Uterine Serous Carcinoma Cell Research Articles

PIK3CA oncogenic mutations represent a major mechanism of resistance to trastuzumab in HER2/neu overexpressing uterine serous carcinomas.

Objectives:We evaluated the role of PIK3CA-mutations as mechanism of resistance to trastuzumab in primary HER2/neu-amplified uterine-serous-carcinoma (USC) cell lines.Methods:Fifteen whole-exome-sequenced USC cell lines were tested for HER2/neu-amplification and PIK3CA-mutations. Four HER2/neu-amplified USC (2-harbouring wild-type-PIK3CA-genes and 2-harbouring oncogenic-PIK3CA-mutations) were evaluated in in vitro dose-titration-proliferation-assays, cell-viability and HER2 and S6-protein-phosphorylation after exposure to trastuzumab. USC harbouring wild-type-PIK3CA were transfected with plasmids encoding oncogenic PIK3CA-mutations (i.e., H1047R/R93Q) and exposed to trastuzumab. Finally, trastuzumab efficacy was tested by using two USC xenograft mouse models.Results:Seven out of fifteen (46%) of the USC cell lines were HER2/neu-amplified by fluorescence in situ hybridisation. Within these tumours four out of seven (57%) were found to harbour oncogenic PIK3CA-mutations vs two out of eight (25%) of the HER2/neu not amplified cell lines (P=0.01). HER2/neu-amplified/PIK3CA-mutated USC were highly resistant to trastuzumab when compared with HER2/neu-amplified/wild-type-PIK3CA cell lines (P=0.02). HER2/neu-amplified/PIK3CA wild-type cell lines transfected with oncogenic PIK3CA-mutations increased their resistance to trastuzumab (P<0.0001). Trastuzumab was effective in reducing tumour growth (P=0.001) and improved survival (P=0.0001) in mouse xenografts harbouring HER2-amplified/PIK3CA wild-type USC but not in HER2-amplified/PIK3CA-mutated tumours.Conclusions:Oncogenic PIK3CA mutations are common in HER2/neu-amplified USC and may constitute a major mechanism of resistance to trastuzumab treatment.

Solitomab, an EpCAM/CD3 bispecific antibody construct (BiTE), is highly active against primary uterine serous papillary carcinoma cell lines in vitro

Uterine serous carcinoma is an aggressive form of endometrial cancer that carries an extremely poor prognosis. Solitomab is a novel bispecific single-chain antibody construct that targets epithelial cell adhesion molecule on tumor cells and also contains a CD3 binding region. We evaluated the expression levels of epithelial cell adhesion molecule and the invitro activity of solitomab against primary uterine serous carcinoma cell lines invitro and ex-vivo in the ascites of patients with uterine serous carcinoma. The purpose of this study was to determine the frequency of expression of epithelial cell adhesion molecule on uterine serous carcinoma cell lines and the ability of solitomab to modulate immune responses (T-cell proliferation, activation, cytokine production, and tumor killing) to tumor cells when it is combined with lymphocytes and epithelial cell adhesion molecule-positive cell lines or epithelial cell adhesion molecule-positive ascitic fluid invitro. Epithelial cell adhesion molecule expression was evaluated by flow cytometry in a total of 14 primary uterine serous carcinoma cell lines. Sensitivity to solitomab-dependent cellular-cytotoxicity was tested against a panel of primary uterine serous carcinoma cell lines that express different levels of epithelial cell adhesion molecule in standard 4-hour chromium release assays. The proliferative activity, activation, cytokine secretion (ie, type I vs type II), and cytotoxicity of solitomab in autologous tumor-associated T cells in the ascitic fluid of patients with uterine serous carcinoma was also evaluated by carboxyfluorescein succinimidyl ester and flow-cytometry assays. Differences in epithelial cell adhesion molecule expression, solitomab-dependent cellular-cytotoxicity levels were analyzed with the use of an unpaired ttest. T-cell activation marker increase and cytokine release were analyzed by a paired t test. Surface expression of epithelial cell adhesion molecule was found in 85.7% (12 of 14) of the uterine serous carcinoma cell lines that were tested by flow cytometry. Epithelial cell adhesion molecule-positive cell lines were found resistant to natural killer cells or T-cell-mediated killing after exposure to peripheral blood lymphocytes in 4-hour chromium-release assays (mean killing ± standard of the mean, 2.7% ± 3.1% after incubation of epithelial cell adhesion molecule-positive cell lines with control bispecific antibody construct). In contrast, after incubation with solitomab, epithelial cell adhesion molecule-positive uterine serous carcinoma cells became highly sensitive to T-cell cytotoxicity (mean killing, 25.7% ± 4.5%; P < .0001) by peripheral blood lymphocytes. Exvivo incubation of autologous tumor-associated lymphocytes with epithelial cell adhesion molecule that expressed malignant cells in ascites with solitomab resulted in a significant increase in T-cell proliferation in both CD4+ and CD8+ T cells, increase in T-cell activation markers (ie, CD25 and HLA-DR), and a reduction in number of viable uterine serous carcinoma cells in ascites (P < .001). Solitomab induces robust immunologic responses invitro that result in increased T-cell activation, proliferation, production of cytokines, and direct killing of tumor cells. These findings suggest that solitomab may represent a novel, potentially effective agent for the treatment of recurrent/metastatic and/or chemo-resistant uterine serous carcinoma-overexpressing epithelial cell adhesion molecule.

