Mamoru Nukatsuka

Enhancement by streptozotocin of O−2 radical generation by the xanthine oxidase system of pancreatic β-cells

Spin‐trapping techniques and electron spin resonance (ESR) spectroscopy were used to study the relationship between the effect of streptozotocin (STZ) on pancreatic β‐cells and free radical formation by these cells. Results showed that STZ enhanced generation of the DMPO‐OH radical adduct, which is a degradation product of the superoxide anion (O− 2) in the presence of cellular components, in a hypoxanthine‐xanthine oxidase (XOD) system with a homogenate of β‐cells. This enhancing effect was also observed in a system without cellular components; STZ increased the signal height due to the O− 2 radical in a concentration‐dependent manner and caused a maximum of 150% enhancement at a concentration of 1.5 mM. Thus, STZ seemed to enhance the generation of the O− 2 radical in the XOD system, probably by some mechanism of its interaction with XOD. Pancreatic β‐cells exhibited a high XOD activity and a very low superoxide dismutase activity. Therefore, the present result supports the possibility that the cytotoxic effect of STZ is closely related to free radical generation in pancreatic β‐cells.

Dendritic cells might be one of key factors for eliciting antitumor effect by chemoimmunotherapy in vivo.

In this study, we demonstrated that chemoimmunotherapy using S-1, a novel oral fluoropyrimidine anticancer drug, combined with lentinan (LNT), a β (1→3) glucan, was effective in vivo, and we clarified the augmentation of the function of dendritic cells (DCs) in vivo and in vitro. The survival period of Colon-26–bearing mice treated with S-1+LNT was significantly more prolonged than that of mice treated with S-1 alone (P<0.05). On the other hand, LNT did not prolong the survival period when combined with S-1 in Colon-26–bearing athymic mice. The frequency of CD86+ DCs infiltrated into Colon-26 was increased in mice treated with S-1+LNT, and splenic DCs harvested from mice treated with S-1+LNT showed more potent T-cell proliferation activity than that of DCs from mice treated with S-1 alone (P<0.05). Furthermore, the activity of cytotoxic T lymphocytes (CTLs) in splenocytes of S-1+LNT–treated mice was specific and more potent than that of CTLs from mice treated with S-1 alone (P<0.05). These results suggest that modulation of specific immunity with LNT has a significant role in enhanced antitumor effects through the modification of DC function. We demonstrated that DCs might play an important role in chemotherapy, and the combination therapy of S-1 and LNT presents a promising chemoimmunotherapy, which might lead to better survival for cancer patients.

Generation of alloxan free radicals in chemical and biological systems: implication in the diabetogenic action of alloxan.

Electron spin resonance (ESR) studies that on reaction with NADPH, alloxan was reduced forming labile anion radicals giving a 7-line signal with g = 2.005. These radicals were also produced on incubation of alloxan with rat liver subcellular fractions and their production was greatly enhanced by NADPH. Alloxan effectively scavenged superoxide anion generated by a xanthine-xanthine oxidase (XOD) system in association with its reduction to these anion radicals. These radicals were also formed during incubation of alloxan with rat pancreatic beta-cells. These results suggest that the cytotoxicity of alloxan is related to the formation of alloxan anion radicals.

Preclinical rationale for combined use of endocrine therapy and 5-fluorouracil but neither doxorubicin nor paclitaxel in the treatment of endocrine-responsive breast cancer.

PurposeOur previous study indicated that concurrent administration of 4-OH-tamoxifen (TAM) and 5-fluorouracil (5-FU), but not doxorubicin (Dox), resulted in additive antitumor effects on endocrine-responsive breast cancer cells. We further clarified the effects of combined administration of endocrine therapy with chemotherapeutic agents in this study.MethodsConcurrent treatment with 4-OH-TAM and paclitaxel (Ptx) was investigated in estrogen receptor (ER)-positive breast cancer cells. Additionally, the combined effects of estrogen depletion from culture medium mimicking estrogen ablative therapy with 5-FU, Dox, and Ptx were investigated.ResultsConcurrent treatment with 4-OH-TAM and Ptx yielded less than additive antitumor effects in ER-positive breast cancer cells, as observed with Dox in our previous study. More interestingly, estrogen depletion with 5-FU, but with neither Dox nor Ptx, yielded additive antitumor effects on these cells. We also performed preliminary experiments to elucidate the mechanisms of action responsible for the combined antitumor effects observed. Ptx up-regulated the level of expression of one of the molecules related to TAM resistance, Eph-A2, as observed with Dox in our previous study. Estrogen depletion down-regulated the level of expression of one of the molecules related to 5-FU resistance, thymidylate synthase, as observed with 4-OH-TAM in our previous study.ConclusionsThese findings, together with those of our previous study, suggest that concurrent treatment with endocrine therapy, administration of TAM, or estrogen ablative therapy and 5-FU but neither Dox nor Ptx may yield additive antitumor effects on endocrine-responsive breast cancer.

