Platelet-derived Endothelial Cell Growth Research Articles

Insights from the SNP analysis of TYMP gene linking MNGIE.

TYMP gene, which codes for thymidine phosphorylase (TP) is also known as platelet-derived endothelial cell growth factor (PD-ECGF). TP plays crucial roles in nucleotide metabolism and angiogenesis. Mutations in the TYMP gene can lead to Mitochondrial Neurogastrointestinal Encephalopathy (MNGIE) syndrome, a rare genetic disorder. Our main objective was to evaluate the impact of detrimental non-synonymous single nucleotide polymorphisms (nsSNPs) on TP protein structure and predict harmful variants in untranslated regions (UTR). We employed a combination of predictive algorithms to identify nsSNPs with potential deleterious effects, followed by molecular modeling analysis to understand their effects on protein structure and function. Using 13 algorithms, we identified 119 potentially deleterious nsSNPs, with 82 located in highly conserved regions. Of these, 53 nsSNPs were functional and exposed, while 79 nsSNPs reduced TP protein stability. Further analysis of 18 nsSNPs through 3D protein structure analysis revealed alterations in amino acid interactions, indicating their potential impact on protein function. This will help in the development of faster and more efficient genetic tests for detecting TYMP gene mutations.

1,3,4-Oxadiazole: An Emerging Scaffold to Inhibit the Thymidine Phosphorylase as an Anticancer Agent.

Thymidine phosphorylase (TP), also referred to as "platelet-derived endothelial cell growth factor" is crucial to the pyrimidine salvage pathway. TP reversibly transforms thymidine into thymine and 2-deoxy-D-ribose-1-phosphate (dRib-1-P), which further degraded to 2-Deoxy-D-ribose (2DDR), which has both angiogenic and chemotactic activity. In several types of human cancer such as breast and colorectal malignancies, TP is abundantly expressed in response to biological disturbances like hypoxia, acidosis, chemotherapy, and radiation therapy. TP overexpression is highly associated with angiogenic factors such as vascular endothelial growth factor (VEGF), interleukins (ILs), matrix metalloproteases (MMPs), etc., which accelerate tumorigenesis, invasion, metastasis, immune response evasion, and resistant to apoptosis. Hence, TP is recognized as a key target for the development of new anticancer drugs. Heterocycles are the primary structural element of most chemotherapeutics. Even 75% of nitrogen-containing heterocyclic compounds are contributing to the pharmaceutical world. To create the bioactive molecule, medicinal chemists are concentrating on nitrogen-containing heterocyclic compounds such as pyrrole, pyrrolidine, pyridine, imidazole, pyrimidines, pyrazole, indole, quinoline, oxadiazole, benzimidazole, etc. The Oxadiazole motif stands out among all of them due to its enormous significance in medicinal chemistry. The main thrust area of this review is to explore the synthesis, SAR, and the significant role of 1,3,4-oxadiazole derivatives as a TP inhibitor for their chemotherapeutic effects.

The proatherogenic effect of high salt diet combined with focal hypoperfusion on spontaneous hypertension rat

