RESUMO
BACKGROUND: Pancreatic cancer is a deadly disease. Discovery of the mutated genes that cause the inherited form(s) of the disease may shed light on the mechanism(s) of oncogenesis. Previously we isolated a susceptibility locus for familial pancreatic cancer to chromosome location 4q32-34. In this study, our goal was to discover the identity of the familial pancreatic cancer gene on 4q32 and determine the function of that gene. METHODS AND FINDINGS: A customized microarray of the candidate chromosomal region affecting pancreatic cancer susceptibility revealed the greatest expression change in palladin (PALLD), a gene that encodes a component of the cytoskeleton that controls cell shape and motility. A mutation causing a proline (hydrophobic) to serine (hydrophilic) amino acid change (P239S) in a highly conserved region tracked with all affected family members and was absent in the non-affected members. The mutational change is not a known single nucleotide polymorphism. Palladin RNA, measured by quantitative RT-PCR, was overexpressed in the tissues from precancerous dysplasia and pancreatic adenocarcinoma in both familial and sporadic disease. Transfection of wild-type and P239S mutant palladin gene constructs into HeLa cells revealed a clear phenotypic effect: cells expressing P239S palladin exhibited cytoskeletal changes, abnormal actin bundle assembly, and an increased ability to migrate. CONCLUSIONS: These observations suggest that the presence of an abnormal palladin gene in familial pancreatic cancer and the overexpression of palladin protein in sporadic pancreatic cancer cause cytoskeletal changes in pancreatic cancer and may be responsible for or contribute to the tumor's strong invasive and migratory abilities.
Assuntos
Adenocarcinoma/genética , Cromossomos Humanos Par 4/genética , Proteínas do Citoesqueleto/genética , Predisposição Genética para Doença/genética , Mutação , Neoplasias Pancreáticas/genética , Fosfoproteínas/genética , Actinina/genética , Western Blotting , Carcinoma in Situ/genética , Movimento Celular , Citoesqueleto/fisiologia , Progressão da Doença , Eletroforese em Gel de Poliacrilamida , Regulação Neoplásica da Expressão Gênica , Células HeLa , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , Linhagem , Lesões Pré-Cancerosas/genética , Proto-Oncogenes/genética , TransfecçãoRESUMO
BACKGROUND: Identification and characterization of genes that are relevant to pancreatic cancer remains a priority for developing detection and diagnostic tests and identifying targets for treatment. MATERIALS AND METHODS: In order to discover relevant genes, we developed a microarray composed of 5763 pancreas and pancreatic cancer cDNA clones, representing genes of known and unknown function. The Pittsburgh Pancreas Enriched ARray (PittPEAR) was used to compare the gene expression differences between pancreatic cancer and normal pancreas. RESULTS: Two hundred and sixty-four genes were identified: 85 were overexpressed and 176 were underexpressed in cancer compared to normal tissue. Two of the top five genes included the cell cycle division 37 (CDC37) and period Drosophila homolog protein 1 (PER1), which play critical roles in cell division and transcriptional regulation, respectively. Underexpression of many genes probably reflected the loss of acinar and islet cells from the tumors. The biological functions of overexpressed genes include immune response genes, cytoskeletal and genes related to the extracellular matrix, cell invasion, migration, adhesion and motility. Apoptosis and transcription factor genes were also identified. CONCLUSION: We conclude that the PittPEAR microarray provides a useful tool for identifying genes that are relevant to the development and maintenance of pancreatic cancer.
