Induction of anti-VEGF therapy resistance by upregulated expression of microseminoprotein (MSMP).

Anti-vascular endothelial growth factor (VEGF) therapy has demonstrated efficacy in treating human metastatic cancers, but therapeutic resistance is a practical limitation and most tumors eventually become unresponsive. To identify microenvironmental factors underlying the resistance of cancer to antiangiogenesis therapy, we conducted genomic analyses of intraperitoneal ovarian tumors in which adaptive resistance to anti-VEGF therapy (B20 antibody) developed. We found that expression of the microseminoprotein, prostate-associated (MSMP) gene was substantially upregulated in resistant compared with control tumors. MSMP secretion from cancer cells was induced by hypoxia, triggering MAPK signaling in endothelial cells to promote tube formation in vitro. Recruitment of the transcriptional repressor CCCTC-binding factor (CTCF) to the MSMP enhancer region was decreased by histone acetylation under hypoxic conditions in cancer cells. MSMP siRNA, delivered in vivo using the DOPC nanoliposomes, restored tumor sensitivity to anti-VEGF therapy. In ovarian cancer patients treated with bevacizumab, serum MSMP concentration increased significantly only in non-responders. These findings imply that MSMP inhibition combined with the use of antiangiogenesis drugs may be a new strategy to overcome resistance to antiangiogenesis therapy.

Downregulation of miRNA-31 induces taxane resistance in ovarian cancer cells through increase of receptor tyrosine kinase MET.

Ovarian cancer is one of the most aggressive female reproductive tract tumors. Paclitaxel (PTX) is widely used for the treatment of ovarian cancer. However, ovarian cancers often acquire chemotherapeutic resistance to this agent. We investigated the mechanism of chemoresistance by analysis of microRNAs using the ovarian cancer cell line KFr13 and its PTX-resistant derivative (KFr13Tx). We found that miR-31 was downregulated in KFr13Tx cells, and that re-introduction of miR31 re-sensitized them to PTX both in vitro and in vivo. miR-31 was found to bind to the 3'-UTR of mRNA of MET, and the decrease in MET correlated to higher sensitivity to PTX. Furthermore, co-treatment of KFr13Tx cells with MET inhibitors sensitized the tumor cells to PTX both in vitro and in vivo. In addition, lower levels of miR31 and higher expression of MET in human ovarian cancer specimens were significantly correlated with PTX chemoresistance and poor prognosis. This study demonstrated miR31-dependent regulation of MET for chemoresistance of ovarian cancer, raising the possibility that combination therapy with a MET inhibitor and PTX will increase PTX efficacy.

Weekly paclitaxel/5-fluorouracil followed by platinum retreatment for patients with recurrent ovarian cancer: a single institution experience.

PURPOSE: Since the prognosis of recurrent ovarian cancer patients is still poor, we need to establish a useful treatment strategy to achieve their long-term survival. We treated recurrent ovarian cancer patients with weekly paclitaxel (PTX)/5-fluorouracil (5-FU) followed by platinum retreatment to investigate its clinical efficacy in a preliminary manner. METHODS: Sixteen patients with recurrent ovarian cancer, pretreated with taxane and platinum, were treated with weekly paclitaxel (PTX)/5-fluorouracil (FU). PTX (80 mg/m2) on day 1, 8, and 15 was combined with a bolus injection of 5-FU (500 mg/m2) on day 2, 9, and 16. Chemotherapy was given every four weeks. Patients with stable disease or progressive disease were subsequently retreated with a platinum-containing regimen. Response was evaluated by RECIST criteria or CA125 criteria. Toxicities were evaluated according to the National Cancer Institute-common toxicity criteria (NCI-CTC) version 3. RESULTS: Among five patients with sensitive disease, one of four patients with measurable tumor and one without measurable tumor responded to weekly PTX/5-FU. Among 11 patients with resistant disease, none of five patients with measurable tumor and three of six patients without measurable tumor responded to weekly PTX/5-FU. Overall objective response rate by weekly PTX/5-FU was 31.3% (5/16). Among 16 patients, 13 patients who showed no response or progressive disease (three with sensitive disease, ten with resistant disease) received platinum retreatment after weekly PTX/5FU. All three patients with sensitive disease and three of ten patients with resistant disease revealed response to platinum retreatment. Overall objective response rate by platinum retreatment after weekly PTX/5-FU was 46.2% (6/13). CONCLUSIONS: Weekly PTX/5FU followed by platinum retreatment could be a useful treatment strategy for recurrent ovarian cancer patients. We need to establish the standard treatment strategy for recurrent ovarian cancer patients with a poor prognosis.

