Thymidine kinase as a proliferative marker: clinical relevance in 1,692 primary breast cancer patients

G-Quadruplex-Programmed Versatile Nanorobot Combined with Chemotherapy and Gene Therapy for Synergistic Targeted Therapy

Developing synergistic targeted therapeutics to improve treatment efficacy while reducing side effects has proven promising for anticancer therapies, but how to conveniently modulate multidrug cooperation remains a challenge. Here, a novel synergistic strategy using a G-quadruplex-programmed versatile nanorobot (G4VN) containing two subunits of DNAzyme (DzG4) and ligand-drug conjugates (LDCs) is proposed to precisely target tumors and then execute both gene silencing and chemotherapy. As the core module of this nanorobot, a well-designed G4 responding to a high level of K+ in tumor microenvironment smartly kills three birds with one stone, which makes two TfR aptamers proximate to improve their efficiency of targeting tumor cells, and in situ activates a split 10-23 DNAzyme to downregulate target mRNA expression, meanwhile promotes the cell uptake of a GSH-responsive LDCs to enhance drug efficacy. Such a design enables a potently synergistic anticancer therapy with low side effects in vivo, showing great promise for broad applications in precision disease treatment.

A Smart Deoxyribozyme-Programmable Catalytic DNA Circuit for High-Contrast MicroRNA Imaging

Synthetic catalytic DNA circuits have been recognized as a promising signal amplification toolbox for sensitive intracellular imaging, yet their selectivity and efficiency are always constrained by uncontrolled off-site signal leakage and inefficient on-site circuitry activation. Thus, the endogenously controllable on-site exposure/activation of DNA circuits is highly desirable for achieving the selective imaging of live cells. Herein, an endogenously activated DNAzyme strategy was facilely integrated with a catalytic DNA circuit for guiding the selective and efficient microRNA imaging in vivo. To prevent the off-site activation, the circuitry constitute was initially caged without sensing functions, which could be selectively liberated by DNAzyme amplifier to guarantee the high-contrast microRNA imaging in target cells. This intelligent on-site modulation strategy can tremendously expand these molecularly engineered circuits in biological systems.

Serum thymidine kinase activity in patients with hormone receptor-positive and HER2-negative metastatic breast cancer treated with palbociclib and fulvestrant

BACKGROUND

Biomarkers for cyclin-dependent kinase 4/6 inhibitors, such as palbociclib, for patients with hormone receptor-positive/HER2-negative metastatic breast cancer are lacking. Thymidine kinase is a proliferation marker downstream of the cyclin-dependent kinase 4/6 pathway. We prospectively investigated the prognostic role of serum thymidine kinase activity (sTKa), in patients treated with Palbociclib + fulvestrant.

PATIENTS AND METHODS

PYTHIA was a phase II, single-arm, multicentre, trial that enrolled 124 post-menopausal women with endocrine-resistant hormone receptor-positive/HER2-negative metastatic breast cancer. Serum samples were collected pre-treatment (pre-trt; n = 122), at day 15 of cycle 1 (D15; n = 108), during the one week-off palbociclib before initiating cycle 2 (D28; n = 108) and at end of treatment (n = 76). sTKa was determined centrally using Divitum®, a refined ELISA-based assay with a limit of detection of 20 Divitum Units (Du)/L. The primary study endpoint was progression-free survival, assessed for its association with pre- and on-treatment sTKa.

RESULTS

Data from 122 women were analysed. Pre-treatment sTKa was not associated with clinical characteristics and moderately correlated with tissue Ki-67. Palbociclib + fulvestrant markedly suppressed sTKa levels at D15, with 83% of patients recording levels below limit of detection. At D28, sTKa showed a rebound in 60% of patients. At each timepoint, higher sTKa was associated with shorter progression-free survival (each p < 0.001), with the strongest effect at D15.

CONCLUSIONS

STKa is an independent prognostic biomarker in patients treated with palbociclib. High pre-treatment sTKa and its incomplete suppression during treatment may identify patients with poorer prognosis and primary resistance. This warrants validation in prospective comparative trials. CLINICALTRIALS.

GOV IDENTIFIER

NCT02536742; EudraCT 2014-005387-15.

A novel FRET-based dendritic hybridization chain reaction for tumour-related mRNA imaging

A novel FRET-based dendritic hybridization chain reaction (D-HCR) for TK1 mRNA imaging in living cells was developed. Compared with traditional complex D-HCR methods, it includes the advantages of having a simple design, an accurate signal and is suitable for use with living cells.

Avoiding False Positive Signals: A Powerful and Reliable Au-Se Dual-Color Probe

Nucleic acids as the important tumor markers play a crucial role in the identification of cancer. Various kinds of probes such as gold nanoparticles and graphene oxide have been explored to detect different nucleic acid markers. However, the existing probes are mostly used to detect a single tumor marker and susceptible to harsh conditions in the complex and dynamic physiological environment, which may lead to false positive results and greatly limit the sensing performance of the probe. Herein, a powerful and reliable Au-Se probe was developed for high-fidelity imaging of two cancer markers simultaneously in living cells. Compared with the traditional nucleic acid probe based on the Au-S bond, this probe was more stable against biological thiols and could effectively distinguish normal cells and cancer cells to avoid false positive results, which is more suitable for imaging in a complex physiological environment. This strategy will provide more valuable insights into designing and exploring novel biosensors in the future.

Circulating Biomarkers of CDK4/6 Inhibitors Response in Hormone Receptor Positive and HER2 Negative Breast Cancer

CDK4/6 inhibitors (CDK4/6i) and endocrine therapy are the standard treatment for patients with hormone receptor-positive and HER2 negative (HR+/HER2-) metastatic breast cancer. Patients might show intrinsic and acquired resistance, which leads to treatment failure and progression. Circulating biomarkers have the potential advantages of recognizing patients who might not respond to treatment, monitoring treatment effects and identifying markers of acquired resistance during tumor progression with a simple withdrawal of peripheral blood. Genomic alterations on circulating tumor DNA and serum thymidine kinase activity, but also circulating tumor cells, epigenetic or exosome markers are currently being tested as markers of CDK4/6i treatment response, even though none of these have been integrated into clinical practice. In this review, we discuss the recent advancements in the development of circulating biomarkers of CDK4/6i response in patients with HR+/HER2-breast cancer.

