Toshio Hirakawa

Histological classification of ovarian cancer.

 The histology of ovarian tumors exhibits a wide variety of histological features. The histological classification of ovarian tumors by the World Health Organization (WHO) is based on histogenetic principles, and this classification categorizes ovarian tumors with regard to their derivation from coelomic surface epithelial cells, germ cells, and mesenchyme (the stroma and the sex cord). Epithelial ovarian tumors, which are the majority of malignant ovarian tumors, are further grouped into histological types as follows: serous, mucinous, endometrioid, clear cell, transitional cell tumors (Brenner tumors), carcinosarcoma, mixed epithelial tumor, undifferentiated carcinoma, and others. Clear cell and endometrioid carcinomas are highly associated with endometriosis. In stage distribution, serous carcinoma is found predominantly is stage III or IV. In contrast, clear cell and endometrioid carcinomas tend to remain confined to the ovary. Clear cell and endometrioid carcinomas may be unique histological types compared with serous carcinomas with respect to stage distribution and association with endometriosis.

Basal Membrane Localization of MRP1 in Human Placental Trophoblast

The placental trophoblast is considered to act as a barrier between mother and fetus, mediating the exchange of various materials across the placenta. ATP-binding cassette (ABC) transporters such as P-glycoprotein (P-gp) and multidrug-resistance protein (MRP) are expressed in the placenta and function as efflux transport systems for xenobiotics. In the present study, we aimed to determine the localization of MRP1 in the human placenta in comparison with that of P-gp. Western blotting analysis with human placental membrane vesicles indicated that P-gp and MRP1 are localized on the brush-border membranes and basal membranes, respectively. Immunohistochemical analysis with human normal full-term placenta showed that anti-P-gp monoclonal antibody F4 stained the brush-border side of the trophoblast cells, whereas anti-MRP1 monoclonal antibody MRPr1 stained the basal side. These results confirm that P-gp and MRP1 are located on the brush-border membranes and basal membranes, respectively, of human full-term placental trophoblast. MRP1 was also detected on the abluminal side of blood vessels in the villi. Accordingly, MRP1 may play a role distinct from that of P-gp, which is considered to restrict the influx of xenobiotics into the fetus.

Squamous cell carcinoma arising in mature cystic teratoma of the ovary. Clinicopathologic and topographic analysis.

Clinical and pathologic features of 28 patients with squamous cell carcinoma (SCC) arising in mature cystic teratoma (MCT) of the ovary were analyzed. The overall 5-year survival rate of these patients was 52%. Clinical staging (Stage 1 versus Stages II or more), histologic differentiation (well versus moderately or poorly differentiated SCC), and the presence of vascular invasion were factors affecting the prognosis of these patients. In 11 tumors, including 2 of the 4 examined in stepwise serial sections, the SCC was considered to have originated from a columnar epithelium (ciliated or nonciliated) or from a metaplastic squamous epithelium. On the other hand, no SCC was a direct transition from the ordinary epidermis of the teratomatous skin tissue. These results strongly support the proposal that SCC arising in MCT derives from the columnar epithelium.

Prognostic implications of the nuclear localization of Y-box-binding protein-1 and CXCR4 expression in ovarian cancer: Their correlation with activated Akt, LRP/MVP and P-glycoprotein expression

The nuclear localization of Y‐box‐binding protein‐1 (YB‐1) is known to be a poor prognostic factor in several human malignancies, including ovarian carcinoma. Following on from our basic study dealing with microarray analyses of YB‐1‐associated gene expression in ovarian cancer cells, we examined whether nuclear localization of YB‐1 is associated with the expression of CXCR4, a vault protein named lung resistance‐related vault protein (LRP/MVP), phosphorylated Akt (p‐Akt) or P‐glycoprotein (P‐gp) in human ovarian carcinoma. Fifty‐three surgically resected ovarian carcinomas treated with paclitaxel and carboplatin were examined immunohistochemically for nuclear YB‐1 expression and intrinsic expression of p‐Akt, P‐gp, LRP/MVP and CXCR4. Nuclear expression of YB‐1 demonstrated significant correlation with p‐Akt, P‐gp and LRP expression, but no relationship with CXCR4 expression. By multivariate analysis, only YB‐1 nuclear expression and CXCR4 expression were independent prognostic factors with regard to overall survival. These results indicate that YB‐1 nuclear expression and CXCR4 expression are important prognostic factors in ovarian carcinoma. (Cancer Sci 2007; 98: 1020–1026)