Antiestrogenic activity of DP-TAT-59, an active metabolite of TAT-59 against human breast cancer.

Abstract Purpose: The purpose of this study was to clarify the mechanism(s) of antiestrogenic action of DP-TAT-59 ((Z)-2-(4-(1-(4-hydroxyphenyl)-2-(4-isopropyl-phenyl)-1-butenyl)phenoxy)-N,N-dimethyl- ethylamine), the main active metabolite of TAT-59. Methods: Using 4-OH-tamoxifen (a hydroxylated metabolite of tamoxifen) as a reference compound, we examined the relationship between hormone-dependent tumor cells and DP-TAT-59 and characterized estrogen receptor (ER) complexes with DP-TAT-59 using ion-exchange chromatography. Results: DP-TAT-59 inhibited the in vitro proliferation of MCF-7 cells under serum-free conditions at a lower concentration than did 4-OH-tamoxifen. The conditioned medium (CM) obtained from the culture supernatant of MCF-7 cells in the presence of these antiestrogens suppressed the growth of ER-negative cell lines, but that from ER-negative human mammary carcinoma MX-1 cells did not. The CM from DP-TAT-59-treated cells showed a higher growth-inhibitory potency against human mammary carcinoma ZR-75-1 cells than did that from 4-OH-tamoxifen-treated cells. The growth-inhibitory potency of the CM was neutralized by the addition of the anti-TGF-β antibody. The CM obtained from cells treated with DP-TAT-59 contained more TGF-β and less TGF-α than that treated with 4-OH-tamoxifen. As the antiestrogenic activity of TAT-59 might be mediated through ER, the interaction of these antiestrogens with a cytoplasmic receptor of MCF-7 cells was examined. While the competitive binding of [3H]-estradiol with these antiestrogens to ER was similar, ER complexes with DP-TAT-59 showed a different elution profile by ion-exchange chromatography, indicating that DP-TAT-59 formed a different complex with ER from either 4-OH-tamoxifen or estradiol. Conclusion: These findings suggest that at least a part of the growth suppressive ability of DP-TAT-59 against human mammary carcinoma might depend on the production of growth inhibitory factors and/or the suppression of production of growth factors from ER-positive cells, and that the production of growth inhibitory factors might be stimulated by ER complexes with antiestrogens rather than with estrogen.

Interaction of DP-TAT-59, an active metabolite of new triphenylethylene-derivative (TAT-59), with estrogen receptors

DP-TAT-59, (Z)-2-(4-(1-(4-hydroxyphenyl)-2-(4-isopropylphenyl)-1-butenyl) phenoxy)-N, N-dimethylethylamine, has been reported to inhibit estrogen-stimulated growth of MCF-7 cells as well as rat uterus at lower concentrations than the hydroxymetabolite of tamoxifen (4-OH-TAM). In the present study, the growth of mouse Leydig cell tumor, B-1F cells were also more effectively inhibited by DP-TAT-59 than 4-OH-TAM. Additionally, the expression of estrogen responsive element ligated CAT gene transfected into B-1F cells was also suppressed by DP-TAT-59. Thus, the interaction of DP-TAT-59 with estrogen receptor (ER) was characterized and compared with that of 4-OH-TAM using immature rat and bovine uteri. The dissociation constant of DP-TAT-59 to ER of immature rat uterus was 0.24 nM and was similar to that of 4-OH-TAM (Kd = 0.20 nM) and estradiol (Kd = 0.29 nM). Using sucrose density gradients, the sedimentation constant of DP-TAT-59 with bovine uterus was 4.9S, which was similar to that of estradiol (5.1S) and 4-OH-TAM (5.3S). However, the elution profile of the DP-TAT-59-ER complex from a DEAE-Sephadex column was different for both estradiol-and 4-OH-TAM-ER complexes. These results suggest that ER forms different complexes with DP-TAT-59 than estradiol or 4-OH-TAM, while the ER binding affinity of these compounds are similar to each other.

Prolongation of survival period and improvement of cancer cachexia by long term administration of UFT

We assayed the antitumoral and anticachectic activity of an oral fluoropyrimidine, UFT using the Colon-26-bearing murine cachexia model in terms of the survival period and parameters corresponding to clinical symptoms. Tumor growth was inhibited by UFT dose-dependently at the dose range of 12.5-25.0 mg/kg per day. Although UFT did not show significant growth inhibition at 15.0 and 12.5 mg/kg to which UFT gave little toxicity, the survival period was shown to be superior to the case of maximum tolerated dose (25.0 mg/kg per day). Next, we compared the maximum increase of life span (ILS) value for an administration schedule of continuous 9 days and 5 weeks which mimics the clinical schedule and found that the ILS value in the latter group was superior to the former and UFT improved cachexia, in the same manner. In the following experiments, we have clarified that UFT decreased the level of both plasma interleukin-6 (IL-6) and tumorous prostaglandin E2 (PGE2) and it highly accelerated IL-6 production from Colon-26. These findings suggest that UFT therapy, in low-toxic dose, could be useful to cachectic patients with poor performance status.

