Dihydropyrimidine dehydrogenase and thymidylate synthase activities in hepatocellular carcinomas and in diseased livers

Reproductive and developmental toxicities of 5-fluorouracil in model organisms and humans

Chemotherapy, as an important clinical treatment, has greatly enhanced survival in cancer patients, but the side effects and long-term sequelae bother both patients and clinicians. 5-Fluorouracil (5-FU) has been widely used as a chemotherapeutic agent in the clinical treatment of various cancers, but several studies showed its adverse effects on reproduction. Reproductive toxicity of 5-FU often associates with developmental block, malformation and ovarian damage in the females. In males, 5-FU administration alters the morphology of sexual organs, the levels of reproductive endocrine hormones and the progression of spermatogenesis, ultimately reducing sperm numbers. Mechanistically, 5-FU exerts its effect through incorporating the active metabolites into nucleic acids directly, or inhibiting thymidylate synthase to disrupt the function of DNA and RNA, leading to profound effects on cellular metabolism and viability. However, some studies suggested that the toxicity of 5-FU on reproduction is reversible and certain drugs used in combination with 5-FU during chemotherapy could protect reproductive systems from 5-FU damage both in females and males. Herein, we summarise the recent findings and discuss underlying mechanisms of the 5-FU-induced reproductive toxicity, providing a reference for future research and clinical treatments.

Research Progress of Epithelial-mesenchymal Transition Treatment and Drug Resistance in Colorectal Cancer

Colorectal cancer (CRC) is one of the most common malignancies in the world that seriously affects human health. Activation of epithelial-mesenchymal transition (EMT) is a physiological phenomenon during embryonic development that is essential for cell metastasis. EMT participates in various biological processes associated with trauma repair, organ fibrosis, migration, metastasis, and infiltration of tumor cells. EMT is a new therapeutic target for CRC; however, some patients with CRC develop resistance to some drugs due to EMT. This review focuses specifically on the status of treatments that target the EMT process and its role in the therapeutic resistance observed in patients with CRC.

Dihydroartemisinin as a Sensitizing Agent in Cancer Therapies

Cancer is one of the major threats to human health. Although humans have struggled with cancer for decades, the efficacy of treatments for most tumors is still very limited. Dihydroartemisinin (DHA) is a derivative of artemisinin, a first-line antimalarial drug originally developed in China. Beyond the anti-malarial effect, DHA has also been reported to show anti-inflammatory, anti-parasitosis, and immune-modulating properties in vitro and in vivo. Furthermore, an increasing number of studies report that DHA possesses anticancer activities on a wide range of cancer types both in vitro and in vivo, as well as enhances the efficacy of chemotherapy, targeted therapy, and even radiotherapy. However, the mechanisms of DHA on different tumors differ in various ways. In this review, we intend to summarize how DHA sensitizes cancer cells to anti-cancer therapies, highlight its molecular mechanisms and pharmacological effects in vitro and in vivo as well as in current clinical trials, and discuss potential issues concerning DHA. Hopefully, more attention will be paid to DHA as a sensitizer for cancer therapy in the future.

Dihydropyrimidine dehydrogenase predicts survival and response to interferon-α in hepatocellular carcinoma

Metastasis and recurrence contribute to poor prognosis of hepatocellular carcinoma (HCC). Recently, we reported that interferon-α (IFN-α) can suppress metastasis of HCC; however, the underlying mechanism has not been fully described. In this study, we demonstrated that expression of dihydropyrimidine dehydrogenase (DPYD), a pyrimidine catabolic enzyme, was dose-dependently downregulated by IFN-α in HCC tissues from nude mice. Notably, DPYD expression was found to be significantly increased in HCC cell lines with higher metastatic potentials compared with their controls. Moreover, upregulation of DPYD in HCC cells could promote in vitro migration, invasion, and in vivo lung metastasis, and inducing changes characteristic of epithelial-mesenchymal transition (EMT). In contrast, knockdown of DPYD inhibited these processes. Mechanistically, DPYD functioned as a positive regulator of EMT in HCC by targeting the p38/NF-κB/Snail1 pathway. Clinically, tissue microarray analysis showed that high DPYD expression was positively associated with aggressive tumor characteristics, including larger tumor size, tumor recurrence, and advanced tumor node metastasis (TNM) stage, and independently correlated with poorer overall survival times after curative resection. HCC patients with low DPYD expression have better response to IFN-α therapy. Taken together, our findings elucidate that IFN-α could downregulate DPYD expression to inhibit EMT and HCC metastasis, and suggest that DPYD might be a potential prognostic biomarker and a therapeutic target for HCC.