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.

mRNA-Activated Multifunctional DNAzyme Nanotweezer for Intracellular mRNA Sensing and Gene Therapy

Deoxyribozyme (DNAzyme) is regarded as a promising gene therapy drug. However, poor cellular uptake efficacy and low biological stability limit the utilization of DNAzyme in gene therapy. Here, we report a well-known programmable DNAzyme-based nanotweezer (DZNT) that provides a new strategy for the detection of TK1 mRNA and survivin mRNA-targeted gene silencing therapy. At the end of the DZNT arm, there are two functionalized single-stranded DNA and each consists of two parts: the segment complementary to TK1 mRNA and the split-DNAzyme segment. The hybridization with intracellular TK1 mRNA enables the imaging of TK1 mRNA. Meanwhile, the hybridization draws the split-DNAzyme close to each other and activates DNAzyme to cleave the survivin mRNA to realize gene silencing therapy. The results demonstrate that the DZNT nanocarrier has excellent cell penetration, good biocompatibility, and noncytotoxicity. DZNT can image intracellular biomolecule TK1 mRNA with a high contrast. Furthermore, the split-DNAzyme can efficiently cleave the survivin mRNA with the aid of TK1 mRNA commonly present in cancer cells, accordingly can selectively kill cancer cells, and has no harm to normal cells. Taken together, the multifunctional programmable DZNT provides a promising platform for the early diagnosis of tumors and gene therapy.

CDK4/6 inhibitors: A focus on biomarkers of response and post-treatment therapeutic strategies in hormone receptor-positive HER2-negative breast cancer

CDK4/6 inhibitors (CDK4/6i) in combination with endocrine therapy are the mainstay of treatment for patients with hormone receptor-positive, HER2 negative (HR+/HER2neg) metastatic breast cancer. However, resistance - either de novo or acquired - invariably occurs, leading to treatment failure and cancer progression. Genomic alterations, gene expression data and circulating biomarkers have been correlated to response to treatment, but to date no biomarker has been approved to stratify patients. Treatment strategies after progression on CDK4/6i are yet to be standardized. Current approaches include endocrine therapy alone or in combination with target therapy, or chemotherapy. New agents are in clinical development based on potential mechanisms of acquired resistance. Here we will review recent advancements in biomarkers of response to CDK4/6i, and in post- treatment therapeutic strategies.

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.

Current Therapeutic Progress of CDK4/6 Inhibitors in Breast Cancer

The clinical use of selective cyclin-dependent kinase (CDK) 4/6 inhibitors has significantly improved the prognosis of patients with hormone receptor (HR)-positive human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer (ABC/mBC), which almost achieved the double progression-free survival (PFS) in combination with endocrine therapy (ET) compared with ET alone. To date, there are 3 CDK4/6 inhibitors (palbociclib, ribocilcib and abemaciclib) approved by the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) to treat patients with HR+/HER2-ABC/mBC in the first and later lines. The aim of this review is to summarize the current clinical use and ongoing clinical trials of CDK4/6 inhibitors, the published overall survival data, and the potential biomarkers and resistance to CDK4/6 inhibitors.

Transcriptomic Profiling Identifies Differentially Expressed Genes in Palbociclib-Resistant ER+ MCF7 Breast Cancer Cells

Acquired resistance to cyclin-dependent kinases 4 and 6 (CDK4/6) inhibition in estrogen receptor-positive (ER+) breast cancer remains a significant clinical challenge. Efforts to uncover the mechanisms underlying resistance are needed to establish clinically actionable targets effective against resistant tumors. In this study, we sought to identify differentially expressed genes (DEGs) associated with acquired resistance to palbociclib in ER+ breast cancer. We performed next-generation transcriptomic RNA sequencing (RNA-seq) and pathway analysis in ER+ MCF7 palbociclib-sensitive (MCF7/pS) and MCF7 palbociclib-resistant (MCF7/pR) cells. We identified 2183 up-regulated and 1548 down-regulated transcripts in MCF7/pR compared to MCF7/pS cells. Functional analysis of the DEGs using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database identified several pathways associated with breast cancer, including ‘cell cycle’, ‘DNA replication’, ‘DNA repair’ and ‘autophagy’. Additionally, Ingenuity Pathway Analysis (IPA) revealed that resistance to palbociclib is closely associated with deregulation of several key canonical and metabolic pathways. Further studies are needed to determine the utility of these DEGs and pathways as therapeutics targets against ER+ palbociclib-resistant breast cancer.

Plasma Thymidine Kinase Activity as a Biomarker in Patients with Luminal Metastatic Breast Cancer Treated with Palbociclib within the TREnd Trial

PURPOSE

Thymidine kinase 1 (TK1) is downstream to the CDK4/6 pathway, and TK activity (TKa) measured in blood is a dynamic marker of outcome in patients with advanced breast cancer (ABC). This study explores TK1 as a biomarker of palbociclib response, both in vitro and in patients with ABC.

EXPERIMENTAL DESIGN

Modulation of TK1 levels and activity by palbociclib were studied in seven estrogen receptor-positive breast cancer cell lines: sensitive (PDS) and with palbociclib acquired resistance (PDR). TKa was assayed in plasma obtained at baseline (T0), after one cycle (T1), and at disease progression on palbociclib (T2) in patients enrolled in the "To Reverse ENDocrine Resistance" (TREnd) trial (n = 46).

RESULTS

Among E2F-dependent genes, TK1 was significantly downregulated after short-term palbociclib. Early TKa reduction by palbociclib occurred in PDS but not in PDR cells. In patients, median TKa (mTKa) at T0 was 75 DiviTum units per liter (Du/L), with baseline TKa not proving prognostic. At T1, mTKa decreased to 35 Du/L, with a minority of patients (n = 8) showing an increase-correlating with a worse outcome than those with decreased/stable TKa (n = 33; mPFS 3.0 vs 9.0 months; P = 0.002). At T2, mTKa was 251 Du/L; patients with TKa above the median had worse outcomes on post-study treatment compared with those with lower TKa (2.9 vs 8.7 months; P = 0.05).

CONCLUSIONS

TK is a dynamic marker of resistance to palbociclib which may lead to early identification of patients in whom treatment escalation may be feasible. In addition, TKa may stratify prognosis in patients with acquired resistance to palbociclib.

5-fluorouracil and other fluoropyrimidines in colorectal cancer: Past, present and future

5-Fluorouracil (5-FU) is an essential component of systemic chemotherapy for colorectal cancer (CRC) in the palliative and adjuvant settings. Over the past four decades, several modulation strategies including the implementation of 5-FU-based combination regimens and 5-FU pro-drugs have been developed and tested to increase the anti-tumor activity of 5-FU and to overcome the clinical resistance. Despite the encouraging progress in CRC therapy to date, the patients' response rates to therapy continue to remain low and the patients' benefit from 5-FU-based therapy is frequently compromised by the development of chemoresistance. Inter-individual differences in the treatment response in CRC patients may originate in the unique genetic and epigenetic make-up of each individual. The critical element in the current trend of personalized medicine is the proper comprehension of causes and mechanisms contributing to the low or lack of sensitivity of tumor tissue to 5-FU-based therapy. The identification and validation of predictive biomarkers for existing 5-FU-based and new targeted therapies for CRC treatment will likely improve patients' outcomes in the future. Herein we present a comprehensive review summarizing options of CRC treatment and the mechanisms of 5-FU action at the molecular level, including both anabolic and catabolic ways. The main part of this review comprises the currently known molecular mechanisms underlying the chemoresistance in CRC patients. We also focus on various 5-FU pro-drugs developed to increase the amount of circulating 5-FU and to limit toxicity. Finally, we propose future directions of personalized CRC therapy according to the latest published evidence.

