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Promoter methylation of the PTEN gene is a common molecular change in breast cancer.

About 25–50% of women with Cowden disease, a syndrome associated with germ‐line mutations of the PTEN gene (at 10q23), develop breast cancer (BC), but PTEN mutations have been found in only 5% of sporadic BCs. However, 29–48% of BCs display loss of heterozygosity in 10q23, and about 40% of BCs show a decrease or absence of PTEN protein levels at the time of diagnosis. Promoter hypermethylation has been identified as an alternative mechanism of tumor‐suppressor gene inactivation, but its importance in PTEN silencing in sporadic BC is unknown. We investigated PTEN promoter hypermethylation in 90 sporadic BCs and its correlations with 11 molecular and pathologic parameters, including mRNA levels of PTEN. The study, a methylation‐specific PCR assay, was carried out with methylated specific primers designed in a region with scarce homology with the psiPTEN pseudogene. Expression was analyzed by real‐time PCR. We found that the PTEN promoter was hypermethylated in 43 BCs (48%). PTEN hypermethylation was associated with ERBB2 overexpression, larger size, and higher histologic grade (P = 0.012, 0.03, and 0.009, respectively). We concluded that PTEN promoter hypermethylation is a common event in sporadic BC, correlating with other well‐established prognostic factors of this malignancy. Additionally, PTEN mRNA expression was lower in tumors with aberrant methylation.

Cancer Antigen 125 Associated With Multiple Benign and Malignant Pathologies

Background:Cancer antigen (CA) 125 tumor-associated antigen is a high molecular glycoprotein used for follow-up of epithelial ovarian cancer. The test is often requested as a differential diagnosis in patients with pleural or peritoneal fluid. This study analyzes the prevalence of CA-125 increases in a population of patients attending a general hospital and discusses the possible clinical implications of increased levels.Methods:On 4 different days, 380 CA-125 assays were performed in randomly selected patients attending our hospital. Serum CA-125 was measured with a commercial enzyme immunoassay, and clinical records were reviewed for assessment of clinical parameters.Results:Sixty-one patients (16%) had increased CA-125. The pathologies of these patients were heart failure in 9 (14.7%), lung disease 11 (18%), hepatic cirrhosis in 7 (11.4%), malignant tumors in 9 (14.7%), intra-abdominal nonhepatic disease in 6 (10%), previous surgery in 17 (27.8%), and miscellaneous in 2 (3%). Effusions were seen in 34 patients (55.7%).Conclusions:Our data confirm the variety of benign and malignant pathologies coursing with increased CA-125. Cardiovascular and chronic liver disease were the most frequent diagnoses in patients with increased CA-125; this supports the opinion that CA-125 lacks utility as a marker for malignancy. CA-125 could have a role in the follow-up of cardiovascular, hepatic, and tumoral diseases with serosal involvement.

Allelic loss of the PTEN region (10q23) in breast carcinomas of poor pathophenotype

Loss of heterozygosity (LOH) in loci of the 10q23 region that harbor the PTEN gene and mutations in the sequence of this gene have been found in several primary human tumors including breast carcinomas, suggesting that this gene could be implicated in their pathogenesis. We investigated allelic losses in microsatellites of the 10q23 region, and their correlations with nine pathologic parameters in 105 breast carcinomas. The LOH analysis was performcd by amplifying DNA by PCR, using five markers of the 10q23 region (D10S1687, D10S541, D10S2491, D10S583 and D10S571). LOH in at least one marker of the PTEN region was found in 29.5% of tumors. The statistical comparison between carcinomas with and without LOH in terms of the pathologic parameters showed significant differences in age (p=0.03), lymph node metastases (p=0.02), and higher histological grade (p=0.02); a trend toward significance was found for progesterone receptors (p=0.05). LOH in an individual marker and statistically significant relationships to tumor characteristics were observed at locus D10S541 for lymph node metastases (p=0.04), at D10S2491 (intragenic to the PTEN gene) for lymph node metastases (p=0.02), and at D10S583 for progesterone receptors (p=0.01) and for high grade (p=0.03). These results suggest the PTEN gene, or other genes of the 10q23 region, could be functionally related to breast cancer, probably influencing the development of histological features associated with poor prognosis.

