A mathematical model of population dynamics for Batesian mimicry system.

We analyse a mathematical model of the population dynamics among a mimic, a corresponding model, and their common predator populations. Predator changes its search-and-attack probability by forming and losing its search image. It cannot distinguish the mimic from the model. Once a predator eats a model individual, it comes to omit both the model and the mimic species from its diet menu. If a predator eats a mimic individual, it comes to increase the search-and-attack probability for both model and mimic. The predator may lose the repulsive/attractive search image with a probability per day. By analysing our model, we can derive the mathematical condition for the persistence of model and mimic populations, and then get the result that the condition for the persistence of model population does not depend on the mimic population size, while the condition for the persistence of mimic population does depend the predator's memory of search image.

Subunit interactions within the Chlamydomonas flagellar spokehead.

The radial spoke (RS)/central pair (CP) system in cilia and flagella plays an essential role in the regulation of force generation by dynein, the motor protein that drives cilia/flagella movements. Mechanical and mechanochemicl interactions between the CP and the distal part of the RS, the spokehead, should be crucial for this control; however, the details of interaction are totally unknown. As an initial step toward an understanding of the RS-CP interaction, we examined the protein-protein interactions between the five spokehead proteins (radial spoke protein (RSP)1, RSP4, RSP6, RSP9, and RSP10) and three spoke stalk proteins (RSP2, RSP5, and RSP23), all expressed as recombinant proteins. Three of them were shown to have physiological activities by electroporation-mediated protein delivery into mutants deficient in the respective proteins. Glutathione S-transferase pulldown assays in vitro detected interactions in 10 out of 64 pairs of recombinants. In addition, chemical crosslinking of axonemes using five reagents detected seven kinds of interactions between the RS subunits in situ. Finally, in the mixture of the recombinant spokehead subunits, RSP1, RSP4, RSP6, and RSP9 formed a 7-10S complex as detected by sucrose density gradient centrifugation. It may represent a partial assembly of the spokehead. From these results, we propose a model of interactions taking place between the spokehead subunits.

Suppression of ovarian cancer by muscle-mediated expression of soluble VEGFR-1/Flt-1 using adeno-associated virus serotype 1-derived vector.

Vascular endothelial growth factor (VEGF) is known to play a major role in angiogenesis in a variety of tumors. A soluble form of Flt-1 (sFlt-1), a VEGF receptor, is potentially useful as an antagonist of VEGF, and accumulating evidences suggest the applicability of sFlt-1 in tumor suppression by means of anti-angiogenesis. We previously demonstrated the efficacy of sflt-1 gene expression in situ to suppress tumor growth and ascites in ovarian cancer. Here, we demonstrate the therapeutic applicability of muscle-mediated expression of sFlt-1 in tumor-bearing mice. Initially, tumor suppressive action was confirmed by inoculating sFlt-1-expressing ovarian cancer (SHIN-3) cells into mice, both subcutaneously and intraperitoneally. To validate the therapeutic efficacy in a more clinically relevant model, adeno-associated virus vectors encoding sflt-1 were introduced into mouse skeletal muscles and were subsequently inoculated with tumor cells. As a result, high serum sFlt-1 levels were constantly observed, and the growth of both subcutaneously- and intraperitoneally-inoculated tumors was significantly suppressed. No delay in wound healing or adverse events of neuromuscular damage were noted, body weight did not change, and laboratory data, such as those representing liver and renal functions, were not affected. These results indicate that sFlt-1 suppresses growth and peritoneal dissemination of ovarian cancer by the inhibition of angiogenesis, and thus suggest the usefulness of gene therapy for ovarian cancer.

Radial spoke proteins of Chlamydomonas flagella.

The radial spoke is a ubiquitous component of '9+2' cilia and flagella, and plays an essential role in the control of dynein arm activity by relaying signals from the central pair of microtubules to the arms. The Chlamydomonas reinhardtii radial spoke contains at least 23 proteins, only 8 of which have been characterized at the molecular level. Here, we use mass spectrometry to identify 10 additional radial spoke proteins. Many of the newly identified proteins in the spoke stalk are predicted to contain domains associated with signal transduction, including Ca2+-, AKAP- and nucleotide-binding domains. This suggests that the spoke stalk is both a scaffold for signaling molecules and itself a transducer of signals. Moreover, in addition to the recently described HSP40 family member, a second spoke stalk protein is predicted to be a molecular chaperone, implying that there is a sophisticated mechanism for the assembly of this large complex. Among the 18 spoke proteins identified to date, at least 12 have apparent homologs in humans, indicating that the radial spoke has been conserved throughout evolution. The human genes encoding these proteins are candidates for causing primary ciliary dyskinesia, a severe inherited disease involving missing or defective axonemal structures, including the radial spokes.