An aptamer-tethered, DNAzyme-embedded molecular beacon for simultaneous detection and regulation of tumor-related genes in living cells

Simultaneous detection and regulation of tumor-related genes presents a promising strategy for early diagnosis and treatment of cancer, but achieving this has been a huge challenge for both chemical and biomedical communities. Towards this objective, we have devised a novel aptamer-tethered, DNAzyme-embedded molecular beacon (MB) for multiple functions in cancer cells. In this design, a tumor targeting aptamer was employed to specifically deliver the sensor into cancer cells for target gene detection, and an RNA-cleaving DNAzyme was embedded to realize gene regulation. Both aptamer-tethering and DNAzyme-embedding had little influence on the sensor performance, with a detection limit of ∼2 nM and high specificity. After delivering into tumor cells, our device could monitor the tumor-related genes by producing detectable fluorescence signals, and regulate the gene expression at both mRNA and protein levels as evidenced by the RT-PCR and western blot analyses. This study provides a simple and efficient strategy to rationally combine various functional nucleic acids for multi-functional applications in living cells, which hold great potential for cancer diagnosis and therapy.

Mechanisms of Resistance to CDK4/6 Inhibitors: Potential Implications and Biomarkers for Clinical Practice

The recent arrival of CDK4/6 inhibitor agents, with an approximate doubling of progression-free survival (PFS) associated with their use in hormone receptor-positive, HER2-negative advanced breast cancer (BC), has radically changed the approach to managing this disease. However, resistance to CDK4/6 inhibitors is considered a near-inevitability in most patients. Mechanisms of resistance to these agents are multifactorial, and research in this field is still evolving. Biomarkers with the ability to identify early resistance, or to predict the likelihood of successful treatment using CDK4/6 inhibitors are yet to be identified, and represent an area of unmet clinical need. Here we present selected mechanisms of resistance to CDK4/6 inhibitors, largely focussing on roles of Rb, cyclin E1, and the PIK3CA pathway, with discussion of associated biomarkers which have been investigated and applied in recent pre-clinical and clinical studies. These biological drivers may furthermore influence clinical treatment strategies adopted beyond CDK4/6 resistance.

The combination of AroCell TK 210 ELISA with Prostate Health Index or prostate-specific antigen density can improve the ability to differentiate prostate cancer from noncancerous conditions

BACKGROUND

Prostate-specific antigen (PSA) is an established tumour marker for prostate cancer (PCa). Serum thymidine kinase 1 is a possible new marker for the detection of PCa. The aim of the study was to investigate the diagnostic value of the AroCell TK 210 enzyme-linked immunosorbent assay (ELISA) together with free PSA, [-2]proPSA, and Prostate Health Index (PHI) in differentiating PCa from benign urological conditions.

METHODS

Serum samples from 140 patients with PSA values in the range between 2 and 10 µg/L were collected at the Ljubljana University Medical Centre and the Maribor University Medical Centre. Thymidine kinase (TK1) protein levels were determined using the AroCell TK 210 ELISA and PSA-related parameters analysed with commercial assays.

RESULTS

Serum TK1 protein, total and free PSA, proPSA, PSA density (PSAD), and PHI levels in patients with confirmed PCa were significantly higher than in patients with benign urological conditions (P < 0.05). Overall, the AroCell TK 210 ELISA results showed a significant correlation with PHI ( r = 0.25, P = 0.0031). Receiver-operating characteristic curve analyses were used to compare the area under the curve (AUC) of TK 210 ELISA, PHI, and PSA density. For PHI, the AUC was 0.73, comparable to those of TK 210 ELISA (0.67) and PSAD (0.66), with no significant differences in pairwise comparisons (PHI vs TK 210 ELISA P = 0.32, PHI vs PSAD P = 0.24, and TK 210 ELISA vs PSAD P = 0.95). The AUC for the combination of TK1 plus PSAD was significantly higher than those for the individual PSA-related biomarkers and marginally PHI, while the AUC for the combination of TK1 plus PHI was significantly higher than those for the individual PSA-related biomarkers except for PHI and marginally for PSAD. Total PSA concentration was the only marker, that was significantly higher in patients with an increasing Gleason grade.

CONCLUSIONS

These results suggest that TK1 protein determinations together with PHI or PSAD could be a valuable additional tool in PCa management.

Prognostic role of serum thymidine kinase 1 activity in patients with hormone receptor-positive metastatic breast cancer: Analysis of the randomised phase III Evaluation of Faslodex versus Exemestane Clinical Trial (EFECT)

BACKGROUND

Thymidine kinase 1 (TK1) plays a critical role in DNA synthesis and cell proliferation. Recent studies have shown potential for serum TK1 activity (sTKa) as a prognostic marker and indicator of early response to endocrine therapy in advanced breast cancer. The aim of this study is to assess the correlation between sTKa and patient outcome.

PATIENTS AND METHODS

The Evaluation of Faslodex versus Exemestane Clinical Trial (EFECT) was a double-blind, double-dummy, randomised trial of fulvestrant versus exemestane after progression on non-steroidal aromatase inhibitor therapy, in postmenopausal women with advanced breast cancer. Retrospective analyses of serum archived from EFECT were conducted. sTKa was assessed using the DiviTum® assay on samples collected at baseline, after three and six months of endocrine therapy, and at disease progression.

RESULTS

The median time to progression (mTTP) for patients with low baseline sTKa levels was 5.03 months (95% confidence interval [CI]: 3.91-5.89) versus 2.57 months (95% CI: 2.04-3.52) in patients with high sTKa baseline levels (P < 0.0001). On treatment, patients whose sTKa increased from baseline had a significantly shorter mTTP (3.39 months, 95% CI: 2.14-4.11) than those without an sTKa increase (5.39 months, 95% CI: 4.01-6.68) (P = 0.0045). Similar results were observed in the separate EFECT treatment arms. After adjusting for major prognostic factors, sTKa remained an independent marker.

CONCLUSION

sTKa is a potential circulating prognostic marker in patients with advanced breast cancer treated with endocrine therapy. It may also represent a tool for upfront identification of endocrine therapy resistance and early positive response to therapy. Independent validation of these results is warranted.