Abstract 3103: Cyclin E amplification predicts sensitivity of primary Uterine Serous Carcinoma (USC) cell lines to the cdk2 inhibitor CYC065

Abstract We evaluated the in vitro effectiveness of the cdk2 inhibitor CYC065 on multiple primary chemotherapy-resistant USC cell lines with or without CCNE1 amplification. CCNE1-amplified primary cell lines were significantly more sensitive than wild type USC cell lines to CYC065 in vitro (i.e., IC50: mean±STDV = 61.75±13.22 nM and 103.16± 21.9 nM for CCNE1-amplified USC-ARK-2 and USC-ARK-7 cell lines, respectively and 539.2±182.1 nM for the wild type USC-ARK-4 cell line, p = 0.0048). Consistently, low concentrations of CYC065 (i.e., 100 - 300 nM) caused a dose dependent arrest in the G1 phase of the cell cycle specifically in CCNE1-amplified primary USC cell lines. Importantly, CCNE1 knockdown in the USC-ARK-2 cell line resulted in a 9.29-fold increase in the CYC065 IC50 when compared to the MOCK-transfected USC-ARK-2 cell line (p = 0.021). Finally, when primary CCNE1-amplified USC cell lines also harboring ERBB2 amplification (50% of CCNE1-amplified USC cell lines) were incubated in vitro with the combination of CYC065 and Herceptin (a monoclonal antibody targeting the product of the ERBB2 gene, HER2/neu), an increased inhibitory effect was reported in the combination treatment when compared to Herceptin or CYC065 used as single agent (i.e.,% viable cells: mean±STDV = 71.4±0.85, 65.4±14.2, 42.2±2.1 for the Herceptin, the CYC065 and the combination treatment on USC-ARK-2, respectively; p = 0.014). Together these findings identify CYC065 as a promising drug to be considered alone or in combination in the treatment of patients harboring CCNE1-amplified USC. Citation Format: Emiliano Cocco, Stefania Bellone, Salvatore Lopez, Elena Bonazzoli, Federica Predolini, Jonathan D. Black, Alessandro D. Santin. Cyclin E amplification predicts sensitivity of primary Uterine Serous Carcinoma (USC) cell lines to the cdk2 inhibitor CYC065. [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 3103. doi:10.1158/1538-7445.AM2015-3103

Abstract 2461: SYD985, a novel HER2-targeting antibody-drug conjugate, shows strong antitumor activity in primary USC cell lines with low (1+) and moderate (2+) HER2/Neu expression

