Clinical value of thymidine kinase in patients with cervical carcinoma

Biomarker analysis and clinical relevance of TK1 on the cell membrane of Burkitt's lymphoma and acute lymphoblastic leukemia

TK1 is an enzyme involved in DNA synthesis and repair. TK1 is usually found elevated in cancer patients’ serum, which makes it a useful tumor proliferation biomarker that strongly correlates with cancer stage, metastatic capabilities, and recurrence risk. In this study, we show that TK1 is upregulated and localizes on the plasma membrane of Burkitt’s lymphoma, acute promyelocytic leukemia, T cell leukemia, and acute lymphoblastic leukemia (ALL). Using flow cytometry, we confirmed that TK1 localizes on the surface of Raji, HL60, and Jurkat cell lines and on ALL clinical samples. Using fluorescent microscopy, we found a strong association of TK1 with the plasma membrane in Raji, HL60, and Jurkat cell lines. These findings were also confirmed by scanning electron microscopy. Our study also shows that this phenomenon does not occur on normal resting or proliferating lymphocytes. In addition, we show that membrane TK1 is found in all oligomeric forms ranging from monomer to tetramer and exhibits enzymatic activity. These findings suggest TK1 as a possible target for immunotherapy with the potential to be utilized in the treatment of hematological cancers.

Serum thymidine kinase activity: analytical performance, age-related reference ranges and validation in chronic lymphocytic leukemia

Background

To date no age-related reference ranges are available for serum thymidine kinase (TK1) activity. Being a proliferation marker, it may be used as a prognostic marker in malignant diseases, including chronic lymphocytic leukemia (CLL). Our aim was to establish age-specific reference ranges for TK1 and examine its utility as a screening marker in CLL, a disease of the elderly.

Methods

Serum TK1 activity was measured by a competitive chemiluminescent immunoassay in 369 healthy adults and 115 de novo CLL patients.

Results

We observed a statistically significant decline in TK1 activity from young (18–35 years) to middle-aged (36–60 years) and further on to elderly (60–86 years) healthy individuals. Age-related reference range was: <30 U/L for young, <25 U/L for middle-aged and <19 U/L for elderly. There was no difference in TK1 activity between the studied healthy men and women. In CLL patients, TK1 activity was the highest in the advanced Rai stages. The area under the receiver operating characteristic curve (ROC-AUC) for TK1 was 0.840 (95% CI: 0.787–0.892), for differentiating CLL patients from age and sex matched healthy controls, with a cut-off value of 10.5 U/L (sensitivity: 80.9%, specificity: 73.4%). TK1 was significantly elevated in CD38+/Zap70+ CLL patients, and showed significant correlation with WBC and absolute B-cell count.

Conclusion

In the healthy, serum TK1 activity does not differ in the two sexes but declines significantly with age. As such, use of age-related reference ranges is warranted, especially when evaluating CLL patients who generally belong to the elderly age group.

The role of thymidine kinase in cancer diseases

Thymidine kinase 1 (TK 1-fetal) is a cell cycle-dependent marker that increases dramatically during the S-phase of the cell cycle. In this review, the authors discuss serum levels of thymidine kinase in a variety of neoplasias. Determination of thymidine kinase helps to monitor the follow-up of solid tumours and haematological malignancies as well as indicating the efficacy of adjuvant and palliative chemotherapy. Elevated levels of thymidine kinase must always be interpreted together with a detailed knowledge of the patient's condition because nonspecific elevations of serum levels (inflammatory and autoimmune diseases) must be excluded.

Molecular Strategies of Deoxynucleotide Triphosphate Supply Inhibition Used in the Treatment of Gynecologic Malignancies

Chemotherapies targeting deoxynucleotide triphosphate synthesis are of high medical interest in the treatment of gynecologic malignancies. In this article, we focus on targeted inhibitors of ribonucleotide reductase, an enzyme in charge of ribonucleotide reduction to their corresponding deoxyribonucleotide to be used as the building blocks of DNA. We also discuss human clinical trials have utilized ribonucleotide reductase subunit-specific inhibitors, particularly trials for women with cervical cancer.

