Abstract 643: Establishment and mutation analysis of a novel malignant peritoneal mesothelioma cell line, TU-MM-1

Malignant peritoneal mesothelioma (MPM) is a rare aggressive neoplasm of the peritoneum, and its molecular biological characteristics and mechanisms of development are poorly understood. We, therefore, established a new cell line of human MPM, TU-MM-1, to elucidate its biological properties and to develop novel therapeutic strategies. The cells showed polygonal morphology, grew in monolayers without contact inhibition and were arranged like a jigsaw puzzle. The chromosome numbers ranged from 41 to 44. A low rate of proliferation was observed and the doubling time was 67.9 h. Genomic DNA sequencing revealed that TU-MM-1 cells harbored missense mutations in APC, LATS2, BRCA1/2, and TP53, and mutation of a splice donor site in BAP1 and loss of CDKN2A gene. We observed the absence of BAP1 and p16INK4a proteins, underexpression of LATS2 protein, and overexpression of p53 protein in TU-MM-1 cells in western blot analysis. Heterotransplantation to nude mice produced tumors that had the characteristics of the original tumor. This cell line may be useful for studying biological properties and contribute to novel treatment strategies.

Citation Format: Seiya Sato, Nao Oumi, Hiroaki Itamochi, Tetsuro Oishi, Tasuku Harada, Toru Sugiyama. Establishment and mutation analysis of a novel malignant peritoneal mesothelioma cell line, TU-MM-1. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 643.

Establishment and characterization of a novel ovarian clear cell carcinoma cell line, TU-OC-2, with loss of ARID1A expression

A new cell line of human ovarian clear cell carcinoma (CCC), TU-OC-2, was established and characterized. The cells were polygonal in shape, grew in monolayers without contact inhibition and were arranged in islands like pieces of a jigsaw puzzle. The chromosome numbers ranged from 41 to 96. A low rate of proliferation was observed and the doubling time was 37.5 h. The IC50 values of cisplatin, 7-ethyl-10-hydroxycamptothecin (SN38), which is an active metabolite of camptothecin, and paclitaxel were 7.7 μM, 17.7 nM and 301 nM, respectively. The drug sensitivity assay indicated that TU-OC-2 was sensitive to SN38, but resistant to cisplatin and paclitaxel. Mutational analysis revealed that TU-OC-2 cells have no mutations of PIK3CA in exons 9 and 20 and of TP53 in exons 4-9. We observed the loss of ARID1A protein expression in TU-OC-2 cells by western blot analysis and in the original tumor tissue by immunohistochemistry. This cell line may be useful for studying the chemoresistant mechanisms of CCC and exploring novel therapeutic targets such as the ARID1A-related signaling pathway.

Abstract 3556: Fibroblast growth factor receptor 2 is associated with poor overall survival in clear cell carcinoma of the ovary and may be a novel therapeutic approach

Objective: Clear cell carcinoma of the ovary (CCC) has a poor prognosis because of its resistance to conventional platinum- or taxane-based chemotherapy. We previously found that both gene and protein expression of fibroblast growth factor receptor (FGFR) 2 are increased in CCC. FGFR activate intracellular signaling pathways that are known to regulate key biological processes. Overexpression of FGFR2 has been reported in several cancers such as lung, pancreatic, breast and colorectal cancers, and has been associated with a poor prognosis. We therefore investigated whether FGFR2 could be a biomarker and a therapeutic target for CCC.

Methods: We analyzed the protein expression of FGFR2 by immunohistochemical staining in paraffin-embedded tumors from 112 CCC patients, and evaluated the association of this molecular parameter with clinical outcome. Next, we examined the expression of proteins of the FGFR2 signaling pathway in 12 ovarian cancer cell lines (11 CCC and one serous adenocarcinoma) by western blotting. The sensitivity of the cells to a FGFR inhibitor was determined by WST-8 assay, and cell cycle distribution was assessed by flow cytometry.