Biomedical applications of nanoflares: Targeted intracellular fluorescence probes

Nanoflares are intracellular probes consisting of oligonucleotides immobilized on various nanoparticles that can recognize intracellular nucleic acids or other analytes, thus releasing a fluorescent reporter dye. Single-stranded DNA (ssDNA) complementary to mRNA for a target gene is constructed containing a 3'-thiol for binding to gold nanoparticles. The ssDNA "recognition sequence" is prehybridized to a shorter DNA complement containing a fluorescent dye that is quenched. The functionalized gold nanoparticles are easily taken up into cells. When the ssDNA recognizes its complementary target, the fluorescent dye is released inside the cells. Different intracellular targets can be detected by nanoflares, such as mRNAs coding for genes over-expressed in cancer (epithelial-mesenchymal transition, oncogenes, thymidine kinase, telomerase, etc.), intracellular levels of ATP, pH values and inorganic ions can also be measured. Advantages include high transfection efficiency, enzymatic stability, good optical properties, biocompatibility, high selectivity and specificity. Multiplexed assays and FRET-based systems have been designed.

Multiplexed determination of intracellular messenger RNA by using a graphene oxide nanoprobe modified with target-recognizing fluorescent oligonucleotides

A multiplexed graphene oxide (GO) fluorescent nanoprobe is described for quantification and imaging of messenger RNAs (mRNAs) in living cells. The recognizing oligonucleotides (with sequences complementary to those of target mRNAs) were labeled with different fluorescent dyes. If adsorbed on GO, the fluorescence of the recognizing oligonucleotides is quenched. After having penetrated living cells, the oligonucleotides bind to target mRNAs and dissociate from GO. This leads to the recovery of fluorescence. Using different fluorescent dyes, various intracellular mRNAs can be simultaneously imaged and quantified by a high content analysis within a short period of time. Actin mRNA acts as the internal control. This GO-based nanoprobe allows mRNA mimics to be determined within an analytical range from 1 to 400 nM and a detection limit as low as 0.26 nM. Up to 3 intracellular mRNAs (C-myc, TK1, and actin) can be detected simultaneously in a single living cell. Hence, this nanoprobe enables specific distinction of intracellular mRNA expression levels in cancerous and normal cells. It can be potentially applied as a tool for detection of cancer progression and diagnosis. Graphical abstract A multiplexed graphene oxide (GO)-based fluorescent nanoprobe is described for quantification and imaging of intracellular messenger RNAs. After penetrating living cells, the recovered fluorescence of the dissociated recognizing oligonucleotides can be analyzed , and this allows for simultaneous detection of up to 3 intracellular messenger RNAs.

Plasma thymidine kinase-1 activity predicts outcome in patients with hormone receptor positive and HER2 negative metastatic breast cancer treated with endocrine therapy

The aim of this study was to investigate if thymidine kinase-1 (TK1), a well-known proliferation marker, could represent a valid circulating biomarker to identify hormone receptor positive (HR+)/HER2 negative (HER2neg) metastatic breast cancer (MBC) patients most likely to benefit from endocrine therapy (ET). We used the DiviTum™ assay to analyze TK1 activity in cell lysates of three HR+/HER2neg BC cell lines and in plasma of 31 HR+/HER2neg MBC patients receiving ET. Blood samples were collected at treatment initiation, after one month and at disease progression. CTCs count and ESR1/PIK3CA mutations in circulating tumor DNA were performed and correlated with TK1 activity. TK1 activity was reduced in the two endocrine-sensitive cell lines after 2 days of treatment. In patients, high baseline TK1 activity correlated with CTCs positivity (p-value=0.014). Patients with low baseline levels of TK1 activity had a significantly better PFS compared to those with high baseline TK1 activity (p-value=0.012). Patients with an early drop of TK1 activity after one month of treatment had a significantly better PFS compared to those who experienced an increase (p-value=0.0026). Our study suggests that TK1 could be a potential prognostic, predictive and monitoring marker of early ET response in HR+/HER2neg MBC patients.

Prognostic Value of S-Phase Fraction in 920 Breast Cancer Patients: Focus on T1N0 Status

The aim of this study was to reexamine the prognostic role of tumor cell kinetics measured by S-phase fraction (SPF) and to establish its clinically relevant threshold values. SPF was determined by flow cytometry in a group of 920 consecutive breast cancer patients, all followed at our institute for 10 years (1988 to 1998). Mean age was 60.5 years (27–89 years). Median follow-up was 63 months (3–150 months). All patients had initial surgical treatment. SPF quartiles were: Q1=3.08%, median value = 5.98%, Q3=10.22%. A significant difference in overall specific survival was obtained between two populations divided by a cutoff at Q1 (p<0.0001). A multifactorial analysis including SPF and known prognostic factors such as tumor size, node status, histological grade, ER and PR status was performed using the Cox model in a population of 719 patients: univariate analysis showed that each of these factors had significant influence on overall survival. Multivariate analysis selected three of them, ranked by decreasing order of hazard ratio (HR) value: SPF (HR: 3.88, p<0.001), tumor size (HR: 2.49, p<0.001) and nodal status (HR: 2.28, p<0.001). In addition, when tumors were stratified according to SPF quartile values, there were statistically different overall survival curves in patients with small tumors (<2 cm) and in axillary node-negative patients.

Mutation Analysis in the Coding Sequence of Thymidine Kinase 1 in Breast and Colorectal Cancer

We report the first mutational study of thymidine kinase 1 (TK1) performed in human solid tumors. We sequenced cDNAs representing the complete coding region of TK1 in human breast (n=22) and colorectal (n=26) cancer. Codon 106 near the ATP binding site constantly differed (ATG → GTG; Met → Val) from the one deposited by Bradshaw and Deininger in the Genbank database (Accession number NM_003258). Silent polymorphisms at codon 11 (CCC → CCT; Pro → Pro) and codon 75 (GCG → GCA; Ala → Ala) were frequently detected in tumors as well as in normal tissues. In breast cancer the two polymorphisms were observed in 63.6% of the samples analyzed. No significant association could be found between polymorphisms and TK activity. In colorectal cancer the incidence of the two changes was 73.1% and 69.2%, respectively. Interestingly, one colon cancer with high cytosolic TK activity displayed two missense mutations located in and near the putative phosphorylation site by tyrosine kinase (s) (TAT → CAT; Tyr → His) and by cAMP-, cGMP-dependent protein kinase (TAC → TGC; Tyr → Cys), respectively; adjacent normal mucosa showed no mutation. This may open new avenues that imply TK1 activity in tumor cell proliferation.

Thymidine kinase 1 combined with CEA, CYFRA21-1 and NSE improved its diagnostic value for lung cancer

AIMS

Thymidine kinase 1 (TK1) is a tumor biomarker in human malignancies. The purpose of this study was to evaluate the diagnostic efficiency of this marker for lung cancer using the combined analysis of carcinoembryonic antigen (CEA), cytokeratin-19 fragment (CYFRA21-1), neuron specific enolase (NSE) and TK1.

