, HIF1A, DLC1, and XPO1. This 4-gene classifier aimed to identify stage I lung adenocarcinoma patients with a high risk of relapse. Our initial study evaluated patients in five independent cohorts from various regions of the world, suggesting that the 4-gene classifier was robust and representative of most lung adenocarcinomas. In an attempt to further validate this classifier, we have used a meta-analysis based approach to study 12 cohorts consisting of 1069 TNM stage I lung adenocarcinoma patients. These cohorts were obtained through a systematic search of public gene expression datasets and all suitable datasets were analyzed. Kaplan-Meier analysis of each cohort showed that the classifier was significantly associated with prognosis in ten of the twelve cohorts (p<0.05). The association was highly consistent across all cohorts regardless of the ethnic diversity or microarray platform and there was no evidence of heterogeneity across all cohorts (I2 = 0.0%, p=0.98). The pooled estimate demonstrated that patients classified as high risk had worse overall survival for all stage I (Hazard Ratio [HR], 2.66; 95% Confidence Interval [CI], 1.93-3.67; P<0.0001) patients and in stratified analyses of stage IA (HR, 2.69; 95%CI, 1.66-4.35; P<0.0001) and stage IB (HR, 2.69; 95%CI, 1.74-4.16; P<0.0001) patients. These results suggest that the 4-gene classifier provides independent prognostic stratification of stage IA and stage IB patients beyond conventional clinical factors and may assist clinicians in decisions regarding postoperative management of early stage patients.nnCitation Format: Hirokazu Okayama, Aaron J. Schetter, Teruhide Ishigame, Ana I. Robles, Takashi Kohno, Jun Yokota, Seiichi Takenoshita, Curtis C. Harris. The expression of four genes as a prognostic classifier for stage I lung adenocarcinoma in 12 independent cohorts. [abstract]. In: Proceedings of the AACR-IASLC Joint Conference on Molecular Origins of Lung Cancer; 2014 Jan 6-9; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2014;20(2Suppl):Abstract nr B35.

Abstract A34: Nitric Oxide enhances inflammation, microRNA-21 expression and KRAS-induced lung carcinogenesis

Mutant KRAS in lung cancers induce molecular pathways that regulate cellular proliferation, survival and inflammation, which enhance tumorigenesis. Inducible nitric oxide synthese (NOS2) up-regulation and sustained nitric oxide (NO•) generation are induced during the inflammatory response and correlate positively with lung tumorigenesis. To explore the mechanistic contribution of NOS2 to KRAS-induced lung tumorigenesis and inflammation, we used a genetic strategy of crossing NOS2 knockout (NOS2KO) C57BL6 inbred mice with a KRASG12D-driven mouse lung cancer model. KRASG12D/NOS2KO mice exhibited delayed lung tumorigenesis, resulting in a longer overall survival time compared with that of KRASG12D/NOS2WT (wildtype) controls. Correspondingly, tumors in KRASG12D/NOS2KO mice had reduced tumor cell proliferation in adenomas and carcinomas. NOS2-deficiency also led to dramatically suppressed inflammatory response by attenuation of macrophage recruitment into alveoli and within tumor foci. In contrast, FOXP3+ regulatory T cells were increased in tumors from KRASG12D/NOS2KO mice. We further analyzed the expression of microRNA-21 (miR-21), an oncogenic non-coding RNA involved in oncogenic Ras signaling, by quantitative reverse transcription PCR and in situ hybridization. Lung carcinomas dissected from KRASG12D/NOS2KO mice showed a significantly reduced miR-21 expression along with decreased tumor cell proliferation, suggesting that NOS2-deficiency could attenuate RAS signaling pathways that transactivate miR-21 expression. Therefore, deletion of NOS2 decreases lung tumor growth as well as inflammatory responses initiated by oncogenic KRAS, suggesting that both KRAS and NOS2 cooperate in driving lung tumorigenesis and inflammation. Inhibition of NOS2 may have a therapeutic value in lung cancers with oncogenic KRAS mutations.