Clinical significance of the thymidylate synthase, dihydropyrimidine dehydrogenase, and thymidine phosphorylase mRNA expressions in hepatocellular carcinoma patients receiving 5-fluorouracil-based transarterial chemoembolization treatment

Purpose

To determine whether 5-fluorouracil (5-FU) sensitivity is associated with the mRNA expressions of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and thymidine phosphorylase (TP) in patients with hepatocellular carcinoma (HCC) treated with 5-FU-based transarterial chemoembolization (TACE).

Methods

Formalin-fixed, paraffin-embedded tumor specimens from 40 patients treated with 5-FU-based TACE were selected for the examination of TS, DPD, and TP expression level by a quantitative real-time reverse transcription- polymerase chain reaction (PCR) technique. Patients were categorized into high and low expression groups according to the median expression level of each enzyme. Associations between the mRNA expression levels of TS, DPD, and TP and clinical parameters including treatment efficacies, clinicopathological factors, and prognosis were assessed.

Results

High DPD expression was associated with worse treatment outcome, including intrahepatic disease progression rate (hazard ratio [HR] for high DPD versus low DPD, 2.212; 95% confidence interval [CI], 1.030–4.753; P = 0.042), extrahepatic disease progression rate (HR for high versus low DPD, 3.171; 95% CI, 1.003–10.023; P = 0.049), and progression-free survival (HR for high versus low DPD, 2.308; 95% CI, 1.102–4.836; P = 0.027). No correlation was found between the mRNA expression of TS/TP and treatment outcome.

Conclusion

DPD mRNA expression level was negatively correlated with the clinical outcomes of HCC patients treated with 5-FU-based TACE. These results provide indirect evidence that high DPD mRNA expression is a predictive marker of treatment resistance for 5-FU.

Molecular aspects of cancer cell resistance to chemotherapy

Cancer cell resistance to chemotherapy is still a heavy burden that impairs treatment of cancer patients. Both intrinsic and acquired resistance results from the numerous genetic and epigenetic changes occurring in cancer cells. Most of the hallmarks of cancer cells provide general mechanisms to sustain stresses such as the ones induced by chemotherapeutic drugs. Moreover, specific changes in the target bring resistance to specific drugs like modification in nucleotide synthesis enzymes upon anti-metabolite exposure, in microtubule composition upon spindle poison treatment, in topoisomerase activity upon topoisomerase inhibitor incubation or in intracellular signaling pathways when targeting tyrosine kinase receptors. Finally, the stemness properties of a few cancer cells as well as components of the tumor stroma, like fibroblasts and tumor-associated macrophages but also hypoxia, also help tumor to resist to anticancer agents. These processes provide an additional level of complexity to the understanding of the tumor resistance phenomenon. This review aims to describe the different general mechanisms as well as some examples of specific on target modifications inducing cancer cell resistance to chemotherapy at the molecular level. Perspectives to develop more efficient treatment, using genomic signature or more specific biomarkers to characterize putative resistance mechanisms in patients before choosing the more appropriate treatment, will also be discussed.

Role of thymidylate synthase and dihydropyrimidine dehydrogenase mRNA expressions in gallbladder carcinoma

PURPOSE

Thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) are important enzymes in the metabolism of 5-fluorouracil, which have been examined as possible predictive markers. We conducted this study to clarify the role of TS and DPD expressions in gallbladder carcinoma (GBC).

METHODS

The subjects were 28 patients who underwent surgical resection of GBC. We examined intratumoral TS and DPD mRNA expressions, using the Danenberg tumor profile method. The expression levels were classified into two groups, based on median values. Clinicopathological variables, including prognosis, were then compared between the high and low expression groups.

RESULTS

There was a significant difference in the incidence of lymph node metastasis between the high and low TS expression groups. The incidence of advanced clinical stage was higher in the low TS expression group than in the high TS expression group. However, no clear correlation was observed between the DPD mRNA expression and any clinicopathological variable. There was no significant difference in the postoperative survival rates between the groups, in accordance with the expression of TS or DPD genes.