Abstract Introduction: Uterine serous carcinoma (USC) is an aggressive form of endometrial cancer which carries an extremely poor prognosis. Up to 35% of USC may overexpress the HER2/neu oncogene at strong (i.e., 3+) levels and and additional 45% of USC express HER2/Neu at moderate (2+) or low (1+) levels. For tumors with moderate/low HER2/neu expression, there is no sufficient targeted therapy. SYD985 (Synthon Biopharmaceuticals BV, Nijmegen, The Netherlands) is a novel HER2-targeting antibody-drug conjugate (ADC) composed of the mAb trastuzumab linked to a highly potent DNA-alkylating agent (i.e., duocarmycin). The objective of this study was to explore the anti-tumor activity of SYD985 and to compare it to trastuzumab emtansine (T-DM1) in USC in in vitro and in vivo studies. Methods: Nine primary USC cell lines were evaluated for HER2/neu surface expression by IHC and flow cytometry and gene amplification using FISH assays. The cytotoxicity of SYD985 and T-DM1 was evaluated using cell lines with differential HER2/Neu expression (i.e., 1+, 2+, and 3+). Proliferation and viability experiments were performed using propidium iodide-based, flow cytometry assays. In vivo activity of SYD985 in mouse xenograft models is ongoing. Results: SYD985 was 55 to 115 times more potent when compared to T-DM1 in primary USC cell lines with 1+ and 2+ HER2/neu expression. Specifically, in the HER2/neu 1+ the IC50's for SYD985 and T-DM1 were 0.065 μg/mL and 3.58 μg/mL, respectively (p = 0.004). In the HER2/neu 2+ cell lines the IC50's of SYD985 and T-DM1 were 0.016 μg/mL and 1.82 μg/mL, respectively (p = 0.005). In the HER2/neu 3+ cell lines a statistical trend was noted when comparing the cytotoxicity of SYD985 with T-DM1; the IC50's were 0.011 μg/mL and 0.035 μg/mL, respectively (p = 0.06). Conclusions: SYD985 is a novel ADC endowed with remarkable activity against not only USC with strong (3+) HER2/neu overexpression but also (as previously shown for SYD985 in breast cancer) versus USC with low to moderate (i.e., 1+/2+) HER2/neu expression. SYD985 is significantly more potent than T-DM1 in comparative in vitro experiments. Currently, in vivo experiments in USC xenografts not responsive to T-DM1 are ongoing. This is a significant discovery as we do not currently have an adequate targeted therapy to HER2/neu 1+ and 2+ expressing tumors. Thus, clinical studies with SYD985 in patients with biologically aggressive endometrial cancer (e.g., USC) resistant to standard salvage chemotherapy are warranted. Citation Format: Jonathan D. Black, Salvatore Lopez, Emiliano Cocco, Stefania Bellone, Elena Bonazzoli, Carlton Schwab, Diana English, Peter Goedings, Patrick Beusker, Miranda van der Lee, Marco Timmers, Wim Dokter, Thomas Rutherfor, Peter Schwartz, Alessandro Santin. SYD985, a novel HER2-targeting antibody-drug conjugate, shows strong antitumor activity in primary USC cell lines with low (1+) and moderate (2+) HER2/Neu expression. [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 2461. doi:10.1158/1538-7445.AM2015-2461

Dacomitinib (PF-00299804), a second-generation irreversible pan-erbB receptor tyrosine kinase inhibitor, demonstrates remarkable activity against HER2-amplified uterine serous endometrial cancer in vitro.

Uterine serous carcinoma (USC) is an aggressive subtype of endometrial cancer that carries an extremely poor prognosis. Up to 35 % of USC may overexpress the epidermal growth factor receptor-2 (HER2/neu) at strong (i.e., 3+) level by immunohistochemistry (IHC) or harbor HER2/neu gene amplification by fluorescence in situ hybridization (FISH). In this study, we assessed the sensitivity of a panel of USC cell lines with and without HER2/neu gene amplification to dacomitinib (PF-00299804), an irreversible pan-human epidermal growth factor receptor tyrosine kinase inhibitor. Eight primary cell lines (i.e., four harboring HER2/neu gene amplification by FISH and four FISH- cell lines), all demonstrating similar in vitro growth rates, were evaluated in viability/proliferation assays. The effect of dacomitinib on cell growth, cell cycle distribution, and signaling was determined using flow cytometry-based assays. Dacomitinib caused a significantly stronger growth inhibition in HER2/neu FISH+ USC cell lines when compared to FISH- USC (dacomitinib half maximal inhibitory concentration (IC50) mean ± SEM = 0.02803 ± 0.003355 μM in FISH+ versus 1.498 ± 0.2209 μM in FISH- tumors, P < 0.0001). Dacomitinib growth inhibition was associated with a significant and dose-dependent decline in phosphorylated HER2/neu and S6 transcription factor and a dose-dependent and time-dependent cell cycle arrest in G0/G1 in FISH+ USC. Dacomitinib is remarkably effective against chemotherapy-resistant HER2/neu gene-amplified USC. Clinical studies with dacomitinib in HER2/neu FISH+ USC patients resistant to standard salvage chemotherapy are warranted.