Association between mRNA expression of chemotherapy-related genes and clinicopathological features in colorectal cancer: A large-scale population analysis.

To establish the individualized treatment of patients with colorectal cancer, factors associated with chemotherapeutic effects should be identified. However, to the best of our knowledge, few studies are available on this topic, although it is known that the prognosis of patients and sensitivity to chemotherapy depend on the location of the tumor and that the tumor location is important for individualized treatment. In this study, primary tumors obtained from 1,129 patients with colorectal cancer were used to measure the mRNA expression levels of the following genes associated with the effects of standard chemotherapy for colorectal cancer: 5-fluorouracil (5-FU)-related thymidylate synthase (TYMS), dihydropyrimidine dehydrogenase (DPYD) and thymidine phosphorylase (TYMP); folate-related dihydrofolate reductase (DHFR), folylpolyglutamate synthase (FPGS) and gamma-glutamyl hydrolase (GGH); irinotecan-related topoisomerase I (TOP1); oxaliplatin-related excision repair cross-complementing 1 (ERCC1); biologic agent-related vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR). Large-scale population analysis was performed to determine the association of gene expression with the clinicopathological features, in particular, the location of the colorectal cancer. From the results of our analysis of the mRNA expression of these 10 genes, we noted the strongest correlation between DPYD and TYMP, followed by TYMS and DHFR. The location of the colorectal cancer was classified into 4 regions (the right‑ and left-sided colon, rectosigmoid and rectum) and was compared with gene expression. A significant difference in all genes, apart from VEGF, was noted. Of the remaining 9 genes, the highest expression of TYMS and DPYD was observed in the right‑sided colon; the highest expression of GGH and EGFR was noted in the left-sided colon; the highest expression of DHFR, FPGS, TOP1 and ERCC1 was noted in the rectosigmoid, whereas TYMP expression was approximately equivalent in the right-sided colon and rectum, and higher than that in other locations. The data generated from this study may prove to be useful for the development of individualized chemotherapeutic treatments for patients with colorectal cancer, and will mean that the tumor location is taken into account.

Microsomal reduction of alloxan produces alloxan anion radicals

the water surface has been previously observed by us, as the pitting o f aluminum foils was increased in this area, craters on Plexiglass were only observed in Plexiglass plates immersed at the water surface, and gallstone destruction was increased if the water surface was several millimeters instead of many centimeters above the stone (unpubl.); in all cases, shock waves were reflected to the focal area. Killing of tumor cells and haemolysis in vitro were also increased near a free surface [5]. Furthermore, Carstensen reported an increased rate of killing of Drosophila larvae by unfocused shock waves if the larvae were positoned at the water surface [10]. The findings can be explained by cavitation, especially an increased generation of gas bubbles, which is easily observed in the water below the surface, and which enables bubbleshock wave interaction. There is evidence that bubble-shock wave interaction is a mechanism responsible for shock wave damage in tissues [11]. It is suggested that further attempts of tumor therapy should be undertaken with shock waves with more effective, optimized waveforms, eliminating the need for the presence of a nearby water surface. These waveforms differ f rom the forms generated by current lithotripters.

5-Chloro-2,4-dihydroxypyridine, CDHP, prevents lung metastasis of basal-like breast cancer cells by reducing nascent adhesion formation

A drug for metastasis prevention is necessary. The orally administered anticancer drug S‐1 contributes to cancer therapy. In a mouse xenograft model of metastatic breast cancer from our previous study, the administration of S‐1 inhibited lung metastasis. However, the mechanism of inhibition remains elusive. S‐1 contains 5‐chloro‐2,4‐dihydroxypyridine (CDHP), which does not have the antigrowth activity, but prevents the degradation of 5‐fluorouracil, an anticancer reagent. In this study, we found that CDHP treatment shrinks cell morphology in metastatic basal‐like breast cancer cell lines. Wound healing assays showed reduced cell migration in CDHP‐treated cells. At the molecular level, CDHP treatment reduced the number of nascent adhesions, whereas the number of mature focal adhesions was not changed. These findings indicate that CDHP impairs focal adhesion formation, which results in a reduction in cell migration. For the in vivo metastasis assay, we used a highly lung‐metastatic cell line. We xenografted them into immunodeficient mice, and administered CDHP. To determine whether CDHP prevents metastasis, we measured the weights of harvested lungs. The results showed that the lung weights of the CDHP‐treated animals were not significantly different compared to the no‐tumor controls, whereas the vehicle group showed a number of metastatic foci and an increase in lung weight. These observations indicate that CDHP administration prevents metastasis. This study reveals a novel effect of CDHP for lung metastasis prevention. Our findings may facilitate the establishment of future metastasis prevention therapies.