Objective: To explore the histopathology, monocytes phenotypes and brain mRNA transcription of angiogenic and atherogenic factors preliminarily in spontaneous hypertensive rats (SHRs) fed with high salt diet and subjected to chronic focal hypoperfusion. Methods: A total of 21 SHRs were randomly assigned into SHR with normal diet (SHR-ND group, n=7), SHR fed with high salt (8%) chows (SHR-HSD group, n=14) groups. After induction of high salt diet for 20 weeks, unilateral carotid artery occlusion was applied to one half of SHR-HSD (SHR-HSD-UCAO, n=7) group for 10 weeks to mimic chronic focal cerebral hypoperfusion. The neuropathology, monocytes phenotypes and brain transcription of fibroblast growth factor (FGF-b), platelet-derived endothelial cell growth factor (PD-ECGF), angiogenin (ANG), transforming growth factor-β (TGF-β) and vascular endothelial growth factor A (VEGF-A) among three groups were compared. Results: The systolic blood pressure ((246±12) mmHg vs (220±16) mmHg, P=0.0291, 1 mmHg=0.133 kPa) and diastolic blood pressure ((189±15) mmHg vs (164±12) mmHg, P=0.0143) of SHR-HSD group were elevated significantly compared with those of SHR-ND group. Compared with normotensive Wistar-Kyoto (WKY), SHR-ND, SHR-HSD and SHR-HSD-UCAO groups demonstrated lipohyalinosis, vessel wall thickening, lumen narrowing and multiple enlarged perivascular space and diffuse disarrangement of nerve fiber and myelin vacuolation in corpus callosum pathologically. The ratio of CD11b(+) CD68(+) monocytes in peripheral blood of SHR-HSD group was higher compared with both SHR-ND and SHR-HSD-UCAO groups (P=0.000 8). The mean inflorescence index (MFI) of CD86 and CD206 showd considerable decline in SHR-HSD-UCAO group compared with those of SHR-HSD group (P=0.018 7 and 0.016 8, respectively). The CD86 MFI of CD11b+CD68+ monocytes in SHR-HSD-UCAO group was remarkably higher than that of SHR-ND and SHR-HSD groups (P=0.000 5). Compared with SHR-ND and SHR-HSD groups, the brain mRNA transcription of angiogenic factors including PD-ECGF and ANG were down-regulated (P=0.004 6 and 0.000 2, respectively), while the atherogenic factors including TGF-β and VEGF-A were up-regulated in SHR-HSD-UCAO group (P<0.000 1 and P=0.045, respectively). Conclusion: SHR-HSD-UCAO group shares the pathophysiological characteristics with advanced stage arteriosclerotic cerebral small vessel disease (aCSVD), including neuropathology, imbalanced circulating monocytes phenotypes and down-regulated angiogenic factors.

Exploring the protective effects of schizandrol A in acute myocardial ischemia mice by comprehensive metabolomics profiling integrated with molecular mechanism studies

Schizandrol A (SA) is an bioactive component isolated from the Schisandra chinensis (Turcz.) Baill., which has been used as a remedy to prevent oxidative injury. However, whether the cardioprotective effect of SA is associated with regulating endogenous metabolites remains unclear, thus we performed comprehensive metabolomics profiling in acute myocardial ischemia (AMI) mice following SA treatment. AMI was induced in ICR mice by coronary artery ligation, then SA (6 mg·kg−1·d−1, ip) was administered. SA treatment significantly decreased the infarct size, preserved the cardiac function, and improved the biochemical indicators and cardiac pathological alterations. Moreover, SA (10, 100 M) significantly decreased the apoptotic index in OGD-treated H8c2 cardiomycytes in vitro. By using HPLC-Q-TOF/MS, we conducted metabonomics analysis to screen the significantly changed endogenous metabolites and construct the network in both serum and urine. The results revealed that SA regulated the pathways of glycine, serine and threonine metabolism, lysine biosynthesis, pyrimidine metabolism, arginine and proline metabolism, cysteine and methionine metabolism, valine, leucine and isoleucine biosynthesis under the pathological conditions of AMI. Furthermore, we selected the regulatory enzymes related to heart disease, including ecto-5’-nucleotidase (NT5E), guanidinoacetate N-methyltransferase (GAMT), platelet-derived endothelial cell growth factor (PD-ECGF) and methionine synthase (MTR), for validation. In addition, SA was found to facilitate PI3K/Akt activation and inhibit the expression of NOX2 in AMI mice and OGD-treated H9c2 cells. In conclusion, we have elucidated SA-regulated endogenous metabolic pathways and constructed a regulatory metabolic network map. Furthermore, we have validated the new potential therapeutic targets and underlying molecular mechanisms of SA against AMI, which might provide a reference for its future application in cardiovascular diseases.

