Serum thymidine kinase 1 levels predict cancer-free survival following neoadjuvant, surgical and adjuvant treatment of patients with locally advanced breast cancer

Thymidine kinase 1 concentration and activity in metastatic breast cancer under CDK4/6 inhibitor therapy

We investigated whether TK1 concentration or activity in the blood, drawn at baseline and under therapy, might have value for therapy management in 110 hormone receptor-positive (HR+), HER2-negative (HER2-) metastatic breast cancer (mBC) patients treated with CDK4/6 inhibitors (CDK4/6i) and/or endocrine therapy (ET). TK1 concentration and activity were not significantly correlated with each other in matched samples. In the CDK4/6i cohort at baseline, high TK1 concentration and activity were significantly associated with a decreased PFS and primary resistance. Longitudinal sampling revealed a higher variability of TK1 concentration under therapy compared to TK1 activity that was reduced during therapy. Elevated TK1 activity after six months of CDK4/6i and an increase in TK1 concentration from baseline to six months under CDK4/6i significantly correlated with a decreased PFS. These results indicate a possible value of TK1 concentration and activity before and during CDK4/6i for HR+/HER2- mBC patients to guide treatment that warrants further investigation.

Development of a Novel Recombinant Full-Length IgY Monoclonal Antibody against Human Thymidine Kinase 1 for Automatic Chemiluminescence Analysis on a Sandwich Biotin-Streptavidin Platform for Early Tumour Discovery

Serum thymidine kinase 1 protein (STK1p) concentration has been used successfully as a reliable proliferating serum biomarker in early tumour discovery and clinical settings. It is detected by an enhanced chemiluminescence (ECL) dot blot assay with the biotin-streptavidin (BSA) platform (a gold standard) based on chicken anti-human thymidine kinase 1 IgY polyclonal antibody (hTK1-IgY-pAb). However, ECL dot blotting is a semiautomatic method that has been limited to large-scale applications due to the differences among batches of antibodies from individual hens, and the skill level of operation technicians sometimes results in unstable STK1p values. Therefore, a highly stable recombinant chicken full-length IgY monoclonal antibody in combination with a fully automated sandwich biotin-streptavidin (sandwich-BSA) platform was developed. Hens were immunized with 31-peptide, a key sequence of human TK1 (hTK1), before constructing an immune phage display scFv library. Finally, a recombinant full-length IgY monoclonal antibody (hTK1-IgY-rmAb#5) with high-affinity binding with human recombinant TK1 (rhTK1) ( $3.95\times {10}^{-10}$  mol/L), high sensitivity with hTK1 calibrators (slope of linear curve: 89.98), and high specificity with low/elevated STK1p ( $r\approx 0.92$ -0.963) was identified. hTK1-IgY-rmAb#5 showed a specific immune response with thymidine kinase 1 (TK1) in TK1-positive/negative cell lysates by Western blotting and immunohistochemistry (IHC) in normal and cancer tissues. In particular, the detection of TK1 serum samples from health centres showed a high coincidence rate ( $r=0.988,n=90$ ) between hTK1-IgY-rmAb#5 and hTK1-IgY-pAb and between the semiautomatic ECL dot blot BSA platform and the novel automatic chemiluminescence sandwich-BSA platform ( $r=0.857,n=292$ ). hTK1-IgY-rmAb#5 is stable and highly sensitive for detecting the lowest STK1p value at 0.01 pmol/L (pM). The accuracy is high ( $\text{SD}<2.5\%$ ) between different batches. It is easy to use the novel hTK1-IgY-rmAb#5 on a new automatic chemiluminescence sandwich-BSA platform. It will be beneficial for large-scale health screenings.

Is serum thymidine kinase 1 a prognostic biomarker in primary tumor location of colorectal carcinomas?

AIM

To assess whether serum thymidine kinase 1 (STK1p), CEA and CA19.9 can be used as prognostic biomarkers in the primary tumor location (PTL) of colorectal carcinoma (CRC). Additional clinical factors of TNM stage, pathological grade, age and sex were also included.

