HO-1 is a poor prognostic NSCLC predictor and its over-expression may increase the metastatic potential of NSCLC. Based on our findings and those of others, HO-1 may be considered as a novel NSCLC therapeutic target.

High-mobility group box 1 (HMGB1) is a versatile protein with intranuclear and extracellular functions. It is involved in invasion and metastasis in various human malignancies. However, the role of HMGB1 in non-small cell lung cancer (NSCLC) is unclear. We hypothesized that HMGB1 expression is a determinant of cellular invasiveness and metastasis in lung cancer. We examined HMGB1 expression in 48 NSCLC specimens by quantitative real-time PCR. High HMGB1 expression was significantly associated with clinically advanced stages (stage III-IV) (P < 0.05) and was correlated to expression of matrix metalloproteinase-9 (MMP-9) (P < 0.05). Patients with high levels of HMGB1 expression had poorer clinical prognosis. The expression level of MMP-9 and metastatic ability in vitro were significantly higher in an HMGB1-overexpressing human NSCLC cell lines (A549 and H23). The treatment with HMGB1 small interfering RNA reduced MMP-9 expression and the cellular metastatic ability in NSCLC cells. We also demonstrated that phosphoinositide 3-kinase/Akt and NF-κB-related pathways contributed to the HMGB1-induced MMP-9 expression and cellular metastatic ability.

Resveratrol exhibits potential anti-carcinogenic activities. Heme oxygenase-1 (HO-1) is involved in angiogenesis and tumor metastasis. Matrix metalloproteinases (MMPs) are key enzymes in the degradation of extracellular matrix, and their expression may be dysregulated in lung cancer metastasis. In this study, we investigated the anti-invasive mechanism of resveratrol in lung cancer cells. HO-1 was shown to be elevated (approximately 4.7-fold) in lung cancer tumor samples as compared with matched normal tissues. After treatment of lung adenocarcinoma cell line A549 cells with resveratrol (50 microM) for 24 h, the migratory and invasive abilities (38 and 30% inhibition, respectively) of A549 cells were significantly reduced. Resveratrol significantly inhibited HO-1-mediated MMP-9 (35% inhibition) and MMP-2 (28% inhibition) expression in lung cancer cells. Nuclear factor (NF)-kappaB inhibitor induced a marked reduction in MMP-9 and MMP-2 expression, suggesting NF-kappaB pathway could play an important role. Furthermore, HO-1 inhibition and silencing significantly suppressed MMPs and invasion of lung cancer cells. Our results suggest that resveratrol inhibited HO-1 and subsequently MMP-9 and MMP-2 expression in lung cancer cells. The inhibitory effects of resveratrol on MMP expression and invasion of lung cancer cells are, in part, associated with the HO-1-mediated NF-kappaB pathway.