Effect of vacuum sealing drainage on the clinical effect of high perianal abscess and the expression of vascular endothelial growth factor and platelet-derived endothelial cell growth factor

Objective To observe the clinical effect of vacuum sealing drainage (VSD) in the treatment of high perianal abscess and its effect on the expression of vascular endothelial growth factor (VEGF) and PD-ECGF. Methods 40 cases of high perianal abscess were divided into 2 groups according to the random digital table method, with 20 cases in each group. In the study group, + VSD was closed to the internal and mouth closure of perianal abscess, and the control group was performed the traditional low position incision of the perianal abscess. Postoperative pain, , anal function, healing time, hospitalization time, treatment cost and recurrence rate were compared between the 2 groups. Serum levels of VEGF and PD-ECGF and their phosphorylation levels were detected at different time points. Results There were significant differences in pain and anal function score, wound healing and hospitalization time, treatment cost, recurrence rate between the study group and the control group (P 0.05). The postoperative 7 d study group (0.62±0.025) and the control group (0.45±0.038) all increased significantly, which was statistically significant compared with the postoperative 1 d (P 0.05). The postoperative 7 d study group (0.67±0.029) and the control group (0.49±0.016) all increased significantly, which was statistically significant compared with the postoperative 1 d (P<0.05). The difference was statistically significant between the two groups postoperative 7 d (P<0.05). Conclusion The application of VSD technology in patients with high anal abscess can make pain relief and heal and shorten hospitalization time, save cost and reduce relapse rate, and the anal function is effectively protected. By promoting the expression of VEGF and PD-ECGF, we can regulate wound angiogenesis and promote wound healing. Key words: Vacuum sealing drainage; High perianal abscess; Clinical efficacy; Vascular endothelial growth factor; Platelet-derived endothelial cell growth factor

Distinct substrate specificity and physicochemical characterization of native human hepatic thymidine phosphorylase.

Thymidine phosphorylase (TP; EC 2.4.2.4) is involved regulation of intra- or extracellular thymidine concentration, angiogenesis, cancer chemotherapy, radiotherapy, as well as tumor imaging. Although the liver is main site of pyrimidine metabolism and contains high levels of TP, nonetheless, purification and characterization of human hepatic TP has not been accomplished. We here report the purification and characterization of native human hepatic TP. The enzyme was purified to apparent homogeneity by a procedure shorter and more efficient than previously reported methods. Human hepatic TP has an apparent Kthymidine of 285 ± 55 μM. Like the enzyme from other tissues, it is highly specific to 2'-deoxyribosides. However, in contrast to TP from other normal tissues, the hepatic enzyme is active in the phosphorolysis of 5'-deoxy-5-fluorouridine, and the riboside 5-fluorouridine. Furthermore, native hepatic TP exists in different aggregates of 50 kDa subunits, with unknown aggregation factor(s) while TP from extra tissues exists as a homodimer. Isoelectric point was determined as 4.3. A total of 65 residues in the N-terminal were sequenced. The sequence of these 65 amino acids in hepatic TP has 100% sequence and location homology to the deduced amino acid sequence of the platelet derived-endothelial cell growth factor (PD-ECGF) cDNA. However, and contrary to PD-ECGF, the N-terminal of hepatic TP is blocked. The block was neither N-formyl nor pyrrolidone carboxylic acid moieties. The differences in substrate specificities, existence in multimers, and weak interaction with hydroxyapatite resin strongly suggest that hepatic TP is distinct from the enzyme in normal extrahepatic tissues. These results may have important clinical implications when TP is involved in activation or deactivation of chemotherapeutic agents in different tissues.

Abstract 1442: Novel linkage of thymidine catabolism and the glycolytic pathway in human cancer cells