METHODS

STK1p was determined by an ECL-dot-blot assay, and CEA/CA19.9 was determined by an automatic electrochemiluminescence analyzer in a retrospective presurgery of right-colon carcinoma (R-CC, n = 90), left-colon carcinoma (L-CC, n = 128) and rectal carcinoma (RC, n = 270). Prognostic factors were evaluated by COX and overall survival (OS).

RESULTS

The multivariate-COX and OS in relation to the prognostic factors of PTL in CRC were different and complex. An elevated STK1p value was significantly associated with poor OS in RC (P = 0.002) and L-CC (P = 0.037) but not in R-CC (P > 0.05). Elevated CEA (P≈.000) and CA19.9 (P≈.000) were significantly associated with poor OS in RC but not in L-CC and R-CC. Multivariate-COX showed that STK1p (P = 0.02, HR = 1.779, 95%CI 1.30-7.582), CEA (P = 0.001, HR = 2.052, 95%CI 1.320-3.189), CA19.9 (P≈.000, HR = 2.574, 95%CI 1.592-4.162) and TNM-stage (P≈.000, HR = 2.368, 95%CI 1.518-3.694) were independent prognostic factors in RC, while TNM-stage was an independent prognostic factor only in R-CC (P = 0.011, HR = 3.139, 95% CI 1.30-7.582) and L-CC (P≈.000, HR = 4.168, 95%CI 1.980-8.852). Moreover, elevated STK1p was significantly more sensitive (P < .001) for predicting mortality than CEA and CA19.9. No correlation was found between STK1p, CEA or AFP.

CONCLUSION

Combining TNM stage and suitable biomarkers, STK1p provides further reliable information on the survival of PTL of CRC.

Concentration of human thymidine kinase 1 discover invisible malignant human tumours

Early discover of risk progression of invisible carcinomas is important for a prerequisite successful treatment. Here, we investigated whether concentration of human thymidine kinase 1 (HTK1) discover invisible malignant human tumours. The HTK1 concentration of tumour cellular based on HTK1 IgY-polyclonal-antibody (HTK1-IgY-pAb) was determined by using a novel automatic chemiluminescence analyser with sandwich biotin-streptavidin (SBSA) platform. Minimum number of cells able to be detected by this technology used cells with low and high concentration of HTK1. The limit visibility by tumour imaging is approximately 1 mm in diameter, corresponding to approximately 10⁹ cells with a cell diameter of 1 µm. Based on a HTK1 standard curve and a molecular weight of HTK1 of 96 kD, the HTK1protein (HTK1p) concentration per cell was calculated to be 0.021 pg. Assuming 200 pg in total protein/cell, approximately 50 × 10⁶ growing malignant cells in the body were calculated to releases HTK1 into 5-liter blood. A HTK1 values of 3.914, 0.435 and 0.009 pmol/L corresponds to 10 × 10⁵, 2 × 10⁵ and 1 × 10⁵ growing malignant cells, respectively. The lowest detectable sensitivity of HTK1 is 0.009 pmol/L in 1 × 10⁵ growing malignant cells and 0.01 pmol/L in blood serum, detectable in health screening. Comparing the novel automatic chemiluminescence analyser with the original ECL dot-blot assay using serum HTK1p (health screening, n = 265) showed high correlation (r = 0.8743, P < .000). In conclusion, the novel automatic chemiluminescence analyser with SBSA platform is a reliable method with high accuracy to determine carcinoma invisible.