CONCLUSION

Low TS mRNA was correlated with a high incidence of lymph node metastasis and advanced clinical stage. Therefore, TS gene expression may help identify patients at increased risk of the progression of GBC.

Role of thymidylate synthase and dihydropyrimidine dehydrogenase mRNA in intrahepatic cholangiocarcinoma

PURPOSE

Thymidylate synthase (TS) and dihydropyrimidine dehydrogenase (DPD) are important enzymes in the metabolism of 5-fluorouracil and possible predictive markers. We conducted this study to clarify if TS and DPD gene expressions are a prognostic indicator for intrahepatic cholangiocarcinoma (IHCC).

METHODS

The subjects of this study were 21 patients with IHCC who had undergone surgical resection. Intratumoral TS and DPD mRNA expressions were examined using the Danenberg tumor profile method and classified into two groups according to the median value of each. We then compared the clinicopathological variables, including prognosis, between the high and low expression groups.

RESULTS

Low DPD expression was correlated with macroscopic type, namely, mass-forming + infiltrative (P = 0.08). Postoperative survival rates in the low DPD expression group were significantly lower than those in the high DPD expression group. Multivariate analysis revealed macroscopic type to be an independent prognostic factor, whereas TS mRNA expression did not correlate with any clinicopathological variables, including prognosis.

CONCLUSIONS

Low DPD mRNA expression was related to macroscopic type and associated with poor prognosis. DPD mRNA expression in tumor cells is suggested to be an important regulator of malignant behavior in IHCC.

Role of dihydropyrimidine dehydrogenase and thymidylate synthase expression in immunohistochemistry of intrahepatic cholangiocarcinoma

AIMS

  Dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) are key enzymes in the metabolism of 5-fluorouracil and have been implicated as possible prognostic markers for cancer patients. However, the clinical roles of DPD and TS in intrahepatic cholangiocarcinoma (IHCC) have not been investigated. The aim of this study was to clarify the clinicopathological role of DPD and TS expressions in IHCC.

METHODS

  Twenty-nine patients who had undergone hepatic resection for IHCC were enrolled in this study. Expressions of DPD and TS in the resected IHCC specimens were examined using anti-DPD or anti-TS antibody. The patients were divided into positive and negative groups according to DPD/TS expressions: DPD-positive group (n = 18) and DPD-negative group (n = 11)/TS-positive group (n = 14) and TS-negative group (n = 15). Clinicopathological factors were compared between the two groups.

RESULTS

  The overall survival rate was significantly lower in the DPD-negative group than in the DPD-positive group (1-year 36.4% vs. 77.4%, 3-year 18.2% vs. 43.0%; P < 0.05). The disease-free survival rate in the DPD-negative group tended to be lower than that in the DPD-positive group. The overall survival rate or disease-free survival rate did not appear to be associated with the TS-expression status. The Ki-67 labeling index in the DPD-negative group was significantly higher than that in the DPD-positive group (16.9 ± 3.2% vs.13.2 ± 3.3%; P < 0.05).

CONCLUSIONS

  The negative DPD expression was significantly associated with the enhanced tumor cell proliferation and poorer prognosis in patients with IHCC. DPD expression is a potential prognostic indicator for IHCC.

Determination of 5-fluorouracil and dihydrofluorouracil levels by using a liquid chromatography-tandem mass spectrometry method for evaluation of dihydropyrimidine dehydrogenase enzyme activity

PURPOSE

5-Fluorouracil (5-FU), acting as a pyrimidine antagonist, is a major chemotherapy drug used for the treatment of tumors such as gastrointestinal, breast, ovary, and head and neck cancers. The key and rate-limiting enzyme in 5-FU catabolism is dihydropyrimidine dehydrogenase (DHPDH), whose partial or complete deficiency exposes to a severe 5-FU toxicity in patients. The determination of DHPDH activity in patients before the treatment and setting up a personalized therapy for each patient receiving the drug can help us to prevent the possible risk of toxicity.

METHODS

To isolate peripheral blood mononuclear cells (PBMCs), EDTA-anticoagulated blood samples were collected from randomly selected 47 patients and examined for 5-FU and its metabolite dihydrofluorouracil (FUH2) by using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) to observe DHPDH activity at different intervals (0 and 4th hour) indirectly.