Dual HER2 targeting impedes growth of HER2 gene-amplified uterine serous carcinoma xenografts.

Uterine serous carcinoma (USC) is an aggressive subtype of endometrial cancer that commonly harbors HER2 gene amplification. We investigated the effectiveness of HER2 inhibition using lapatinib and trastuzumab in vitro and in xenografts derived from USC cell lines and USC patient-derived xenografts. Immunohistochemistry and FISH were performed to assess HER2 expression in 42 primary USC specimens. ARK1, ARK2, and SPEC2 cell lines were treated with trastuzumab or lapatinib. Cohorts of mice harboring xenografts derived from ARK2 and SPEC2 cell lines and EnCa1 and EnCa2 primary human USC samples were treated with either vehicle, trastuzumab, lapatinib, or the combination of trastuzumab and lapatinib. Acute and chronic posttreatment tumor samples were assessed for downstream signaling alterations and examined for apoptosis and proliferation. HER2 gene amplification (24%) correlated significantly with HER2 protein overexpression (55%). All models were impervious to single-agent trastuzumab treatment. Lapatinib decreased in vitro proliferation of all cell lines and in vivo growth of HER2-amplified xenografts (ARK2, EnCa1). In addition, dual therapy with trastuzumab and lapatinib resulted in significant antitumor activity only in ARK2 and EnCa1 tumors. Dual HER2 therapy induced on target alteration of downstream MAPK and PI3K pathway mediators only in HER2-amplified models, and was associated with increased apoptosis and decreased proliferation. Although trastuzumab alone did not impact USC growth, dual anti-HER2 therapy with lapatinib led to improved inhibition of tumor growth in HER2-amplified USC and may be a promising avenue for future investigation.

T-DM1, a novel antibody-drug conjugate, is highly effective against primary HER2 overexpressing uterine serous carcinoma in vitro and in vivo.

Amplification of c-erbB2 has been reported in over 30% of uterine serous carcinoma (USC) and found to confer poor survival because of high proliferation and increased resistance to therapy. In this study, we evaluated for the first time Trastuzumab emtansine (T-DM1), a novel antibody–drug conjugate, against multiple epidermal growth factor receptor-2 (HER2)-positive USC cells in vitro followed by developing a supportive in vivo model. Fifteen primary USC cell lines were assessed by immunohistochemistry (IHC) and flow cytometry for HER2 protein expression. C-erbB2 gene amplification was evaluated using fluorescent in situ hybridization. Sensitivity to T-DM1 and trastuzumab (T)-induced antibody-dependent cell-mediated cytotoxicity was evaluated in 5-h chromium release assays. T-DM1 and T cytostatic and apoptotic activities were evaluated using flow-cytometry-based proliferation assays. In vivo activity of T-DM1 versus T in USC xenografts in SCID mice was also evaluated. High levels of HER2 protein overexpression and HER2 gene amplification were detected in 33% of USC cell lines. T-DM1 was considerably more effective than trastuzumab in inhibiting cell proliferation and in causing apoptosis (P = 0.004) of USC showing HER2 overexpression. Importantly, T-DM1 was highly active at reducing tumor formation in vivo in USC xenografts overexpressing HER2 (P = 0.04) and mice treated with TDM-1 had significantly longer survival when compared to T-treated mice and control mice (P ≤ 0.0001). T-DM1 shows promising antitumor effect in HER2-positive USC cell lines and USC xenografts and its activity is significantly higher when compared to T. T-DM1 may represent a novel treatment option for HER2-positive USC patients with disease refractory to trastuzumab and traditional chemotherapy.