Relationship between thymidine kinase 1 before radiotherapy and prognosis in breast cancer patients with diabetes

In a retrospective study design, we explored the relationship between serum thymidine kinase 1 (TK1) concentration before radiotherapy and clinical parameters and evaluated the prognostic value of serum TK1 concentration before radiotherapy in breast cancer patients with type 2 diabetes mellitus. The present study finally consisted of 428 breast cancer patients with a mean age of 53.0 years. Compared with low TK1 group, the high TK1 group tended to have larger tumor size (P=0.011) and had more lymph node number (P=0.021). Significant differences were also observed in clinical stages I, II and III (P=0.000). There was no significant difference between TK1 and other clinical parameters. For disease-free survival (DFS), the univariate analysis indicated that the high TK1 increased the risk of poor prognosis (HR = 2.38, 95% CI: 1.64–4.23, P=0.000). The Kaplan–Meier curve indicated the high TK1 group was poorer than that in the low TK1 group (P=0.002). For the overall survival (OS), similar results were found that the high TK1 was related to poor OS (HR = 1.89, 95% CI: 1.34–3.67, P=0.000). The multivariate Cox regression indicated that the TK1 was still associated with DFS (HR = 1.83, 95% CI: 1.22–3.17, P=0.001) and OS (HR = 1.63, 95% CI: 1.19–2.08, P=0.006). The high pretreatment serum TK1 levels in breast cancer patients were associated with poor OS and DFS. TK1 could be a potential predictive factor in differential diagnosis of poor prognosis from all patients.

Prognostic role of serum thymidine kinase 1 kinetics during neoadjuvant chemotherapy for early breast cancer

Background

Emerging data support the use of thymidine kinase 1 (TK1) activity as a prognostic marker and for monitoring of response in breast cancer (BC). The long-term prognostic value of TK1 kinetics during neoadjuvant chemotherapy is unclear, which this study aimed to elucidate.

Methods

Material from patients enrolled to the single-arm prospective PROMIX trial of neoadjuvant epirubicin, docetaxel and bevacizumab for early BC was used. Ki67 in baseline biopsies was assessed both centrally and by automated digital imaging analysis. TK1 activity was measured from blood samples obtained at baseline and following two cycles of chemotherapy. The associations of TK1 and its kinetics as well as Ki67 with event-free survival and overall survival (OS) were evaluated using multivariable Cox regression models.

Results

Central Ki67 counting had excellent correlation with the results of digital image analysis (r = 0.814), but not with the diagnostic samples (r = 0.234), while it was independently prognostic for worse OS [adjusted hazard ratio (HR_adj) = 2.72, 95% confidence interval (CI) 1.19-6.21, P = 0.02]. Greater increase in TK1 activity after two cycles of chemotherapy resulted in improved event-free survival (HR_adj = 0.50, 95% CI 0.26-0.97, P = 0.04) and OS (HR_adj = 0.46, 95% CI 0.95, P = 0.04). There was significant interaction between the prognostic value of TK1 kinetics and Ki67 (p_interaction 0.04).

Conclusion

Serial measurement of serum TK1 activity during neoadjuvant chemotherapy provides long-term prognostic information in BC patients. The ease of obtaining serial samples for TK1 assessment motivates further evaluation in larger studies.

•

This is a correlative analysis of a prospective phase II study on neoadjuvant chemotherapy for breast cancer.

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Serial measurement of serum TK1 activity during treatment provides independent long-term prognostic information.

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We demonstrate the validity and clinical utility of both central and automated image analysis-based Ki67 assessment.

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Finally, we explore the biologic correlations between TK1 and Ki67.

STK1p as a prognostic biomarker for overall survival in non-small-cell lung carcinoma, based on real-world data

Aim:

A prospective investigation of serum thymidine kinase 1 concentration (STK1p) was performed to evaluate its prognostic value in patients with non-small-cell lung carcinoma (NSCLCs).

Patients & methods:

The STK1p values of 127 patients were determined by an enhanced chemiluminescent dot blot assay. The patients were recruited from March 2011 to December 2017.

Results:

Kaplan–Meier plot showed that patients with elevated STK1p values had worse overall survival (OS), especially patients of early/middle stages. Multi-variable COX regression showed that STK1p value and combined treatment surgery + chemotherapy were independent prognostic factors for favorable OS.

Conclusion:

STK1p is helpful in predicting OS of early/middle stages (I–IIIA) NSCLCs patients following a nonrandomized individual adapted treatment, but is may be not recommended in advanced stages (IIIB + IV) of NSCLCs.