Results: One hundred and eight of 112 (96%) CCC tumors showed positive expression of FGFR2. No significant associations between the levels of FGFR2 expression and patient age or disease stage were found. The 5-year survival rate of patients with moderate or strong tumor expression of FGFR2 was significantly lower than those with an absent or low tumor expression of FGFR2 (54% vs. 79%). Multivariable analysis revealed that FGFR2 expression and disease stage were independent prognostic factors. All 11 CCC cell lines expressed substantial amounts of FGFR2 protein compared with the serous adenocarcinoma cell line. The protein expression level of 8 of 11 CCC cell lines was more than five times that of the serous adenocarcinoma cell line, and thus we defined these CCC cell lines as high FGFR2-expressing cells. The FGFR inhibitor effectively suppressed the growth of high FGFR2-expressing CCC cells compared with low FGFR2-expressing cells, with induction of G1 cell cycle arrest and downregulation of phosphorylated (p-) Akt and p-ERK expression.

Conclusions: The FGFR2 protein may be a promising biomarker that is predictive of patient outcome, and FGFR2 is a potential therapeutic target for CCC. Further study of FGFR inhibitor in the treatment of CCC is warranted.

Citation Format: Hiroaki Itamochi, Nao Oumi, Tetsuro Oishi, Fuminori Taniguchi, Tadahiro Shoji, Hiroyuki Fujiwara, Toru Sugiyama, Mitsuaki Suzuki, Junzo Kigawa, Tasuku Harada. Fibroblast growth factor receptor 2 is associated with poor overall survival in clear cell carcinoma of the ovary and may be a novel therapeutic approach. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3556. doi:10.1158/1538-7445.AM2015-3556

Establishment and mutation analysis of a novel malignant peritoneal mesothelioma cell line, TU-MM-1, using whole genome sequencing

A new cell line of human malignant peritoneal mesothelioma (MPM), TU-MM-1, was established and characterized. The cells showed polygonal morphology, grew in monolayers without contact inhibition and were arranged like a jigsaw puzzle. The chromosome numbers ranged from 41 to 44. A low rate of proliferation was observed and the doubling time was 67.9 h. Genomic DNA sequencing revealed that TU-MM-1 cells harbored missense mutations in APC, LATS2, BRCA1/2, and TP53, and mutation of a splice donor site in BAP1 and loss of CDKN2A gene. We observed the absence of BAP1 and p16(INK4a) proteins, underexpression of LATS2 protein, and overexpression of p53 protein in TU-MM-1 cells in western blot analysis. Heterotransplantation to nude mice produced tumors that had the characteristics of the original tumor. This cell line may be useful for studying biological properties and contribute to novel treatment strategies.

Abstract 4742: Comprehensive analysis of the PI3K-Akt-mTOR pathway in epithelial ovarian carcinoma

[Background] Ovarian clear cell carcinoma (CCC) has shown resistance to standard chemotherapy for epithelial ovarian cancer (EOC). Patients with CCC have a worse prognosis than those with ovarian serous adenocarcinoma (SAC), which is a dominant subtype of EOC. Recently, several reports have focused on mTOR as a therapeutic target for CCC, and the mTOR inhibitor temsirolimus (CCI-779) combined with carboplatin and paclitaxel is in phase II trial for stage III/IV CCC (GOG268 study). However, no molecular biomarker to predict prognosis and/or therapeutic benefit from these agents has been identified. This study evaluated the activation status of all key members of the PI3K-Akt-mTOR pathway in CCC compared with SAC, and to elucidate its clinical relevance as a prognostic biomarker.

[Material& Methods] We studied 70 patients with CCC and 70 with SAC through formalin-fixed, paraffin-embedded tissues and clinical records collected from Tottori University, Iwate Medical University, and Jichi Medical University hospitals. Samples were subjected to immunohistochemistry for expression of PIK3CA, PTEN, p-AKT (Ser473), p-mTOR, p-p70S6K and p-4E-BP1. The expression levels were evaluated by immuno-reactive score (IRS). For statistical analyses, IRS values of 0-3 were scored as poor expression, IRS 4-8 as moderate expression and 9-12 as strong. Additionally, freshly frozen tissues obtained from 31 of 70 patients with CCC and 36 of 70 with SAC were examined for hotspot mutations of the PIK3CA gene by direct sequencing and gene amplification by FISH. The association of these molecular parameters with histologic subtype and clinical outcome were evaluated.