Inhibition of peritoneal dissemination of ovarian cancer by tyrosine kinase receptor inhibitor SU6668 (TSU-68).

SU6668 (TSU-68) is a small-molecule synthetic inhibitor of the angiogenic related receptor tyrosine kinases Flk-1/KDR, PDGFRbeta, and FGFR1. Using a mouse model of peritoneally disseminated ovarian cancer, we investigated whether SU6668 inhibits peritoneal dissemination and prolongs survival time. BALB/c nude mice were intraperitoneally (i.p.) inoculated with SHIN-3 (VEGF-hypersecretory) or KOC-2S (PDGF-hypersecretory) ovarian serous adenocarcinoma cells with marked peritoneal dissemination ability. From the day after i.p. inoculation of tumor cells, SU6668 was orally administered 6 times weekly at a daily dose of 100 mg/kg or 400 mg/kg. The SU6668-administered group and the vehicle-administered control group were compared for the number of tumor vascular endothelial cells, weight of peritoneally disseminated tumors, amount of ascitic fluid and survival time. As a result, these 3 parameters were significantly smaller in the SHIN-3-inoculated, SU6668-administered mice than in the control group (p = 0.03, p = 0.002, and p = 0.02, respectively). The mean survival time was significantly longer, at 58.1 +/- 11.2 days, in the SU6668-administered mice than that (34.5 +/- 8.8 days) in the control group (p = 0.002). Similarly, in the KOC-2S-inoculated mice, the oral administration of SU6668 significantly reduced these 3 parameters (p = 0.04, p = 0.04, and p = 0.03, respectively), and significantly prolonged survival (16.6 +/- 1.7 days vs. 11.0 +/- 0.7 days, p = 0.008). Thus, the oral administration of SU6668 inhibited angiogenesis and peritoneal dissemination and prolonged survival in mice with peritoneally disseminated ovarian cancer. These effects were observed with both the VEGF- and PDGF-hypersecretory cell lines. Our results suggest that molecular targeting with oral SU6668 will become a new therapeutic strategy targeting peritoneally disseminated ovarian cancer.

Antinuclear antibody reduces the pregnancy rate in the first IVF-ET treatment cycle but not the cumulative pregnancy rate without specific medication.

PROBLEM: It has been shown that the presence of antinuclear antibody (ANA) might reduce pregnancy rates after in vitro fertilization-embryo transfer (IVF-ET). However, the mechanism of implantation failure by ANA has not yet been clarified. This study was performed to investigate the impact of ANA on pregnancy rates after IVF-ET, and the necessity of specific medication for infertile women who have ANA in their sera. METHOD OF STUDY: A total of 108 infertile women were treated by IVF-ET or intracytoplasmic sperm injection (ICSI)-ET. ANA was examined by an indirect fluorescent antibody procedure. Data from women under 40 years old were analyzed retrospectively. RESULTS: The implantation rates per embryo transferred in the first treatment cycles were 14.8% (eight of 54) and 32.4% (33 of 102), in women with and without ANA, respectively. There was a significant difference in the implantation rates between the two groups (P < 0.05). The pregnancy rates per ET in the first treatment cycles were 28% (seven of 25) and 54.2% (26 of 48), respectively. There was also a significant difference in the pregnancy rates between the two groups (P < 0.05). Afterwards, treatments with IVF-ET or ICSI-ET were repeatedly performed for unsuccessful patients, without any specific medication for ANA. The average ET cycles were 1.80 +/- 1.13 and 1.27 +/- 0.54, in women with and without ANA, respectively. The cumulative pregnancy rates per patient were 68% (17 of 25) and 55.6% (35 of 63), respectively. There was no significant difference in the overall pregnancy rates between the two groups. CONCLUSIONS: These findings suggest that ANA might have an impact on implantation failure in women treated by IVF-ET or ICSI-ET. ANA reduced the pregnancy rates in the first IVF-ET or ICSI-ET cycles but not the cumulative pregnancy rates without medication. This indicates that the mechanisms of implantation failure by ANA could be solved, and effective and safe medication should be developed for better implantation rates, especially in the first treatment cycle.