Elevated thymidine kinase 1 in serum following neoadjuvant chemotherapy predicts poor outcome for patients with locally advanced breast cancer

Patients with locally advanced breast cancer (LABC) commonly have an unfavorable prognosis. A molecular predictor for the identification of at-risk patients is urgently required. Thymidine kinase 1 in serum (S-TK1) is an enzyme involved in the synthesis of DNA precursors. In studies using immunohistochemistry, it was reported to be a more useful proliferation marker than Ki-67 in breast, lung and colorectal carcinoma. In the present study, we extended the research of prior breast carcinoma studies by postulating that in patients with LABC, overexpression of S-TK1 following neoadjuvant chemotherapy predicts cancer outcome. An experimental design consisting of 48 patients with LABC was prospectively constructed and analyzed. All patients received neoadjuvant chemotherapy and definitive surgical therapy. Study homogeneity was maintained by standardized treatment, surveillance and compliance protocols. The S-TK1 concentration was detected using the anti-TK1 chicken IgY antibody, using a dot-blot immuno-assay. After a median follow-up of 30 months, the results indicated a statistically significant trend (unadjusted). Patients with high S-TK1 overexpression had a significantly higher incidence of recurrence (P=0.006) and cancer death (P= 0.0128) than those with low S-TK1 overexpression. A multivariate analysis provided identical results. The hazards ratio for developing recurrence in patients with higher S-TK1 expression was 6-7 times higher than the hazards ratio in patients with lower expression. In conclusion, our results indicate that a high S-TK1 concentration in sera from LABC patients receiving neoadjuvant chemotherapy is predictive of cancer outcome.

Deoxynucleoside salvage facilitates DNA repair during ribonucleotide reductase blockade in human cervical cancers

Cells generate 2'-deoxyribonucleoside triphosphates (dNTPs) for both replication and repair of damaged DNA predominantly through de novo reduction of intracellular ribonucleotides by ribonucleotide reductase (RNR). Cells can also salvage deoxynucleosides by deoxycytidine kinase/thymidine kinase 1 in the cytosol or by deoxyguanosine kinase/thymidine kinase 2 in mitochondria. In this study we investigated whether the salvage dNTP supply pathway facilitates DNA damage repair, promoting cell survival, when pharmacological inhibition of RNR by 3-aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP, NSC no. 663249) impairs the de novo pathway. Human cervical cancer cells were subjected to radiation with or without 3-AP under medium deoxynucleoside concentrations of 0, 0.05, 0.5 and 5.0 µM. Efficacy of DNA damage repair was assessed by γ-H2AX flow cytometry and focus counts, by single cell electrophoresis (Comet assay), and by caspase 3 cleavage assay as a marker of treatment-induced apoptosis. Cell survival was assessed by colony formation. We found that deoxyribonucleotide salvage facilitates DNA repair during RNR inhibition by 3-AP and that salvage reduces the radiochemosensitivity of human cervical cancer cells.

Identification and validation of genes involved in cervical tumourigenesis

Background

Cervical cancer is the most common cancer among Indian women. This cancer has well defined pre-cancerous stages and evolves over 10-15 years or more. This study was undertaken to identify differentially expressed genes between normal, dysplastic and invasive cervical cancer.

Materials and methods

A total of 28 invasive cervical cancers, 4 CIN3/CIS, 4 CIN1/CIN2 and 5 Normal cervix samples were studied. We have used microarray technique followed by validation of the significant genes by relative quantitation using Taqman Low Density Array Real Time PCR. Immunohistochemistry was used to study the protein expression of MMP3, UBE2C and p16 in normal, dysplasia and cancers of the cervix. The effect of a dominant negative UBE2C on the growth of the SiHa cells was assessed using a MTT assay.

