Altered Cell-Cycle Control, Inflammation and Adhesion in High-Risk Persistent Bronchial Dysplasia

Persistent bronchial dysplasia (BD) is associated with increased risk of developing invasive squamous cell carcinoma (SCC) of the lung. We hypothesized that differences in gene expression profiles between persistent and regressive BD would identify cellular processes that underlie progression to SCC. RNA expression arrays (Affymetrix Hu 1.0) comparing baseline biopsies from 32 bronchial sites that persisted/progressed to 31 regressive sites showed 395 differentially expressed genes (ANOVA, FDR</=0.05). Thirty-one pathways showed statistically significant evidence of altered activity between the two groups. Multiple pathways were associated with cell cycle control/proliferation, inflammation, or epithelial differentiation/cell-cell adhesion. Polo-like kinase 1 (PLK1) was associated with multiple cell cycle pathways. Cultured persistent BD cells showed increased PLK1 expression, and following treatment with PLK1 inhibitor, showed induction of apoptosis, G2/M phase arrest and decreased proliferation compared to untreated cells. These effects were not seen in normal or regressive BD cultures. Inflammatory pathway activity was decreased in persistent BD and the presence of an inflammatory infiltrate was more common in regressive BD. Regressive BDs were also associated with trends toward overall increases in macrophages and T-lymphocytes and altered polarization of these inflammatory cell subsets. Increased desmoglein 3 and plakoglobin expression was associated with higher grade and persistence of BD. The results identify alterations in cell cycle control, inflammatory activity, and epithelial differentiation/cell-cell adhesion in the persistent subset of BDs that are associated with high risk for progression to invasive SCC. These pathways may provide strong markers of risk and effective targets for lung cancer prevention.

63

Merrick DT, Edwards MG, Franklin WA, Sugita M, Keith RL, Miller YE, Friedman MB, Dwyer-Nield LD, Tennis MA, O'Keefe MC, Donald EJ, Malloy JM, van Bokhoven A, Wilson S, Koch PJ, O'Shea C, Coldren C, Orlicky DJ, Lu X, Baron AE, Hickey G, Kennedy TC, Powell R, Heasley L, Bunn PA, Geraci M, Nemenoff RA