RESUMO
OBJECTIVES: The majority of solid human malignancies demonstrate DNA aneuploidy as a consequence of chromosomal instability. We wanted to investigate whether Aurora A, Aurora B, BUB1B and Mad2 were associated with the development of aneuploidy in colorectal adenocarcinomas as suggested by several in vitro studies, and if their protein levels were related to alterations at the corresponding chromosomal loci. MATERIALS AND METHODS: Expression levels of these spindle proteins were investigated by immunohistochemistry using tissue micro-arrays in a series of DNA aneuploid and diploid colorectal adenocarcinomas previously examined for genomic aberrations by comparative genomic hybridization. RESULTS: All proteins were overexpressed in malignant tissues compared to controls (P < 0.001 for all). BUB1B level was significantly reduced in aneuploid compared to diploid cancers (P = 0.001), whereas expression of the other proteins was not associated with DNA ploidy status. High levels of Aurora A (P = 0.049) and low levels of Aurora B (P = 0.031) were associated with poor prognosis, but no associations were revealed between protein expression and genomic aberration. CONCLUSIONS: A significant reduction of BUB1B level was detected in aneuploid compared to diploid colorectal cancers, consistent with earlier studies showing that loss of spindle checkpoint function may be involved in development of DNA aneuploidy. Our data also show that spindle proteins are overexpressed in colorectal cancers, and that expression of the Aurora kinases is associated with prognosis in colorectal cancer.
Assuntos
Aneuploidia , Neoplasias Colorretais/genética , Regulação Neoplásica da Expressão Gênica , Proteínas Serina-Treonina Quinases/genética , Estudos de Coortes , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , DNA de Neoplasias/genética , Diploide , Citometria de Fluxo , Genótipo , Humanos , Imuno-Histoquímica , Hibridização de Ácido Nucleico , Fenótipo , Proteínas Serina-Treonina Quinases/metabolismo , Valores de Referência , Análise de SobrevidaRESUMO
BACKGROUND: Long term ulcerative colitis (UC) increases the risk of colorectal cancer (CRC). DNA aneuploidy is a common feature of both dysplastic and non-dysplastic colonic epithelia from patients with longstanding UC, and is regarded as an early sign of possible malignant transformation. The spindle proteins Aurora A, BUB1B and Mad2 have been implicated as contributors to aneuploidy and carcinogenesis. AIMS: To investigate the role of these spindle proteins in relation to DNA aneuploidy and during the progressive morphological changes in ulcerative colitis associated colorectal cancer (UCCRC). METHODS: Tissue microarrays were made from 31 colectomy specimens from patients with longstanding UC. Expression of Aurora A, BUB1B and Mad2 was investigated by immunohistochemistry and their relation to ploidy status, mucosal morphology and Ki67 levels was explored. RESULTS: Expression of Aurora A and BUB1B was significantly associated with the progressive morphological changes of UCCRC. In the progression from non-dysplastic to dysplastic mucosa, Aurora A expression decreased while BUB1B expression increased. There was an increasing incidence of aneuploidy with progression towards cancer; expression of all spindle proteins was associated with the level of Ki67 but not with aneuploidy. CONCLUSION: Due to the significant differences in Aurora A and BUB1B expression in dysplastic compared non-dysplastic mucosa, these proteins may serve as putative biological markers for the progressive morphological changes in UC associated carcinogenesis. The close relationship to Ki67 levels reflect that spindle proteins are expressed in tissues with a high proliferative rate; a role for these proteins in the development of aneuploidy was not found.
Assuntos
Biomarcadores Tumorais/metabolismo , Colite Ulcerativa/metabolismo , Neoplasias do Colo/metabolismo , Lesões Pré-Cancerosas/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Aurora Quinases , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Ciclo Celular/metabolismo , Colectomia , Colite Ulcerativa/complicações , Colite Ulcerativa/genética , Colite Ulcerativa/patologia , Neoplasias do Colo/etiologia , Neoplasias do Colo/genética , DNA de Neoplasias/genética , Progressão da Doença , Humanos , Mucosa Intestinal/metabolismo , Antígeno Ki-67/metabolismo , Proteínas Mad2 , Proteínas de Neoplasias/metabolismo , Ploidias , Lesões Pré-Cancerosas/etiologia , Lesões Pré-Cancerosas/genética , Proteínas Repressoras/metabolismoRESUMO
Gain of chromosome 18q and translocation t(14;18) are] frequently found in B-cell non-Hodgkin's lymphomas (B-NHL). Increased BCL2 transcription and BCL2 protein expression have been suggested to be the result of the gain. We utilized FISH, PCR and array CGH to study BCL2 and chromosome 18 copy number changes and rearrangements in 93 cases of B-NHL. BCL2 protein was expressed in >75% of the tumor cells in 92% of the cases by immunohistochemistry. Gain of BCL2 was associated with a 25% increase in BCL2 expression levels (immunoblotting), whereas t(14;18) resulted in a 55% increase in BCL2 levels compared to cases without BCL2 alterations. The tumor cell (spontaneous) apoptotic fractions were similar for the cases with different BCL2 genotypes. However, the normal cell apoptotic fractions were higher for the tumors with t(14;18) compared to the tumors without BCL2 alterations, while the tumors with gain of BCL2 only showed intermediate levels. Low-level gains of parts of chromosome 18 were found in 14 of the 38 B-NHL cases with t(14;18), with a consensus region 18pter-q21.33 that did not include the BCL2 gene. The 11 cases with 18q gain only showed a consensus region encompassing 18q21.2-18q21.32 and 18q21.33, which contain PMAIP1/MALT1 and BCL2, respectively.