Lung cancer is one of the most common types of tumors, with a high mortality rate. We investigate if thymidine kinase 1 in serum (STK1p) is a reliable prognostic marker for survival in non-small-cell lung carcinoma. We recruited 127 patients in this study. STK1p level was determined using a high-sensitive chemiluminescent dot blot assay. Patients with elevated STK1p values had worse overall survival, especially patients in the early/middle cancer stages. Analysis showed that STK1p is an independent prognostic factors for overall survival. We concluded that STK1p is helpful predicting the efficacy of treatment in non-small-cell lung carcinoma for those in the early/middle stages.

Molecular characterisation of TP53 mutated squamous cell carcinomas of the lung to identify putative targets for therapy

Personalised cancer treatment depends on identification of therapeutically relevant biological subgroups of patients for assessing effect of treatment and to discover new therapeutic options. By analyses in heterogeneous patient populations, the effects may be lost in noise. Squamous cell carcinoma of the lung is a major killer worldwide. Despite recent advances, mortality is high and response to therapies varies greatly from patient to patient. Target search in biologically relevant subgroups may identify treatment options not so far discovered. A total of 198 patients undergoing surgery for squamous cell carcinomas of the lung were included in the study. The tumours were analysed for copy number alterations (n = 152) and gene expression from tumour (n = 188) and normal lung (n = 21), with both data levels present in 140 patients. We studied alterations in tumours harbouring mutations in TP53 and in previously published gene expression subtypes. Genes with consistent alterations in both genomic levels were identified as putative biomarkers. Results were validated in TCGA. The most convincing biomarker in TP53 mutated squamous cell carcinomas of the lung was BIRC5 with amplification in 36% of mutated samples, 5% in wild-type samples and a 17%-fold change of expression between TP53 mutated tumours and normal lung tissue. BIRC5 was significantly altered in the classical and primitive subtypes. We suggest BIRC5 as a putative predictive biomarker and putative druggable target in squamous cell lung carcinomas harbouring TP53 mutation or classified as classical and primitive subtypes.

Plasma thymidine kinase 1 activity and outcome of ER+ HER2- metastatic breast cancer patients treated with palbociclib and endocrine therapy

Purpose

Previous cohort studies have reported plasma TK1 activity (pTKa) as a potential prognostic biomarker in estrogen receptor-positive (ER+) HER2-negative (HER2−) metastatic breast cancer (MBC). In this prospective study, we report here the prognostic impact of pTKa in ER+/HER2− MBC patients treated with endocrine therapy and CDK4/6 inhibitor.

Experimental design

Patients were included into the prospective, ethics committee-approved ALCINA study (NCT02866149). Eligibility criteria were patients with ER+/HER2− MBC treated at Institut Curie with endocrine therapy and palbociclib. Plasma samples were obtained at baseline and after 4 weeks of treatment. pTKa was quantified by the DiviTum® assay (Biovica, Sweden).

Results

From May 2016 to August 2018, 103 patients treated with endocrine therapy and palbociclib were included. Patients had received a median of two prior systemic therapies for MBC (range 0–14). Median follow-up was 13.8 months (range 6–31), with median PFS and OS of 9.6 months (95%CI [7.0–11.3]) and 28 months (95%CI [23–not reached]), respectively. Median baseline pTKa was 292 Du/L (range 20–27,312 Du/L, IQR [89–853]). After adjusting for other prognostic factors, baseline pTKa remained an independent prognostic factor for both PFS (HR = 1.3 95%CI [1.1–1.4], p = 0.0005) and OS (HR = 1.3 95%CI [1.2–1.6], p < 0.0001), and 4-week pTKa was associated with OS (HR = 1.6 95%CI [1.3–2], p < 0.0001). That survival prediction was significantly improved by the addition of baseline pTKa to clinicopathological characteristics. Adding pTKa changes at 4 weeks to baseline pTKa did not further increase survival prediction.