Results

Our study, for the first time, has identified 20 genes to be up-regulated and 14 down-regulated in cervical cancers and 5 up-regulated in CIN3. In addition, 26 genes identified by other studies, as to playing a role in cervical cancer, were also confirmed in our study. UBE2C, CCNB1, CCNB2, PLOD2, NUP210, MELK, CDC20 genes were overexpressed in tumours and in CIN3/CIS relative to both Normal and CIN1/CIN2, suggesting that they could have a role to play in the early phase of tumorigenesis. IL8, INDO, ISG15, ISG20, AGRN, DTXL, MMP1, MMP3, CCL18, TOP2A AND STAT1 were found to be upregulated in tumours. Using Immunohistochemistry, we showed over-expression of MMP3, UBE2C and p16 in cancers compared to normal cervical epithelium and varying grades of dysplasia. A dominant negative UBE2C was found to produce growth inhibition in SiHa cells, which over-expresses UBE2C 4 fold more than HEK293 cells.

Conclusions

Several novel genes were found to be differentially expressed in cervical cancer. MMP3, UBE2C and p16 protein overexpression in cervical cancers was confirmed by immunohistochemistry. These will need to be validated further in a larger series of samples. UBE2C could be evaluated further to assess its potential as a therapeutic target in cervical cancer.

Serum biomarkers for early detection of gynecologic cancers

Ovarian, endometrial, and cervical cancers are three of the most common malignancies of the female reproductive organs. CA 125, historically the most reliable serum marker for ovarian cancer, is elevated in 50% of early-stage ovarian tumors. For endometrial cancers, there are no established serum markers. SCC, which is the best studied serum marker for squamous cell carcinomas, has been unreliable; SCC is elevated in cervical squamous cell carcinomas ranging from 28–85% of the time. Recent proteomics-based analyses show great promise for the discovery of new and more useful biomarkers. In this review, we will discuss the currently utilized serum tumor markers for gynecologic cancers and the novel biomarkers that are now under investigation.

Thymidine kinase 1 and thymidine phosphorylase expression in non-small-cell lung carcinoma in relation to angiogenesis and proliferation

The thymidine salvage pathway enzymes thymidine kinase 1 (TK1) and thymidine phosphorylase (TP) compete for thymidine as a substrate and catalyze opposing synthetic and catabolic reactions that have been implicated in the control of proliferation and angiogenesis, respectively. We investigated the relationship between the expression of TK1 and TP as they relate to proliferation (Ki-67 labeling index) and angiogenesis (Chalkley count of CD31-stained blood vessels) in a series of 110 non-small-cell lung cancer (NSCLC) tumors from patients prospectively enrolled in an imaging trial. TK1 and TP exhibited similar patterns of immunohistochemical distribution, in that each was found in both the nucleus and the cytoplasm of tumor cells. Each enzyme exhibited a significant positive correlation between its levels of nuclear and cytoplasmic expression. A significant positive correlation between TK1 expression and the Ki-67 labeling index (r = 0.53, p<0.001) was observed. TP was significantly positively correlated with Chalkley scoring of CD31 staining in high vs low Chalkley scoring samples (mean TP staining of 115.8 vs 79.9 scoring units, p<0.001), respectively. We did not observe a substantial inverse correlation between the TP and TK1 expression levels in the nuclear compartment (r = -0.17, p=0.08). Tumor size was not found to be associated with TK1, TP, Ki-67, or Chalkley score. These findings provide additional evidence for the role of thymidine metabolism in the complex interaction of proliferation and angiogenesis in NSCLC.

Elevated levels of thymidine kinase 1 peptide in serum from patients with breast cancer

OBJECTIVES

Thymidine kinase (TK) has an important role in DNA synthesis and is thus related to cell proliferation and turn-over. Traditionally, TK has been measured by enzymatic activity or radioimmunoassays. These assays are difficult to adapt to random access instruments. The aim of this study was to evaluate a new immunological sandwich assay for detection of TK peptides in serum from breast cancer patients.

MATERIAL AND METHODS

Serum samples were collected from patients with breast cancer and stored frozen at -70 degrees C. The samples were collected after surgery, after metastatic tumor recurrence and after chemotherapy due to tumour recurrence. Patients' serum samples were analysed by the TK enzyme-linked immunosorbent assay (ELISA).