Concomitant expression of p16INK4a and p14ARF in primary breast cancer and analysis of inactivation mechanisms

The INK4a/ARF locus encodes two tumour suppressor proteins, p16INK4a and p14ARF, which act in the two main cell‐cycle control pathways, p16–Rb and p14–p53 respectively. The present study examined the mRNA expression of these genes by reverse transcription‐polymerase chain reaction (RT‐PCR), and the inactivation mechanisms that alter these levels, in 100 primary breast carcinomas. Furthermore, the interdependence of these mechanisms was examined, since it has been reported that p14ARF is altered in most tumours in concordance with p16INK4a. The results show that promoter hypermethylation, tested by methylation‐specific PCR (MSP), was the major mechanism of inactivation of these genes and was present in 31 (31%) and 50 (50%) of the tumours that showed decreased p16INK4a and p14ARF expression, respectively. Hemizygous deletion was the second cause of down‐regulation. Homozygous deletion was rare and mutation was absent. In most tumours overexpressing p16INK4a or p14ARF, no detectable inactivation mechanisms were observed. Finally, the results indicate that these proteins are often co‐altered in primary breast tumours and that p16INK4a and p14ARF had non‐independent behaviour, since they were silenced or overexpressed concomitantly with a significant correlation (p < 0.05). Copyright

Implication of Polycomb Members Bmi-1, Mel-18, and Hpc-2 in the Regulation of p16INK4a, p14ARF, h-TERT, and c-Myc Expression in Primary Breast Carcinomas

Purpose: Deregulation of mammalian Polycomb group (PcG) members may contribute to human carcinogenesis. p16INK4a and p14ARF tumor suppressors, human telomerase reverse transcriptase (h-TERT), and oncoprotein c-Myc have been implicated in the regulation of the cell cycle and proliferation mediated by PcG proteins, mainly Bmi-1, in mice and in cell culture experiments. Here, we examine whether these in vitro findings can be extrapolated to the in vivo situation. Experimental Design: We measure the expression of PcG members Bmi-1, Mel-18, and Hpc-2 and their potential targets by reverse transcription-PCR, immunostaining, and Western blotting in a series of 134 breast carcinomas and correlate the data with several clinical-pathologic variables of the tumors. Results: Expression of PcG genes was variably detected, but overexpression of Bmi-1 was the most frequent PcG alteration observed. In addition, statistical direct correlation in expression level of the three PcG members was detected. A correlation between c-Myc and Bmi-1 expression levels was observed; however, there was no correlation between expression of Bmi-1 and p16INK4a, p14ARF, or h-TERT. However, expression of the other PcG members Mel-18 and Hpc-2 correlated with the cell cycle regulators. Moreover, PcG mRNA–altered expression correlated significantly with certain clinical-pathologic variables associated with poor prognosis. Conclusions: Our data suggest that the oncogenic role of Bmi-1 in human primary breast carcinomas is not determined by its capacity to inhibit INK4a/ARF proteins or to induce telomerase activity.

Prevalence of aberrant methylation of p14ARF over p16INK4a in some human primary tumors

The INK4a/ARF locus encodes two unrelated tumor suppressor proteins, p16INK4a and p14ARF, which participate in the two main cell-cycle control pathways, p16-Rb and p14-p53. Methylation of CpG promoter islands has been described as a mechanism of gene silencing. Exon 1 of the p16INK4a gene and the p14ARF promoter gene reside within CpG islands. Therefore, both can become methylated de novo and silenced. It has recently been proposed that the methylation changes in certain genes could be used as molecular markers for the detection of almost all forms of human cancer. Here, we analyzed concomitantly in each tumor sample and normal tissue the methylation status of p16INK4a and p14ARF by methylation-specific PCR (MSP) in 100 breast, 95 colon and 27 bladder carcinomas. A series of clinicopathological parameter were obtained from the medical records of the patients, p14ARF showed a higher rate of hypermethylation than p16INK4a in all three tumor types. p16INK4a and p14ARF aberrant methylation was significantly correlated with poor prognosis clinicopathological parameters of the three tumor types. We conclude that both p16INKa and p14ARF hypermethylation may be involved in breast, colon and bladder carcinogenesis, with special emphasis on the role of the lesser studied p14ARF gene, and that tumors with aberrant methylation in the two genes were associated with worse prognosis.

Persistence of tumor DNA in plasma of breast cancer patients after mastectomy.

AbstractBackground: We investigated tumor DNA changes before and after mastectomy in the plasma of breast cancer patients with no disseminated disease and eventually investigated these changes’ relationship to specific pathological parameters of the tumors. Methods: We studied 41 patients. DNA extracted from tumor and normal breast tissues, mononuclear blood cells, and plasma was used for molecular studies. Alterations in the microsatellite markers D17S855, D17S654, D16S421, TH2, D10S197, and D9S161, as well as point mutations in the p53 gene and aberrant methylation of p16INK4a, were used to identify and characterize tumor and plasma DNA. A number of tumor clinicopathological parameters were analyzed in each patient. Results: We found that 18 (44%) of the 27 patients with alterations in tumor DNA presented the same plasma DNA alteration before mastectomy, and persistence of the same molecular features was detected in plasma DNA 4 to 6 weeks postmastectomy in 8 (19.5%) patients. Patients with vascular invasion, more than three lymph node metastases, and higher histological grade at diagnosis displayed plasma DNA after mastectomy with a significant difference. Conclusions: Persistence of plasma DNA with features of tumor DNA may be present after mastectomy in breast cancer patients, and its relation to bad-prognosis histological parameters may suggest undetectable micrometastatic disease.

