Mutations in the EGFR tyrosine kinase domain define a new molecular type of lung carcinoma, more frequent in particular subsets of patients. The SSCP assay is a rapid and reliable method for the detection of EGFR kinase domain mutations in lung cancer.

Mutations in the PIK3CA gene have recently been reported in different human neoplasms, including breast cancer. This paper reports the results of a systematic analysis of PIK3CA mutations in different histological types of breast carcinoma. One hundred and eighty invasive breast carcinomas, comprising 74 ductal, 56 lobular, 22 mucinous, 20 medullary, and eight papillary, were selected on the basis of their histological type in a consecutive series of 780 breast cancers. Exons 1-20 of the PIK3CA gene were subjected to SSCP analysis followed by direct sequencing. PIK3CA mutations were observed in 46 (26%) of the 180 tumours examined: 23 (50%) mutations were located in exon 9, and 23 (50%) in exon 20. Mutations were frequent in lobular (46%), less frequent in ductal (22%), and uncommon in medullary (10%), mucinous (5%), and papillary tumours (12%) (p = 0.0002). Mutations in exon 9 were more frequent in lobular carcinomas (30% of cases) than in the other histological types (less than 5% of cases) (p = 0.00014). No significant differences were observed in the distribution of mutations in exon 20. There was no significant correlation between PIK3CA mutations and other clinicopathological and biological variables, including age, tumour size, lymph node metastases, oestrogen receptor (ER) status, progesterone receptor (PgR) status, p53 gene mutations, and p53 protein expression. The findings indicate that in invasive breast carcinomas, PIK3CA alterations are mainly present in lobular and ductal tumours, whereas the other histological types, known to be associated with a favourable prognosis, show a very low incidence of PIK3CA mutations.

The HDMX protein is closely related to HDM2 with which it shares different structural domains, particularly the p53 binding domain and the ring finger domain, where the two HDM proteins interact. Several oncogenic forms derived from splicing of HDM2 have been described in cancer. This work aimed at investigating whether analogous forms of HDMX exist in human tumors. Here, we report the characterization of an aberrantly spliced form of HDMX, HDMX211, isolated from the thyroid tumor cell line, ARO. HDMX211 binds and stabilizes the HDM2 protein. Although it lacks the p53 binding domain, HDMX211 also stabilizes p53 by counteracting its degradation by HDM2. However, the resulting p53 is transcriptionally inactive and increasingly associated to its inhibitor HDM2. Expression of HDMX211 strongly enhances the colony-forming ability of human cells in the presence or absence of wild-type p53. Conversely, depletion of HDMX211 by small interfering RNA significantly reduces the growth of ARO cells and increases their sensitivity to chemotherapy. Screening of lung cancer biopsies shows the presence of HDMX211 in samples that overexpress HDM2 protein, supporting a pathologic role for this new protein. This is the first evidence of a variant form of HDMX that has oncogenic potential independently of p53. HDMX211 reveals a new mechanism for overexpression of the oncoprotein HDM2. Most interestingly, it outlines a possible molecular explanation for a yet unclarified tumor phenotype, characterized by simultaneous overexpression of HDM2 and wild-type p53. (Cancer Res 2005; 65(21): 9687-94)

Purpose: The Int6 gene was originally identified as a common insertion site for the mouse mammary tumor virus in virally induced mouse mammary tumors. Recent studies indicate that Int6 is a multifaceted protein involved in the regulation of protein translation and degradation through binding with three complexes: the eukaryotic translation initiation factor 3, the proteasome regulatory lid, and the constitutive photomorphogenesis 9 signalosome. This study aimed to investigate the prognostic role of Int6 in a large series of stage I non^small cell lung cancers (NSCLC) patients with long-term follow-up. Experimental Design: We determined the methylation status of Int6 DNA by methylationspecific PCR and the steady-state levels of Int6 RNA by quantitative real-time reverse transcription-PCR in 101 NSCLCs and matched normal lung tissues. Results: In 27% of the tumors, Int6 RNA levels were reduced relative to normal tissue. In 85% of the tumors with reduced Int6 expression, the transcription promoter and first exon were hypermethylated, whereas only 4% of the tumors with elevated Int6 RNA levels were hypermethylated (P < 0.000001). Low levels of Int6 RNA were found a significant predictor of overall and disease-free survival (P = 0.0004 and P = 0.0020, respectively). A multivariate analysis confirmed that low Int6 expression was the only independent factor to predict poor prognosis, for both overall (P = 0.0006) and disease-free (P = 0.024) survival. Conclusions: Our results suggest that Int6 expression, evaluated by quantitative real-time PCR, may represent a new prognostic factor in patients with stage I NSCLC.The Int6 gene was first identified as a common insertion site for mouse mammary tumor virus in virally induced mouse mammary tumors and a preneoplastic lesion (1). In each case, mouse mammary tumor virus integrated into an intron in the opposite transcriptional orientation of Int6. Transcription of the affected allele was terminated at a cryptic transcription stop signal in the reverse mouse mammary tumor virus long terminal repeat sequence causing the expression of a truncated chimeric RNA that encodes a COOH-terminally deleted product. Overexpression of these truncated proteins can confer the capability of anchorage-independent growth on mammary epithelial cells and fibroblasts in culture and injection of these cells into nude mice can lead to tumor development (2, 3). Because we found no mutations in the remaining allele of the mouse mammary tumor virus -induced tumors, we have hypothesized that the truncated Int6 protein may act as dominant-negative oncoprotein.The Int6 gene has been highly conserved through evolution, from fission yeast to humans, with the intriguing exception of budding yeasts that have a related protein called Pci8p (4). Int6 was later independently rediscovered several times by investigators working in different areas of biological research (5). Asano et al. found that Int6 is identical to the p48 subunit of the eukaryotic translation initiation factor3 (eIF3) complex that pla...

Purpose: The aim of this study was to evaluate the prevalence and the clinical significance of HIN-1 mRNA expression in early stage non-small cell lung carcinomas (NSCLCs). Results: Seventy one (78%) tumors showed a reduction of HIN-1 mRNA compared with the normal counterpart. The range of reduction varied greatly, from ؊2-fold to ؊3350-fold. Setting a cutoff at ؊46-fold (median value of HIN-1 mRNA reduction), 46 cases (51%) had a markedly reduced expression, and 45 cases (49%) showed a normal or slightly reduced expression. A statistically significant association between low HIN-1 mRNA levels and T status was observed (P ‫؍‬ 0.036). Univariate survival curves, estimated using the method of Kaplan-Meier, defined a significant association between HIN-1 expression and both overall survival (P ‫؍‬ 0.0095) and disease-free survival (P ‫؍‬ 0.0122). A multivariate analysis, performed by Cox's proportional hazards regression model, confirmed that a low HIN-1 expression was the only significant factor to predict poor prognosis.Conclusions: Our data indicate that HIN-1 expression, measured by real-time reverse transcription-PCR, is a possible prognostic factor in patients with stage I NSCLC. Additional studies are required to further validate this potential prognostic marker.