Abstract Thymidine phosphorylase (TP), a rate-limiting enzyme in the thymidine catabolic pathway, catalyzes the reversible conversion of thymidine to thymine and 2-deoxy-D-ribose 1-phosphate (DR1P). We previously demonstrated that TP is identical to an anigogenic factor, platelet-derived endothelial cell growth factor (PD-ECGF). Although many reports indicate that TP has angiogenic activity and plays a pivotal role in tumor progression, the mechanism of the TP functions is not fully understood. Here, we find that TP-mediated thymidine catabolism can supply the carbon source in the glycolytic pathway and thus contribute to cell survival under conditions of nutrient deprivation. In certain procaryotes, phosphopentosemutase converts thymidine-derived DR1P to 2-deoxy-D-ribose 5-phosphate (DR5P), which is then converted to glyceraldehyde 3-phosphate (GAP) and acetaldehyde by deoxyriboaldorase (DERA). Given that GAP is an intermediate in the glycolytic pathway and the pentose phosphate pathway (PPP), we hypothesized that the activation of thymidine catabolism by TP could supply the carbon source for those pathways. However, the thymidine catabolic pathway in mammalian cells remains unclarified. We used 13C-labeled thymidine (13C5-thymidine) as a tracer and examined whether 13C5-thymidine-derived metabolites enter the glycolytic pathway and the PPP in TP-expressing cancer cells using capillary electrophoresis time-of-flight mass spectrometry. Thymidine was converted to metabolites, including glucose 6-phosphate, lactate, 5-phospho-α-ribose 1-diphosphate, and serine, via the glycolytic pathway both in vitro and in vivo. These thymidine-derived metabolites were required for the survival of cells under low-glucose conditions. Furthermore, enhanced thymidine catabolism was observed in human gastric cancer. These findings suggest that the thymidine catabolism plays an important role in the survival and growth of cancer cells in a microenvironment where glucose is insufficient. Citation Format: Sho Tabata, Masatatsu Yamamoto, Hisatsugu Goto, Yasuhiko Nishioka, Masaru Tomita, Tomoyoshi Soga, Tatsuhiko Furukawa, Shin-ichi Akiyama. Novel linkage of thymidine catabolism and the glycolytic pathway in human cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1442.

Synthesis, SAR elucidations and molecular docking study of newly designed isatin based oxadiazole analogs as potent inhibitors of thymidine phosphorylase

Thymidine phosphorylase is an enzyme involved in pyrimidine salvage pathway that is identical to platelet-derived endothelial cell growth factor (PD-ECGF) and gliostatin. It is enormously up regulated in a variety of solid tumors. Furthermore, surpassing of TP level protects tumor cells from apoptosis and helps cell survival. Thus TP is identified as a prime target for developing novel anticancer therapies. A new class of exceptionally potent isatin based oxadiazole (1–30) has been synthesized and evaluated for thymidine phosphorylase inhibitory potential. All analogs showed potent thymidine phosphorylase inhibition when compared with standard 7-Deazaxanthine, 7DX (IC50 = 38.68 ± 1.12 µM). Molecular docking study was performed in order to determine the binding interaction of these newly synthesized compounds, which revealed that these synthesized compounds established stronger hydrogen bonding network with active site of residues as compare to the standard compound 7DX.

Thymidine catabolism promotes NADPH oxidase-derived reactive oxygen species (ROS) signalling in KB and yumoto cells

Thymidine phosphorylase (TP) is a rate-limiting enzyme in the thymidine catabolic pathway. TP is identical to platelet-derived endothelial cell growth factor and contributes to tumour angiogenesis. TP induces the generation of reactive oxygen species (ROS) and enhances the expression of oxidative stress-responsive genes, such as interleukin (IL)-8. However, the mechanism underlying ROS induction by TP remains unclear. In the present study, we demonstrated that TP promotes NADPH oxidase-derived ROS signalling in cancer cells. NADPH oxidase inhibition using apocynin or small interfering RNAs (siRNAs) abrogated the induction of IL-8 and ROS in TP-expressing cancer cells. Meanwhile, thymidine catabolism induced by TP increased the levels of NADPH and intermediates of the pentose phosphate pathway (PPP). Both siRNA knockdown of glucose 6-phosphate dehydrogenase (G6PD), a rate-limiting enzyme in PPP, and a G6PD inhibitor, dihydroepiandrosterone, reduced TP-induced ROS production. siRNA downregulation of 2-deoxy-D-ribose 5-phosphate (DR5P) aldolase, which is needed for DR5P to enter glycolysis, also suppressed the induction of NADPH and IL-8 in TP-expressing cells. These results suggested that TP-mediated thymidine catabolism increases the intracellular NADPH level via the PPP, which enhances the production of ROS by NADPH oxidase and activates its downstream signalling.

Minoxidil Promotes Hair Growth through Stimulation of Growth Factor Release from Adipose-Derived Stem Cells.