MAIN METHODS

From 2013 to 2014, 147 patients with lung cancer and 228 patients with lung benign diseases who were admitted to our hospital were reviewed. Peripheral blood samples were collected for the detection of TK1, CEA, CYFRA21-1 and NSE. The diagnostic value of each marker was analyzed using receiver operating characteristic (ROC) curves and logistic regression equations.

KEY FINDINGS

The serum levels of TK1, CEA, CYFRA21-1 and NSE were significantly higher than those in patients with lung benign diseases (all P<0.05). The TK1 concentration was dependent on TNM stage (P=0.005). The ROC curve analyses showed that the diagnostic value of TK1 combined with CEA, CYFRA21-1 and NSE in lung cancer was significantly higher than that of each biomarker alone (all P<0.0001). In addition, TK1 combined with CEA, CYFRA21-1, or NSE could also improve the diagnosis of the squamous cell carcinoma, adenocarcinoma and small cell lung cancer subtypes, respectively.

SIGNIFICANCE

The combined detection of TK1 and the other three markers significantly improved the diagnosis of lung cancer. Furthermore, the detection of TK1 combined with that of CYFRA21-1, CEA or NSE increased the diagnostic value of TK1 for lung squamous cell carcinoma, adenocarcinoma and SCLC, respectively.

Nuclear-targeted siRNA delivery for long-term gene silencing

Developing effective nonviral siRNA delivery systems for long-term gene silencing remains a great challenge. Here we present a nuclear-targeted siRNA delivery system that can induce long-term gene silencing in cancer cells. The nanocarrier consists of gold nanoparticles modified with a dense shell of synthetic siRNAs and nuclear localization signal (NLS) peptides. The NLS peptide could translocate the nanocarrier into the nucleus and the siRNA was designed to target the promoter of thymidine kinase 1 and trigger the RNA-directed DNA methylation, thereby enabling the nuclear-targeted gene silencing. Compared with traditional gene silencing in cytoplasm, long-lasting gene knockdown could be achieved for the nuclear-targeted nanocarrier, which lasts for more than 30 days. The long-term gene silencing induced by nuclear-targeted siRNA delivery could effectively inhibit the proliferation of cancer cells and prevent the formation of a tumor in a mouse model.

MnO2 nanosheet mediated "DD-A" FRET binary probes for sensitive detection of intracellular mRNA

The donor donor-acceptor (DD-A) FRET model has proven to have a higher FRET efficiency than donor-acceptor acceptor (D-AA), donor-acceptor (D-A), and donor donor-acceptor acceptor (DD-AA) FRET models. The in-tube and in-cell experiments clearly demonstrate that the "DD-A" FRET binary probes can indeed increase the FRET efficiency and provide higher imaging contrast, which is about one order of magnitude higher than the ordinary "D-A" model. Furthermore, MnO2 nanosheets were employed to deliver these probes into living cells for intracellular TK1 mRNA detection because they can adsorb ssDNA probes, penetrate across the cell membrane and be reduced to Mn2+ ions by intracellular GSH. The results indicated that the MnO2 nanosheet mediated "DD-A" FRET binary probes are capable of sensitive and selective sensing gene expression and chemical-stimuli changes in gene expression levels in cancer cells. We believe that the MnO2 nanosheet mediated "DD-A" FRET binary probes have the potential as a simple but powerful tool for basic research and clinical diagnosis.

Fluorescence resonance energy transfer-based hybridization chain reaction for in situ visualization of tumor-related mRNA

The ability to visualize tumor-related mRNA in situ in single cells would distinguish whether they are cancer cells or normal cells, which holds great promise for cancer diagnosis at an early stage. Fluorescence resonance energy transfer (FRET) and hybridization chain reactions (HCRs) were combined with amplified sense tumor-related mRNA (TK1 mRNA) in situ with high sensitivity in single cells and tissue sections. Using this strategy, each copy of the target mRNA can propagate a chain reaction of hybridization events between two alternating hairpins to form a nicked duplex that contains repeated FRET units, amplifying the fluorescent signal. The detection limit of 18 pM is about three orders of magnitude lower than that of a non-HCR method (such as the binary-probe-system). Meanwhile, due to the FRET strategy, complicated washing steps are not necessary and experimental time is sharply reduced. As far as we know, this is the first report of a fluorescence in situ hybridization (FISH) strategy that can simultaneously fulfil signal amplification and is wash-free. We believe that this FRET-based HCR strategy has great potential as a powerful tool in basic research and clinical diagnosis.

A DNA tetrahedron-based molecular beacon for tumor-related mRNA detection in living cells

We report a DNA tetrahedron-based molecular beacon for tumor-related TK1 mRNA detection in living cells, where the target sequence can induce the tetrahedron from contraction to extension, resulting in fluorescence restoration.

Muscle-invasive bladder cancer is characterized by overexpression of thymidine kinase 1

OBJECTIVE

Thymidine kinases have an important role in the synthesis of DNA and exhibit high activity in rapidly proliferating cells. Thymidine kinase 1 (TK1) activity has been shown to be increased in various cancer types and proposed as a prognostic parameter. Aim of the present study was to investigate TK1 in muscle-invasive urothelial carcinoma (UC).

METHODS

Corresponding UC and benign samples from paraffin embedded tissue of 111 patients treated with cystectomy for invasive UC from 1996 to 2006 were immunohistochemically (IHC) assessed for TK1. IHC expression patterns were evaluated in a semiquantitative fashion by 2 independent reviewers. Localization of staining was categorized into pure nuclear and additional cytoplasmic localization. Uni- and multivariate analyses were performed to assess differential expression in normal and UC tissue and to evaluate the diagnostic and predictive capability of TK1 by correlation to clinical data. To correlate TK1 expression with molecular subtypes of UC, analysis of TK1 RNA expression levels of the Cancer Genome Atlas UC cohort was performed.

RESULTS

TK1 was significantly overexpressed in invasive UC, compared to benign urothelium (P<0.0001), and cytoplasmic expression was more often found in cancer tissue than in benign tissue (P = 0.0001). No correlations of TK1 protein expression patterns to standard histopathological determinants were detected. In univariate analysis, TK1 nuclear and cytoplasmic expression was associated with improved cancer-specific survival (P = 0.0119). However, only metastasis status and histologic grade were identified as independent predictors of cancer-specific survival in multivariate analysis. TK1 expression was merely found in the basal layers of benign urothelium. RNA overexpression of TK1 could be correlated to the biologically more aggressive basal UC subtype.

CONCLUSIONS

TK1 expression is significantly different in invasive UC and benign urothelium, which underlines its potential as a diagnostic marker. Although TK1 is considered to be a marker of proliferation, and TK1 RNA overexpression is associated with an aggressive UC subtype, its capability as a predictive IHC biomarker for invasive UC remains limited.

