A Possible Inhibitory Role of Sialic Acid on MUC1 in Peritoneal Dissemination of Clear Cell-Type Ovarian Cancer Cells.

The role of sialic acids on MUC1 in peritoneal dissemination of ovarian cancer cells was investigated. A human ovarian carcinoma cell line, ES-2, was transfected with full-length MUC1 containing 22 or 42 tandem repeats. These transfectants were less adherent to monolayers of patient-derived mesothelial cells than ES-2/mock transfectants. When these cells were inoculated into the abdominal cavity of female nude mice, mice that had received the transfectants showed better survival. When the transfectants were mixed with sialidase and injected, the survival was poorer, whereas when they were mixed with N-acetyl-2,3-dehydro-2-deoxyneuraminic acid, a sialidase inhibitor, the survival was significantly prolonged. These behaviors, concerned with peritoneal implantation and dissemination observed in vitro and in vivo, were dependent on the expression of MUC1. Therefore, sialic acid linked to MUC1 in the form, at least in part, of sialyl-T, as shown to be recognized by monoclonal antibody MY.1E12, is responsible for the suppression of adhesion of these cells to mesothelial cells and the suppression of peritoneal implantation and dissemination.

The significance of lymphatic space invasion and its association with vascular endothelial growth factor-C expression in ovarian cancer.

The aim of this study is to investigate the significance of lymphatic space invasion (LSI) and tumor VEGF-C expression in the lymphatic spread of ovarian cancer. By performing immunostaining using human ovarian cancer specimens, we first investigated the association between the extent of LSI and tumor VEGF-C expression, tumor lymphangiogenesis, or the lymphatic metastasis. Moreover, by performing in vitro and in vivo experiments, we elucidated the role of VEGF-C in tumor lymphangiogenesis and lymph node metastasis as well as its role as a therapeutic target in ovarian cancer. The presence of LSI was associated with lymph node metastasis in patients with ovarian cancer. VEGF-C overexpression was significantly associated with the increased LSI and LVD in ovarian cancer. VEGF-C stimulated the lymphangiogenesis in vitro, induced the new lymph vessel formation, and increased the lymph node metastasis in mice models of ovarian cancer. The attenuation of VEGF-C expression by the treatment with mTORC1 inhibitor significantly inhibited lymphangiogenesis, and decreased lymph node metastasis in mice models of ovarian cancer. The presence of LSI is an indicator of nodal metastasis and is associated with higher tumor VEGF-C expression and worse clinical outcome of ovarian cancer patients. VEGF-C plays a crucial role in tumor lymphangiogenesis and lymph node metastasis of ovarian cancer.

Cell surface expression of hyaluronan on human ovarian cancer cells inversely correlates with their adhesion to peritoneal mesothelial cells.

Eight of 15 human ovarian carcinoma cell lines were shown to express high levels of hyaluronan (HA) on their surfaces. The role of cell surface HA in its adhesion to mesothelial cells, which is potentially involved in peritoneal dissemination, was evaluated. Three human ovarian carcinoma cell lines, ES-2, MH, and KF cells, were repeatedly sorted into variant cell lines with high levels of cell surface HA (ES-2/HA+7, MH/HA+7, and KF/HA+7) and with low cell surface HA (ES-2/HA-7, MH/HA-7, and KF/HA-7). The ability of these cells to adhere to peritoneal mesothelial cells was compared. ES-2/HA+7, MH/HA+7, and KF/HA+7 cells were less adherent to mesothelial cells than the ES-2/HA-7, MH/HA-7, and KF/HA-7 cells. On ovarian carcinoma cells, high cell surface HA levels seem to inversely correlate with their capacity to adhere and disseminate to the peritoneum. Considering that peritoneum implantation is the primary ovarian cancer complication, HA cell surface expression may be considered a property associated with a less aggressive phenotype, which is contrary to the general perception that HA expression is associated with malignant progression.

Combination of abducens nerve palsy and ipsilateral postganglionic Horner syndrome as an initial manifestation of uterine cervical cancer.

A 74-year-old woman presented with abducens nerve palsy, postganglionic Horner syndrome and sensory disturbance in the territory of the ophthalmic nerve on the left side. Cranial magnetic resonance imaging demonstrated a gadolinium-enhanced lesion within the left cavernous sinus. Thereafter, uterine cervical cancer was detected as the origin of this intra-cavernous sinus metastasis. We emphasize that the combination of abducens nerve palsy and ipsilateral postganglionic Horner syndrome may indicate a lesion located within the posterior portion of the cavernous sinus or in its vicinity. Moreover, this is the first reported case of uterine cervical cancer with intra-cavernous sinus metastasis.

