Purpose: NF-E2-related factor 2 (Nrf2), a key transcription regulator for antioxidant and detoxification enzymes, is abundantly expressed in cancer cells. In this study, therefore, the role of Nrf2 in cancer cell proliferation and resistance to anticancer drugs was investigated. Experimental Design: We used three human lung cancer cell lines with different degrees of Nrf2 activation: Nrf2 was highly activated in A549 cells, slightly activated in NCI-H292 cells, and not activated in LC-AI cells under unstimulated conditions. Result: A549 cells showed higher resistance to cisplatin compared with NCI-H292 and LC-AI cells. The resistance to cisplatin was significantly inhibited in A549 but not in NCI-H292 or LC-AI cells by knockdown of Nrf2 with its specific small interfering RNA (Nrf2-siRNA). The cell proliferation was also most prominently inhibited in A549 cells by treatment with Nrf2-siRNA. In A549 cells, the expression of self-defense genes, such as antioxidant enzymes, phase II detoxifying enzymes, and drug efflux pumps, was significantly reduced by Nrf2-siRNA concomitant with a reduction of the cellular glutathione level. The degree of DNA crosslink and apoptosis after treatment with cisplatin was significantly elevated in A549 cells by Nrf2-siRNA. Knockdown of Nrf2 arrested the cell cycle at G 1 phase with a reduction of the phosphorylated form of retinoblastoma protein in A549 and NCI-H292 cells but not in LC-AI cells. Conclusion: These results indicate that the Nrf2 system is essential for both cancer cell proliferation and resistance to anticancer drugs. Thus, Nrf2 might be a potential target to enhance the effect of anticancer drugs.

Inflammation, protease/anti-protease imbalance and oxidative stress play important roles in the pathogenesis of emphysema. Nrf2 counteracts oxidative tissue damage and inflammation through transcriptional activation via the anti-oxidant responsive element (ARE). To clarify the protective role of Nrf2 in the development of emphysema, the susceptibility of Nrf2-knockout mice to cigarette smoke (CS)-induced emphysema was examined. In Nrf2-knockout mice, emphysema was first observed at 8 weeks and exacerbated by 16 weeks following CS-exposure, whereas no pathological abnormalities were observed in wild-type mice. Neutrophilic lung inflammation and permeability lung damage were significantly enhanced in Nrf2-knockout mice 8 weeks after CSexposure. Importantly, neutrophil elastase activity in bronchoalveolar lavage fluids was markedly higher in Nrf2-knockout mice preceding the pronounced neutrophil accumulation. The expression of secretory leukoprotease inhibitor, a potent inhibitor of neutrophil elastase, was inducible in wild-type, but not in Nrf2-knockout mice. This protease/anti-protease imbalance, together with the lack of inducible expression of ARE-regulated anti-oxidant/anti-inflammatory genes, may explain the predisposition of Nrf2-knockout mice to neutrophilic inflammation. Indeed, specific activators of Nrf2 induced the expression of the SLPI gene in macrophages. These results indicate that Nrf2 protects against the development of emphysema by regulating not only the oxidant/ anti-oxidant balance, but also inflammation and the protease/anti-protease balance.

Histological subtyping of pulmonary adenocarcinoma has recently been updated based on predominant pattern, but data on reproducibility are required for validation. This study first assesses reproducibility in subtyping adenocarcinomas and then assesses further the distinction between invasive and non-invasive (wholly lepidic) pattern of adenocarcinoma, among an international group of pulmonary pathologists. Two ring studies were performed using a micro-photographic image-based method, evaluating selected images of lung adenocarcinoma histologic patterns. In the first study, 26 pathologists reviewed representative images of typical and ‘difficult’ histologic patterns. A total number of scores for the typical patterns combined (n = 94) and the difficult cases (n = 21) were 2444 and 546, respectively. The mean kappa score (± s.d.) for the five typical patterns combined and for difficult cases were 0.77 ± 0.07 and 0.38 ± 0.14, respectively. Although 70% of the observers identified 12–65% of typical images as single pattern, highest for solid and least for micropapillary, recognizing the predominant pattern was achieved in 92–100%, of the images except for micropapillary pattern (62%). For the second study on invasion, identified as a key problem area from the first study, 28 pathologists submitted and reviewed 64 images representing typical as well as ‘difficult’ examples. The kappa for typical and difficult cases was 0.55 ± 0.06 and 0.08 ± 0.02, respectively, with consistent subdivision by the same pathologists into invasive and non-invasive categories, due to differing interpretation of terminology defining invasion. In pulmonary adenocarcinomas with classic morphology, which comprise the majority of cases, there is good reproducibility in identifying a predominant pattern and fair reproducibility distinguishing invasive from in-situ (wholly lepidic) patterns. However, more precise definitions and better education on interpretation of existing terminology are required to improve recognition of purely in-situ disease, this being an area of increasing importance.

These results demonstrated in vivo that 15d-PGJ2 plays a protective role against ALI by exploiting the Nrf2-mediated transcriptional pathway.