Análise da imunoexpressão do PCNA e p53 em carcinoma de células escamosas oral: correlação com a gradação histológica de malignidade e características clínicas

OBJETIVO: Analisar a imunoexpressão das proteínas PCNA e p53 em carcinoma de células escamosas oral (CCEO) vislumbrando verificar uma possível correlação entre o escore de malignidade e os dados clínicos dos pacientes. MÉTODOS: Selecionou-se 14 casos de CCEO e classificando-os de acordo com uma adaptação do sistema de gradação histológica de malignidade proposto por Anneroth, Batsakis, Luna, enquadrando-se 7 casos como baixo escore de malignidade (Grupo I) e 7 casos como alto escore (Grupo II). As informações dos pacientes foram coletadas através de fichas clínicas e os dados tabulados. Realizou-se, então, o estudo imuno-histoquímico utilizando anticorpos monoclonais anti-PCNA e anti-p53, obtendo-se o índice de positividade (IP) em cada caso. RESULTADOS: Identificou-se um IP médio ao PCNA de 56,0% no Grupo I e 83,8% no Grupo II. Com relação à p53 o IP médio no Grupo I e no Grupo II correspondeu, respectivamente, a 41,2% e 41,4%. A análise estatística demonstrou correlação significativa entre o índice de células PCNA positivas e o escore de malignidade. Nenhuma outra correlação foi observada. CONCLUSÕES: O maior número de células PCNA positivas correlacionou-se com elevado escore de malignidade em CCEOs, sugerindo maior atividade proliferativa nestas lesões, entretanto, tal correlação não se estabeleceu quando da análise da imunoexpressão da p53.

Loss of heterozygosity of p53, BRCA1, VHL, and estrogen receptor genes in breast carcinoma: correlation with related protein products and morphologic features

Correlation of loss of heterozygosity (LOH) of p53, BRCA1, VHL, and estrogen receptor (ER) genes with the expression of related protein products and morphologic features predictive of aggressive biologic behavior was investigated to determine the significance of LOH in these genes. DNA from 35 formalin-fixed, paraffin-embedded breast carcinomas was obtained by microdissection of histologic sections. LOH was determined by polymerase chain reaction (PCR) using primers TP53, D3S1038, D17S855, and ESR for p53, VHL, BRCA1, and ER genes, respectively. p53, ER, and progesterone receptor (PR) protein expression was evaluated by immunohistochemistry. Morphologic evaluation included histologic type, and histologic and nuclear grades. TP53 LOH was identified in 13 (52%), BRCA1 LOH in 3 (17%), VHL LOH in 1 (4%), and ER LOH in 4 (21%) of 25, 17, 24, and 19 informative cases, respectively. p53 and ER protein expression was identified in 20 (57%) and 25 (71%) cases, respectively. TP53 LOH directly correlated with both high histologic and nuclear grade (P<0.01). BRCA1, VHL, and ER LOH was not frequent enough for correlation to morphologic features. Although 4 of 4 ER and 7 of 13 p53 LOH cases expressed related proteins, LOH did not correlate with protein expression. TP53 LOH may be an event contributing to aggressive biologic behavior since it is strongly associated with high histologic and nuclear grade. Missense or nonsense mutations may explain the absence of detectable p53 protein in 6 of 13 cases with p53 LOH. All 4 ER LOH cases expressed ER protein. BRCA1 and VHL LOH is infrequent in sporadic breast carcinoma.

Biophenotypes and survival of BRCA1 and TP53 deleted breast cancer in young women