Increased nuclear localization of transcription factor YB-1 in acquired cisplatin-resistant ovarian cancer

Abstract Purpose. Nuclear expression of Y box-binding protein (YB-1), a member of the DNA-binding protein family, was recently reported to have a much higher concentration in cisplatin-resistant cancer cell lines than in their drug-sensitive parental counterparts, suggesting the ability to induce cisplatin resistance. Ovarian cancer has been generally treated with cisplatin-based chemotherapy and often recurs due to acquired cisplatin resistance. The aim of our study is to elucidate the association between nuclear YB-1 and cisplatin resistance in human ovarian cancer using cultured cell lines and surgical specimens. Methods. Intracellular YB-1 localization was examined by Western blot analysis for both cisplatin sensitive and resistant human ovarian cancer cell lines. Moreover, 35 pairs of surgical specimens derived from primary and matched recurrent ovarian cancers of the same patient were evaluated for their nuclear YB-1 expression by immunohistochemical staining. Results. Western blot analysis for nuclear and cytoplasmic extracts indicated that cisplatin-resistant cells showed much higher nuclear YB-1 expression than sensitive parental cells. Immunohistochemical analysis showed that ten paired cases turned from negative nuclear YB-1 in primary lesions to positive nuclear YB-1 in recurrent lesions, whereas only two paired cases showed a reverse turn from positive to negative. Conclusions. The expression of YB-1 in the nucleus seems to be associated with acquired cisplatin resistance in ovarian cancers. Nuclear YB-1 might be a useful predictive marker indicating cisplatin sensitivity and/or a target molecule to treat recurring ovarian cancers by cisplatin-based second-line chemotherapy.

Prognostic significance of microvessel density, vascular cuffing and vascular endothelial growth factor expression in ovarian carcinoma: a special review for clear cell adenocarcinoma.

Our purpose is to demonstrate the relationship between microvessel density (MVD), vascular cuffing (VC), vascular endothelial growth factor (VEGF) expression and clinicopathological parameters in ovarian cancer. Surgical specimens from 105 primary ovarian cancers were examined for vascularization and VEGF expression by immunohistochemical staining. The higher MVD group (MVD> or =70) and the positive VEGF group were associated with better progression-free survival only in early stages. The significant association of the MVD with better progression-free survival was recognized only in the patients with clear cell adenocarcinomas. The complete VC group showed a similar trend as MVD though there was no statistical difference. A multivariate analysis revealed MVD to correlate independently with progression-free survival. In ovarian carcinoma, MVD was found to be an independent prognostic factor. In addition, the higher MVD with clear cell adenocarcinoma had the better prognosis. The clinicopathological role of angiogenesis should be analyzed taking account of histologic type.

Isolation and Characterization of Human Trophoblast Side-Population (SP) Cells in Primary Villous Cytotrophoblasts and HTR-8/SVneo Cell Line

