Thymidine phosphorylase mRNA level predicts survival of patients with advanced oropharyngeal cancer

Evaluation of pemetrexed and etoposide as therapeutic regimens for human papillomavirus-positive oral and oropharyngeal cancer

Although human papillomavirus (HPV) positive oral and oropharyngeal cancers have distinct epidemiologic and molecular characteristics compared to HPV-negative cancers, all patients with oral and oropharyngeal cancers received same standard regimen regardless of HPV status. For these reasons, specific regimens for patients with HPV-positive oral and oropharyngeal cancer are needed. Differentially expressed genes (DEG) between HPV-positive and HPV-negative oropharyngeal cancers were re-analyzed and categorized from public database. Then, druggable targets to HPV-positive oral and oropharyngeal cancer were identified and were validated with E6/E7, which is oncogene of HPV, transfected oral and oropharyngeal cancer cell lines and HPV infected cell lines. In DEG analysis, HPV-positive oral and oropharyngeal cancer showed distinct disease entity from HPV-negative cancers. Unlike HPV-negative oral and oropharyngeal cancer, thymidylate synthase (TS) and topoisomerase II (Topo II) were overexpressed in HPV-positive cancers. Transfection of Lenti-virus containing E6/ E7 to HPV-negative oral and oropharyngeal cancer cells induced upregulation of TS and Topo II in those cells. Although cisplatin, which is standard regimen in head and neck cancers, showed more effectiveness in HPV-negative cells, 5-FU and pemetrexed, which are TS inhibitors, or etoposide, which is Topo II inhibitors, worked more effectively in HPV-positive cells. In addition, cisplatin/etoposide and cisplatin/pemetrexed combination regimens showed synergic effects in HPV-positive cells. Pemetrexed or etoposide alone, or in combination with other chemotherapeutic agents such as cisplatin, can be used as novel substitutes in a regimen of concurrent chemoradiotherapy or a palliative regimen for HPV-positive oral and oropharyngeal cancer patients. However, a well-designed clinical trial is needed.

A polymorphism in the TYMP gene is associated with the outcome of HLA-identical sibling allogeneic stem cell transplantation

Thymidine phosphorylase (TYMP), an enzyme involved in nucleotide synthesis, has been implicated in critical biological processes such as DNA replication, protection against mutations, and tissue repair. In this work, we retrospectively evaluated the influence of a polymorphism in the TYMP gene (rs112723255; G/A) upon the outcome of 448 patients subjected to allogeneic stem cell transplantation (allo-SCT) from an human leukocyte antigen (HLA)-identical sibling donor. The TYMP genotype of patients correlated with overall survival-carriers of the minor allele (A) being at an increased risk of dying after transplantation (hazard ratio, HR = 1.9; P = 0.004). This effect was mostly due to differences in transplant toxicity-related mortality (HR = 2.5; P = 0.029). In addition, the TYMP genotype of donors was associated with the risk of chronic graft-versus-host disease (GVHD)-carriers of the minor allele being at an increased risk of developing this complication ([HR] = 1.7; P = 0.039). The impact of such polymorphism on the risk of chronic GVHD is limited to patients transplanted in early stage disease (HR = 2.2; P = 0.019). The combination of a donor harboring the minor allele with a patient homozygous for the major allele was associated with the highest risk of chronic GVHD (HR = 2.8; P = 0.008). These findings provide the first evidence of the significant impact of the TYMP genotype upon the clinical outcome of patients treated with HLA-identical sibling allo-SCT.

Novel mRNA isoforms and mutations of uridine monophosphate synthetase and 5-fluorouracil resistance in colorectal cancer

The drug fluorouracil (5-FU) is a widely used antimetabolite chemotherapy in the treatment of colorectal cancer. The gene uridine monophosphate synthetase (UMPS) is thought to be primarily responsible for conversion of 5-FU to active anticancer metabolites in tumor cells. Mutation or aberrant expression of UMPS may contribute to 5-FU resistance during treatment. We undertook a characterization of UMPS mRNA isoform expression and sequence variation in 5-FU-resistant cell lines and drug-naive or -exposed primary and metastatic tumors. We observed reciprocal differential expression of two UMPS isoforms in a colorectal cancer cell line with acquired 5-FU resistance relative to the 5-FU-sensitive cell line from which it was derived. A novel isoform arising as a consequence of exon skipping was increased in abundance in resistant cells. The underlying mechanism responsible for this shift in isoform expression was determined to be a heterozygous splice site mutation acquired in the resistant cell line. We developed sequencing and expression assays to specifically detect alternative UMPS isoforms and used these to determine that UMPS was recurrently disrupted by mutations and aberrant splicing in additional 5-FU-resistant colorectal cancer cell lines and colorectal tumors. The observed mutations, aberrant splicing and downregulation of UMPS represent novel mechanisms for acquired 5-FU resistance in colorectal cancer.