Dual HER2 targeting impedes growth of HER2 gene-amplified uterine papillary serous carcinoma xenografts

Purpose:Uterineserouscarcinoma(USC)isanaggressivesubtypeofendometrialcancerthatcommonly harbors HER2 gene amplification. We investigated the effectiveness of HER2 inhibition using lapatinib and trastuzumab in vitro and in xenografts derived from USC cell lines and USC patient-derived xenografts. Experimental Design: Immunohistochemistry and FISH were performed to assess HER2 expression in 42 primary USC specimens. ARK1, ARK2, and SPEC2 cell lines were treated with trastuzumab or lapatinib. Cohorts of mice harboring xenografts derived from ARK2 and SPEC2 cell lines and EnCa1 and EnCa2 primaryhumanUSCsamplesweretreatedwitheithervehicle,trastuzumab,lapatinib,orthecombinationof trastuzumab and lapatinib. Acute and chronic posttreatment tumor samples were assessed for downstream signaling alterations and examined for apoptosis and proliferation. Results: HER2 gene amplification (24%) correlated significantly with HER2 protein overexpression (55%). All models were impervious to single-agent trastuzumab treatment. Lapatinib decreased in vitro proliferation of all cell lines and in vivo growth of HER2-amplified xenografts (ARK2, EnCa1). In addition, dual therapy with trastuzumab and lapatinib resulted in significant antitumor activity only in ARK2 and EnCa1 tumors. Dual HER2 therapy induced on target alteration of downstream MAPK and PI3K pathway mediators only in HER2-amplified models, and was associated with increased apoptosis and decreased proliferation. Conclusions: Although trastuzumab alone did not impact USC growth, dual anti-HER2 therapy with lapatinib led to improved inhibition of tumor growth in HER2-amplified USC and may be a promising avenue for future investigation. Clin Cancer Res; 20(24); 6517–28. � 2014 AACR.

HER2/neu gene amplification determines the sensitivity of uterine serous carcinoma cell lines to AZD8055, a novel dual mTORC1/2 inhibitor

ObjectiveTo evaluate c-erbB2 gene amplification in a series of primary uterine serous carcinoma (USC) cell lines. To assess the efficacy of AZD8055, a novel dual mTORC1/2 inhibitor against primary HER2/neu amplified vs HER2/neu not amplified USC cell lines. MethodsTwenty-two primary USC cell lines were evaluated for c-erbB2 oncogene amplification by FISH assays. In vitro sensitivity to AZD8055 was evaluated by flow-cytometry-based viability and proliferation assays. Cell cycle profile and downstream cellular responses to AZD8055 were assessed by measuring the DNA content of cells and by phosphorylation of the S6 protein by flow-cytometry. ResultsNine of 22 (40.9%) USC cell lines demonstrated c-erbB2 gene amplification by FISH. AZD8055 caused a strong differential growth inhibition in USC cell lines, with high HER-2/neu-expressors demonstrating significantly higher sensitivity when compared to low HER-2/neu-expressors (AZD-8055 IC50 mean±SEM=0.27±0.05μM in c-erbB2 amplified versus 1.67±0.68μM in c-erbB2 not amplified tumors, P=0.03). AZD8055 growth-inhibition was associated with a significant and dose-dependent increase in the percentage of cells blocked in the G0/G1 cell cycle phase and a dose-dependent decline in pS6 levels in both c-erbB2 amplified vs c-erbB2 not amplified USC cell lines. ConclusionsAZD8055 may represent a novel targeted therapeutic agent in patients harboring advanced/recurrent/refractory USC. c-erbB2 gene amplification may represent a biomarker to identify USC patients who may benefit most from the use of AZD8055.