Recently, numerous studies have identified that immature cell populations including stem cells and progenitor cells can be found among “side-population” (SP) cells. Although SP cells isolated from some adult tissues have been reported elsewhere, isolation and characterization of human trophoblast SP remained to be reported. In this study, HTR-8/SVneo cells and human primary villous cytotrophoblasts (vCTBs) were stained with Hoechst 33342 and SP and non-SP (NSP) fractions were isolated using a cell sorter. A small population of SP cells was identified in HTR-8/SVneo cells and in vCTBs. SP cells expressed several vCTB-specific markers and failed to express syncytiotrophoblast (STB) or extravillous cytotrophopblast (EVT)-specific differentiation markers. SP cells formed colonies and proliferated on mouse embryonic fibroblast (MEF) feeder cells or in MEF conditioned medium supplemented with heparin/FGF2, and they also showed long-term repopulating property. SP cells could differentiate into both STB and EVT cell lineages and expressed several differentiation markers. Microarray analysis revealed that IL7R and IL1R2 were exclusively expressed in SP cells and not in NSP cells. vCTB cells sorted as positive for both IL7R and IL1R2 failed to express trophoblast differentiation markers and spontaneously differentiated into both STB and EVT in basal medium. These features shown by the SP cells suggested that IL7R and IL1R2 are available as markers to detect the SP cells and that vCTB progenitor cells and trophoblast stem cells were involved in the SP cell population.

Expression of angiogenesis factors in monolayer culture, multicellular spheroid and in vivo transplanted tumor by human ovarian cancer cell lines.

We examined the expression of four angiogenesis factors (vascular endothelial growth factor (VEGF), interleukin-8 (IL-8), platelet-derived endothelial cell growth factor (PD-ECGF) and basic fibroblast growth factor (bFGF)) in five human ovarian cancer cell lines by Northern blot analysis and immunohistochemical staining. The cancer cells were grown as a subconfluent monolayer culture, a multicellular aggregate (spheroid) in a three-dimensional culture, and a nude mouse-transplanted subcutaneous tumor in order to simulate the cellular conditions of ovarian cancers in peritonitis carcinomatosa, i.e. floating single tumor cells, multicellular aggregates and peritoneally implanted tumors. In each cell line, the expression of VEGF was detected in a monolayer culture and obviously enhanced in a three-dimensional culture. IL-8 was expressed in two of five cultured cell lines, but neither PD-ECGF nor bFGF was detected. Each cell line-derived transplanted tumor expressed immunohistochemical products of the four angiogenesis factors examined. These observations were confirmed by surgical specimens and suggested that ovarian cancer cells expressed different kinds and/or doses of angiogenesis factors depending on the form of the changed tumor cells during peritoneal implant formation.

Clinicopathologic study of squamous cell carcinoma of the ovary

Clinicopathologic study was performed on 10 squamous cell carcinomas of the ovary. All four patients with stage II or III lesions had deteriorated within 1 year after the operation, and four of six patients with stage I lesions had survived over 5 years. Clinical findings of the patients with ovarian SCC, including age, chief complaint, clinical stage, and outcome of the patients, were similar to those of common epithelial cancer. The effectiveness of chemotherapy was not shown in this study. Histopathologic study revealed that squamous cell carcinoma may arise not only from epidermis, but also from squamous metaplastic epithelium of respiratory gland.

Association between RCAS1 expression and clinical outcome in uterine endometrial cancer

RCAS1, which acts as a ligand for a putative receptor on immune cells such as peripheral lymphocytes and natural killer cells, is strongly expressed in human cancers. RCAS1 can induce these cells to undergo apoptotic cell death, which suggests that RCAS1 expression may prohibit the stromal reaction occurring in a tumour. To clarify the clinical significance of RCAS1 expression in uterine endometrial cancer, we analysed the association between RCAS1 expression and clinicopathologic variables by statistical methods. With the use of immunohistochemical techniques, we performed a retrospective study of RCAS1 expression in resected tumour tissue from 147 patients with uterine endometrial cancer. We evaluated the statistical correlation between RCAS1 expression and clinicopathologic variables. RCAS1 was expressed in 106 of 147 patients with uterine endometrial cancer ; 30 of these 147 patients showed RCAS1 overexpression. Overexpression of RCAS1 was significantly correlated with age at surgery, stage, extent of myometrial invasion, and positive peritoneal cytologic results. Multivariate analysis revealed that RCAS1 expression and metastasis were clinically significant prognostic factors for the overall survival. These findings indicated that analysis for RCAS1 expression can provide crucial information about the clinical behaviour of uterine endometrial cancer, which may be valuable for the management of patients with this disease.