Oleic acid is indispensable for intraerythrocytic proliferation of Plasmodium falciparum.

Serum-derived fatty acids are essential for the intraerythrocytic proliferation of Plasmodium falciparum in humans. We previously reported that only limited combinations of fatty acids can support long-term parasite culture, and palmitic acid (C16:0)/oleic acid (C18:1, n-9), palmitic acid (C16:0)/vaccenic acid (C18:1, n-7), or stearic acid (C18:0) are required in these combinations, implying that these fatty acids are key molecules for intraerythrocytic parasite growth (Mi-Ichi et al. 2006). Here, we analysed profiles of parasitaemia changes as well as morphologies during the erythrocytic cycle and confirmed the importance of C16:0 and C18:1, n-9. We also provide evidence that C18:1, n-9 but not other C18 monoenoic or dienoic acids maintain the synchronicity of parasite development in serum-free medium when paired with C16:0, resulting in maintained exponential growth. Thus, C18:1, n-9 is indispensable for the intraerythrocytic proliferation of P. falciparum.

Intraerythrocytic Plasmodium falciparum utilize a broad range of serum-derived fatty acids with limited modification for their growth.

Plasmodium falciparum causes the most severe form of malaria. Utilization of fatty acids in serum is thought to be necessary for survival of this parasite in erythrocytes, and thus characterization of the parasite fatty acid metabolism is important in developing a new strategy for controlling malaria. Here, we examined which combinations of fatty acids present in human serum support the continuous culture of P. falciparum in serum-free medium. Metabolic labelling and gas chromatography analyses revealed that, despite the need for particular fatty acids for the growth of intraerythrocytic P. falciparum, it can metabolize a broad range of serum-derived fatty acids into the major lipid species of their membranes and lipid bodies. In addition, these analyses showed that the parasite's overall fatty acid composition reflects that of the medium, although the parasite has a limited capacity to desaturate and elongate serum-derived fatty acids. These results indicate that the Plasmodium parasite is distinct from most cells, which maintain their fatty acid composition by coordinating de novo biosynthesis, scavenging, and modification (desaturation and elongation).

High-temperature and high-pressure in situ SCC device for synchrotron radiation diffraction experiments and application using an austenitic stainless steel.

Suppressing the stress corrosion cracking (SCC) by reducing the carbon content in austenitic stainless steels is apparently not effective on core shrouds used in boiling water reactors in Japan: trans-granular cracking was found in the shrouds. To clarify the mechanism of the cracking, in situ stress measurements on specimens under stretched conditions in hot water have been attempted in the present study. An in situ device for diffraction measurements at synchrotron radiation facilities has been developed, and in situ experiments have been carried out at SPring-8. The SUS316L steel specimen was solution heat-treated, surface-ground and then placed in the in situ device. Sapphire windows were used for the light path in the device. A sufficient diffracted beam intensity was obtained through two sapphire windows and water. The side-inclination method was used for measuring the stress exerted on the specimen. A 2theta-sin2psi plot showed that a tensile stress was induced. The measured stress value is considered to be the summation of stresses owing to pre-straining, in situ loading and residual stress owing to surface grinding.

Effects of mifepristone (RU486) treatment on the development of uterine adenomyosis induced by pituitary grafting in mice.

To evaluate the effects of mifepristone (RU486) on the development of uterine adenomyosis induced by pituitary grafting (PG), 3 groups of mice receiving pituitary grafts at 7 weeks of age were given RU486 in food (20 mg/kg chow) from 3-14 (RU486-3 group) or 10-14 (RU486-10 group) weeks of age, or were given no further treatment (PG control group), respectively. All the mice were killed at 14 weeks of age. The uterine weight was significantly decreased in both RU486-treated groups compared with the PG control group. The incidence of adenomyosis was also decreased significantly in both the RU486-3 group (0/10 mice) and RU486-10 group (2/10 mice) compared with the PG control group (7/9 mice). To look for vascular changes in the uterine tissues, which have been reported to be related to the development of adenomyosis, immunohistochemical staining of von Willebrand factor in the blood vessels was performed. The mean surface area and minor axis of blood vessels in the uterus were thereby found to be significantly decreased in the RU486-10 group compared to the PG control group. The results clearly indicated that RU486, a potent antiprogestin, could inhibit the genesis of uterine adenomyosis in mice, and at the same time caused shrinkage of the vascular system. As in humans, progesterone as well as the vascular system therefore appear to be important factors in the pathogenesis of uterine adenomyosis in this mouse model.

