Satoshi Takakura

Allelic imbalance and mutations of the PTEN gene in ovarian cancer

The PTEN/MMAC1/TEP1 tumor‐suppressor gene, which maps to chromosome 10q23.3, is mutated and homozygously deleted in a variety of human tumors, including endometrioid‐type ovarian tumors. We examined 33 primary ovarian cancers and 3 ovarian borderline tumors for allelic imbalance (AI) of the 10q23.3 region using 5 polymorphic markers, including an insertion/deletion‐type polymorphic marker identified in intron 4 of the PTEN gene. AI at one or more loci was detected in 12 of 31 (39%) informative ovarian cancers and none of 3 ovarian borderline tumors. The commonly deleted region was mapped between the D10S215 and D10S541 loci, including the PTEN locus. Moreover, the incidence of AI at the PTEN locus (38%) was the highest among the 5 loci examined. Therefore, we searched for mutations in the entire coding region of the PTEN gene by PCR‐SSCP and sequencing analyses in these tumors and 7 ovarian cancer cell lines. Mutations were detected in 3 of the 33 (9%) ovarian cancers: 2 cases with double mutations and 1 case with a mutation on 1 allele accompanied by deletions on both alleles in the poly T tract preceding the splice acceptor site in intron 7. An intragenic deletion was detected in 1 of the 7 (14%) ovarian cancer cell lines. PTEN mutations were detected not only in the endometrioid type but also in the serous and mucinous types of ovarian cancer. However, PTEN was not mutated in the 12 tumors that showed AI of the PTEN locus. Our results suggest that the PTEN gene plays an important role in the development of a subset but diverse histological types of ovarian tumors. However, it is possible that another tumor‐suppressor gene in the close vicinity of the PTEN gene is also inactivated by AI of the 10q23.3 region. Int. J. Cancer 85:160–165, 2000. ©2000 Wiley‐Liss, Inc.

Frequent microsatellite instability and BAX mutations in T cell acute lymphoblastic leukemia cell lines

Allelic status of the BAT26 and BAT25 loci was examined in 117 leukemia/lymphoma cell lines consisting of 44 B-lymphoid lineage cell lines, 30 T-lymphoid cell lines and 43 myeloid cell lines to define the lineage specificity of microsatellite instability (MSI) in hematological malignancies. Seventeen (15%) cell lines were defined as having MSI. The incidence of MSI was significantly (P < 0.01) higher in cell lines of lymphoid lineage (15/74; 20%) than in those of myeloid lineage (2/43; 5%). In the cell lines of lymphoid lineage, the incidence of MSI in T cell acute lymphoblastic leukemia (T-ALL) (11/30; 37%) was significantly (P < 0.01) higher than those in B-lineage malignancies (4/44; 9%). The 17 cell lines with MSI were subjected to the mutation analysis of the coding microsatellites in 13 candidate genes. Frameshift mutations were most frequently detected in the BAX gene (14/17, 82%), while the hMSH3, hMSH6, TGFbetaRII, DRP and IGFIIR genes were less frequently mutated (24-47%). The present result indicates that MSI is involved in the development and/or progression of lymphoid malignancies, especially of T-ALL, through the inactivation of BAX and several other genes.

Allelic imbalance in chromosome band 18q21 and SMAD4 mutations in ovarian cancers

Recently, three candidate tumor suppressor genes, SMAD2 (MADR2/JV18–1), SMAD4 (DPC4), and DCC, were identified in chromosome band 18q21. We examined allelic imbalance (AI) in 18q21 using six polymorphic microsatellite markers in 38 primary ovarian cancers and four ovarian borderline tumors. AI at one or more loci was detected in 15 of 37 (41%) informative ovarian cancers and in none of the four borderline tumors. Frequent AI was detected at the D18S46 (31%) and D18S474 (36%) loci, which were adjacent to the SMAD4 gene, and at the D18S69 (33%) locus, which was telomeric to the DCC gene. Therefore, we searched for mutations of the SMAD4 gene in 42 primary tumors and eight cell lines by PCR‐SSCP and sequencing analyses. Missense mutations were detected in two ovarian tumors and three ovarian cancer cell lines, whereas silent mutation was detected in a primary ovarian cancer. These results suggest that there are at least two tumor suppressor genes on chromosome arm 18q and that SMAD4 is of importance in ovarian tumorigenesis. Genes Chromosomes Cancer 24:264–271, 1999.

Adjuvant chemotherapy in a pregnant woman with endodermal sinus tumor of the ovary.

BACKGROUND: The administration of chemotherapeutic drugs during pregnancy is rare. We describe a case of malignant ovarian tumor complicating pregnancy. CASE: After laparotomy at 18 weeks of gestation, the patient received three courses of cisplatin, vinblastine, and bleomycin. Elective cesarean delivery was performed at 31 weeks of gestation. A normal infant was delivered, and no evidence of tumor recurrence was observed. Metastasis to the liver was detected in the fifth month after delivery. However, this was treated successfully with three courses of cisplatin, etoposide, and bleomycin. There was no evidence of recurrence observed at 65 months after the initial treatment. CONCLUSION: Although the risk of chemotherapy to the fetus cannot be assessed based on a single case, this experience is encouraging.