Analysis of genetic and epigenetic processes that influence p14ARF expression in breast cancer

The INK4a/ARF locus encodes two unrelated cell cycle-regulatory proteins that both function in tumor suppression, p16INK4a and p14ARF. In human tumors including breast cancer, alterations affecting selectively p14ARF have been poorly analysed. We have performed a comprehensive analysis of the inactivation mechanisms (mutation, homozygous and hemizygous deletion, and promoter hypermethylation) in a large series of 100 primary breast carcinomas. RT–PCR showed expression variable of the p14ARF transcript, with 17% demonstrating overexpression and 26% demonstrating decreased expression. No detectable alterations were observed in the majority of cases with overexpressed p14ARF mRNA, but 77% of tumors with decreased expression presented at least one of these genetic/epigenetic alterations. Nevertheless, a statistically significant correlation was observed between decreased p14ARF expression and several poor prognostic parameters.

Wild type p73 overexpression and high-grade malignancy in breast cancer.

The overexpression of wild type p73 is the most frequent alteration of p73 in malignancies. We investigated, in 70 breast carcinomas, p73 mRNA expression and its relationship to p53 mutations, determined by an immunohistochemical method, and loss heterozygosity (LOH) status of the 1p36 region, together with its possible implication in the pathogenesis of breast carcinomas. LOH, amplifying DNA by PCR using 5 markers, of 1p36 region (one intragenic to p73 gene) was found in 17% of cases but no significant correlation was observed with p73 overexpression. p53 positive immunostaining was present in 33% of breast carcinomas, and these exhibited a statistically significant relation with p73 overexpressed tumors. Overexpression of p73 mRNA was observed in 19 tumors (27%). The analysis of cases with p73 overexpression and cases with normal mRNA expression, in terms of age and pathologic characteristics of the tumors showed a significant association of p73 overexpression and tumors with lymph node metastases, vascular invasion and higher pathologic stage. These results suggest that p73 overexpression is a molecular alteration that could be implicated in the tumorigenesis of breast carcinomas and, eventually, in a poor clinical behavior.

Loss of heterozygosity in BRCA1 and BRCA2 markers and high-grade malignancy in breast cancer

Loss of heterozygosity (LOH) in loci of the 17q21 and 13q12‐13 regions can collaborate in the inactivation of BRCA1, BRCA2, and possibly other genes implicated in the pathogenesis of breast carcinomas. We investigate allelic losses in microsatellites of the BRCA1 and BRCA2 regions, and their correlations with seven pathologic parameters in 140 breast carcinomas. Those cases showing LOH in the region of the RB gene, 13q14, were excluded from the study. The LOH analysis was performed by amplifying DNA by PCR, using four markers of the 17q21 region (D17S856, D17S855, D17S1323, and D17S1327) and four markers of the 13q12‐13 region (D13S290, D13S260, D13S310, and D13S267). LOH in the BRCA1 region was found in 47% of tumors, correlating significantly with estrogen receptor content (p = 0.025), progesterone receptors (p = 0.004), higher grade (p = 0.0008), peritumoral vessel invasion (p = 0.001), and lymph node metastases (p = 0.002). When we excluded the cases with LOH in the BRCA2 region and those not informative for it, the significance disappeared. In the BRCA2 region, a rate of LOH of 51% was found; it correlated significantly with estrogen receptor content (p = 0.002), progesterone receptors (p =0.03), peritumoral vessel invasion (p = 0.005), higher grade (p =0.002), and lymph node metastases (p = 0.001). When cases with BRCA1 losses and those not informative were excluded, again the significance disappeared. Concomitant losses in the BRCA1 and BRCA2 regions were found in 32% of cases, correlating significantly with lymph node metastases (p = 0.0002), estrogen receptor content (p = 0.003), progesterone receptors (p = 0.001), histologic grade (p =0.01), and peritumoral vessel invasion (p = 0.0004). These results suggest that concomitant losses in both regions could have a functional effect, influencing the presence of a poor tumor pathophenotype in breast carcinomas.