Serum thymidine kinase 1 concentration as a predictive biomarker in prostate cancer

Background Thymidine kinase 1 (TK1) recycles DNA before cell division. We do not know if baseline blood concentrations of TK1 predict death in prostate cancer within 30 years. Our objective is to determine if there is an association between baseline levels of TK1 and future prostate cancer-specific mortality. Methods With a "proof of concept" approach, we performed a nested case-control study among 1782 individuals screened for prostate cancer between 1988 and 1989. The concentration of TK1 was measured in frozen serum from 330 men, 36 of whom have died of prostate cancer. The primary endpoint was prostate cancer-specific mortality and outcomes after 30 years were analyzed using logistic regression modeling odds ratios (Ors). Results The estimated OR (adjusted for age) for dying from prostate cancer among the men who had a TK1 value in the upper tertile was 2.39 (95% confidence interval 1.02-5.63). The corresponding OR, regardless of the cause of death, was 2.81 (1.24-6.34). Conclusions High levels of TK1 predicts death in prostate cancer within 30 years of follow-up

Expression of Cyclins A, E and Topoisomerase II α correlates with centrosome amplification and genomic instability and influences the reliability of cytometric S-phase determination

BACKGROUND: The progression of normal cells through the cell cycle is meticulously regulated by checkpoints guaranteeing the exact replication of the genome during S-phase and its equal division at mitosis. A prerequisite for this achievement is synchronized DNA-replication and centrosome duplication. In this context the expression of cyclins A and E has been shown to play a principal role. RESULTS: Our results demonstrated a correlation between centrosome amplification, cell cycle fidelity and the level of mRNA and protein expression of cyclins A and E during the part of the cell cycle defined as G1-phase by means of DNA content based histogram analysis. It is shown that the normal diploid breast cell line HTB-125, the genomically relatively stable aneuploid breast cancer cell line MCF-7, and the genomically unstable aneuploid breast cancer cell line MDA-231 differ remarkably concerning both mRNA and protein expression of the two cyclins during G1-phase. In MDA-231 cells the expression of e.g. cyclin A mRNA was found to be ten times higher than in MCF-7 cells and about 500 times higher than in HTB-125 cells. Topoisomerase II α showed high mRNA expression in MDA compared to MCF-7 cells, but the difference in protein expression was small. Furthermore, we measured centrosome aberrations in 8.4% of the MDA-231 cells, and in only 1.3% of the more stable aneuploid cell line MCF-7. MDA cells showed 27% more incorporation of BrdU than reflected by S-phase determination with flow cytometric DNA content analysis, whereas these values were found to be of the same size in both HTB-125 and MCF-7 cells. CONCLUSIONS: Our data indicate that the breast cancer cell lines MCF-7 and MDA-231, although both DNA-aneuploid, differ significantly regarding the degree of cell cycle disturbance and centrosome aberrations, which partly could explain the different genomic stability of the two cell lines. The results also question the reliability of cytometric DNA content based S-phase determination in genomically unstable tumor cell populations

Dynamics of Serum Thymidine Kinase 1 at the First Cycle of Neoadjuvant Chemotherapy Predicts Outcome of Disease in Estrogen-Receptor-Positive Breast Cancer

Pathologic complete response (pCR) predicts the long-term outcome of neoadjuvantly treated (NAC) breast cancer (BC) but is reached in <10% of hormone-receptor-positive patients. Biomarkers enabling adjustment or interruption of an ineffective therapy are desired. Here, we evaluated whether changes in the serum concentration of thymidine kinase 1 (sTK1) during NAC could be utilized as a biomarker. In the PROMIX trial, women with localized HER2- BC received neoadjuvant epirubicin/docetaxel in six cycles. sTK1 was measured with an ELISA in 54 patients at cycles 1–4 and in an additional 77 patients before and 48 h after treatment 1. Treatment resulted in a 2-fold increase of sTK1 before and a 3-fold increase 48 h after the cycles, except for the first cycle, where half of the patients reacted with a significant decrease and the other half with an increase of sTK1. In Kaplan–Meier estimates of ER+ patients divided by the median of the post/pre-treatment sTK1 ratio at the first treatment cycle, OS was 97.7% and 78% (p = 0.005), and DFS was 90.7% and 68% (p = 0.006), respectively. Thus, the response of sTK1 at the first cycle of chemotherapy could be used both as an early biomarker for the guidance of chemotherapy and for the study of inherent tumor chemo-sensitivity, which could predict long-term outcome prior to therapy

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

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

Diagnostic DNA-Flow- vs. -Image-Cytometry in Effusion Cytology

Aims: To determine the sensitivity and specificity of flow‐ and image‐cytometry for the detection of DNA‐aneuploidy as a marker for malignant cells in effusions. Methods: 200 effusions (80 tumor cell‐positive, 74 negative and 46 cytologically equivocal) were stained with DAPI‐SR for DNA‐flow‐ and with Feulgen‐Pararosaniline for ‐image‐cytometry. They were measured using a PAS‐flow‐cytometer and an AutoCyte‐QUIC‐DNA‐workstation according to the ESACP consensus reports for DNA‐flow‐ and ‐image‐cytometry, respectively [7,23,29,49]. Results: Sensitivity of DNA‐aneuploidy for the identification of malignant cells was 32.1% for DNA‐flow‐ and 75.0% for ‐image‐cytometry, specificity of ‐euploidy in benign cells was 100.0% for both methods. Positive predictive value of DNA‐aneuploidy for the identification of malignant cells was 100.0% for both techniques, negative predictive value of DNA‐euploidy was 48.6% for DNA‐flow‐ and 72.0% for ‐image‐cytometry. Conclusions: Searching for DNA‐aneuploidy as a diagnostic marker for neoplastic cells in serous effusions image‐cytometry revealed superior sensitivity as compared with monoparametric flow cytometry