Conclusion

This study demonstrates the clinical validity of pTKa as a new circulating prognostic marker in ER+/HER2− MBC patients treated with endocrine therapy and palbociclib.

A meta-analysis of serological thymidine kinase 1 as a marker for colorectal benign and malignant tumor risk assessment

The present study investigated whether a concentration of serum thymidine kinase 1 (STK1p) could be used to distinguish between healthy individuals, patients with colorectal benign tumors and individuals with colorectal cancer (CRC). The effectiveness of surgery on patients with CRC was monitored. A total of 20 publications containing patients with CRC (n=1,836), patients with colorectal benign tumors (n=774) and healthy controls (n=1,701) were analysed in the present meta-analysis. The publications were collected from PubMed, Embase, CENTRAL, CNKI, Wanfang, VIP and SinoMed databases from January 1, 2009 until August 31, 2019. Articles were analyzed according to sensitivity (Forest plot) and publication bias (Begg's plot, Egger's linear regression) using fixed or random effect models to calculate the weighted mean difference. Study quality was checked using the Newcastle-Ottawa Scale Document Quality Assessment Scale. The meta-analysis followed the PRISMA statement. The results revealed that STK1p significantly distinguished healthy individuals and those with colorectal benign tumors from patients with CRC, and from patients with benign tumors (P<0.000001). STK1p levels also decreased by 40% following surgery (P<0.0001), which corresponded to half-life of ~1 month. The quality of the present study was high and no bias was identified among publication. It was concluded that STK1p was a reliable biomarker for the early detection of benign lesions, which may therefore prevent their future development into colorectal malignancies. STK1p may also be used for the clinical dynamic monitoring of the effectiveness of surgery in patients with CRC. Combining STK1p with colorectal-associated biomarkers, in addition to the determination of tumor stage and grade may therefore be of use.

Preoperative Serum Thymidine Kinase Activity as Novel Monitoring, Prognostic, and Predictive Biomarker in Pancreatic Cancer

OBJECTIVE

The aim of the study was to investigate serum thymidine kinase 1 (S-TK) activity as a diagnostic and prognostic marker for patients with pancreatic ductal adenocarcinoma (PDAC).

METHODS

Using the sensitive TK activity assay DiviTum, preoperative serum samples from 404 PDAC, 28 chronic pancreatitis, and 25 autoimmune pancreatitis patients and 83 healthy volunteers were analyzed. The preoperative S-TK activities of 54 PDAC patients who received neoadjuvant therapy (nTx) were also compared with those of 258 PDAC patients who did not receive nTx.

RESULTS

The preoperative S-TK activities of PDAC patients were significantly higher and discriminatory from autoimmune and chronic pancreatitis patients and control groups. The S-TK activity in PDAC patients was associated with overall survival. Patients with S-TK activity of less than 80 Du (DiviTum units)/L demonstrated median survival of 20.3 months with an estimated 18.0% 5-year survival rate; for S-TK activity of 80 Du/L or greater, median survival was 15.1 months with a 6.8% 5-year survival rate. For early-stage PDAC, these differences were even more pronounced. The S-TK activity in the nTx group was significantly higher than that in the group not receiving nTx.

CONCLUSIONS

Pancreatic ductal adenocarcinomas reveal a significant increase in S-TK activity, which is associated with overall survival, especially in early tumor stages. Serum thymidine kinase 1 activity may be a useful parameter for monitoring nTx efficacy.

血清胸苷激酶1在肝癌中表达升高和BCLC分期相关

目的

探讨血清胸苷激酶1(thymidine kinase 1, TK1)在肝癌患者中的表达水平、对肝癌诊断价值及其对预后的指导意义.

方法

采用免疫印迹增强化学发光法检测77例肝癌患者(肝癌组)、41例肝硬化患者(肝硬化组)和47例健康对照者(对照组)血清TK1水平, 对肝癌组患者随访观察2年, 以死亡为终点事件. 非正态分布的计量资料, 采用中位数和四分位数间距表示, 各组间比较采用非参数检验的Kruskal Wallis检验. 通过ROC曲线和ROC曲线下面积(area under curve, AUC)评价TK1对肝癌的诊断价值. 采用Kaplan-Meier法进行生存分析, Log Rank法进行差异性检验, 以P<0.05为差异有统计学意义.

