Molecular Analysis of the 9p21 Locus and p53 Genes in Ewing Family Tumors

Abstract

SUMMARY:The EWS-ETS rearrangements, and their respective fusion gene products, are specifically associated with histopathologically Ewing family tumors (EFT). These translocations are implicated in generating malignant transformation of EFT, but the presence of additional genetic alterations must be considered in the pathogenesis of such tumors. We analyzed 26 samples (biopsies and/or nude mice xenotransplants) collected from 19 patients with an EFT to determine whether molecular and cytogenetic alterations of the G 1 /S checkpoint genes are implicated in the pathogenesis of EFT. We found inactivating p53 mutations in three (16%) cases, which correlated with a loss of p21 WAF1/Cip1 expression and with a monosomy of chromosome 17 in two cases. Homozygous deletion of the p16 INK4A /p14 ARF gene was detected in four (21%) cases, three with codeletion of the p15 INK4B gene and with chromosome 9 abnormalities. In all of these cases, expression of the implicated genes was absent. Hypermethylation of the p16 INK4A and p15 INK4B genes was detected in two (10%) and three (16%) cases, respectively, and was correlated with a low level of gene expression. Neither cyclin D1, nor MDM2 and CDK4 amplification was observed. Kaplan-Meier analysis showed that patients with tumors carrying homozygous deletion of the 9p21 locus, or point mutations of the p53 gene, had poorer outcomes than those without these molecular alterations (p ϭ 0.005). In conclusion, 58% (11 of 19) of the analyzed patients showed genetic or epigenetic alterations in either the 9p21 locus or p53 tumor suppressor genes, defining a subgroup of patients with poor clinical outcome. This fact points to an important role of the G 1 /S cell cycle checkpoint dysregulation in the pathogenesis of EFT. (Lab Invest 2001, 81:803-814).

Adenovirus-mediated p53 gene therapy in pediatric soft-tissue sarcoma cell lines: sensitization to cisplatin and doxorubicin

“…63,64 p53 mutations are common in RMS with nearly 50% of cases exhibiting a lesion in the p53 gene. 63,65 p53 mutations are not as common in ES with frequencies of 3-16%; 31,66 however, the subset of ES patients with mutant p53 have a markedly poorer outcome. 30 The frequency of p53 mutations in undifferentiated STS in children is unknown.…”

“…28 p53 alterations in ES are not common (approximately 10%) but are associated with poor outcomes. [29][30][31] As in RMS, 20-25% of ES patients present with metastatic disease, which reduces 2-year survival from approximately 70 to 40%. 32,33 Cure rates of up to 70-75% have been reported in cases with localized disease, 34 but patients presenting with metastatic disease almost always have a fatal outcome.…”

In Ewing's sarcoma CCN3(NOV) inhibits proliferation while promoting migration and invasion of the same cell type

“…Therefore, CCN3 may be one of the few molecular markers with prognostic relevance in this neoplasm. Indeed, although several clinical factors have been reported to have a prognostic value (Bacci et al, 2000), few genetic and molecular markers have clearly emerged so far (de Alava et al, 1998Wei et al, 2000;Lopez-Guerrero et al, 2001;Ozaki et al, 2001;Perri et al, 2001;Zielenska et al, 2001;Hattinger et al, 2002;Manara et al, 2002;Ohali et al, 2003) and for none of them there is a general consensus since findings are often sporadic and in conflict. Moreover, the biological basis for the supposed prognostic impact of all these markers has not been clarified.…”

Establishment and Characterization of a Continuous Human Chondrosarcoma Cell Line, ch-2879: Comparative Histologic and Genetic Studies with Its Tumor of Origin

“…High molecular weight DNA was obtained by proteinase K (Life Technologies) digestion and purification using conventional phenol-chloroform protocol. Samples were analyzed for molecular alterations of the G1 to S phase cell cycle transition as previously described (López-Guerrero et al, 2001). dPCR was used to detect homozygous deletion of the 9p21 locus genes: the presence of homozygous deletion was confirmed by the loss of the PCR product corresponding to p15 INK4B , p16 INK4A , and p14…”

“…Molecular alterations of the regulatory genes implicated in cell cycle control play an important role in human tumorigenesis. Mutations of the p53 tumor suppressor gene are the most common genetic alteration in human tumors, followed by the genetic alterations of the 9p21 locus that have been demonstrated in a wide variety of neoplasms (López-Guerrero et al, 2001). p14 ARF protein is a potent regulator of the cell cycle, acting upstream in the p53 pathway by binding to MDM2 and preventing p53 degradation, thus permitting p53-induced apoptosis or growth arrest (Lundberg and Weinberg, 1999;Sharpless and DePinho, 1999).…”