RESULTS

In receiver operating characteristics (ROC) analyses of TK1 for diagnosis of breast cancer, the area under the curve (AUC) collected four weeks after surgery was 0.56 (95% CI 0.47-0.65), for samples collected postsurgically after tumour recurrence 0.73 (95% CI 0.65-0.80), and after chemotherapy 0.64 (95% CI 0.56-0.72).

CONCLUSIONS

This study indicates that the tumour proliferation marker TK has a potential as a serum marker in breast cancer. Further studies are warranted to verify this observation.

Serum tumor markers in the management of ovarian, endometrial and cervical cancer

CA 125 is the most reliable serum marker for ovarian carcinoma. Whereas its role in the screening of the malignancy is controversial, serum CA 125 assay is very useful for both the differential diagnosis of ovarian masses, particularly in postmenopause, and the monitoring of the response to chemotherapy and follow-up of patients with histologically proven ovarian carcinoma. Tumor-associated antigens other than CA 125, such as CA 19.9, CA 15.3 and TAG.72, firstly identified in gastro-intestinal or breast malignancies, have been detected also in tissue and serum samples from patients with ovarian carcinoma. In particular CA19.9 offers the advantage of high sensitivity for mucinous histotype, which often fails to express CA 125. Serum CA 125 correlates with the clinical course of disease better than the other antigens, and in patients with positive CA 125 assay at diagnosis the concomitant evaluation of CA 19.9 or CA 72.4 or CA 15.3 does not offer any additional benefit for monitoring ovarian carcinoma. Conversely, the serial measurements of these other antigens may represent an interesting biochemical tool for the management of patients with negative CA 125 assay. Serum alphaFP and betaHCG are very useful in the preoperative evaluation and management of nondysgerminomatous ovarian germ cell tumors, whereas elevated serum inhibin levels can be detected in patients with granulosa cell tumors of the ovary. As for endometrial carcinoma, preoperative serum CA 125 levels correlate with stage, depth of myometrial invasion, histologic grade, cervical invasion, peritoneal cytology, lymph node status and clinical outcome. Moreover, serial CA 125 assay is a good indicator of disease activity and a useful biochemical tool for post-treatment surveillance of patients with endometrial carcinoma. SCC is the most reliable serum marker for squamous cell cervical carcinoma, and in patients with this malignancy pretreatment SCC levels are related to tumor stage, tumor size, depth of cervical invasion, lymph-vascular space involvement, lymph node status and clinical outcome. Serial SCC measurements parallel the response to radiotherapy and chemotherapy as well as the clinical course of disease after the completion of treatment. Serum CYFRA 21.1 seems to be less sensitive than serum SCC for squamous cell cervical carcinoma. Elevated CA 125 levels can be often detected in patients with cervical adenocarcinoma. The future for tumor marker research is represented by the emerging technologies of transcriptional profiling and proteomics.

Production and characterisation of a novel chicken IgY antibody raised against C-terminal peptide from human thymidine kinase 1

Egg yolk is a good source of highly specific antibodies against mammalian antigens because of the phylogenetic distance between birds and mammals. Chicken egg yolk immunoglobulins (IgY) were generated to a synthetic 31-amino acid peptide from the C-terminal of human HeLa thymidine kinase 1 (TK1) enzyme. The anti-TK1 IgY antibody was purified using affinity chromatography against the 31-amino acid peptide. The purified antibody inhibited the catalytic activity of the TK1 enzyme in the CEM TK1(+) cells and recognized the 25-kDa subunit and tetrameric form of TK1, which has a pI value of 8.3. No immunoreaction was observed in CEM TK1(-) cells. Western blot of the serum TK1 (S-TK1) also showed that only a single band was found in the serum of patients with malignancies. No band was seen in healthy serum. Furthermore, dot blots and enhanced chemiluminescence (ECL) detection of S-TK1 performed on sera of preoperative patients with gastric cancer (GC) (n=31) and healthy controls (n=62) showed that the levels of S-TK1 in the sera of cancer patients were significantly different (P<0.01). Using ECL dot blots, 0.1 pg of TK1 in 3 microl sera could be detected. Immunohistostaining of tissues in the 11 advanced-stage cancer patients (four breast carcinomas, three hepatocarcinomas and four thyroid carcinomas) indicated that a strong staining of TK1 enzyme was found in the cytoplasm of malignant cells. No staining or weak staining was seen in normal tissues. We suggest that screening for TK1 using anti-TK1 IgY may be potentially useful for serological and immunohistochemical detection of TK1 as an early prognosis and for monitoring patients undergoing treatment.