Minoxidil directly promotes hair growth via the stimulation of dermal papilla (DP) and epithelial cells. Alternatively, there is little evidence for indirect promotion of hair growth via stimulation of adipose-derived stem cells (ASCs). We investigated whether minoxidil stimulates ASCs and if increased growth factor secretion by ASCs facilitates minoxidil-induced hair growth. Telogen-to-anagen induction was examined in mice. Cultured DP cells and vibrissae hair follicle organ cultures were used to further examine the underlying mechanisms. Subcutaneous injection of minoxidil-treated ASCs accelerated telogen-to-anagen transition in mice, and increased hair weight at day 14 post-injection. Minoxidil did not alter ASC proliferation, but increased migration and tube formation. Minoxidil also increased the secretion of growth factors from ASCs, including chemokine (C-X-C motif) ligand 1 (CXCL1), platelet-derived endothelial cell growth factor (PD-ECGF), and platelet-derived growth factor-C (PDGF-C). Minoxidil increased extracellular signal–regulated kinases 1/2 (ERK1/2) phosphorylation, and concomitant upregulation of PD-ECGF and PDGF-C mRNA levels were attenuated by an ERK inhibitor. Subcutaneous injection of CXCL1, PD-ECGF, or PDGF-C enhanced anagen induction in mice, and both CXCL1 and PDGF-C increased hair length in ex vivo organ culture. Treatment with CXCL1, PD-ECGF, or PDGF-C also increased the proliferation index in DP cells. Finally, topical application of CXCL1, PD-ECGF, or PDGF-C with 2% minoxidil enhanced anagen induction when compared to minoxidil alone. Minoxidil stimulates ASC motility and increases paracrine growth factor signaling. Minoxidil-stimulated secretion of growth factors by ASCs may enhance hair growth by promoting DP proliferation. Therefore, minoxidil can be used as an ASC preconditioning agent for hair regeneration.

Growth mechanisms and morphological structural features of large uterine leiomyoma

To investigate the growth mechanisms of large uterine leiomyoma (LULM) on the basis of a clinical morphology examination, by providing immunohistochemical (IHC) characteristics of the expression of growth factors (transforming growth factor-beta (TGFβ) and platelet-derived endothelial cell growth factor (PD-ECGF)) and markers of stemness (CD117/c-kit, Connexin 43, Nestin) and proliferation (Ki-67). The investigators examined surgical specimens from 38 women diagnosed with simple uterine leiomyoma (ULM), who had been divided into two groups: 1) 21 patients with LULM (>6 cm in diameter) (a study group); 2) 17 patients with small ULM (<4 cm in diameter) (a comparison group). Each group was also divided into two age subgroups (younger (<45 years) and older (≥45 years) subgroups (1a (n=12), 1b (n=9), 2a (n=8) and 2b (n=9), respectively. Histological specimens were used to make IHC examination with antibodies against TGFβ, PD-ECGF, CD117/c-kit, Connexin 43, Nestin, and Ki-67. The growth mechanisms of LULM of simple histological structure were found to be associated with the larger number of growth zones in the tumors, with their enhanced cellular proliferative activity, and with the appearance of cells with signs of stemness, which is combined with the preserved subsequent maturation of tumor cells and determines the benign nature of LULM. There were differences in the molecular profile of LULM and small ULM, as well as LULM in perimenopausal and young women by the expression levels of Ki-67, TGFβ, PD-ECGF, CD117, and Connexin 43, which can be used for diagnosis, prediction, and development of targeted therapies.

Platelet-rich plasma has beneficial effects in mice with osteonecrosis of the femoral head by promoting angiogenesis.