Vacuolar H(+)-ATPase localized in plasma membranes of malaria parasite cells, Plasmodium falciparum, is involved in regional acidification of parasitized erythrocytes.

Recent biochemical studies involving 2',7'-bis-(2-carboxyethyl)-5, 6-carboxylfluorescein (BCECF)-labeled saponin-permeabilized and parasitized erythrocytes indicated that malaria parasite cells maintain the resting cytoplasmic pH at about 7.3, and treatment with vacuolar proton-pump inhibitors reduces the resting pH to 6.7, suggesting proton extrusion from the parasite cells via vacuolar H(+)-ATPase (Saliba, K. J., and Kirk, K. (1999) J. Biol. Chem. 274, 33213-33219). In the present study, we investigated the localization of vacuolar H(+)-ATPase in Plasmodium falciparum cells infecting erythrocytes. Antibodies against vacuolar H(+)-ATPase subunit A and B specifically immunostained the infecting parasite cells and recognized a single 67- and 55-kDa polypeptide, respectively. Immunoelectron microscopy indicated that the immunological counterpart of V-ATPase subunits A and B is localized at the plasma membrane, small clear vesicles, and food vacuoles, a lower extent being detected at the parasitophorus vacuolar membrane of the parasite cells. We measured the cytoplasmic pH of both infected erythrocytes and invading malaria parasite cells by microfluorimetry using BCECF fluorescence. It was found that a restricted area of the erythrocyte cytoplasm near a parasite cell is slightly acidic, being about pH 6.9. The pH increased to pH 7.3 upon the addition of either concanamycin B or bafilomycin A(1), specific inhibitors of vacuolar H(+)-ATPase. Simultaneously, the cytoplasmic pH of the infecting parasite cell decreased from pH 7.3 to 7.1. Neither vanadate at 0.5 mm, an inhibitor of P-type H(+)-ATPase, nor ethylisopropylamiloride at 0.2 mm, an inhibitor of Na(+)/H(+)-exchanger, affected the cytoplasmic pH of erythrocytes or infecting parasite cells. These results constitute direct evidence that plasma membrane vacuolar H(+)-ATPase is responsible for active extrusion of protons from the parasite cells.

Preventive effects of sulphasalazine on colorectal carcinogenesis in mice with ulcerative colitis.

Sulphasalazine has been used in the treatment of ulcerative colitis and is known to be a prodrug and split into sulphapyridine and 5-aminosalicylic acid by bacteria in the colon. An increased incidence of colorectal carcinoma is known to occur in patients with ulcerative colitis, which displays a recurrence-remission cycle on colorectal mucosa, i.e., the ulceration and regeneration periods of the colorectal mucosa. Repeated mucosal necrosis-regeneration sequence in chronic ulcerative colitis induced with 3% dextran sulfate sodium led to colorectal carcinogenesis in azoxymethane-pretreated mice. Additive treatment with sulphasalazine normalized the enlarged organs, i.e. liver, spleen and kidney and anemia and leucocytosis induced with 3% dextran sulfate sodium resulted in the reduction of tumorous regions with high-grade dysplasia.

Preventive effects of a herbal medicine on bone loss in rats treated with a GnRH agonist.

The study was designed to evaluate the effects of a traditional Chinese herbal medicine Hochu-ekki-to (Bu-zong-yi-qi-tang), which was composed of 10 herbal medicines and had been used for the treatment of oligospermia and as a postoperative medication in Japan, on bone loss in rats treated with a gonadotropin-releasing hormone (GnRH) agonist. Female rats at 40 weeks of age were divided into 4 groups of 8 rats each. In the three experimental groups, each animal received subcutaneous injections of the long-acting GnRH agonist, buserelin acetate, once every four weeks throughout the experiment. Beginning at 48 weeks of age, the experimental groups were given diets containing conjugated estrogens or Hochu-ekki-to for 8 weeks. The administration of the GnRH agonist reduced the bone mineral density in the whole femur to 91.0% of that in the control group. However, administration of conjugated estrogens and Hochu-ekki-to increased the serum concentrations of estradiol 16.8- and 5.3-fold respectively compared with concentrations in the GnRH agonist-treated group, resulting in the augmentation of the bone mineral density to 110.3% and 106.2% respectively. These findings indicate that Hochu-ekki-to enhances the reduced bone mineral density and causes a slight elevation of the serum estradiol levels in the chemically castrated rats.

Effects of lentinan on colorectal carcinogenesis in mice with ulcerative colitis.