A "light-up" and "spectrum-shift" response of aptamer-functionalized silver nanoclusters for intracellular mRNA imaging

We have designed a novel multifunctional DNA scaffold for the synthesis of fluorescent silver nanoclusters (Ag NCs) using a one-pot approach. The obtained DNA/Ag NCs presented a "light-up" and "spectrum-shift" response to target DNA in vitro and could further image the tumor-related mRNA in living cells.

Oncolytic tanapoxvirus expressing FliC causes regression of human colorectal cancer xenografts in nude mice

Colorectal cancers are significant causes of morbidity and mortality and existing therapies often perform poorly for individuals afflicted with advanced disease. Oncolytic virotherapy is an emerging therapeutic modality with great promise for addressing this medical need. Herein we describe the in vivo testing of recombinant variants of the tanapoxvirus (TPV). Recombinant viruses were made ablated for either the 66R gene (encoding a thymidine kinase), the 2L gene (encoding a TNF-binding protein), or both. Some of the recombinants were armed to express mouse chemotactic protein 1 (mCCL2/mMCP-1), mouse granulocyte-monocyte colony stimulating factor (mGM-CSF), or bacterial flagellin (FliC). Tumors were induced in athymic nude mice by implantation of HCT 116 cells and subsequently treated by a single intratumoral injection of one of the recombinant TPVs. Histological examination showed a common neoplastic cell type and a range of immune cell infiltration, necrosis, and tumor cell organization. Significant regression was seen in tumors treated with virus TPV/Δ2L/Δ66R/fliC, and to a lesser extent the recombinants TPV/Δ2L and TPV/Δ66R. Our results suggest that oncolytic recombinants of the TPV armed with activators of the innate immune response may be effective virotherapeutic agents for colorectal cancers in humans and should be explored further to fully realize their potential.

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.

Serum thymidine kinase 1 activity in solid tumor (breast and colorectal cancer) patients treated with adjuvant chemotherapy

BACKGROUND

The aim of this study was to evaluate the changing of TK1 (where TK is thymidine kinase) activity before and after adjuvant chemotherapy in patients with breast and colorectal cancer.

METHODS

The study included 16 breast cancer, 25 colorectal cancer, and 38 healthy volunteers as the control group. Blood samples were taken twice from each patient; first at the beginning of the chemotherapy and second after six cycles of chemotherapy. TK1 activity was measured enzyme immunoassay method.

RESULTS

The mean TK1 activity in the breast and colorectal cancer was significantly higher than the controls. TK1 activity in the colorectal cancer was higher than the breast cancer but this difference was not significant. TK1 activity after six doses of chemotherapy was lower than baseline TK1 activity before the start of chemotherapy in breast and colorectal cancer. TK1 activity was positively correlated with CA15-3, before and after chemotherapy in patients with breast cancer. TK1 activity in the colorectal cancer was also positively correlated with CA19-9, before and after chemotherapy. The values for the cutoff point, sensitivity, specificity, and the area under curve were determined for TK1 as >44.36 Du/L, 68.29%, 100% and 0.819, respectively in all subjects.

CONCLUSION

Our results showed that serum TK1 activity in patients with breast and colorectal cancer was significantly higher than that of the healthy controls. Moreover, after the completion of chemotherapy the values were lower than baseline. Pretreatment TK1 activity should be considered as a useful marker for assessment tumor cell proliferation in breast and colorectal cancer. Further work is needed to understand TK1 activity better in large populations of patients with solid tumor.

MicroPET-CT evaluation of interstitial brachytherapy in pancreatic carcinoma xenografts

BACKGROUND

Interstitial brachytherapy (IBT) has been introduced as treatment for unresectable pancreatic cancers to maximize local dose and minimize irradiation of surrounding normal tissue. MicroPET-CT systems provide excellent anatomic and molecular information.

PURPOSE

To use 18F-FDG micro-positron emission tomography (PET)/computed tomography (CT) to evaluate the therapeutic effect of (125)I interstitial brachytherapy on transplantation tumor of human pancreatic carcinoma in Balb/c-nu mice.

MATERIAL AND METHODS

Xenograft models were created by subcutaneous injection of Swl990 human pancreatic cancer cell suspensions into the immunodeficient Balb/c-nu mice. The study was randomly divided into three groups: control group (n = 6), empty seed implant group (n = 6), and (125)I seed implant group (n = 6), respectively. Before and 1 week after treatment, 18F-FDG microPET-CT scan was performed. In-vivo cell proliferation and apoptosis were monitored by thymidine kinase 1 (TK1) immunostaining and Dutp-biotin nick end labeling (TUNEL) assay.

RESULTS

Our results showed that before treatment the SUVmax and SUVmean values among three groups had no significant statistical difference. One week after treatment the SUVmax and SUVmean in (125)I seed implant group were significantly lower than before, while for the empty seed group and control group there were no significant difference compared with before treatment. Immunohistochemical analysis of tumor tissue revealed significantly less TK1 positive cells in (125)I seed implant group than in empty seed group and control group. The index of apoptosis was slightly higher in (125)I seed implant group than in empty seed group and control group as evaluated by TUNEL assay.

CONCLUSION

These results suggest that 18F-FDG microPET-CT may be useful as a non-invasive imaging modality to assess early response to (125)I seed brachytherapy in a pancreatic carcinoma Xenograft.

High levels of inactive thymidine kinase 1 polypeptide detected in sera from dogs with solid tumours by immunoaffinity methods: implications for in vitro diagnostics

Determination of serum thymidine kinase 1 (STK1) activity has been used as a proliferation marker for neoplastic diseases in both human and veterinary medicine. The purpose of this study was to determine STK1 activity and enzyme levels in different dog tumours. Serum samples from three dogs with leukaemia, five with lymphoma, 21 with solid tumours and 18 healthy dogs were analyzed for STK1 activity, using an optimized [(3)H]-deoxythymidine (dThd) phosphorylation assay, and for STK1 protein levels using an immunoaffinity/western blot assay. STK1 activity in dogs with haematological tumours was significantly higher than in the solid tumour and healthy dog groups (mean ± standard deviation [SD] = 65 ± 79, 1.1 ± 0.5, and 1.0 ± 0.4 pmol/min/mL, respectively). Serum samples were analyzed after immunoaffinity isolation by western blot and the TK1 26 kDa band intensities quantified revealing that concentrations were significantly higher in dogs with haematological tumours and solid tumours compared to healthy dogs (mean ± SD=33 ± 12, 30 ± 13, and 10 ± 5 ng/mL, respectively). Pre-incubation with the reducing agent dithioerythritol (DTE) showed a decrease in STK1 activity and protein levels in most samples, but an increase of about 20% in sera from healthy dogs and from those with haematological malignancies. Compared to animals with solid tumours, the specific STK1 activity (nmol [(3)H]-deoxythymidine monophosphate (dTMP)/min/mg of TK1 protein of 26 kDa) was 30-fold higher in haematological malignancies and 2.5-fold higher in healthy dogs, respectively. The results demonstrate that there is a large fraction of inactive TK1 protein, particularly in sera from dogs with solid tumours. The findings are important in the use of STK1 as a biomarker.