Interleukin-10-mediated inhibition of angiogenesis and tumor growth in mice bearing VEGF-producing ovarian cancer.

Interleukin-10 (IL-10) is an immunosuppressive cytokine produced by T lymphocytes and drawing attention as an inhibitor of tumor angiogenesis. In this study, we investigated antiangiogenic and tumor suppressive effects of IL-10 in ovarian cancer cells. mIL-10-expressing plasmid was transferred into two ovarian cancer cell lines, SHIN-3 [vascular endothelial growth factor (VEGF) producing] and KOC-2S (non-VEGF producing). After selection, mIL-10-expressing cells were obtained as SHIN-3/mIL-10 and KOC-2S/mIL-10. No significant differences were observed in in vitro growth properties between mIL-10-expressing cells and control (luciferase expressing) cells in either KOC-2S or SHIN-3. The angiogenic activities of mIL-10-expressing cells were measured by dorsal air sac assay, which detected the number of newly formed blood vessels within a chamber in vivo. In addition, tumor formation was evaluated by s.c. tumor transplantation, and survival was monitored after i.p. injection of ovarian cancer cells into BALB/c nude mice. Both in vivo angiogenic activity and tumor growth were significantly inhibited in SHIN-3/mIL-10 cells compared with the control. Moreover, peritoneal dissemination was inhibited, and the survival period was significantly prolonged (mean survival days > 90 versus 36). In contrast, in the case of KOC-2S cells, no significant differences were observed in any of the parameters tested. These results indicate that IL-10 has suppressive effects on angiogenesis, tumor growth, and peritoneal dissemination of VEGF-producing ovarian cancer cells. Although the mechanisms of the antiangiogenic effect of IL-10 are still unclear, the potential usefulness of IL-10-mediated gene therapy of ovarian cancer was suggested.

Overexpression of thymidylate synthase mediates desensitization for 5-fluorouracil of tumor cells.

The prognosis of cancers of various organs overexpressing thymidylate synthase (TS) has been reported to be poor. It has been suggested that the poor prognosis is partly due to a low sensitivity of TS-overexpressing tumors to TS-targeting 5-fluorouracil (5-FU). To investigate the relationship between TS expression and sensitivity to 5-FU, we used the TS-overexpressing cervical cancer cell line SKG-II/TS and SKG-I/TS that had been established by TS gene transfer. The 50% growth inhibitory concentration (IC(50)) of 5-FU for SKG-II/TS was 24 +/- 6.0 microM, which was 6 times as high as that for the control (4.0 +/- 1.1 microM), showing significantly decreased sensitivity to 5-FU (p < 0.01). The IC(50) of 5-FU for SKG-I/TS was 90 +/- 15 microM, which was over 2 times as high as that for the control (40 +/- 0.6 microM), showing significantly decreased sensitivity to 5-FU (p < 0.05). Thus, TS-overexpressing tumors have decreased sensitivity to 5-FU, which may be one of the factors that determine the prognosis of these tumors.

A feasibility study of paclitaxel and carboplatin therapy in Japanese patients with epithelial ovarian cancer.

The aim of this study was clarification of the feasibility, effects, and adverse events of combination chemotherapy with paclitaxel and carboplatin in Japanese women with epithelial ovarian cancer. In patients with stage Ic to IV epithelial ovarian cancer, primary cytoreductive surgery was performed. Paclitaxel (175 mg/m(2)) was intravenously infused for 3 h. Subsequently, carboplatin was infused, with an area under the plasma concentration-time curve of 5. Ninety-one patients were enrolled in this study. The mean dose of paclitaxel at the sixth course was 161 mg/m(2). Of 51 patients, a complete response was observed in 19 patients (37%), and a partial response in 23 patients (45%). The response rate for clear cell adenocarcinoma was 25%. With regard to adverse events, grade 4 granulopenia was observed in 80% of patients, suggesting dose-limiting toxicity. However, none of the patients developed serious infection. With regard to non-hematological toxicity, grade 2 or 3 alopecia, arythralgia/myalgia, and peripheral neurotoxicity were noted in 97, 29, and 20% of the patients, respectively. Although hematological toxicity was relatively marked, this regimen can be applied in Japanese women.

