Neuropathic Pain Features in Patients with Bone Metastases.

AIMS: The results of previous randomised controlled trials suggest that radiation oncologists should consider the presence of neuropathic pain when they prescribe dose fractionations for painful bone metastases. Although validated screening tools for neuropathic pain features are currently available, the prevalence of such features among patients with painful bone metastases is still poorly understood. The purpose of this study was to estimate the prevalence of neuropathic pain features among patients who received palliative radiotherapy for painful bone metastases. MATERIALS AND METHODS: We conducted a cohort survey of consecutive patients who received palliative radiotherapy for painful bone metastases at St Luke's International Hospital between 2013 and 2014. Patients were prospectively assessed before radiotherapy using the validated screening questionnaire to identify neuropathic pain components in Japanese patients. Pain with neuropathic features was prospectively defined using the total score of the seven-item questionnaire and a cut-off score ≥9. The pain response was assessed 2 months after the start of radiotherapy according to the criteria defined by the International Bone Metastases Consensus Working Party. RESULTS: Eighty-seven patients were assessed. Twenty-four per cent of patients (95% confidence interval: 16-35%) were diagnosed as having pain with neuropathic features. On multivariate analysis, no significant correlations were seen between neuropathic pain features and patient characteristics. Sixty-four patients (74%) were assessable 2 months after the start of radiotherapy. Overall response rates were 59% (95% confidence interval: 33-82%) in patients with neuropathic features and 55% (95% confidence interval: 40-70%) in those without such features. CONCLUSIONS: A considerable proportion of the patients were proven to have bone pain with neuropathic features. Further investigations are warranted to validate symptom assessment tools in cooperation with pain distribution and image findings, and to clarify if the presence of neuropathic pain affects the response to palliative radiotherapy.

Rad18 and Rnf8 facilitate homologous recombination by two distinct mechanisms, promoting Rad51 focus formation and suppressing the toxic effect of nonhomologous end joining.

The E2 ubiquitin conjugating enzyme Ubc13 and the E3 ubiquitin ligases Rad18 and Rnf8 promote homologous recombination (HR)-mediated double-strand break (DSB) repair by enhancing polymerization of the Rad51 recombinase at γ-ray-induced DSB sites. To analyze functional interactions between the three enzymes, we created RAD18(-/-), RNF8(-/-), RAD18(-/-)/RNF8(-/-) and UBC13(-/-)clones in chicken DT40 cells. To assess the capability of HR, we measured the cellular sensitivity to camptothecin (topoisomerase I poison) and olaparib (poly(ADP ribose)polymerase inhibitor) because these chemotherapeutic agents induce DSBs during DNA replication, which are repaired exclusively by HR. RAD18(-/-), RNF8(-/-) and RAD18(-/-)/RNF8(-/-) clones showed very similar levels of hypersensitivity, indicating that Rad18 and Rnf8 operate in the same pathway in the promotion of HR. Although these three mutants show less prominent defects in the formation of Rad51 foci than UBC13(-/-)cells, they are more sensitive to camptothecin and olaparib than UBC13(-/-)cells. Thus, Rad18 and Rnf8 promote HR-dependent repair in a manner distinct from Ubc13. Remarkably, deletion of Ku70, a protein essential for nonhomologous end joining (NHEJ) significantly restored tolerance of RAD18(-/-) and RNF8(-/-) cells to camptothecin and olaparib without affecting Rad51 focus formation. Thus, in cellular tolerance to the chemotherapeutic agents, the two enzymes collaboratively promote DSB repair by HR by suppressing the toxic effect of NHEJ on HR rather than enhancing Rad51 focus formation. In contrast, following exposure to γ-rays, RAD18(-/-), RNF8(-/-), RAD18(-/-)/RNF8(-/-) and UBC13(-/-)cells showed close correlation between cellular survival and Rad51 focus formation at DSB sites. In summary, the current study reveals that Rad18 and Rnf8 facilitate HR by two distinct mechanisms: suppression of the toxic effect of NHEJ on HR during DNA replication and the promotion of Rad51 focus formation at radiotherapy-induced DSB sites.

Woodfruticosin (woodfordin C), a new inhibitor of DNA topoisomerase II. Experimental antitumor activity.