RESULTS

Intra-assay and interassay CV % values of samples from the measurements of the modified methods are found 1.3-11.9, 2.3-9.4 for 5-FU and 3.1-14.4, 3.3-12.6 for FUH2, respectively. The reference values derived from 45 patients treated with 5-FU are 1.84 ± 0.34 ug/gr protein for 5-FU, 40.15 ± 11.43 ng/gr protein for FUH2, respectively. FUH2/5-FU ratio is 21.9 ± 3.72. In addition, the results determined from two patients, in which the lack of DHPDH is considered, were 3.24 and 4.16 ug/gr protein for 5-FU, 4.1 and 6.7 ng/gr protein for FUH2. FUH2/5-FU ratio is 1.26 and 1.61.

CONCLUSION

The measurements of 5-FU, FUH2, and especially their ratio (FUH2/5-FU) by the modified LC-MS/MS method could be used to determine DHPDH enzyme activity.

Significance of dihydropyrimidine dehydrogenase and thymidylate synthase mRNA expressions in hepatocellular carcinoma

AIM

The significance of dihydropyrimidine dehydrogenase (DPD) and thymidylate synthase (TS) gene expressions for the post-surgical prognosis of hepatocellular carcinoma (HCC) has not yet been determined. In the present study, we clarified the significance of DPD and TS gene expressions for the prognosis of HCC.

METHODS

Seventy-four patients, who underwent curative hepatic resection for primary HCC, were evaluated. The DPD and TS mRNA levels of the resected HCC specimens were evaluated using a microdissection technique and quantative real-time RT-PCR. The patients were categorized into high and low groups for each mRNA based on the median value. Various clinicopathological factors, including prognosis, and proliferation index using Ki-67 staining were evaluated in association with the DPD and TS mRNA expression levels.

RESULTS

The low DPD mRNA expression was related to younger age, advanced clinical stage, undifferentiated histology, and microscopic intrahepatic metastasis. The overall and recurrence-free survival were significantly lower in the low DPD group than in the high DPD group (P < 0.05). Furthermore, the proliferation index in the low DPD group was significantly higher than that in the high DPD group (P < 0.01). On the other hand, the high TS group showed a tendency of better prognosis than the low TS group, although it was not statistically significant.

CONCLUSIONS

The low DPD mRNA expression is a significant poor prognostic factor. after curative resection of HCC.

Improved Analysis of 5-Fluorouracil and 5,6-Dihydro-5-Fluorouracil by HPLC With Diode Array Detection for Determination of Cellular Dihydropyrimidine Dehydrogenase Activity and Pharmacokinetic Profiling

Administration of 5-fluorouracil (5-FU) may be associated with severe toxicities in patients who are deficient of dihydropyrimidine dehydrogenase (DPD) activity. For this reason, a sensitive HPLC method for the analysis of 5-FU and 5-fluoro-5,6-dihydrouracil (5-FDHU) was developed in the present study for the determination of DPD activity in nucleated cells of peripheral blood and pharmacokinetic analysis of 5-FU and 5-FDHU in humans. 5-FU and 5-FDHU were extracted from biologic matrices by adding sodium acetate, sodium sulfate, and diethyl ether/propanol. Dried samples were reconstituted in a mobile phase (KH2PO4 35 mmol/L, pH 4.0), isocratically eluted with a Hypersil C18 stationary phase (25 cm x 4.6 mm, 10 microm), and detected by a diode array detector (measurement and reference wavelengths, 215 and 360 nm, respectively). 5-Fluorocytosine (internal standard), 5-FDHU, and 5-FU were eluted within 13 minutes of the injection without interferences. Recoveries ranged between 81% to 85% for all compounds, and the method proved to be linear, with a coefficient of linearity of 0.999. The limits of detection and quantification were 3.2 and 16 ng/mL, respectively, and the within-day and between-day CV were less than 10% for both 5-FU and 5-FDHU. The present assay proved to be sufficiently sensitive and specific to evaluate cellular DPD activity and measure 5-FU and 5-FDHU plasma concentrations in cancer patients, thus allowing therapeutic 5-FU monitoring in patients and identification of DPD-deficient subjects at major risk of severe toxicities.