Serum thymidine kinase activity compared with CA 15-3 in locally advanced and metastatic breast cancer within a randomized trial

The primary objective was to estimate serum thymidine kinase 1 (TK1) activity, reflecting total body cell proliferation rate including cancer cell proliferation, in women with loco regional inoperable or metastatic breast cancer participating in a prospective and randomized study. Secondary objectives were to analyze TK1 in relation to progression-free survival (PFS), overall survival (OS), therapy response and other tumour characteristics, including CA 15-3, widely used as a standard serum marker for disease progression. TK1 and CA 15-3 were analysed in 198 serum samples collected prospectively from women included in the randomized TEX trial between December 2002 and June 2007. TK1 activity was determined by the ELISA based DiviTum™ assay, and CA 15-3 analyses was generated with the electrochemiluminescence immunoassay Cobas Elecsys CA 15-3 II. High pre-treatment TK1 activity predicted shorter PFS (10 vs. 15 months p = 0.02) and OS (21 vs. 38 months, p < 0.0001), respectively. After adjustment for age, metastatic site and study treatment TK1 showed a trend as predictor of PFS (p = 0.059) and was an independent prognostic factor for OS, (HR 1.81, 95 % confidence interval (CI) 1.26-2.61, p = 0.001). There was a trend of shortened OS for women with high CA 15-3 (p = 0.054) in univariate analysis, but not after adjustment for the above mentioned covariates. Both TK1 (p = 0.0011) and CA 15-3 (p = 0.0004) predicted response to treatment. There were statistically different distributions of TK1 and CA 15-3 in relation to the site of metastases. TK1 activity measured by DiviTum™ predicted therapy response, PFS and OS in loco regional inoperable or disseminated breast cancer. These results suggest that this factor is a useful serum marker. In the present material, a prognostic value of CA 15-3 could not be proven.

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.

High thymidine kinase 1 (TK1) expression is a predictor of poor survival in patients with pT1 of lung adenocarcinoma

In this study, we explore the association of thymidine kinase 1 (TK1) expression in tumour tissues with clinical pathological parameters and prognosis in patients with pathological T1 (pT1) lung adenocarcinoma. The expression of TK1 was studied by immunohistochemistry techniques in 80 patients with surgically resected pT1 lung adenocarcinoma, retrospectively and at >10-year follow-up. Compared to patients with low TK1 expression [labelling index (LI) <25.0%], patients with high TK1 expression (LI ≥ 25.0%) showed significantly increased lymphatic/vascular permeation and lymph node involvement and higher stromal invasion grade and pathological stage, and a greater number of patients had a tumour size of 2.1 to 3.0 cm. The 5-year survival and the mortality during follow-up for patients with high TK1 expression were significantly worse than that of patients with low TK1 expression. The prognoses of the cases with grade 0, grade 1 and grade 2 stromal invasions were similar and were better than those of cases with grade 3. In patients with stromal invasion grade 3, the 5-year survival and the mortality during follow-up were significantly worse for patients with high TK1 compared to patients with low TK1 expression. Univariate analyses showed that stromal invasion and TK1 expression were significant prognostic factors, while in the multivariate analysis, TK1 expression and tumour stage were found to be independent prognostic factors, but not stromal invasion. This is the first study showing that TK1 expression in combination with stromal invasion is a more reliable prognostic factor than stromal invasion classification itself in patients with pT1 lung adenocarcinoma. TK1 expression enables a further classification of the patients and opens opportunities for improved treatment outcome.

Serological thymidine kinase 1 is a biomarker for early detection of tumours--a health screening study on 35,365 people, using a sensitive chemiluminescent dot blot assay

Serological thymidine kinase 1 (STK1) is a reliable proliferation marker for prognosis, monitoring tumour therapy, and relapse. Here we investigated the use of STK1 in health screening for early detection of pre-malignant and malignant diseases. The investigation was based on 35,365 participants in four independent health screening studies in China between 2005–2011. All participants were clinically examined. The concentration of STK1 was determined by a sensitive chemiluminescent dot blot ECL assay. The ROCvalue of the STK1 assay was 0.96. At a cut-off STK1 value of 2.0 pM, the likelihood (+) value was 236.5, and the sensitivity and the specificity were 0.78 and 0.99, respectively. The relative number of city-dwelling people with elevated STK1 values (≥2.0 pM) was 0.8% (198/26,484), while the corresponding value for the group of oil-field workers was 5.8% (514/8,355). The latter group expressed significantly higher frequency of refractory anaemia, fatty liver, and obesity, compared to the city dwellers, but no cases of breast hyperplasia or prostate hyperplasia. Furthermore, people working in oil drilling/oil transportation showed higher STK1 values and higher frequency of pre-malignancies and benign diseases than people working in the oil-field administration. In the STK1 elevated group of the city-dwelling people, a statistically significantly higher number of people were found to have malignancies, pre-malignancies of all types, moderate/severe type of hyperplasia of breast or prostate, or refractory anaemia, or to be at high risk for hepatitis B, compared to people with normal STK1 values (<2.0 pM). No malignancies were found in the normal STK1 group. In the elevated STK1 group 85.4% showed diseases linked to a higher risk for pre-/early cancerous progression, compared to 52.4% of those with normal STK1 values. Among participants with elevated STK1 values, 8.8% developed new malignancies or progress in their pre-malignancies within 5 to 72 months, compared to 0.2% among people with normal STK1 values. People who showed elevated STK1 values were at about three to five times higher risk to develop malignancies compared to a calculated risk based on a cancer incidence rate of 0.2–0.3%. We conclude that serological TK1 protein concentration is a reliable marker for risk assessment of pre/early cancerous progression.

XPA-210: a new proliferation marker determines locally advanced prostate cancer and is a predictor of biochemical recurrence

PURPOSE

XPA-210 is a proliferation marker derived from Thymidine kinase-1. It is of clinical significance in kidney, breast, and bladder cancer. There are no data available for XPA-210 in prostate cancer (PC). Herein, we aim to determine the clinical usefulness of XPA-210 in PC.

MATERIALS AND METHODS

In a retrospective study, cancer and benign tissue samples of 103 patients (median age 65 years, median PSA 9.04 ng/ml, median Gleason score 6) who underwent prostatectomy were constructed to a tissue micro array and stained for XPA-210. Semi-quantitative results were correlated with pathological and clinical data by Wilcoxon-Kruskall-Wallis and linear regression analysis. Expression levels in PC were correlated between the time of biochemical recurrence and the time to development of metastasis by the Kaplan-Meier method. Multivariate analysis was done to correlate those with the resection status.