Stage-specific effect of inhibition of autophagy on chemotherapy-induced cytotoxicity.

Anticancer therapies can induce autophagy in tumor cells and the role of autophagy in these cells may depend on the type of tumor, the stage of tumorigenesis, and the nature and extent of the insult. Appropriate modification of autophagy, that is, suppression of cell-protective autophagy or enhancement of cell-killing autophagy could augment cytotoxicity caused by anticancer therapy. Imatinib mesylate is an inhibitor of tyrosine kinases and is used for the therapy of patients with tumors including leukemias, but is not effective as a monotherapy for malignant glioma. To seek a strategy to augment the therapeutic efficacy of imatinib, we examined the mode of cytotoxicity of imatinib in human malignant glioma cells. Since imatinib induced cytotoxicity associated with autophagy, we tested the effect of inhibition of autophagy on imatinib-induced cytotoxicity. We found that imatinib-induced cytotoxicity is attenuated by inhibition of autophagy at an early stage but augmented by inhibition of autophagy at a late stage through increasing apoptosis following mitochondrial damage. Though the mechanism of the stage-specific effect of inhibiting autophagy on cytotoxicity remains to be elucidated, our findings could be useful for developing a new strategy to enhance the efficacy of anticancer therapy by modulating autophagy.

Inhibition of autophagy at a late stage enhances imatinib-induced cytotoxicity in human malignant glioma cells.

Malignant gliomas are common primary tumors of the central nervous system. The prognosis of patients with malignant glioma is poor in spite of current intensive therapy and thus novel therapeutic modalities are necessary. Imatinib mesylate, a tyrosine kinase inhibitor, is effective in the therapy of tumors including leukemias but not as a monotherapy for malignant glioma. Recently, it is thought that the adequate modulation of autophagy can enhance efficacy of anticancer therapy. The outcome of autophagy manipulation, however, seems to depend on the autophagy initiator, the combined stimuli, the extent of cellular damage and the type of cells, and it is not yet fully understood how we should modulate autophagy to augment efficacy of each anticancer therapy. In this study, we examined the effect of imatinib with or without different types of autophagy inhibitors on human malignant glioma cells. Imatinib inhibited the viability of U87-MG and U373-MG cells in a dose dependent manner and caused nonapoptotic autophagic cell death. Suppression of imatinib-induced autophagy by 3-methyladenine or small interfering RNA against Atg5, which inhibit autophagy at an early stage, attenuated the imatinib-induced cytotoxicity. In contrast, inhibition of autophagy at a late stage by bafilomycin A1 or RTA 203 enhanced imatinib-induced cytotoxicity through the induction of apoptosis following mitochondrial disruption. Our findings suggest that therapeutic efficiency of imatinib for malignant glioma may be augmented by inhibition of autophagy at a late stage, and that appropriate modulation of autophagy may sensitize tumor cells to anticancer therapy.

Monitoring autophagy in glioblastoma with antibody against isoform B of human microtubule-associated protein 1 light chain 3.

Autophagy, an evolutionarily conserved response to stress, has recently been implicated in cancer initiation and progression, but the detailed mechanisms and functions have not yet been fully elucidated. One major obstacle to our understanding is lack of an efficient and robust method to specifically monitor autophagic cells in cancer specimens. To identify molecular events associated with autophagy, we performed cDNA microarray analysis of autophagic glioblastoma cell lines. Based on the analysis, we raised a polyclonal antibody against isoform B of human microtubule-associated protein 1 light chain 3 (LC3B). Application of the anti-LC3B antibody revealed the presence of autophagic cells in both in vitro and in vivo settings. Of the 65 glioblastoma tissues, 31 had highly positive cytoplasmic staining of LC3B. The statistical interaction between cytoplasmic staining of LC3B and Karnofsky Performance Scale score was significant. High expression of LC3B was associated with an improved outcome for patients with poorer performance, whereas, for patients with normal performance, survival was better for patients with low staining than with high staining of LC3B. Anti-LC3B antibody provides a useful tool for monitoring the induction of autophagy in cancer cells and tissues.

Biological and therapeutic significance of MUC1 with sialoglycans in clear cell adenocarcinoma of the ovary.