结果

肝癌组患者血清TK1水平为1.85(0.94-3.755)pmol/L, 较肝硬化组的血清TK1水平0.90(0.56-3.13)pmol/L和对照组的血清TK1水平0.72(0.49-1.07)pmol/L明显升高(P<0.05), 肝硬化组和对照组之间TK1水平无差别. 血清TK1对肝癌有诊断价值, AUC为0.739(P<0.05), 诊断界值为1.105, 敏感性为0.714, 特异性为0.693. 血清TK1的水平和患者年龄、谷草转氨酶(aspartate transaminase, AST)、肝功能分级、BCLC分期、血管侵犯、肿瘤大小、肿瘤个数呈正相关(P<0.05). 血清TK1水平在BCLC分期(C+D)期患者高于BCLC(A+B)期患者(P<0.05).

结论

血清TK1在肝癌患者中升高, 可作为诊断肝癌的血清学标志物之一. TK1的水平和肝细胞癌(hepetocellular carcinoma, HCC)患者年龄、AST、肝功能分级、BCLC分期、血管侵犯、肿瘤大小、肿瘤个数正相关. TK1在BCLC(C+D)期患者高于BCLC(A+B)期肝癌患者, 对判断HCC患者的预后有一定指导意义.

Thymidine kinase 1 expression in ovarian serous adenocarcinoma is superior to Ki-67: A new prognostic biomarker

Cancer is a disease with abnormally proliferating cells and therefore proliferation rate is an important index for assessing tumour growth. Ki-67 is a commonly used proliferation marker considered to be an unfavourable prognostic marker in some tumors, while Thymidine kinase 1 (TK1) is an interesting proliferation marker because its levels are highly dependent on the growth stage of cells. To define the immunohistochemistry (IHC) expression of the TK1 in patients with ovarian serous adenocarcinoma and establish its potential role as a new biomarker for progressive disease, we analyzed the expression patterns of TK1 and Ki-67 in 109 patients with ovarian serous adenocarcinoma. TK1 and Ki-67 expression both showed a statistically significant correlation to MD Anderson Cancer Center (MDACC) grade, but not to age, tumour size, lymph node metastasis or pathological TNM (pTNM) stages. TK1 expression, MDACC grades, pathological stages and lymph node metastasis correlate to relapse incident rate and overall survival, but Ki-67 does not. Although TK1 expression, MDACC grade, pTNM stage and lymph node metastasis significantly correlate to relapse in the Cox univariate analysis, in the multivariate Cox analysis only TK1 expression and lymph node metastasis were independent prognostic factors. The overall survival also correlated significantly to TK1 expression, MDACC grade, pTNM stage and lymph node metastasis in the Cox univariate analysis. However, only the pTNM stage was found to be an independent prognostic factor for survival in the Cox multivariate analysis. Therefore, though TK1 expression was an independent prognostic factor for relapse, but not for survival, TK1 is a more informative expression than Ki-67 for LI, relapse and overall survival rates. Thus, when TK1 is combined with MDACC grading, pTNM staging and lymph node metastasis, IHC determination of TK1 expression may improve the overall prediction of prognosis in patients with ovarian cancer.

Serum TK1 is a more reliable marker than CEA and AFP for cancer screening in a study of 56,286 people

BACKGROUND

The World Health Organization (WHO) has estimated that the number of cancer patients will increase by about 70% during the next 25 years world-wide. To deal with this problem, WHO has suggested a focus on prevention of tumor incidence and health screening for early detection of people with tumors.

OBJECTIVE

To investigate the use of thymidine kinase 1 (TK1), CEA and AFP in serum to discover people with malignant tumors through health cancer screening.