The aim of this study was to examine the loss of heterozygosity (LOH) of BRCA1 (17q21) and TP53 (17p13.1) in early-onset breast cancer patients; to correlate biopathological characteristics with molecular alterations; and to investigate the survival of LOH-related cancers. BRCA1 and TP53 LOH were evaluated in 78 early-onset breast cancers (< or = 40 years, Group 1) and 80 patients with age > 55 years (Group 2). Cases were characterized for multiple biological markers (ER, PR, proliferation index (PI), NEU and p53). LOH was carried out on microdissected paraffin embedded tissues; microsatellites D17S855 (BRCA1) and D17S786 (TP53) were amplified by fluorescent PCR and analyzed by an automated DNA sequencer. Early-onset breast cancers showed a higher frequency of ductal histotype (89.7% vs. 56.3% p < 0.001), node-positive (53.8% vs. 38.7%), larger size (p = 0.017), higher mitotic rate (p = 0.025), higher nuclear and final grade (p = 0.01 and p = 0.001, respectively). D17S855 LOH was 32.8% in group 1 vs. 21% in group 2; D17S786 LOH was 50.7% vs. 31.3% (p = 0.03), respectively. BRCA1 LOH was correlated with higher PI (p = 0.032) and higher p53 expression (p < 0.001) in group 1 and with higher NEU expression (p = 0.028) in group 2. TP53 LOH was correlated with p53 overexpression (p = 0.03) in group 1. A worse clinical outcome in early-onset LOH related cancers emerged from follow-up data: TP53 and BRCA1 LOH were associated with a shorter relapse free interval (RFI) (p = 0.03) and a poorer overall survival (OS) (p = 0.04), respectively. This study underlines different biological profiles in the two age groups investigated, probably reflecting different mechanisms of carcinogenesis. In accordance with adverse histopathological features in early-onset patients, LOH-related cancers have an unfavorable prognosis.

Loss of heterozygosity in P53, BRCA1, and estrogen receptor genes and correlation to expression of p53 protein in ovarian epithelial tumors of different cell types and biological behavior

Loss of heterozygosity (LOH) of tumor suppressor genes (TSGs) in ovarian epithelial tumors of differing cell types and biological behavior has not been thoroughly investigated. Moreover, there have been conflicting reports correlating LOH of the p53 gene to overexpression of p53 protein. This study evaluated 34 formalin-fixed, paraffin-embedded ovarian epithelial tumors for LOH by polymerase chain reaction (PCR) for the following microsatellite markers: TP53(17p13.1/p53 gene), D17S579(17q/BRCA1 gene), and ESR (6q24-27/estrogen receptor gene). LOH of the TP53 marker was detected in 4 (44%) of 9 informative serous cystadenocarcinomas (SCa) but in 0 of 4 informative clear cell carcinomas (CCa) and 0 of 5 informative serous tumors of low malignant potential (SLMP). LOH of the BRCA1 marker was detected in 5 (83%) of 6 informative SCa, but in 1 (13%) of 8 informative CCa and 1 (14%) of 7 informative SLMP. LOH of the ESR marker was detected in 4 (50%) of 8 informative SCa, but in 0 of 4 informative CCa and 1 (16%) of 6 informative SLMP. p53 protein overexpression was present in 8 of 12 SCa but did not correlate to TP53 LOH. LOH for TP53, D17S579/ BRCA1, and ESR is common in ovarian SCa, and is observed in primary tumors as well as metastases. In contrast, these genetic alterations are less common in CCa and in the biologically less aggressive SLMP tumors. These data suggest different mechanisms of oncogenesis in ovarian epithelial tumors of different cell types and biological behavior.

Detection of p53 gene mutation by rapid PCR-SSCP and its association with poor survival in breast cancer

We examined the association between mutation of the p53 gene and survival in a large cohort of breast cancer patients. Using a rapid, non-isotopic single-strand conformation polymorphism (SSCP) method we screened for mutations in exons 4-10 of the p53 gene in 375 primary breast cancers from patients with a median follow-up of 57 months. Mutations were found in 19% of tumours. Statistically significant associations were found between p53 mutation and histological grade, hormone receptor status, ploidy and S-phase fraction. No association was found between p53 mutation and axillary lymph node involvement, histological type, tumour size, vascular invasion or patient age. In univariate survival analysis, p53 mutation was strongly associated with poor prognosis. This was maintained in the lymph node-negative and hormone receptor-positive patient subgroups. In multivariate analysis, p53 mutation was associated with poor survival independent of lymph node status, estrogen receptor status and S-phase fraction. Our results demonstrate the feasibility of using a rapid and simple polymerase chain reaction-SSCP screening procedure to detect p53 gene mutation in breast cancer for the provision of prognostic information.