Overexpression of PTEN increases sensitivity to SN-38, an active metabolite of the topoisomerase I inhibitor irinotecan, in ovarian cancer cells.

PURPOSE: PTEN is a tumor suppressor gene that was identified on chromosome 10q23. In addition to its original function as a tumor suppressor, this gene product was recently reported to enhance the sensitivity of cancer cells to anticancer agents. It is for the purpose of this study to investigate its function and the mechanisms by which PTEN enhances the sensitivity of ovarian cancer to antitumor agents. EXPERIMENTAL DESIGN: PTEN cDNA was introduced into the ovarian cancer cell line SHIN-3 and a high-expression cell line (SHIN-3/PTEN) was established. This cell line and a control were further analyzed. RESULTS: SHIN-3 cells did not carry any mutations in its genome after sequencing. In vitro examination of sensitivity to anticancer agents showed that the 50% growth-inhibitory concentration value for irinotecan metabolite (SN-38) in SHIN-3/PTEN was 800 nM, a 6.6-fold higher sensitivity compared with that of the control (5300 nM). There were no differences in sensitivity to cisplatin, paclitaxel, or gemcitabine between SHIN-3/PTEN and the controls. The percentage of apoptotic cells in SHIN-3/PTEN was 16.6 +/- 0.7% 24 h after addition of SN-38, a significant increase over controls (8.6 +/- 0.9%; P < 0.01). Lower topoisomerase I activity was observed in SHIN-3/PTEN, compared with controls. CONCLUSIONS: These results indicate that high PTEN expression enhances the sensitivity of ovarian cancer cells to irinotecan and the induction of apoptosis and the suppression of topoisomerase I activity in cancer cells are suggested as possible mechanisms attributable to high PTEN expression.

Soluble FLT-1 expression suppresses carcinomatous ascites in nude mice bearing ovarian cancer.

Vascular endothelial growth factor (VEGF), a bifunctional protein enhancing vascular permeability and stimulating endothelial growth, is thought to be responsible for fluid accumulation and angiogenesis in ascites tumors. To investigate the effects of stable expression of the soluble form of Flt-1 VEGF receptor (sFlt-1), a known endogenous inhibitor of VEGF, on the malignant ascites tumors, we cotransduced RMG-1 human ovarian cancer cells with adeno-associated virus vectors carrying the sFlt-1 cDNA and Neo gene or Neo gene alone and isolated both the sFlt-1-expressing clone and the Neo-expressing clone. In vitro growth characteristics were essentially the same. As expected, conditioned medium collected from the sFlt-1-expressing cells significantly inhibited the human umbilical vein endothelial cell proliferation in the presence of recombinant VEGF. Expression of sFlt-1 significantly suppressed RMG-1 cell-induced angiogenesis in vivo in the mouse dorsal air sac assay model. We then inoculated sFlt-1- or Neo alone-expressing cells i.p. into female BALB/c nude mice. The average volume of ascites fluid, number of leaked RBCs, and number of cancer cells were significantly lower in mice injected with sFlt-1-expressing cells than in the controls. Survival time was significantly prolonged in mice injected with sFlt-1-expressing cells. These results suggest that inhibition of VEGF activity by sFlt-1 expression may provide a means to control carcinomatous ascites and angiogenesis of malignant ascites tumors.

Involvement of microsatellite instability in lymph node metastasis of endometrial carcinoma.

We evaluated microsatellite instability (MSI) in primary lesions and lymph node metastatic lesions in 66 patients with endometrial carcinoma (FIGO stage IIIC) accompanied by lymph node metastasis. DNA was extracted from paraffin-embedded tissue of both the primary and lymph node metastatic lesions of endometrial carcinoma, and MSI was evaluated using microsatellite markers at five loci. Microsatellite instability was positive in the primary lesion in 27 patients (41%). All patients with MSI-positive primary lesions also showed MSI-positive in lymph node metastatic lesions. Of the other 39 patients with MSI-negative primary lesions, 4 showed MSI-positive in lymph node metastatic lesions. As the result of individual identification by polymerase chain reaction (PCR) using short tandem repeat loci in these 4 patients, PCR profiles of primary and metastatic lesions matched with those of normal controls in all 4 patients. Therefore, it was confirmed that both primary and metastatic lesions developed from the same individual. These results suggest that MSI is also involved in lymph node metastasis in the development and/or progression of endometrial carcinoma in some patients.