Clinical relevance of thymidylate synthase (TS) activity for S-1-based chemotherapy in squamous cell carcinoma of the oral cavity

Expression of thymidylate synthase predicts clinical outcomes of S-1-based chemotherapy in squamous cell lung cancer

Non-small cell lung cancer (NSCLC) patients with squamous cell carcinoma (SCC) histology have limited chemotherapeutic options. Treatment with S-1 combined with carboplatin (CBDCA) has been shown to provide a significant survival benefit in SCC patients compared with treatment with combined CBDCA and paclitaxel. The aim of the present study was to investigate the association between the expression of molecular markers related to the pharmacological action of S-1, including thymidylate synthase (TS), orotate phosphoribosyltransferase (OPRT) and dihydropyrimidine dehydrogenase (DPD), and the clinical efficacy of S-1-based chemotherapy in SCC patients. The immunohistochemical expression of TS, OPRT and DPD were retrospectively analyzed in tumor biopsy and resection specimens from patients with advanced SCC (n=32). Immunohistochemical H-scores were calculated and their association with S-1/CBDCA response was evaluated. Median progression-free survival time was significantly longer in patients with low TS H-scores than in those with high TS H-scores (162.5 vs. 97 days; P=0.004); by contrast, overall survival time was not observed to differ significantly between these groups (P=0.185). In the multivariate analysis, low TS expression was a significant positive factor for progression-free survival rate (hazard ratio, 0.40; P=0.021). A low TS H-score was also associated with an increased response to S-1-based chemotherapy compared with a high TS H-score (P=0.002). This indicates that SCC patients with low TS expression can benefit significantly from S-1-based chemotherapy, and that H-score measurement of intratumoral TS expression may represent a useful predictive biomarker for response to S-1-based chemotherapy by patients with SCC-type NSCLC.

Full length articles published in BJOMS during 2010-11--an analysis by sub-specialty and study type

Full length articles such as prospective and retrospective studies, case series, laboratory-based research and reviews form the majority of papers published in the British Journal of Oral and Maxillofacial Surgery (BJOMS). We were interested to evaluate the breakdown of these types of articles both by sub-specialty and the type of study as well as the proportion that are written by UK colleagues compared to overseas authors over a 2 year period (2010-11). A total of 191 full length articles across all sub-specialties of our discipline were published, with 107 papers (56%) coming from UK authors. There were proportionately more oncology papers arising from the UK than overseas (60 and 30% of total respectively) while the opposite was found for cleft/deformity studies (10% and 22%). There was only one laboratory-based study published from the UK compared with 27 papers from overseas. The number of quality papers being submitted to the Journal continues to increase, and the type of article being published between UK and overseas probably reflects different practices and case-loads amongst colleagues. The relatively few UK laboratory based studies published in BJOMS compared to overseas authors are most likely due to authors seeking the most prestigious journals possible for their work.

A double-modulation strategy in cancer treatment with a chemotherapeutic agent and siRNA

5-Fluorouracil (5-FU) is broadly considered the drug of choice for treating human colorectal cancer (CRC). However, 5-FU resistance, mainly caused by the overexpression of antiapoptotic proteins such as Bcl-2, often leads ultimately to treatment failure. We here investigated the effect of Bcl-2 gene silencing, using small interfering RNA (siRNA) (siBcl-2), on the efficacy of 5-FU in CRC. Transfection of siBcl-2 by a Lipofectamine2000/siRNA lipoplex effectively downregulated Bcl-2 expression in the DLD-1 cell line (a CRC), resulting in significant cell growth inhibition in vitro upon treatment with 5-FU. For in vivo treatments, S-1, an oral formulation of Tegafur (TF), a prodrug of 5-FU, was used to mimic 5-FU infusion. The combined treatment of polyethylene glycol (PEG)-coated siBcl-2-lipoplex and S-1 showed superior tumor growth suppression in a DLD-1 xenograft model, compared to each single treatment. Surprisingly, daily S-1 treatment enhanced the accumulation of PEG-coated siBcl-2-lipoplex in tumor tissue. We propose a novel double modulation strategy in cancer treatment, in which chemotherapy enhances intratumoral siRNA delivery and the delivered siRNA enhances the chemosensitivity of tumors. Combination of siRNA-containing nanocarriers with chemotherapy may compensate for the limited delivery of siRNA to tumor tissue. In addition, such modulation strategy may be considered a promising therapeutic approach to successfully managing 5-FU-resistant tumors.

A predictive factor for the response to S-1 plus cisplatin in gastric cancer

AIM: To prove that the protein expression level of thymidylate synthase is a predictive factor for the response to S-1/cisplatin (CDDP) chemotherapy in gastric cancer.

METHODS: We measured the protein expression levels of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), and orotate phosphoribosyltransferase (OPRT) in advanced gastric cancer. Before S-1/CDDP chemotherapy, tumor specimens from primary sites were obtained by endoscopic biopsy and analyzed by enzyme-linked immunosorbent assay. The chemotherapeutic effects on the primary sites were evaluated by endoscopic biopsy performed more than once after S-1/CDDP chemotherapy. The effects are a predictive factor for the response to S-1/CDDP chemotherapy in patients with advanced gastric cancer, as evaluated by endoscopic biopsy over time.

RESULTS: The protein expression level of TS was significantly higher (P < 0.05) in the tumor than in the normal tissue, and significantly lower (P < 0.05) in the responders than in the non-responders. We were able to evaluate the correlation between changes in the protein expression levels of TS, DPD and OPRT and chemotherapeutic responses in 7 patients by assessing tumor tissues more than twice. In the responders, the protein expression level of TS was < 40 ng/mg protein. However, there were significant increases in the protein expression levels of TS (P < 0.01) and DPD (P < 0.05) after chemotherapy in 3 patients. In these cases, the patient assessment changed from “responder” to “non-responder”. In the non-responders, the protein expression level of TS was > 40 ng/mg protein.

CONCLUSION: We have confirmed that the protein expression level of TS is a predictive factor for the response to S-1/CDDP chemotherapy in patients with advanced gastric cancer.