Platelet-rich plasma (PRP) is autologous and multifunctional. Platelet concentrate from blood contains highly concentrated platelets and various types of cells, including growth factors. PRP promotes the recovery of cell proliferation and differentiation. Osteonecrosis of the femoral head is a disease caused by femoral head damage or an insufficient blood supply, which leads to the death of bone cells and abnormal bone marrow composition. The subsequent repair of bone cells may result in changes to the structure of femoral head, femoral head collapse and joint dysfunction. PRP may promote the repair of injured articular cartilage in patients with joint diseases through the removal of harmful inflammatory factors. In the present study, the therapeutic effects and primary mechanism of PRP action were investigated using a glucocorticoid-induced femoral head osteonecrosis mouse model. Dexamethasone (DEX) and phosphate-buffered saline were used as controls. The therapeutic efficacy of PRP to treat osteonecrosis in murine femoral heads was evaluated by assessing clinical arthritis scores. The present study indicated that mice with osteonecrosis of the femoral head treated with PRP exhibited downregulated expression of interleukin (IL)-17A, IL-1β, tumor necrosis factor-α, receptor activator of nuclear factor κ-B ligand, IL-6 and interferon-γ in the inflammatory tissue. In addition, the levels of hepatocyte growth factor, intercellular adhesion molecule-1, osteopontin, platelet-derived endothelial cell growth factor, vascular endothelial growth factor, platelet-derived growth factor, insulin-like growth factor-1 and transforming growth factor-β were increased following treatment with PRP. Joint tissue histological staining demonstrated that PRP alleviated osteonecrosis of the femoral head and reduced humoral and cellular immune responses that promoted beneficial effects on the histological parameters. Furthermore, the concentration of glucocorticoids were significantly decreased in the serum of PRP-treated mice with osteonecrosis compared with the DEX group (P<0.01). Notably, PRP promoted beneficial effects in mice with osteonecrosis of the femoral head by stimulating angiogenesis. Therefore, the present study indicated that treatment with PRP promotes beneficial effects by preventing joint inflammation, cartilage destruction and bone damage, and stimulating the repair of joint tissue in mice with osteonecrosis of the femoral head. These preclinical data suggest that PRP may be developed as a novel method of treating osteonecrosis of the femoral head.

Abstract 1822: Antitumor activity of agents targeting the angiogenic factors angiopoietin-2 and thymidine phosphorylase in mouse models of lung and pancreatic neuroendocrine cancer

Abstract Angiogenesis is a critical component of the initiation, maintenance and progression of tumors, and has been the target of extensive drug development. In clinical practice there are several approved and investigational anti-angiogenesis drugs, the majority of which primarily target the VEGF pathway, however their long term effectiveness remains limited. In designing new drug regimens, it is important to consider other known angiogenic factors that likely contribute to the pro-angiogenic phenotype. We evaluated two such factors: thymidine phosphorylase (TP) (aka platelet-derived endothelial cell growth factor, PD-ECGF), an enzyme that can stimulate endothelial cell migration, and angiopoietin 2 (Ang2), a member of the Ang/Tie2 signaling pathway. To target TP, we used a novel, highly specific, orally available small molecule inhibitor, which we had previously designed, named AEAC. To target Ang2, we used an Ang2 neutralizing peptibody, L1-7[N] (provided by CTEP-NCI), which is a genetically engineered peptide-Fc fusion protein that specifically binds Ang2. In a mouse NCI-H460 NSCLC sc xenograft model, AEAC and L1-7[N] produced 33% and 67% reductions, respectively, in tumor growth, and the combination produced a small, but statistically significant further reduction, when compared to either agent used alone. Tumor growth inhibition was paralleled by a reduction in Ki-67 staining. L1-7[N] also produced a large infiltration of macrophages (F4/80+) into the tumors after treatment. We also tested the drug combination in a mouse genetic model of pancreatic neuroendocrine tumors (PNET). PNET are one the few human solid tumors that are clinically responsive to angiogenesis inhibitors used alone. These mice have a conditional knockout of the Men1 gene in the endocrine pancreatic cells (Pdx1-Cre;Men1 mice) mimicking a primary genetic alteration seen in human disease. Men1 KO PNET experiments were initiated when the mice were 10-11 months old, and drug treatment was daily (5 days per week) for 3 weeks. To date, we have not seen any antiangiogenic or antitumor effects of the drugs. Upon sacrifice, the mice were found to have extensive insulinomas, involving around 70% of the entire pancreas. CD31(+) and F4/80(+) cells in the pancreas showed that most of them concentrated inside the PNET, however there was no change after the treatments. Studies are currently underway to determine if higher doses and/or starting treatment at an earlier time would be more efficacious. Citation Format: Evelyn Aranda, Ziqiang Yuan, Steven K. Libutti, Edward L. Schwartz. Antitumor activity of agents targeting the angiogenic factors angiopoietin-2 and thymidine phosphorylase in mouse models of lung and pancreatic neuroendocrine cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1822. doi:10.1158/1538-7445.AM2017-1822

ChemInform Abstract: Recent Discovery of Non‐Nucleobase Thymidine Phosphorylase Inhibitors Targeting Cancer

AbstractReview: 124 refs.

