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ORAL 07 - Lung Cancer Pathogenesis (ID 91)
- Event: WCLC 2015
- Type: Oral Session
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
ORAL07.03 - MMP12 and LMO7 Are Key Genes Involved in the Early Pathogenesis of Squamous Cell Carcinoma of the Lung (ID 1173)
10:45 - 12:15 | Author(s): B. Carrol
Lung cancer is the most lethal cancer type worldwide. In order to increase patient survival it is important to improve our understanding of the early changes associated with lung cancer progression. The progression of lung squamous cell carcinoma (SqCC) from pre-invasive lesions involves a series of histological changes which includes squamous metaplasia, mild, moderate and severe dysplasia, and carcinoma in situ (CIS). In these pre-invasive lesions the basement membrane is intact and there is no possibility of metastatic spread, which is in contrast to SqCC where there is the potential for metastasis as soon as invasion occurs. Our laboratory has a unique cohort of patients with pre-invasive lung SqCC lesions. Within this cohort there is a discrepancy between the prevalence of pre-invasive lesions and the incidence of invasive lung cancer, which suggests that not all pre-invasive lesions progress to invasive carcinomas. This tissue collection forms an internationally unique resource of lesions and will shed light on the molecular characteristics of lesions that progress compared to those that either regress or remain stable. The aim of this study was to identify and characterize key genes involved in the early pathogenesis of lung SqCC.
Following histological review by two histopathologists to confirm that pre-malignant tissue is present in the biopsy specimens, the epithelial component of interest was laser-capture micro-dissected. This is vital in order to eliminate any cross-contamination from unwanted cells and to ensure that pre-invasive CIS specific gene expression profiles are generated. We have performed genome-wide gene expression Illumina’s Whole-Genome DASL® arrays in 20 progressive and 19 regressive pre-invasive lung SqCC lesions. The protein expression of Matrix metallopeptidase 12 (MMP12) and LIM domain 7 (LMO7) was also determined in the 39 pre-invasive lung cancer lesions by immunostaining analysis. The functional role of MMP12 and LMO7 in cell migration and invasion was demonstrated by MMP12 and LMO7-shRNA knockdown in different squamous cell carcinoma cell lines and human bronchial epithelial cells (HBECs), respectively.
We found 939 genes significantly differently expressed between the progressive and the regressive pre-invasive lung SqCC lesions. We identified a remarkably elevated expression of a spectrum of genes in the progressive lung SqCC lesions involved in different related cancer pathways including chromosome instability, p53 signalling and Wnt/β-catenin signalling. MMP12 and LMO7 were found within the highest significantly differently expressed genes and were therefore chosen to pursue studies focused on understanding the potential mechanisms leading to the development of lung SqCC. In agreement with the gene expression data the expression of MMP12 and LMO7 proteins were up-regulated and down-regulated, respectively, in progressive when compared with regressive lesions. Inhibiting MMP12 by MMP12 knockdown significantly reduced the migration and invasion of different squamous cell carcinoma cell lines (A431, H357 and H376). We also established HBECs knockdown targeting LMO7. We observed a significant increase in the migration and invasion of HBECs cells in the LMO7 shRNA knockdown compared to control.
Our results suggest that MMP12 and LMO7 may be potential therapeutic markers for lung cancer at early stage.
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