Additive effects of oral fluoropyrimidine derivative S-1 and radiation on human hypopharyngeal cancer xenografts

CONCLUSION

The results presented here provide evidence of the enhancing effect of oral fluoropyrimidine derivative S-1 in concomitant chemoradiotherapy for head and neck cancer and further insights into its biological mechanism.

OBJECTIVE

To investigate the additive effect of S-1 and radiation for human hypopharyngeal cancer.

MATERIALS AND METHODS

Nude mice bearing hypopharyngeal cancer cells (H891) were used for an in vivo model. S-1 was administered at a volume of 0.01 mg/g body weight per mouse for 14 days, and tumors were irradiated with 2.0 Gy on days 1 and 8. Mice treated with either radiation or S-1 alone were used as controls. The growth of tumors in each group was measured and, after completion of the treatment, a focused DNA array was used to determine mRNA expression levels in the tumors of 132 genes related to 5-fluorouracil (5-FU), radiation or carcinogenesis.

RESULTS

The additive antitumor effect of S-1 and radiation was statistically confirmed on day 14 (p=0.01). DNA array assay showed significant changes in expression of several genes, including DNA repair gene POLD, angiogenesis-related genes bFGF and TP, DNA topoisomerase TOP2A, and nucleoside transporter gene ENT1.

Decreased expression of thymidine phosphorylase/platelet-derived endothelial cell growth factor in basal cell carcinomas

Thymidine phosphorylase (TP)/platelet-derived endothelial cell growth factor is associated with tumor angiogenesis. We evaluated the TP mRNA and protein expression in basal cell carcinomas (BCC) and in various skin tumors including numerous BCC histological simulants. Immunohistochemistry was performed on 99 paraffin sections of formalin-fixed skin tumors using monoclonal antibodies (mAb) against TP. TP mRNA levels were measured by real time RT-PCR in whole BCCs (wBCC) and laser capture microdissected (LCM) BCC tumor cells. TP immunostaining was negative in all BCC variants and in most of the benign trichogeneic tumors studied. By contrast, TP was constantly immunodetected in actinic keratosis (AK), squamous cell carcinomas (SCC), syringomatous carcinomas (SC), basosquamous carcinomas (BSC) and melanomas. TP mRNA levels were low and statistically not different in wBCC and normal skin but were strongly downregulated in LCM-BCC as compared with LCM-normal epidermis. We concluded that (i) anti-TP mAb is an useful marker to differentiate BCC from AK, SCC, BSC and SC but not from trichoblastic tumors, (ii) the lack of TP protein expression in BCC tumoral cells is linked to transcriptional regulatory mechanisms, (iii) the low TP mRNA levels in whole BCC may be related to the low intra-tumoral microvessel density, the slow growth and the very low metastatic potential of these tumors.

Thymidylate synthase and thymidine phosphorylase gene expression as predictive parameters for the efficacy of 5-fluorouraci-based adjuvant chemotherapy for gastric cancer

AIM: To investigate the prognostic role of thymidylate synthase (TS) and thymidine phosphorylase (TP) mRNA levels in T3 or T4 gastric cancer treated with 5-fluorouraci-based adjuvant chemotherapy.

METHODS: Fifty-one patients with T3 or T4 gastric cancer received systemic 5-fluorouraci-based adjuvant chemotherapy, and intratumoral expression of TS and TP in 51 gastric cancer tissue samples was tested by real-time quantitative PCR.

RESULTS: The median disease-free survival (DFS) time was 10.2 mo in the patients. There were no significant differences in DFS between the groups with high and low levels of TP. However, the group with low level of TS had a longer DFS (14.4 mo vs 8.3 mo, P = 0.017). The median overall survival (OS) time was 18.5 mo, and there were significant differences in OS between the groups with high and low levels of TS or TP (for TS, 17.0 mo vs 21.3 mo, P = 0.010; for TP, 16.6 mo vs 22.5 mo, P = 0.009). Moreover, the coupled low expression of these two genes was strongly associated with a longer survival time of patients as compared with that of a single gene.

CONCLUSION: Expression of TS and TP mRNA is a useful predictive parameter for the survival of postoperative gastric cancer patients after 5-fluorouracil-based adjuvant chemotherapy.