Woodfruticosin (woodfordin C) (WFC), a new inhibitor of DNA topoisomerase II (topo-II), was isolated from methanol extract of Woodfordia fruticosa Kurz (Lythraceae) and studied for in vitro and in vivo antitumor activities in comparison with Adriamycin (ADR) and etoposide (ETP), well known inhibitors of topo-II. The inhibitory activity against DNA topo-II shown by WFC was much stronger than that shown by ETP or ADR. WFC inhibited strongly intracellular DNA synthesis but not RNA and protein synthesis. On the other hand, WFC had a weaker growth inhibitory activity against various human tumor cells than ETP or ADR, but it showed remarkable activity against PC-1 cells and moderate activity against MKN45 and KB cells. Furthermore, WFC had in vivo growth inhibitory activity against s.c. inoculated colon38. These results indicate that the mechanism by which WFC exhibits antitumor activity may be through inhibition of topo-II.

Cell killing mode of liblomycin (NK313), a novel dose-survival relationship different from bleomycins.

Liblomycin (NK313) is a novel derivative of bleomycin (BLM) and peplomycin (PEP). The cell kill kinetics of NK313 on rat ascites hepatoma AH66 were compared with those of PEP. NK313 induced intracellular DNA cleavage and arrested cell cycle progression at the G2 phase similarly to PEP. The cytocidal effect of NK313, however, was found to be different from that of PEP as described below: 1) The dose-survival curve for cells exposed to PEP for 1 hour was upward concave, whereas in case of NK313, the survival curve was linear. PEP was more effective to AH66 than NK313 at lower concentration, but at higher concentration, NK313 was much more effective. 2) The time-survival curve for cells treated with either NK313 or PEP was biphasic. NK313, however, did not induce temporary resistance of AH66 cells to NK313, while PEP induced resistance to PEP. 3) NK313 was effective against the cells which became temporarily resistant to PEP by the treatment of PEP. These differences suggest that NK313 might be of value to treat PEP-insensitive tumor cells.

Factor analysis of in vitro antitumor activities of platinum complexes.

Factor analysis was applied to the data matrix of in vitro growth inhibitory activities of 52 platinum complexes against 9 tumor cell lines, L1210, P388, Lewis lung, AH66, AH66F, HeLa S3, KB, HT-1197 and HT-1376 cell lines. Three factors were obtained by the principal factor analysis method. After the varimax rotation of these three factors, tumor cell lines were classified into four groups according to their factor loadings. The platinum complexes were characterized by the factor scores. Cisplatin was situated in an extreme position as compared with the other platinum complexes. In vivo antitumor activities of the platinum complexes were tested against L1210 and LL murine tumor models. The in vivo activity against L1210 showed a negative correlation with that against LL. Factor 2 scores of the complexes obtained by factor analysis of in vitro antitumor activities showed a good correlation with these in vivo antitumor activities. Then, the structure-factor 2 score relationships among platinum complexes were analyzed by the Free-Wilson method. From this analysis, structure-activity relationships for carrier ligands and leaving groups are proposed. Factor analysis is suggested to be a useful method to establish an efficient screening system for platinum complexes.

Action of ubenimex on aminopeptidase activities in spleen cells and peritoneal macrophages from mice.

The action of ubenimex on aminopeptidase (APase) activity was studied in intact spleen cells and peritoneal macrophages from mice. Ubenimex strongly inhibited hydrolyzing activities against arginine-beta-naphtylamide (Arg-NA), Lys-NA and Pro-NA in both cells. Inhibition of hydrolysis of Leu-NA, Met-NA and Ala-NA was relatively small or not observed. When both cells were incubated in HANKS' solution, hydrolyzing activities against Arg-NA, Lys-NA and Pro-NA were released to the medium, while Leu-NA and Met-NA-hydrolyzing activities were mostly bound. In addition, the Leu-NA-hydrolyzing activity in the spleen cells was kinetically studied. The Arg-NA and Leu-NA-hydrolyzing activities in four fractions prepared from the homogenate of spleen cells were also studied kinetically. From these studies it was suggested that ubenimex inhibits aminopeptidase B and a Pro-NA-hydrolyzing enzyme more effectively than Leu-APase in intact spleen cells and peritoneal macrophages from mice.