Suppression of the tumorigenic phenotype by chromosome 18 transfer into pancreatic cancer cell lines

Abstract

A number of lines of evidence have suggested that the long arm of chromosome 18 apart from SMAD4 may carry a tumor-suppressor gene(s) that plays a role in the early stage of pancreatic ductal carcinogenesis. Thus, adenovirus-mediated introduction of SMAD4 does not suppress in vitro growth in cells with completely inactivated SMAD4, and frequent loss of 18q at the SMAD4 locus is observed in pancreatic cancers but no abnormalities of the normal SMAD4 homolog have been detected. In this study, we introduced a normal copy of chromosome 18 into some pancreatic ductal carcinoma cells with and without a complete inactivation of SMAD4. Both anchorage-dependent and -independent proliferation as well as invasiveness were significantly suppressed in the hybrid clones compared with that of their parental cells. Moreover, significant suppression of tumorigenesis was observed after inoculation in nude mice, irrespective of the SMAD4 status. Our present study provides the first functional evidence of the existence of an additional tumor-suppressor gene(s), other than SMAD4 and DCC, that is responsible for the pathogenesis in the early stage of pancreatic ductal carcinogenesis.

Restoration of SMAD4 by gene therapy reverses the invasive phenotype in pancreatic adenocarcinoma cells

“…The SMAD4 (Ramachandra et al, 2002) gene is located on chromosome 18q21, a putative location for other tumour-suppressor genes (TSGs, Lefter et al, 2002). It is inactivated in half of pancreatic carcinomas (Calonge and Massague, 1999), and as we reported previously, SMAD4 inactivation is associated with a poor prognosis (Yatsuoka et al, 2000).…”

“…In adenocarcinoma, malignant transformation of epithelial cells is the result of a sequence of oncogene and TSG mutations (Takaku et al, 1998). By stable transfer of chromosome 18, we have previously demonstrated the existence of an additional TSG, other than SMAD4, responsible for the pathogenesis in the early stage of pancreatic ductal carcinogenesis (Lefter et al, 2002). In addition, an interesting finding constituted the fact that the highly frequent activating mutation of KRAS occurs early in gastrointestinal cancer and was reported to disrupt jointly the TGF-b antiproliferative responses incurred by SMAD4 silencing, a later event (Wilentz et al, 2000), through the inhibition of the SMAD2/3 function (Calonge and Massague, 1999).…”

Chromosome 12, frequently deleted in human pancreatic cancer, may encode a tumor-suppressor gene that suppresses angiogenesis

“…We transferred a normal copy of chromosome 12 into pancreatic cancer cell lines by the microcell-mediated chromosome transfer (MMCT) technique 16,17 and analyzed its phenotype. MMCT has been proven to be a useful tool providing functional evidence for identification of TSG in a variety of cancers such as pancreatic cancer, 21 colon cancer, 26,27 prostate cancer, 28 Wilms' tumor, 29 and melanoma. 30 This technique also led the way to the isolation of the NBS gene.…”

“…For each cell line, the PI was estimated as previously described. 21 Data from two independent experiments were pooled, averaged, and then statistically analyzed.…”

Monochromosomal Hybrids and Chromosome Transfer: A Functional Approach for Gene Identification

“…The identification and cloning of RNAseT2 (52) represents an illustrative example of the application of chromosome transfer strategy. The modulation of cancer cell phenotypes following chromosome transfer (55)(56)(57)(58) indicates the presence of responsible genes on specific chromosomes. Based on these observations, we believe that chromosome transfer is a productive approach for identifying genes involved in growth/tumor suppression.…”