METHODS

Of a cohort in 486,085 people of a routine health screening at the Health Centre, Fujun 180 Hospital, Quanzhou city, China, 56,286 people were investigated according to the presence of cancer during 2009-2014. The concentration of CEA and AFP were determined by an electrochemiluminescence immunoassay from Roche Diagnostics e601GmbH and STK1 by a commercial kit based on an enhanced chemiluminescent dot blot assay.

RESULTS

The cancer incident rate increased from 0.048/100,000 to 0.220/100,000. The most common types of tumors were those of the liver, cervix and lung. STK1 correlated to tumor growth rate, was more sensitive than CEA and AFP for discovering people with malignant tumors and more sensitive among people who had diagnosis of malignant tumor. STK1 was also a prognostic biomarker for death at 10-40 months follow-up, while CEA and AFP were not. A combination of these markers increased the sensitivity by about 30%.

CONCLUSION

STK1 is a reliable biomarker for discovering people with malignant tumors in cancer screening.

Breast and prostate cancer patients differ significantly in their serum Thymidine kinase 1 (TK1) specific activities compared with those hematological malignancies and blood donors: implications of using serum TK1 as a biomarker

Background

Thymidine kinase 1 (TK1) is a cellular enzyme involved in DNA precursor synthesis, and its activity has been used as a proliferation marker for monitoring malignant diseases. Here, for the first time, we evaluated both TK1 activity and protein levels in sera from patients with different malignancies.

Methods

Serum samples from patients with myelodysplastic syndrome (MDS, n = 22), breast cancer (n = 42), prostate cancer (n = 47) and blood donors (n = 30) were analyzed for TK1 protein and activity levels, using a serum TK1 (STK1) protein assay based on antibodies and an activity assay that measured [³H]-deoxythymidine (dThd) phosphorylation. The molecular forms of TK1 in sera from some of these patients were analyzed using size-exclusion chromatography.

Results

Mean STK1 activities in sera from MDS, breast and prostate cancer were 11 ± 17.5, 6.7 ± 19 and 1.8 ± 1.4 pmol/min/mL, differing significantly from blood donors (mean ± standard deviation (SD) = 1.1 ± 0.9 pmol/min/mL). Serum TK1 protein (25 kDa polypeptide) levels were also significantly higher in MDS, breast, prostate cancer compared to blood donors (mean ± SD = 19 ± 9, 22 ± 11, 20 ± 12, and 5 ± 3.5 ng/mL, respectively). The STK1 specific activities of sera from patients with MDS and blood donors were significantly higher when compared with activities in sera from breast and prostate cancer patients. Size-exclusion analysis of sera from breast and prostate cancer showed that the detected active TK1 was primarily a high molecular weight complex, similar to the forms found in sera from MDS patients and blood donors. However, Western blotting demonstrated high TK1 25 kDa protein levels in fractions lacking TK1 activity in sera from cases with breast and prostate cancer.

Conclusions

These results demonstrate that there are differences in the specific activities and the subunit compositions of STK1 in hematological malignancies compared with breast and prostate cancer. This fact has several important implications for the use of STK1 as a tumor biomarker. One is that STK1 protein assays may differentiate early-stage tumor development in breast and prostate cancer more effectively than STK1 activity assays.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1073-8) contains supplementary material, which is available to authorized users.

Non-Viral Deoxyribonucleoside Kinases--Diversity and Practical Use

Deoxyribonucleoside kinases (dNKs) phosphorylate deoxyribonucleosides to their corresponding monophosphate compounds. dNks also phosphorylate deoxyribonucleoside analogues that are used in the treatment of cancer or viral infections. The study of the mammalian dNKs has therefore always been of great medical interest. However, during the last 20 years, research on dNKs has gone into non-mammalian organisms. In this review, we focus on non-viral dNKs, in particular their diversity and their practical applications. The diversity of this enzyme family in different organisms has proven to be valuable in studying the evolution of enzymes. Some of these newly discovered enzymes have been useful in numerous practical applications in medicine and biotechnology, and have contributed to our understanding of the structural basis of nucleoside and nucleoside analogue activation.