Clinical significance of interleukin-1 receptor antagonist in patients with cervical carcinoma

OBJECTIVE

Our purpose was to determine the clinical significance of interleukin-1 receptor antagonist (IL-1ra), which is an endogenous inhibitor cytokine of IL-1, in patients with cervical carcinoma.

METHODS

Tissue IL-1ra expression and serum IL-1ra level were examined by enzyme-linked immunosorbent assay (ELISA), Western blotting, and immunohistochemistry in normal controls and patients with cervical carcinoma.

RESULTS

Tissue IL-1ra protein level by ELISA was significantly higher in squamous cell carcinoma (n = 9) than in the normal cervix (n = 7) and adenocarcinoma (n = 3). Western blotting confirmed the main presence of intracellular IL-1ra type 1 in squamous cell carcinoma. Immunohistochemistry demonstrated significant IL-1ra expression only in tumor cells of squamous cell carcinoma. Elevation of serum IL-1ra level was found in patients with squamous cell carcinoma (n = 38) compared to normal women (n = 13), but not in patients with adenocarcinoma (n = 9). Although serum IL-1ra level did not correlate with clinical stage or any other tumor marker, high serum IL-1ra level was associated with pelvic lymph node metastasis and poor prognosis in patients with squamous cell carcinoma. On the other hand, these results were not obtained in patients with cervical adenocarcinoma.

CONCLUSION

IL-1ra may play important roles in local and general malignant behaviors in patients with cervical squamous cell carcinoma, and measurement of serum IL-1ra level may be useful in predicting patient survival.

Thymidine kinase in epithelial ovarian cancer: relationship with the other pyrimidine pathway enzymes

TK is a pyrimidine metabolic pathway enzyme involved in salvage DNA synthesis. What roles TK may play in epithelial ovarian cancer and the relationships between TK and the other pyrimidine pathway enzymes remain unclear. We examined TK1 gene expression by RT-PCR and related it to gene expression of TS, TP and DPD in 69 samples from epithelial ovarian cancer, 8 low-malignant-potential tumors, 16 benign ovarian tumors and 34 normal ovaries. Additionally, cytosolic and serum TK activities were determined by radioenzymatic assay. TK1 gene expression, the ratio of TK1 to TS gene expression, that of TK1 to TP and that of TK1 to DPD were significantly higher in epithelial ovarian cancer than in normal ovaries. In epithelial ovarian cancer, TK1 gene expression correlated with cytosolic and serum TK activities, TS and TP gene expression and the ratio of TP to DPD gene expression. Patients with high-TK1 gene expression had a significantly poorer survival than those with low TK1 gene expression. Combined analysis demonstrated that the relative risk of cancer death for tumors with high TK1, high TS and high TP gene expression was greater than that for tumors with high TK1 gene expression alone. TK1 gene expression together with TS, TP and DPD gene expression may play important roles in influencing the malignant behavior of epithelial ovarian cancer. Combination therapy including TK inhibitor is a possible therapeutic intervention in patients with epithelial ovarian cancer.

Thymidine kinase: diagnostic and prognostic potential

Thymidine kinase is a cell cycle-dependent marker that can be detected in the serum of patients diagnosed with many different types of cancer. Serum levels of thymidine kinase have also been shown to reflect the progression of cancer as well as an indication of the efficacy of chemotherapeutic intervention. A new monoclonal antibody assay for thymidine kinase has been developed, which is capable of detecting thymidine kinase in both serum and tumor tissue. Thymidine kinase assay kits should be available at low cost and could serve as an effective low cost test for the detection and progression of many types of human cancer.