Lentinan; i.e., polysaccharides extracted from a kind of black mushroom shiitake, has been clinically applied as an antitumor and antimetastatic drug, and has been reported to prevent both chemical and viral carcinogenesis. It is known that lentinan affects the tumorous vascular system resulting in the induction of hemorrhagic necrosis which is dependent on T-cells in the tumor. Repeated mucosal necrosis-regeneration sequence in chronic ulcerative colitis induced with 3% dextran sulfate sodium led to colorectal carcinogenesis in azoxymethane-pretreated mice. In the present study, the additive treatment with lentinan in the azoxymethane-dextran sulfate sodium treated mice enhanced the colorectal high-grade dysplasia, though not significantly, and the splenic weight. This may show the proliferation of pathogenic splenic T cells resulting in a change for the worse of ulcerative colitis, anemia induced with hemorrhage and colorectal carcinogenesis; i.e., high-grade dysplasia of the mucosa and/or invasive adenocarcinomas of the colorectum. The present results may recommend chemoimmunotherapy while using lentinan, but not immunotherapy using lentinan alone, is indicated for the management of cancer patients.

Does macrophage-colony stimulating factor stimulate rat haematopoietic cells?

It is known that colony stimulating factors (CSFs) stimulate the myeloid cells of bone marrow and splenic cells in rodents. The effects of macrophage (M)-CSF on the activities of thymidylate synthase and thymidine kinase, involved in de novo and salvage pathways for pyrimidine nucleotide synthesis, respectively, in haematopoietic cells of bone marrow and spleen were investigated in rats. A single M-CSF injection did not elevate the mRNA expression levels of the enzymes in bone marrow cells 6 h after treatment, but it enhanced the splenic thymidylate synthase mRNA expression. M-CSF stimulated the splenic thymidylate synthase activity without an increase of the peripheral granulocytes. The effect of M-CSF on granulocytes is considered to be weak compared with that of granulocyte (G)-CSF, because of the indirect secretion of endogenous G-CSF from the cells with M-CSF receptors stimulated by exogenous M-CSF. Since M-CSF was able temporarily to lead progenitor cells from long G1-phase into S-phase, M-CSF might accelerate the anticancer effects when used together with anticancer agents.

Importance of the major extracellular domain of CD9 and the epidermal growth factor (EGF)-like domain of heparin-binding EGF-like growth factor for up-regulation of binding and activity.

Heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) is a member of the EGF family of growth factors. The membrane-anchored form of HB-EGF (proHB-EGF) is mitogenically active to neighboring cells as well as being a precursor of the soluble form. In addition to its mitogenic activity, proHB-EGF has the property of binding to diphtheria toxin (DT), serving as the specific receptor for DT. Tetramembrane-spanning protein CD9, a member of the TM4 superfamily, is physically associated with proHB-EGF at the cell surface and up-regulates both mitogenic and DT binding activities of proHB-EGF. To understand this up-regulation mechanism, we studied essential regions of both CD9 and proHB-EGF for up-regulation. Immunoprecipitation experiments revealed that not only CD9 but also other TM4 proteins including CD63, CD81, and CD82 associate with proHB-EGF on the cell surface. However, these TM4 proteins did not up-regulate DT binding activity of proHB-EGF. Transfection of a series of chimeric constructs comprising CD9 and CD81 showed that the major extracellular domain of CD9 is essential for up-regulation. Assays of DT binding activity and juxtacrine mitogenic activity of the deletion mutants of proHB-EGF and chimeric molecules, derived from proHB-EGF and TGF-alpha, showed that the essential domain of proHB-EGF for up-regulation is the EGF-like domain. These results indicate that the interaction of the extracellular domains of both molecules is important for up-regulation.

Neutral sphingomyelinase activity dependent on Mg2+ and anionic phospholipids in the intraerythrocytic malaria parasite Plasmodium falciparum.

Sphingolipid metabolism and metabolites are important in various cellular events in eukaryotes. However, little is known about their function in plasmodial parasites. Here we demonstrate that neutral sphingomyelinase (SMase) involved in the sphingomyelin (SM) catabolism is retained by the intraerythrocytic parasite Plasmodium falciparum. When assayed in a neutral pH buffer supplemented with Mg(2+) and phosphatidylserine, an activity for the release of the phosphocholine group from SM was detected in parasite-infected, but not in uninfected, erythrocyte ghosts. The SMase activity in the parasite-infected erythrocyte ghosts was enhanced markedly by anionic phospholipids including unsaturated but not saturated phosphatidylserine. Mn(2+) could not substitute for Mg(2+) to activate SMase in parasite-infected erythrocyte ghosts, whereas both Mn(2+) and Mg(2+) activated mammalian neutral SMase. The specific activity level of SMase was higher in isolated parasites than in infected erythrocyte ghosts; further fractionation of lysates of the isolated parasites showed that the activity was bound largely to the membrane fraction of the parasites. The plasmodial SMase seemed not to hydrolyse phosphatidylcholine or phosphatidylinositol. The plasmodial SMase, but not SM synthase, was sensitive to scyphostatin, an inhibitor of mammalian neutral SMase, indicating that the plasmodial activities for SM hydrolysis and SM synthesis are mediated by different catalysts. Our finding that the malaria parasites possess SMase activity might explain why the parasites seem to have an SM synthase activity but no activity to synthesize ceramide de novo.