[Results] Strong expression of nuclear p-AKT(Ser473) in CCC was more frequent than in SAC (24.3% vs. 8.6%, p=0.011). Moderate to strong expression of p-4E-BP1 in CCC was less frequent than in SAC (50.0% vs. 68.6%, p=0.038). There were no significant differences between CCC and SAC in expression of other molecules. Expression of these molecules was not associated with tumor stage or patient outcome. Hotspot mutations of PIK3CA were detected in 22.6% of CCC and 13.9% of SAC. Of CCC, the 5-year overall survival rate was significantly lower in PIK3CA mutant cases than in wild type cases (50.0% vs. 78.0%, p= 0.042). On the other hand, there were no differences in survival rate of SAC between mutant and wild types. Amplification of the PIK3CA gene was detected among 33.3% of both CCC and SAC patients, and did not relate to survival rate of each histological subtype.

[Conclusion] These results suggest that the PIK3CA mutation is a promising prognostic biomarker for CCC. Further studies focusing on patients treated with agents targeting PI3K-Akt-mTOR pathway are warranted to develop predictive biomarkers.

Citation Format: Tetsuro Oishi, Hiroaki Itamochi, Nao Oumi, Misaki Kato, Tadahiro Shoji, Yasushi Saga, Hiroyuki Fujiwara, Muneaki Shimada, Toru Sugiyama, Mitsuaki Suzuki, Junzo Kigawa, Tasuku Harada. Comprehensive analysis of the PI3K-Akt-mTOR pathway in epithelial ovarian carcinoma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4742. doi:10.1158/1538-7445.AM2014-4742

The PI3K/mTOR dual inhibitor NVP-BEZ235 reduces the growth of ovarian clear cell carcinoma

Patients with clear cell carcinoma of the ovary (OCCC) have poor survival due to resistance to standard chemotherapy. OCCC has frequent activating mutations of the PIK3CA gene. The present study was conducted to clarify the efficacy of the inhibition of the PI3K-AKT-mTOR pathway in OCCC. We used 8 OCCC cell lines and 5 ovarian serous adenocarcinoma (OSAC) cell lines. The mutation status of the PIK3CA and KRAS genes was examined by direct sequencing. The IC50 values of NVP-BEZ235 (BEZ235) and temsirolimus were determined by WST-8 assay. Protein expression levels of PI3K-AKT-mTOR pathway molecules were examined by western blotting. Cell cycle distribution was analyzed by flow cytometry. Annexin V staining was used for detecting apoptosis. We also investigated the effects of BEZ235 on OCCC tumor growth in a nude mouse xenograft model. Four of the 8 OCCC cell lines showed a PIK3CA mutation while none of the 5 OSAC cell lines showed a mutation. The IC50 values of BEZ235 for the OCCC cell lines were lower than these values for the OSAC cell lines. The IC50 value of temsirolimus was higher than BEZ235 in the OCCC cell lines. The PIK3CA mutation was more frequently noted in OCCC than OSAC cells, but the sensitivity of these cell lines to BEZ235 or temsirolimus was not related to the mutation status. pHER3 and pAkt proteins were expressed more frequently in OCCC compared with OSAC. However, protein expression levels were distributed widely, and were not related to the sensitivity. Treatment with BEZ235 suppressed expression of pAkt, although treatment with temsirolimus did not. OCCC cells exhibited G1 phase arrest after treatment with BEZ235 and apoptosis with a higher concentration of the agent. BEZ235 significantly inhibited tumor growth in mice bearing OVISE and TU-OC-1 cell tumors. The present study indicated that the PI3K-AKT-mTOR pathway is a potential target for OCCC, and that BEZ235 warrants investigation as a therapeutic agent.