A monoclonal antibody (mAb) MY.1E12 was applied to detect MUC1 with sialylated glycans in a total of 55 formalin-fixed, paraffin-embedded surgical specimens of ovarian clear cell adenocarcinomas. A reverse correlation between the binding levels of this mAb and patient survival was demonstrated. To examine the role of MUC1 in ovarian clear cell carcinomas, two cDNA encoding MUC1 were transfected into ES-2 ovarian clear cell carcinoma cells. By comparing these cells, the role of MUC1 in tumorigenicity, chemosensitivity and survival under anoikis conditions were assessed. The results indicate that MUC1 expressed on ovarian clear cell carcinoma cells is causally involved in the malignant behavior.

Expression of NEU3 (plasma membrane-associated sialidase) in clear cell adenocarcinoma of the ovary: its relationship with T factor of pTNM classification.

Cell surface carbohydrate expression strongly influences the biological characteristics of cancer cells. Especially, it is known that the change of sialic acid expression could be related to the invasive and metastatic potentials of tumors. This study aimed to investigate sialidase expression of ovarian cancer cells and to evaluate the relationship between plasma membrane-associated sialidase (NEU3) expression and various clinicopathological factors in ovarian clear cell adenocarcinoma patients. In 18 cell lines derived from human ovarian cancers (including clear cell, mucinous, and serous adenocarcinoma), sialidase mRNA expression was evaluated by RT-PCR. NEU1 and NEU3 expression levels were found to be elevated in most cell lines while NEU2 and NEU4 expression was rarely elevated. Interestingly, NEU3 expression was detected in all clear cell adenocarcinoma cell lines. In 71 patients with ovarian clear cell adenocarcinoma, treated at Keio University Hospital from February 1983 to February 2002, NEU3 expression was examined by immunohistochemical staining of surgical specimens and clinicopathological factors were reviewed. NEU3 expression was found to be positive in 77.5% of all cases. Furthermore, a high level of NEU3 expression was significantly correlated with T3 factor of pTNM classification on univariate and multivariate analysis. This is the first report to show that NEU3 is expressed in most of ovarian clear cell adenocarcinoma. And our results show that NEU3 expression is correlated with T factor (pTNM classification) in ovarian clear cell adenocarcinoma.

Establishment and characterization of the RMG-V cell line from human ovarian clear cell adenocarcinoma.

A cell line, designated as RMG-V, was established from a patient with clear cell adenocarcinoma of the ovary. The cell line has grown without interruption and has been propagated continuously by serial passaging (more than 36 times) over 5 years. The cells are spindle-shaped, display neoplastic and pleomorphic features, and grow in a jigsaw puzzle-like arrangement while forming monolayers without contact inhibition. These cells proliferate rapidly, and the population doubling time is about 15.5 hours. The number of chromosomes ranges between 77 and 85, with a modal number of 83.

HMOCC-1, a human monoclonal antibody that inhibits adhesion of ovarian cancer cells to human mesothelial cells.

OBJECTIVES: Ovarian carcinoma is one of the most common gynecologic cancers and shows the worst prognosis since current therapies are not sufficiently effective at achieving and maintaining remission. To develop new treatment, a monoclonal antibody recognizing human ovarian cancer cells was raised in KM mice. METHODS: A human monoclonal antibody targeting RMG-I (an ovarian carcinoma cell line) was established with hybridomas of myeloma cells and spleen cells from KM mice. The immunohistochemical reactivity of various types of ovarian carcinoma and other tumors was investigated. RMG-I cells were treated with N-glycosidase F, NaOH, H(2)SO(4), and Gal NAC-alpha-benzyl to investigate the target antigens by Western blotting. The effect of HMOCC-1 on adhesion of RMG-I cells to cultured human mesothelial cells was also investigated. RESULTS: The new human monoclonal antibody, HMOCC-1, was an immunoglobulin M that recognized ovarian epithelial carcinoma. Immunohistochemical staining revealed HMOCC-1 positivity in 83.2% of ovarian carcinomas. The antigen recognized by HMOCC-1 was apparently a glycoprotein since Western blotting yielded a broad band (34.8-49.1 kDa). HMOCC-1 inhibited the attachment of RMG-I cells to monolayers of cultured peritoneal mesothelial cells in a concentration-dependent manner. CONCLUSIONS: This new human monoclonal antibody reacted with most ovarian cancers tested. The antigen recognized by HMOCC-1 is a glycoprotein located on the cell membrane. Inhibition of the attachment of RMG-1 cells to mesothelial cells by HMOCC-1 suggests a potential role for this antibody in the treatment of ovarian cancer.