Serum factors governing intraerythrocytic development and cell cycle progression of Plasmodium falciparum.

Malaria is clinically manifested only when the human malaria parasites in the genus Plasmodium enter the obligatory intraerythrocytic life cycle. Elucidation for the roles of the serum, the key nutrient, and its components is then deemed essential for thorough understanding of the proliferation of Plasmodium cells at the erythrocytic stage. Fractionation and analysis of serum and its components was performed by chromatography, solvent extraction, and subsequent reconstitution experiments. Only fractions containing serum albumin (SA) from the serum and purified intact bovine serum albumin (BSA) showed comparable growth promoting activity with human serum (HS). Delipidated BSA can only effect parasite growth after reconstitution with lipids extracted from intact BSA. Fatty acid (FA) species in the neutral lipid fraction from intact BSA proved likewise when reconstituted with delipidated BSA. Furthermore, the involved FA species have to come in a pair of one saturated and one unsaturated, with palmitic and oleic acids as the best combination. The results were further substantiated by morphological analysis as well as biochemical analysis of the DNA synthesis during the intraerythrocytic development. This study can be a basis to explore the molecular mechanism of lipid traffic within the parasitized red blood cell (RBC), which can be an important adjunct to the development of drugs for malaria therapy.

Correlation between histological differentiation and DNA-synthesizing enzymes in rat colorectal tumors induced with 1, 2-dimethylhydrazine.

Thymidylate synthase and thymidine kinase are key enzymes involved in de novo and salvage pathways for pyrimidine nucleotide synthesis. Colorectal carcinogenesis induced with 1,2-dimethylhydrazine in rats enhanced mRNA expression levels of both enzymes, resulting in the increase of both enzyme activities and bromodeoxyuridine-immunoreactive S-phase cells. Poorly and well differentiated adenocarcinomas of the colorectum showed the relative elevation of activities of thymidylate synthase and thymidine kinase, respectively. These results indicate that the relationship between de novo and salvage pathways for pyrimidine nucleotide synthesis may depend on the histopathological grades of cell differentiation.

Prevention of osteopenia induced with a gonadotropin-releasing hormone agonist in rats.

We investigated the effects of conjugated estrogens as an add-back replacement drug, incadronate sodium as a bisphosphonate, and alfacalcidol as a vitamin D(3) analog on femoral bone mineral density (BMD) and bone mineral content (BMC) in female rats chronically treated with the gonadotropin-releasing hormone (GnRH) agonist leuprorelin acetate. The chemical castration of the rats by the administration of GnRH agonist for 16 weeks reduced the BMD values to 92.3%, 91.3%, and 93.3% of those of the normal control animals in the whole femur, metaphysis, and diaphysis of the femur, respectively. The BMC value was decreased to 91.0% of that of the normal control animals by the chronic GnRH agonist treatment. However, a simultaneous 8-week administration of conjugated estrogens, bisphosphonate, and vitamin D(3) analog markedly augmented the BMC values to 110.3%, 110.1%, and 114.4%, respectively, of those in the rats treated with the GnRH agonist alone. These findings indicate that antiosteoporotic agents could be useful for preventing induced osteopenia under the careful monitoring of biochemical markers of osteoblastic activity or bone resorption and BMD or BMC in patients undergoing GnRH treatment.

Cycloprodigiosin hydrochloride obtained from Pseudoalteromonas denitrificans is a potent antimalarial agent.

Cycloprodigiosin hydrochloride (cPrG*HCl) is a stable fluorescent red pigment obtained from the marine bacterium Pseudoalteromonas denitrificans. It was found that the compound was incorporated into Plasmodium falciparum cells upon incubation and exhibited a potent antimalarial activity with the concentration required for 50% of the activity being 11 nM, which is stronger than that of chloroquine, a well-known antimalarial agent. The compound did not affect growth rate of mammalian cells. Antimalarial activity of cPrG*HCl was also observed in vivo. These results indicate that cPrG*HCl is a potent antimalarial drug.