Endoplasmic reticulum-associated degradation of Niemann-Pick C1: evidence for the role of heat shock proteins and identification of lysine residues that accept ubiquitin

Most cases with Niemann-Pick disease type C carry mutations in NPC1. Some of the mutations, including the most frequent I1061T, give rise to unstable proteins selected for endoplasmic reticulum-associated degradation. The purpose of the current study was to shed mechanistic insights into the degradation process. A proteasome inhibitor MG132 prolonged the life span of the wild-type NPC1 expressed in COS cells. The expressed protein associated with multiple chaperones including heat shock protein 90 (Hsp90), Hsp70, heat shock cognate protein 70 (Hsc70), and calnexin. Accordingly, expression of an E3 ligase CHIP (carboxyl terminus of Hsp70-interacting protein) enhanced MG132-induced accumulation of ubiquitylated NPC1. Co-expression and RNAi knockdown experiments in HEK cells indicated that Hsp70/Hsp90 stabilized NPC1, whereas Hsc70 destabilized it. In human fibroblasts carrying the I1061T mutation, adenovirus-mediated expression of Hsp70 or treatment with an HSP-inducer geranylgeranylacetone (GGA) increased the level of the mutant protein. In GGA-treated cells, the rescued protein was localized in the late endosome and ameliorated cholesterol accumulation. MALDI-TOF mass spectrometry revealed three lysine residues at amino acids 318, 792, and 1180 as potential ubiquitin-conjugation sites. Substitutions of the three residues with alanine yielded a mutant protein with a steady-state level more than three times higher than that of the wild-type. Introduction of the same substitutions to the I1061T mutant resulted in an increase in its protein level and functional restoration. These findings indicated the role of HSPs in quality control of NPC1 and revealed the role of three lysine residues as ubiquitin-conjugation sites.

Establishment and characterization of a novel ovarian clear cell adenocarcinoma cell line, TU-OC-1, with a mutation in the PIK3CA gene

A new cell line of human ovarian clear cell adenocarcinoma (CCC), TU-OC-1, was established and characterized. The cells showed a polygonal-shaped morphology and grew in monolayers without contact inhibition and were arranged like a jigsaw puzzle. The chromosome numbers ranged from 64 to 90. A low rate of proliferation was observed, similar to other CCC cell lines tested (OVTOKO, RMG-I, and OVAS), and the doubling time was 38.4 h. The respective IC50 values of cisplatin and paclitaxel were 12.2 μM and 58.3 nM. Mutational analysis revealed that TU-OC-1 cells harbored a PIK3CA mutation at codon 542 (E542K) in exon 9, which is a mutation hot spot on this gene. We observed that phosphorylated Akt protein was overexpressed in TU-OC-1 cells by western blot analysis. Heterotransplantation to nude mice produced tumors that reflected the original. This cell line may be useful to study the chemoresistant mechanisms of CCC and contribute to novel treatment strategies.

Establishment and characterization of a transgenic mouse model for in vivo imaging of Bmp4 expression in the pancreas

Type-2 diabetes results from the development of insulin resistance and a concomitant impairment of insulin secretion. Bone morphogenetic protein 4 (Bmp4)-Bmp receptor 1A signaling in β cells has recently been reported to be required for insulin production and secretion. In addition, Bmp4 blocks the differentiation and promotes the expansion of endocrine progenitor cells. Bmp4 therefore regulates the maintenance of homeostasis in the pancreas. In this study, we constructed a reporter plasmid carrying 7-kb enhancer and promoter region of the Bmp4 gene upstream of the firefly luciferase gene. We used this construct to produce transgenic mice by pro-nuclear microinjection, for subsequent in vivo monitoring of Bmp4 expression. The bioluminescent signal was detected mainly in the pancreas in three independent lines of transgenic mice. Furthermore, the bioluminescent signal was enhanced in association with the autophagy response to 24-h fasting. These results suggest that pancreatic expression of Bmp4 is involved in responding to the physiological environment, including through autophagy. These mouse models represent useful tools for toxicological screening, and for investigating the mechanisms responsible for pancreatic Bmp4 functions in vivo, with relevance to improving our understanding of pancreatic diseases.

Direct observation of antiferroquadrupolar ordering: resonant X-Ray scattering study of DyB2C2

Antiferroquadrupolar (AFQ) ordering has been conjectured in several rare-earth compounds to explain their anomalous magnetic properties. No direct evidence for AFQ ordering, however, has been reported. Using the resonant x-ray scattering technique near the Dy L(III) absorption edge, we have succeeded in observing the AFQ order parameter in DyB2C2 and analyzing the energy and polarization dependence. The much weaker coupling between the orbital degrees of freedom and the lattice in 4f electron systems than in 3d compounds makes them an ideal platform to study orbital interactions originating from electronic mechanisms.