Teruhiko Tamaya

Coexpression of Gas6/Axl in Human Ovarian Cancers

Objectives: Gas6, the protein product of the growth arrest-specific gene 6 (gas6), a member of the vitamin K-dependent protein family, was identified as a ligand for the Axl/Sky family of receptor tyrosine kinases. The aim is to study for the presence of Gas6 and its receptor Axl and Sky related to specific growth in the ovarian cancers, and to evaluate their plausible growth potential and mechanism. Methods: In ovarian cancers of 90 cases, the histoscores and mRNA levels of Gas6, Axl and Sky were determined by immunohistochemistry and competitive reverse transcription-polymerase chain reaction-Southern blot analysis using the recombinant RNA, respectively. Results: The histoscores and mRNA levels of Gas6 and Axl in ovarian cancers were significantly higher than in normal ovaries, regardless of histopathological type or clinical stage of ovarian cancers. Conclusions: Gas6/Axl pathway could play a role in the complex events taking place during the early changes of ovarian cancer progression.

Biologic implications of the expression of vascular endothelial growth factor subtypes in ovarian carcinoma

Vascular endothelial growth factor (VEGF) has been identified as an important factor for tumor angiogenesis, which is essential for the growth, invasion, and metastasis of solid tumors. This study examines the clinical significance of VEGF subtypes in ovarian carcinoma.

Expression of vascular endothelial growth factor (VEGF) and its mRNA in uterine cervical cancers

SummaryTo know the potential of growth, invasion and metastasis of uterine cervical cancer associated with neovascularization, localization of vascular endothelial growth factor (VEGF) and microvessel density in tumours were determined by immunohistochemical staining, the levels of VEGF subtypes were determined by Western blot analysis and by a sandwich enzyme immunoassay, and the levels of VEGF subtype mRNAs were determined by reverse transcription polymerase chain reaction (RT-PCR) – Southern blot analysis in uterine cervical cancers. The relation between VEGF subtype expressions and microvessel density, histological types and clinical stages of uterine cervical cancers was analysed. The expression of VEGF was seen dominantly in the cancer cells, and correlated with microvessel density in uterine cervical cancers. Among the four subtypes of VEGF, the populations of VEGF165 and VEGF121 were dominant in normal uterine cervices and uterine cervical cancers. The levels of VEGF and VEGF165 and VEGF121 mRNAs were remarkably higher in some stage II and III/IV adenocarcinomas of the cervix than in other cases, including normal cervices. Therefore, the elevation of VEGF165 and VEGF121 might contribute to the relatively late advancing via angiogenic activity in some adenocarcinomas of the cervix.

Expressions of vascular endothelial growth factor (VEGF) and its mRNA in uterine endometrial cancers

To know the potential of growth, invasion and metastasis of uterine endometrial cancer associated with neovascularization, the expressions of VEGF and its mRNA, especially their subtypes, in uterine endometrial cancers and normal uterine endometria as controls were determined by Western blot analyses with a sandwich enzyme immunoassay and RT-PCR-Southern blot analysis, respectively, and the relation between their expressions and histological grades, grades of myometrial invasion and clinical stages of uterine endometrial cancers was analyzed. The levels of VEGF (VEGF165 and VEGF121) protein and mRNA were in a wide range and higher in normal uterine endometria than in the malignant counterparts. The levels of VEGF protein were higher in order of histopathological differentiation (normal uterine endometrium > well-differentiated (G1) > moderately differentiated (G2) and poorly differentiated (G3)) and those of VEGF protein and VEGF121 mRNA were lower in order of the advance of clinical stages (normal uterine endometrium > stage I > stage II > stages III and IV). There was, however, no significant difference in their levels among uterine endometrial cancers classified according to grades of myometrial invasion. This suggests that VEGF is downregulated during uterine endometrial cancer progression with dedifferentiation. Namely, VEGF in some endometrial cancers might contribute to the early process of advancing of malignancy via angiogenic activity.

Expression of platelet-derived endothelial cell growth factor (PD-ECGF) and its mRNA in uterine cervical cancers.

SummaryAngiogenesis contributes to the growth and secondary spreading of solid tumours. Platelet-derived endothelial cell growth factor (PD-ECGF) is identified as such an angiogenic factor. In the present study, the prognosis of the patients with high PD-ECGF uterine cervical cancers was worse than those with low PD-ECGF cancers, and PD-ECGF expression correlated with cellular proliferation and with vascular density and venous invasion in uterine cervical cancers. Therefore, PD-ECGF might contribute to the growth of uterine cervical cancers via angiogenesis related to vascular spreading. Furthermore, PD-ECGF and its mRNA had a wide range and were highly expressed in uterine cervical cancers, especially squamous cell carcinoma, regardless of clinical stage. Therefore, PD-ECGF in uterine cervical cancers might play a role of basic angiogenesis in all processes of advancing of uterine cervical cancers. This indicates that 5′-deoxy-5-fluorouridine might be highly effective in squamous cell carcinoma of the cervix, which possesses a high activity of thymidine phosphorylase to convert 5′-deoxy-5-fluorouridine to 5-fluorouracil, and that some angiogenic inhibitors of new capillary formation might be effective in the inhibition of tumour growth and spreading associated with angiogenesis.