Microsatellite instability in lymphoid leukemia and lymphoma cell lines but not in myeloid leukemia cell lines.

Microsatellite instability (MSI) represents a defect in the DNA mismatch repair system and has been shown to take part in the genesis and/or progression of several human malignancies. In hematological malignancies, the relevance of MSI has been a matter of controversy. Therefore, 29 microsatellite loci were examined for MSI in 57 leukemia and lymphoma cell lines by PCR analysis. Ladder formation of bands representing MSI was observed at multiple loci in 6 of 24 lymphoid leukemia/lymphoma cell lines and in 0 of 33 myeloid leukemia cell lines. Analysis for the BAT‐26 and BAT‐25 loci confirmed the presence of MSI in five of six lymphoid cell lines exhibiting ladder formation of bands. Thus, at least 5 out of 24 (21%) lymphoid leukemia/lymphoma cell lines were considered as being MSI‐positive. These results indicate that MSI contributes to the development of lymphoid but not to myeloid malignancies. Genes Chromosomes Cancer 26:267–269, 1999.

Cytokine gene expression signature in ovarian clear cell carcinoma

Cytokine expression in a tumor microenvironment can impact both host defense against the tumor and tumor cell survival. In this study, we sought to clarify whether the cytokine gene expression profile could have clinical associations with ovarian cancer. We analyzed the expression of 16 cytokine genes (IL-1α, IL-1β, IL-2, IL-4, IL-5, IL-8, IL-10, IL-12p35, IL-12p40, IL-15, IFN-γ, TNF-α, IL-6, HLA-DRA, HLA-DPA1 and CSF1) in 50 ovarian carcinomas. Hierarchical clustering analysis of these tumors was carried out using Cluster software and differentially expressed genes were examined between clear cell carcinoma (CCC) and other subtypes. Following this examination we evaluated the biological significance of IL-6 knockdown in CCC. Unsupervised hierarchical clustering analysis of cytokine gene expression revealed two distinct clusters. The relationship between the two clusters and clinical parameters showed statistically significant differences in CCC compared to other histologies. CCC showed a dominant Th-2 cytokine expression pattern driven largely by IL-6 expression. Inhibition of IL-6 in CCC cells suppressed Stat3 signaling and rendered cells sensitive to cytotoxic agents. The unique cytokine expression pattern found in CCC may be involved in the pathogenesis of this subtype. In particular, high IL-6 expression appears likely to be driven by the tumor cells, fueling an autocrine pathway involving IL-6 expression and Stat3 activation and may influence survival when exposed to cytotoxic chemotherapy. Modulation of IL-6 expression or its related signaling pathway may be a promising strategy of treatment for CCC.

Hypoxia promotes glycogen synthesis and accumulation in human ovarian clear cell carcinoma

Ovarian clear cell carcinoma (OCCC) has several significant characteristics based on molecular features that are distinct from those of ovarian high-grade serous carcinoma. Cellular glycogen accumulation is the most conspicuous feature of OCCC and in the present study its metabolic mechanism was investigated. The amount of glycogen in cells cultured under hypoxia increased significantly and approximately doubled after 48 h (P<0.01) compared to that under normoxic conditions. Periodic acid-Schiff positive staining also demonstrated intracellular glycogen storage. Western blot analysis revealed that HIF1α, which was overexpressed and stabilized under hypoxic conditions, led to an increase in the levels of cellular glycogen synthase 1, muscle type (GYS1), and conversely to a decrease in inactive phosphorylated GYS1 at serine (Ser) 641. Additional increases were observed in both protein phosphatase 1, which dephosphorylates and thereby induces GYS1 enzyme activity, and glycogen synthase kinase 3 beta (GSK3β) phosphorylated at Ser9, which is inactive on phosphorylation of GYS1 and subsequently induces its enzyme activity. By contrast, the level of PYGM-b decreased. These results indicated that the glycogen accumulation under a hypoxic environment resulted in the promotion of glycogen synthesis, but did not lead to inhibition of glycogen degradation and/or consumption. Under hypoxic conditions, HAC2 cells showed activation of the PI3K/AKT pathway caused by a mutation in exon 20 of PIK3CA, encoding the catalytic subunit p110α of PI3K. The resulting activation of AKT (phosphoSer473) also plays a role as a central enhancer in glycogen synthesis through suppression of GSK3β via phosphorylation at Ser9. Hypoxia decreased the cytocidal activity of cisplatin and doxorubicin to various degrees. In conclusion, the hypoxic conditions together with HIF1 expression and stabilization increased the intracellular glycogen contents and resistance to the anticancer drugs.

