Centrosome clustering and cyclin D1 gene amplification in double minutes are common events in chromosomal unstable bladder tumors.
BACKGROUND
Aneuploidy, centrosome abnormalities and gene amplification are hallmarks of chromosome instability (CIN) in cancer. Yet there are no studies of the in vivo behavior of these phenomena within the same bladder tumor.


METHODS
Twenty-one paraffin-embedded bladder tumors were analyzed by conventional comparative genome hybridization and fluorescence in situ hybridization (FISH) with a cyclin D1 gene (CCND1)/centromere 11 dual-color probe. Immunofluorescent staining of alpha, beta and gamma tubulin was also performed.


RESULTS
Based on the CIN index, defined as the percentage of cells not displaying the modal number for chromosome 11, tumors were classified as CIN-negative and CIN-positive. Fourteen out of 21 tumors were considered CIN-positive. All T1G3 tumors were included in the CIN-positive group whereas the majority of Ta samples were classified as CIN-negative tumors. Centrosome clustering was observed in six out of 12 CIN-positive tumors analyzed. CCND1 amplification in homogeneously staining regions was present in six out of 14 CIN-positive tumors; three of them also showed amplification of this gene in double minutes.


CONCLUSIONS
Complex in vivo behavior of CCND1 amplicon in bladder tumor cells has been demonstrated by accurate FISH analysis on paraffin-embedded tumors. Positive correlation between high heterogeneity, centrosome abnormalities and CCND1 amplification was found in T1G3 bladder carcinomas. This is the first study to provide insights into the coexistence of CCND1 amplification in homogeneously staining regions and double minutes in primary bladder tumors. It is noteworthy that those patients whose tumors showed double minutes had a significantly shorter overall survival rate (p < 0.001).
Del Rey
Javier
J
Departament de Biologia Cellular Fisiologia i Immunologia, Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
Prat
Esther
E
Ponsa
Immaculada
I
Lloreta
Josep
J
Gelabert
Antoni
A
Algaba
Ferran
F
Camps
Jordi
J
Miró
Rosa
R
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics*; D018385:Centrosome / Q000737:chemistry / Q000473:pathology*; D043171:Chromosomal Instability; D002880:Chromosomes, Human, Pair 11; D055028:Comparative Genomic Hybridization; D019938:Cyclin D1 / Q000235:genetics*; D005260:Female; D005455:Fluorescent Antibody Technique; D005784:Gene Amplification; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D053208:Kaplan-Meier Estimate; D008297:Male; D048629:Micronuclei, Chromosome-Defective; D008875:Middle Aged; D008938:Mitosis; D009367:Neoplasm Staging; D016612:Paraffin Embedding; D011379:Prognosis; D013997:Time Factors; D014404:Tubulin / Q000032:analysis; D001749:Urinary Bladder Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000401:mortality / Q000473:pathology*
D014408:Biomarkers, Tumor; C530104:CCND1 protein, human; D014404:Tubulin; D019938:Cyclin D1