Project description:Brain metastasis (BM) can affect up to 25% of non-small cell lung cancer (NSCLC) patients during their lifetime. Efforts to characterize patients that will develop BM have been fairly disappointing. Small non-coding microRNAs (miRNAs) regulate the expression of target mRNAs by repressing their translation or regulating their sequence-specific degradation. miRNAs play a role in regulating a variety of targets and, consequently, multiple pathways, which makes them a powerful tool to be exploited for early detection of disease, risk assessment, and prognosis. In this study, we investigated miRNAs that may serve as biomarkers to differentiate between NSCLC patients with and without BM. miRNA microarray profiling was performed on samples from clinically matched NSCLC from patients with BM (BM+) and without BM (BM-). miR-328 and miR-330-3p were able to correctly classify BM+ vs. BM- patients. Gene expression analysis comparing NSCLC parental and stably transfected miR-328 cells identified several significantly differentially-expressed genes, whose expression may be directly or indirectly regulated by miR-328.
Project description:PURPOSE: Bone marrow (BM) is a common homing organ for early disseminated tumor cells (DTC) and their presence can predict the subsequent occurrence of overt metastasis and survival in lung cancer. It is still unclear whether the shedding of DTC from the primary tumor is a random process or a selective release driven by a specific genomic pattern. EXPERIMENTAL DESIGN: DTCs were identified in BM from lung cancer patients by an immunocytochemical cytokeratin assay. Genomic aberrations and expression profiles of the respective primary tumors were assessed by microarrays and FISH analyses. The most significant results were validated on an independent set of primary lung tumors and brain metastases. RESULTS: Combination of DNA copy number profiles (array CGH) with gene expression profiles identified five chromosomal regions differentiating BM-negative from BM-positive patients (4q12-q32, 10p12-p11, 10q21-q22, 17q21 and 20q11-q13). Copy number changes of 4q12-q32 were the most prominent finding, containing the highest number of differentially expressed genes irrespective of chromosomal size (p=0.018). FISH analyses on further primary lung tumor samples confirmed the association between loss of 4q and the BM-positive status. In BM-positive patients 4q was frequently lost (37% vs. 7%), whereas gains could be commonly found among BM-negative patients (7% vs. 17%). The same loss was also found to be common in brain metastases from both small and non-small-cell lung cancer patients (39%). CONCLUSIONS: Thus, our data indicates for the first time that early hematogeneous dissemination of tumor cells might be driven by a specific pattern of genomic changes.