Recent discovery of non-nucleobase thymidine phosphorylase inhibitors targeting cancer

Thymidine phosphorylase (TP, EC 2.4.2.4), an enzyme involved in pyrimidine salvage pathway, is identical to platelet-derived endothelial cell growth factor (PD-ECGF) and gliostatin. It is extremely upregulated in a variety of solid tumours. The TP amplification is associated with concomitant overexpression of many angiogenic factors such as matrix metalloproteases (MMPs), interleukins (ILs), vascular endothelial growth factor (VEGF) etc., resulting in promotion of angiogenesis and cancer metastasis. In addition, overshooting TP level protects tumour cells from apoptosis and helps cell survival. Thus, TP is identified as a prime target for developing novel anticancer therapies. Pioneering research activities investigated a large number of TP inhibitors, most of which are pyrimidine or purine analogues. Recently, an array of structurally diverse non-nucleobase derivatives was designed, synthesized and established as promising TP inhibitors. This review, following an outline on the TP structure and functions, gives an overview of the recent advancement of various non-nucleobase TP inhibitors as novel anti-cancer agents.

Possible role of thymidine phosphorylase in gynecological tumors as an individualized treatment strategy

Thymidine phosphorylase (TP) is structurally similar to platelet-derived endothelial cell growth factor, and it activates 5-fluorouracil (5-FU) prodrugs and also promotes angiogenesis. In the present study, the possibility of using TP expression as a biomarker for 5-FU prodrugs, and the significance of TP as an angiogenic factor, were investigated in patients with gynecological tumors. The subjects enrolled in the study were 188 patients with gynecological tumors who provided informed consent and underwent tumor resection at the Department of Obstetrics and Gynecology of Tokai University Hospital between February 2002 and January 2010. Measurement of the enzymatic activity of TP and dihydropyrimidine dehydrogenase (DPD) was performed by enzyme-linked immunosorbent assay. In addition, immunohistochemistry (IHC) analysis of microvessels by monochrome imaging, western blotting and reverse transcription-polymerase chain reaction were performed. The mean TP activity and the TP/DPD ratio were increased in squamous cell carcinoma of the cervix (306.9 and 2.2 U/mg protein, respectively) and adenosquamous carcinoma (317.6 and 1.4 U/mg protein, respectively) compared with benign tumors and other malignancies, including endometrial (uterine) carcinoma, ovarian serous adenocarcinoma and ovarian mucinous adenocarcinoma. However, these parameters were also elevated in other histological types of cancer such as clear cell adenocarcinoma of the ovary (115.2 and 2.1 U/mg protein, respectively), in which the microvessel area was the largest of all the histological types analyzed. Since high TP expression and a high TP/DPD ratio were identified in other tumors besides cervical cancer, it is possible that patients for whom 5-FU prodrugs are indicated could be selected appropriately if their TP activity is determined and their TP expression is analyzed by IHC prior to initiation of the treatment.

Review on TAS-102 development and its use for metastatic colorectal cancer

TAS-102 is the combination of trifluridine (TFT) with tipiracil (TPI) in a 1:0.5 molar ratio. TFT is a fluoropyrimidine that retains cytotoxic activity in 5-fluorouracil resistant cell lines. Due to TFT short half-life, early clinical development was discouraging. Thereafter, TFT was shown to be promptly degraded by thymidine phosphorylase, also known as platelet-derived endothelial cell growth factor, a pro-angiogenic protein and a poor prognosis marker in colorectal cancer. TPI is a specific antagonist of thymidine phosphorylase and led to an increase in TFT serum levels when both agents are combined. Moreover, TPI is a potential anti-angiogenic molecule and could exert antitumor actions per se. TAS-102 was tested in several Phase I studies published in the early 21st century. The best regimen was settled as 70mg/m(2)/day, q12h, orally given at days 1-5 and days 8-13, each 28days. Recently, the first Phase III trial evaluating TAS-102 in refractory colorectal cancer patients was published. The RECOURSE trial demonstrated a survival advantage of the agent over supportive care, and definitely established TAS-102 as a novel strategy in the current armamentarium against colorectal cancer. Here we review the preclinical data regarding TFT and TPI that led to the development of TAS-102, and the set of clinical data that ultimately proved that TAS-102 improved outcomes in colorectal cancer patients.