RESULTS

Mean staining score was 0.51-0.14 for tumor and benign tissue (P < 0.0001). Tumor staining score was significantly associated with Gleason score <6/≥6 (P < 0.0001) and T2/T >2 (P = 0.0007). When dividing the tumor score by the mean value, higher expression of XPA-210 was associated with a shorter time to biochemical recurrence (P = 0.003) and time to development of metastasis (P = 0.0061). Tumor staining (P = 0.0371) was an independent prognostic factor for biochemical relapse regardless of resection status.

CONCLUSIONS

XPA-210 is a new tissue-based prognostic marker for prostate cancer histopathology. It reliably differentiates tumor and normal prostatic tissue predicting biochemical relapse and onset of metastatic disease. XPA-210 might be clinically useful for individual decision-making in PC-treatment.

XPA-210: a new proliferation marker to characterize tumor biology and progression of renal cell carcinoma

PURPOSE

Recent lung cancer data have shown an association of XPA-210, a key peptide of thymidine kinase, with advanced disease. We thus assessed its proliferation status in primary (M0) and metastatic (M1) renal cell carcinoma (RCC).

METHODS

Paraffin slides from 30 patients (mean age: 61.2 years; range: 42-84) with clear-cell RCC (M0 in 10; non-osseous M1 in 10; osseous M1 in 10) were T-matched for pT1/pT3. Corresponding malignant and benign renal parenchyma were immunohistochemically stained against XPA-210. Staining density was determined by a semi-quantitative score of positive cell shares. Staining intensity included the precise cellular location.

RESULTS

XPA-210 occurred predominantly in the nucleus, with a minor cytoplasmatic component. RCC tissue showed higher density and stronger intensity than did benign renal tissue in both nucleus (P = 0.005) and cytoplasm (P = 0.01). Density and intensity were positively associated with tumor diameters ≤7 cm, whereas they tended to correlate inversely in tumors >7 cm (P 0.07). Density of stained cells was significantly higher in metastatic than in localized RCC in both nucleus and cytoplasm (P < 0.04). Non-osseous M1 tissue showed significantly higher nuclear and cytoplasmatic expression than did M0 tissue (P < 0.05), whereas osseous M1 tissue did not.

CONCLUSIONS

In all RCC tissues, XPA-210 staining was significantly higher in the nucleus than in cytoplasm, potentially owing to large cytoplasmatic spaces as a characteristic histologic feature of clear-cell component. XPA-210 expression gradually increased from localized to metastatic disease, peaking in patients without bone involvement. Therefore, XPA-210 might aid the selection of appropriate adjuvant treatment in high-risk patients.

Thymidine kinase 1 is a potential marker for prognosis and monitoring the response to treatment of patients with breast, lung, and esophageal cancer and non-Hodgkin's lymphoma

Thymidine kinase 1 (TK1) is converting thymidine to thymidine monophosphate, and is related to DNA replication and cell proliferation. The use of the TK1 protein levels as a proliferation marker in malignancies is here summarized. TK1 protein in serum (STK1p) and TK1 expression in tissues were determined by a chemoluminescent dot blot assay and by immunohistochemistry staining, respectively. The expression of TK1 in tumor tissues correlated to pathological stages and clinical grades of carcinomas (ca) of esophagus, lung and in premalignancy of breast ductal ca. STK1p could monitor the out-come of tumor therapy by being correlated to remission [breast ca, non-Hodgkin's lymphoma], relapse [breast ca] and to survival [non-Hodgkin's lymphoma] of patients. In a health screening study of 12,641 persons, STK1p seemed to predict the risk of development of neoplasia related diseases at early stage.

Comparative aspects of the proliferation marker thymidine kinase 1 in human and canine tumour diseases

As cell proliferation is one of the hallmarks of cancer, various types of proliferation markers are used as important tools in diagnosis, prognosis, treatment decision-making and follow-up in clinical oncology. The S phase-specific protein thymidine kinase 1 (TK1) can be used in immunohistochemistry for RNA/protein expression in tissue specimens and for activity or protein/peptide levels in serum from patients. TK1 has been used mainly in haematologic malignancies in humans, but also found beneficial in canine malignancies. As the protein sequence homology is high between humans and dogs, findings in canine models will have a high comparative value in further human research as well. In the present review, we will focus on the recent results concerning TK1's S phase-correlated expression, increased serum levels of TK1 in patients with malignancies and the relevance for veterinary and comparative oncology. Finally, the benefit of recently developed specific anti-TK1 antibodies suitable for immunologic assay is discussed.

Serum thymidine kinase 1 correlates to clinical stages and clinical reactions and monitors the outcome of therapy of 1,247 cancer patients in routine clinical settings

BACKGROUND

Thymidine kinase 1 in serum (STK1) has been found to be a reliable proliferation marker in clinical trials. In this study, we examined the significance of STK1 in routine clinical settings.

METHODS

The concentration of STK1 was determined by a sensitive dot blot ECL assay. The STK1 value was correlated to clinical stage and reactions and used for monitoring the outcome of surgery and/or multidrug chemotherapy of 1,247 patients with five different types of carcinomas (lung, esophagus, gastric, head and neck, and thyroid) in routine clinical settings.

RESULTS

The STK1 values correlated with the clinical stage in patients with lung, esophagus, thyroid, and gastric carcinomas. After treatment, STK1 declined in all tumor groups after treatments (P < 0.01). The STK1 was low (<2 pM) or decreasing during treatment in patients with clinical reactions of complete response (CR) or partial response (PR), but high (>2 pM) or increasing in patients with stable disease (SD) or progressive disease (PD), some of them showing metastasis. STK1 also reflected the differences in clinical reactions when surgery and chemotherapy were compared.

CONCLUSION

We concluded that the concentration of TK1 in serum correlates to clinical stages and clinical reactions and monitors the effect of tumor therapies, not only in controlled clinical trials, but also in routine clinical settings.

Thymidine kinase 1 expression defines an activated G1 state of the cell cycle as revealed with site-specific antibodies and ArrayScan assays

Thymidine kinase 1 (TK1) is a DNA salvage enzyme involved in the synthesis of thymidine triphosphate needed during S phase. Although TK1 has been utilized as a cell proliferation marker for many years no well-characterized antibodies are available. The preparation and properties of two types of poly- and monoclonal anti-TK1 peptide antibodies are described and they are used to determine the levels of TK1 in intact cells. Expression of TK1, c-fos, cyclin B1, Ki67, phosphorylated histone H3, phosphorylated ribosomal protein S6, as well as bromodeoxyuridine (BrdU) incorporation in human normal dermal fibroblast cultures were studied with high-content ArrayScan fluorescence microscopy. The levels of TK1 increased 6-7h after serum re-addition to starved cells as they passed through G1, S and G2/M phases, which was earlier than the increase in Ki67 protein levels and before BrdU incorporation was detected. Thus, a population of activated G1 cells with high TK1 and low Ki67 expression could be identified and their role in cell proliferation can now be clarified.