Quality-of-life outcomes from a randomized phase III trial of dose-dense weekly paclitaxel and carboplatin compared with conventional paclitaxel and carboplatin as a first-line treatment for stage II–IV ovarian cancer: Japanese Gynecologic Oncology Group Trial (JGOG3016)

BACKGROUND Dose-dense weekly paclitaxel (Taxol) and carboplatin (dd-TC) improved survival compared with conventional tri-weekly paclitaxel and carboplatin (c-TC) as a first-line chemotherapy for newly diagnosed stage II-IV ovarian cancer in the Japanese Gynecologic Oncology Group 3016 trial. We report the quality-of-life (QoL) results from this trial. PATIENTS AND METHODS A total of 637 patients were randomly assigned to receive c-TC or dd-TC (c-TC, n = 319; dd-TC, n = 312) and were asked to complete a QoL assessment at baseline, just after the third and sixth chemotherapy cycles, and at 12 months after randomization. QoL was assessed using Functional Assessment of Cancer Therapy (FACT)-general (FACT-G), FACT-taxane subscale (FACT-T), and FACT-ovary subscale (FACT-Ov). The overall QoL and that according to each subscale were analyzed using mixed-effects models adjusted for treatment and time. RESULTS Baseline QoL assessment was completed by 204 out of 319 (63.9%) and 200 out of 312 (64.1%) patients in the c-TC and dd-TC groups, respectively. In these groups, the compliance rates with regard to QoL assessment were 74.5% and 73.0%, respectively, after three chemotherapy cycles; 86.8% and 86.9%, respectively, after six chemotherapy cycles; and 74.2% and 71.6%, respectively, at 12 months after randomization. The overall QoL did not differ significantly between the two treatment groups up to 12 months after randomization (P = 0.46). However, QoL according to the FACT-T subscale was significantly lower in the dd-TC group than in the c-TC group (P = 0.02). CONCLUSION dd-TC does not decrease overall QoL compared with c-TC.

Somatic mutations and genetic polymorphisms of the PPP1R3 gene in patients with several types of cancers

Recently, we found nonsense and missense mutations of the PPP1R3 (protein phosphatase 1, regulatory subunit 3) gene in diverse human cancer cell lines and primary lung carcinomas, indicating that PPP1R3 functions as a tumor suppressor in human carcinogenesis. In this study, to assess the prevalence of PPP1R3 mutations in human primary cancers and the genetic diversity of the PPP1R3 gene in the human population, somatic mutations and genetic polymorphisms in the PPP1R3 gene were examined in 137 pairs of cancerous and non-cancerous tissues of patients with cancers of colon, ovary, and liver. Five somatic mutations including two missense mutations were detected in three cancerous tissues consisting of two colorectal carcinomas and one ovarian carcinoma. Five novel single nucleotide polymorphisms (SNPs) associated with the substitution of amino acids were also identified in cancer patients, in addition to five known nonsynonymous SNPs, including three previously reported ones as having an impact on the susceptibility to insulin resistant disorders. Differences in the activities and properties of multiple PPP1R3 proteins, which are produced in human cells due to variable somatic mutations and genetic polymorphisms in the PPP1R3 gene, can be involved in human carcinogenesis and susceptibility to diseases.

Antitumor effects of interleukin-6 (IL-6)/interleukin-6 receptor (IL-6R) signaling pathway inhibition in clear cell carcinoma of the ovary

Among epithelial ovarian cancers, clear cell carcinoma of the ovary (CCC) has unique clinical and molecular characteristics that include chemoresistance resulting in poor prognosis. It was shown that CCC recently was characterized by specific upregulation of the IL‐6/IL‐6R‐signal transducer and activator of transcription 3 (Stat3) signaling pathway. In this study, we aim to clarify whether IL‐6/IL‐6R mediated signaling pathway could have clinical relations with CCC and to evaluate inhibitory effects of the pathway on CCC carcinogenesis. A total of 84 CCC cases collected from primary surgical specimens were evaluated by the immunohistochemical analysis for IL‐6R and phosphorylated Stat3 (pStat3), and we found that high IL‐6R expression correlated with poor patient survival both by the univariate and multivariate analyses, suggesting that IL‐6/IL‐6R signaling pathway could be implicated in the progression of CCC. We further investigated the effects of IL‐6/IL‐6R mediated signaling pathway inhibition either by IL‐6R small interfering RNA (siRNA) approach or humanized anti‐human IL‐6R antibody (tocilizumab) in CCC. Inhibition of endogenous IL‐6R including tocilizumab in CCC cells did reduce cell invasion ability and restored their response to cytotoxic reagent. These data suggest that IL‐6/IL‐6R signaling pathway could act on CCC cells to enhance invasion and chemoresistance and, therefore, targeting IL‐6/IL‐6R mediated signaling pathway could be a promising therapeutic strategy for CCC.