Naining Wang

Characterization of chromosomal abnormalities in prostate cancer cell lines by spectral karyotyping

Human prostate cancer is characterized by multiple gross chromosome alterations involving several chromosome regions. However, the specific genes involved in the development of prostate tumors are still largely unknown. Here we have studied the chromosome composition of the three established prostate cancer cell lines, LNCaP, PC-3, and DU145, by spectral karyotyping (SKY). SKY analysis showed complex karyotypes for all three cell lines, with 87, 58/113, and 62 chromosomes, respectively. All cell lines were shown to carry structural alterations of chromosomes 1, 2, 4, 6, 10, 15, and 16; however, no recurrent breakpoints were detected. Compared to previously published findings on these cell lines using comparative genomic hybridization, SKY revealed several balanced translocations and pinpointed rearrangement breakpoints. The SKY analysis was validated by fluorescence in situ hybridization using chromosome-specific, as well as locus-specific, probes. Identification of chromosome alterations in these cell lines by SKY may prove to be helpful in attempts to clone the genes involved in prostate cancer tumorigenesis.

Deoxyribonucleic Acid Profile and Tumor Progression in Primary Carcinoma in Situ of the Bladder: A Study of 63 Patients with Grade 3 Lesions

In 63 patients with primary grade 3 carcinoma in situ of the bladder flow cytometric deoxyribonucleic acid (DNA) analysis was performed at diagnosis and during an average followup of 63 months. The results of DNA measurements were related to disease progression, that is invasive tumor and/or metastatic disease. The DNA histograms were classified as diploid (2 patients) or aneuploid (61). A total of 3 categories of aneuploid tumors with different prognostic significance could be defined: 1) carcinoma in situ with 1 aneuploid cell population at diagnosis and with no change to multiple aneuploid cell populations throughout observation, 2) carcinoma in situ with 1 aneuploid cell population at diagnosis but with a later change to multiple aneuploid cell populations and 3) carcinoma in situ with multiple aneuploid cell populations already at diagnosis. At 5 years the progression-free survival for the 3 categories was 94%, 43% and 20%, respectively. Over-all, of the patients with multiple aneuploid cell populations (categories 2 and 3) 76% had progression, in contrast to 19% of those in category 1 (p less than 0.0005). In category 2 development of multiple aneuploid cell populations preceded progression in 8 of 11 progressive cases by an average of 20 months. Therefore, the occurrence of multiple aneuploid cell populations must be considered as a sign of high aggressiveness. We conclude that flow cytometric DNA analysis is a potent predictor of prognosis in cases of primary carcinoma in situ of the bladder.

Prognostic significance of mucosal aneuploidy in stage Ta/T1 grade 3 carcinoma of the bladder

In a prospective series of 71 patients with newly detected grade 3, stages Ta and T1 bladder carcinoma tumor characteristics, including the results of deoxyribonucleic acid (DNA) analysis as well as morphological and DNA characteristics of the grossly normal urothelium, were investigated and related to progression-free survival. The mean duration of followup was 57 months, with a minimum of 24 months. Of the 71 patients 24 underwent primary cystectomy, and 47 were conservatively treated with transurethral resection alone, or followed by instillation therapy or irradiation therapy. Of the cystectomy and conservatively treated patients 2 (8%) and 16 (34%), respectively, died of bladder carcinoma. Among the 47 conservatively treated patients tumor progression could not be predicted by the initial characteristics of tumor stage, papillary or nonpapillary growth, tumor multiplicity, tumor size, existence of 1 or multiple aneuploid cell populations, S phase value, carcinoma in situ and atypia or aneuploidy in the mucosal biopsies. Neither was progression predicted by the recurrence rate during year 1 of observation. However, a change to or persistent mucosal aneuploidy and a change to or persistent morphological abnormality of the mucosa during year 1 of observation were predictive for tumor progression (p = 0.001 and 0.045, respectively). When compared in stepwise regression analysis (Coxs proportional hazard model), DNA aneuploidy in the mucosa at 12 months after diagnosis was a highly significant predictor, whereas morphology added no further prognostic information. Therefore, progression is related to gross chromosomal abnormalities of the mucosa. High risk patients can be identified by evaluation of the grossly normal mucosa, which should be done as part of the initial diagnosis and during followup in conservatively treated patients with stages Ta and T1, grade 3 bladder carcinoma.

Investigation on Cell Proliferation with a New Antibody against Thymidine Kinase 1

The cytosolic thymidine kinase 1 (TK1) is one of the enzymes involved in DNA replication. Based on biochemical studies, TK1 is activated at late G1 of cell cycle, and its activity correlates with the cell proliferation. We have developed a polyclonal anti‐TK1 antibody against a synthetic peptide from the C‐terminus of human TK1. Using this antibody, here we demonstrate the exclusive location of TK1 in the cytoplasm of cells. Cell cycle dependent TK1 expression was studied by simultaneous fluorescence staining for TK1 and bromodeoxyuridine, by using elutriated cells, and by quantitation of the amount TK1 in relation to the cellular DNA content. TK1, which was strongly expressed in the cells in S+G2 period, raised at late G1 and decreased during mitosis. The amount of TK1 increased three folds from late G1 to G2. TK1 positive cells were demonstrated in areas of proliferation activity of various normal and malignant tissues. The new anti‐TK1 antibody works in archival specimens and is a specific marker of cell proliferation.

Chromosome 16q24 Deletion and Decreased E-Cadherin Expression: Possible Association With Metastatic Potential in Prostate Cancer

Deletion of chromosome 16q is a frequent aberration in prostatic carcinoma, indicating the existence of candidate tumor suppressor genes involved in the pathogenesis of prostate cancer.

Evaluation of tumor heterogeneity of prostate carcinoma by flow- and image DNA cytometry and histopathological grading.

Background. Heterogeneity of prostate carcinoma is one of the reasons for pretreatment underestimation of tumor aggressiveness. We studied tumor heterogeneity and the probability of finding the highest tumor grade and DNA aneuploidy with relation to the number of biopsies. Material and methods. Specimens simulating core biopsies from five randomly selected tumor areas from each of 16 Böcking’s grade II and 23 grade III prostate carcinomas were analyzed for tumor grade and DNA ploidy by flow‐ and fluorescence image cytometry (FCM, FICM). Cell cycle composition was measured by FCM. Results. By determination of ploidy and cell cycle composition, morphologically defined tumors can further be subdivided. Heterogeneity of tumor grade and DNA ploidy (FCM) was 54% and 50%. Coexistence of diploid tumor cells in aneuploid specimens represents another form of tumor heterogeneity. The proportion of diploid tumor cells decreased significantly with tumor grade and with increase in the fraction of proliferating cell of the aneuploid tumor part. The probability of estimating the highest tumor grade or aneuploidy increased from 40% for one biopsy to 95% for 5 biopsies studied. By combining the tumor grade with DNA ploidy, the probability of detecting a highly aggressive tumor increased from 40% to 70% and 90% for one and two biopsies, respectively. Conclusion. Specimens of the size of core biopsies can be used for evaluation of DNA ploidy and cell cycle composition. Underestimation of aggressiveness of prostate carcinoma due to tumor heterogeneity is minimized by simultaneous study of the tumor grade and DNA ploidy more than by increasing the number of biopsies. The biological significance of coexistent diploid tumor cell in aneuploid lesions remains to be evaluated.