Clinical Implications of the Expression of Estrogen Receptor-α and -β in Primary and Metastatic Lesions of Uterine Endometrial Cancers

Novel human estrogen receptor (ER)-β was identified in cDNA libraries from human testes. ER-β specifically expresses in the testis, ovary, thymus, spleen, osteoblasts, fetus and uterine endometrium. ER-β might not conserve the same physiological functions as does ER-α. Therefore, expressions of ER-α and ER-β mRNAs in primary and metastatic lesions of uterine endometrial cancers were investigated. The levels of ER-β mRNA were significantly lower than those of ER-α mRNA in uterine endometrial cancers and in normal uterine endometria. The ratio of ER-β to ER-α mRNA in most primary uterine endometrial cancers was similar to that in normal uterine endometria (<0.4% of ER-β mRNA to ER-α mRNA). On the other hand, in 14 of the 20 lymph node metastasis-positive cases of uterine endometrial cancers, the ratio in the metastatic lesion was significantly higher than that in the primary lesion of the corresponding case, and patient prognosis in these cases was extremely poor. Therefore, it is suggested that the intact synchronized expression of ER-β interacting with ER-α might be disrupted, especially in most metastases of uterine endometrial cancers, leading to poor patient prognosis related to estrogen refractoriness.

Clinical implication of expression of vascular endothelial growth factor-C in metastatic lymph nodes of uterine cervical cancers

Vascular endothelial cell growth factor (VEGF)-C levels were significantly (P<0.05) increased in 24 out of 40 metastatic lymph node lesions of uterine cervical cancers. The prognosis of the 24 patients with increased VEGF-C level in metastatic lymph node lesions was poor and the 24-month survival rate was 38%, while the rate of the 16 patients with no change in VEGF-C level in metastatic lymph node lesions was 81%. There was a significant (P<0.01) difference in the 24-month survival rates between the two groups. This is novel, direct evidence that VEGF-C might contribute to the aggressive lymphangitic metastasis in uterine cervical cancers, and that the increase in VEGF-C level from primary tumour to metastatic lymph node might be a prognostic indicator.

Expression of basic fibroblast growth factor and its mRNA in advanced uterine cervical cancers

To know the potential of growth, invasion and metastasis of uterine cervical cancer cells associated with neovascularization, the expression of basic fibroblast growth factor (FGF) and its mRNA in uterine cervical cancers and normal uterine cervices as controls were determined by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction-Southern blot (RT-PCR-SB), respectively. Then, the relations between the expression and the histological grading and clinical staging in cervical cancers were analyzed. The levels of basic FGF and its mRNA were significantly higher in advanced primary uterine cervical cancers, regardless of histological type. Therefore, this status might contribute to the acceleration of growth, invasion, and metastasis with neovascularization in advanced uterine cervical cancers.

Expression of estrogen receptor α and β in myometrium of premenopausal and postmenopausal women

Although a clear role for estrogen receptor (ER) alpha has been established, the contribution of ERbeta in estrogen-dependent development, growth and functions of the myometrium is not understood. As a first step towards understanding the role of ERbeta, we have examined the expression of ERalpha and ERbeta in the human myometrium. With competitive RT-PCR assays, the level of ERbeta mRNA was 10-200 times lower than that of ERalpha mRNA in both premenopausal and postmenopausal myometrium. In premenopausal myometrium, the expression pattern of ERbeta mRNA during the menstrual cycle was similar to that of ERalpha mRNA, with highest levels in peri-ovulatory phase. In postmenopausal myometrium, ERbeta mRNA was significantly higher than it was in premenopausal myometrium, while the level of ERalpha mRNA was lower. The net result was a change in the ratio of ERbeta to ERalpha mRNA expression. The ratio changed from 0.6-1.5 in premenopausal to 2.5-7.6 in postmenopausal myometrium. In premenopausal women, the gonadotropin releasing hormone analogue, leuprorelin acetate, elicited a decrease in ERalpha and an increase in ERbeta mRNA expression to cause a postmenopausal receptor phenotype. Estradiol, on the other hand, reversed ERalpha and ERbeta mRNA expression and their ratio in postmenopausal myometrium to those of premenopausal myometrium. Immunohistochemical staining and Western blot analysis of ERalpha and ERbeta with semiquantitative analysis showed good agreement between mRNA and protein levels. The data indicate that coordinated expression of ERalpha and ERbeta might be necessary for normal estrogen action in myometrium. Furthermore, estrogen appears a dominant regulator of both receptors in the myometrium.

Clinical implications of expression of vascular endothelial growth factor in metastatic lesions of ovarian cancers.

Vascular endothelial growth factor (VEGF) has been identified as an important factor for tumour angiogenesis, which is essential for the growth, invasion and metastasis of solid tumours. Significantly increased VEGF level from the primary tumour to the metastatic lesion of ovarian cancers was found in 8 of 30 cases. The 24-month survival rate of the patients with significantly increased VEGF level was extremely poor (0/8 = 0%) in comparison with that of patients with no change in the level (15/22 = 68%) from the primary tumour to the metastatic lesion. This indicates that VEGF may contribute to the advancement of metastatic lesions, and that VEGF level in metastatic lesions may be a prognostic indicator.