Effects of Platelet-Derived Endothelial Cell Growth Factor and Doppler Perfusion Index in Patients with Colorectal Hepatic Metastases

Background: We aimed to find out if there is a correlation between Doppler perfusion index (DPI) and platelet- derived endothelial cell growth factor (PD-ECGF), which is an angiogenic factor with angiopoietic function, in patients with colorectal carcinoma. Methods: 50 colorectal carcinoma patients (22 cases with liver metastases, 28 cases without liver metastases) and 50 healthy controls were assessed with Doppler ultrasound as a preoperative evaluation. PD-ECGF expression in postoperative specimens of the 50 cases with colorectal carcinoma was assayed by immunohistochemistry and real-time polymerase chain reaction methods. Results: The mean DPI value was 0.29 ± 0.05 in patients suffering from colon cancer with hepatic metastases and 0.12 ± 0.03 in the healthy control group. The DPI value was significantly higher in patients with liver metastases (p < 0.05). PD-ECGF expression in patients with colorectal liver metastases was significantly higher than that in the group without liver metastases (p < 0.05). A positive correlation was found between DPI value and PD-ECGF expression in patients with liver metastases (p < 0.05). Conclusions: DPI and PD-ECGF may be valuable factors when screening hepatic metastases in patients with colorectal cancer and serve as practical measurements in postoperative follow-up.

Thymidine phosphorylase gene variant, platelet counts and survival in gastrointestinal cancer patients treated by fluoropyrimidines.

The predictive value of thymidine phosphorylase gene variants (TP, also called platelet-derived endothelial cell growth factor) and thrombocytosis were controversial and worthy of further study in gastrointestinal cancer (GIC) patients. We screened all of the common missense single nucleotide polymorphisms (MAF ≥ 0.1) in fluoropyrimidines (FU) pathway genes (including TP, TS, ENOSF1 and DPD). Three of them were selected and genotyped using Sequenom MassARRAY in 141 GIC patients. TP expression was assessed by immunohistochemistry. Our aim was to evaluate the prognostic significance of studied genes and platelet counts in GIC patients. Multivariate analyses indicated in rs11479-T allele carriers, platelet counts negatively correlated to overall survival. In addition, T allele of TP: rs11479 was associated with higher TP expression in cancer tissues. We suggest TP: rs11479 variant combined with platelet counts may be useful prognostic makers in GIC patients receiving first-line FU chemotherapy and thrombopoietin factor should be used with caution in the rs11479 T allele bearing patients.

Prognostic factors and status of hormone receptors and angiogenic factors in uterine carcinosarcoma

To determine novel prognostic factors and treatment modalities for uterine carcinosarcoma (UCS). We performed immunohistochemical staining of estrogen receptor (ER)-α, ER-β, progesterone receptor, gonadotropin-releasing hormone receptor, vascular endothelial growth factor (VEGF), platelet-derived endothelial cell growth factor (PD-ECGF) and platelet-derived growth factor receptor (PDGFR)-β in a clinicopathological study of 15 UCS patients. No significant differences were found between the sarcomatous and carcinomatous components with respect to expression of ER-α, ER-β and progesterone receptor. However, VEGF was significantly more frequently expressed in the carcinomatous component, while PD-ECGF and PDGFR-β were significantly more frequently expressed in the sarcomatous component. Only one patient showed gonadotropin-releasing hormone receptor expression in the sarcomatous component. Moreover, ER-β expression in resected specimens, increased serum levels of carbohydrate antigen (CA)-125 and C-reactive protein (CRP), and thrombocytosis were determined as significant UCS prognostic factors. Combination of anti-VEGF therapy and anti-PD-ECGF or anti-PDGFR-β therapy would be expected in advanced or recurrent UCS. Furthermore, careful monitoring for early detection of recurrence should be performed when UCS patients showed preoperative increase in serum CA-125 levels, CRP and platelet counts, and ER-β expression in biopsied or surgically resected specimens.