BMC Cancer 2005, 5:77 http://www.biomedcentral.com/1471-2407/5/77 lesions. An altered expression of this gene has also been proposed as an important event during cervical carcino- genesis [26,27]. Interestingly, the invasive samples show- ing MSH2 amplification presented with a high number of alterations (>40), suggesting a possible connection between increased copy number of this gene and chromo- somal instability in invasive cervical carcinomas. One of the most important genetic events during cervical carcinoma progression is the gain of 3q. This alteration has been detected in early stages of cervical transforma- tion and in cooperation with other imbalances, seems to play an important role in tumor development. Microarray analysis identified among the most prevalent alterations in cervical tumors and cell lines the amplification of the RBP1- RBP2 (Retinol binding protein 1 and 2, 58.8%) and Tp63 (52.9% of the samples) genes, located at 3q21-q22 and 3q27-q29, respectively. Tp63 is a homolog of the p53 tumor suppressor gene. Its protein is inactivated by the E6 HPV oncoprotein and plays a primordial role in the development of squamo- stratified epithelia. Tp63 is highly expressed in the basal stratum of these epithelia with diminished expression in the differentiated strata, suggesting that the presence of this protein preserves the self-renewal capacity of the epi- thelial stem cells after an asymmetric division, in which one of the daughter cell must conserve its epithelial stem- cell properties and the other daughter cell is committed to the differentiation process [28]. This protein has been detected in human cervical tissues in the basal and para- basal layers of the ectocervical squamous epithelium, and it is not present in the differentiated layers. In premalig- nant lesions and invasive squamous tumors, a strong p63 expression has been described [29,30]. The presence of this protein has also been associated with poor survival and locoregional failure after radiation and chemotherapy [31]. Expression of the epidermal growth factor receptor (EGFR, 7p12.3-p12.1), which was found amplified in 52.9% of the invasive tumors that we analyzed, was found to be a prognostic predictor of extrapelvic failure after treatment, and the expression of both molecules was found to be a very good risk factor measurement in patients with stage IIB squamous cell carcinoma of the uterine cervix, who had received radiotherapy and concur- rent chemotherapy [31]. DAB2 on 5p13 was amplified in 58.8% of the invasive cases. The DAB2 gene has been identified as a potent tumor suppressor gene in prostate and ovarian carcinoma [32], and loss of expression of this gene has been associ- ated with the transition of ovarian epithelial cells to pre- malignant states [33]. DAB2 has been implicated in cell positioning control and seems to mediate the require- ment for basement membrane attachment of epithelial cells [34]. To our knowledge, there are no available reports analyzing the expression of this gene in the uterine cervix or in cervical carcinoma. The amplification of this gene seems contrary to its putative role as a tumor sup- pressor gene. A possible explanation for this observation might be the loss of one allele followed by the amplifica- tion of the remaining chromosome. However, since array CGH does not offer any type of information regarding the parental origin of the amplified chromosome, this situa- tion can not be confirmed. Detection of the TERC gene amplification has been recently proposed as a potential marker for the evaluation of cervical carcinoma progression [35]; however, we detected amplification of the clone representing this gene in less than 10% of the samples analyzed by CGH arrays. FISH analysis, as described by Heselmayer et al., detected a higher prevalence of nuclei with a diploid pattern than those with a tetraploid pattern, even in the high grade lesions. Furthermore, the percentage of nuclei with more than 2 copies of 3q, including the tetraploid cells ranged between 3.3 to 50% of the CIN3 (cervical intraepithelial neoplasia grade 3). Dellas et al., [9] used in situ hybridi- zation to analyze the prevalence of 3q amplifications in cervical cancer tissue arrays, detecting low level amplifica- tions in most of the tumors studied. These results suggest that these low copy number gains might not be ade- quately detected by chromosome or even array CGH, due to the contamination with normal cells and/or the pres- ence of a high number of diploid or tetraploid cells in the sample. Regarding DNA losses, the FHIT (fragile histidine triad, 3p14.2) gene suffered losses in 47% of the cases. Aberrant expression of this gene has been well documented in cer- vical carcinoma and has been related to lymph node metastasis, parametrial invasion, and vaginal involve- ment in invasive tumors [36]. An association between FHIT gene abnormalities and infection with particular HPV types has been suggested, since 87% of the cases with absent FHIT expression were positive for HPV16 infection [37]. Furthermore, abnormal expression of this gene has been found in significantly younger patients than those with normal expression, suggesting that abnormalities in the regulation of this gene might be accelerating carcino- genesis in cooperation with HPV [37]. These observations might be related to the preferential integration of HPV into fragile sites, particularly FRA3B, where FHIT is located [38]. Conclusion In conclusion, microarray CGH allowed the detection of particular genes located in regions with common DNA copy number changes in cervical carcinoma. Further stud- ies using CGH arrays with a higher resolution and the Page 5 of 7 (page number not for citation purposes)