Oncogenic PIK3CA gene mutations and HER2/neu gene amplifications determine the sensitivity of uterine serous carcinoma cell lines to GDC-0980, a selective inhibitor of Class I PI3 kinase and mTOR kinase (TORC1/2)

To evaluate PIK3CA mutational status and c-erbB2 gene amplification in a series of primary uterine serous carcinomas (USC) cell lines. To assess the efficacy of GDC-0980, a potent inhibitor of Class I PI3 kinase and mTOR kinase (TORC1/2), against primary USC harboring HER2/neu gene amplification and/or PIK3CA mutations. Twenty-two primary USC cell lines were evaluated for c-erbB2 oncogene amplification by fluorescence in situ hybridization (FISH) assays and for PIK3CA gene mutations by direct DNA sequencing of exons 9 and 20. In vitro sensitivity to GDC-0980 was evaluated by flow-cytometry-based viability and proliferation assays. Downstream cellular responses to GDC-0980 were assessed by measuring phosphorylation of the 4-EBP1 protein by flow-cytometry. Five of 22 (22.7%) USC cell lines contained oncogenic PIK3CA mutations although 9 (40.9%) harbored c-erbB2 gene amplification by FISH. GDC-0980 caused a strong differential growth inhibition in FISH+ USC when compared with FISH- (GDC-0980 IC50 mean ± SEM = 0.29 ± 0.05 μM in FISH+ vs 1.09 ± 0.20 μM in FISH- tumors, P = .02). FISH+ USC harboring PIK3CA mutations were significantly more sensitive to GDC-0980 exposure when compared with USC cell lines harboring wild-type PIK3CA (P = .03). GDC-0980 growth-inhibition was associated with a significant and dose-dependent decline in phosphorylated 4-EBP1 levels. Oncogenic PIK3CA mutations and c-erbB2 gene amplification may represent biomarkers to identify patients harboring USC who may benefit most from the use of GDC-0980.

Metformin Downregulates the Insulin/IGF-I Signaling Pathway and Inhibits Different Uterine Serous Carcinoma (USC) Cells Proliferation and Migration in p53-Dependent or -Independent Manners

Accumulating epidemiological evidence shows that obesity is associated with an increased risk of several types of adult cancers, including endometrial cancer. Chronic hyperinsulinemia, a typical hallmark of diabetes, is one of the leading factors responsible for the obesity-cancer connection. Numerous cellular and circulating factors are involved in the biochemical chain of events leading from hyperinsulinemia and insulin resistance to increased cancer risk and, eventually, tumor development. Metformin is an oral anti-diabetic drug of the biguanide family used for treatment of type 2 diabetes. Recently, metformin was shown to exhibit anti-proliferative effects in ovarian and Type I endometrial cancer, although the mechanisms responsible for this non-classical metformin action remain unclear. The insulin-like growth factors (IGFs) play a prominent role in cancer biology and their mechanisms of action are tightly interconnected with the insulin signaling pathways. Given the cross-talk between the insulin and IGF signaling pathways, the aim of this study was to examine the hypothesis that the anti-proliferative actions of metformin in uterine serous carcinoma (USC) are potentially mediated via suppression of the IGF-I receptor (IGF-IR) pathway. Our results show that metformin interacts with the IGF pathway, and induces apoptosis and inhibition of proliferation and migration of USC cell lines with both wild type and mutant p53. Taken together, our results suggest that metformin therapy could be a novel and attractive therapeutic approach for human USC, a highly aggressive variant of endometrial cancer.

BRCA1 is Expressed in Uterine Serous Carcinoma (USC) and Controls Insulin-Like Growth Factor I Receptor (IGF-IR) Gene Expression in USC Cell Lines

The insulin-like growth factor I receptor (IGF-IR) and BRCA1 affect cell growth and apoptosis. Little information is available about BRCA1 activity on the IGF signaling pathway. This study evaluated the effect of BRCA1 on IGF-IR expression. BRCA1 and IGF-IR immunohistochemistry on archival tissues (35 uterine serous carcinomas [USCs] and 17 metastases) were performed. USPC1 and USPC2 cell lines were transiently cotransfected with an IGF-IR promoter construct driving a luciferase reporter gene and a BRCA1 expression plasmid. Endogenous IGF-IR levels were evaluated by Western immunoblotting. We found high BRCA1 and IGF-IR protein expression in primary and metastatic USC tumors. All samples were immunostained for BRCA1-71% strongly stained; and 33/35 (94%) were stained positive for IGF-IR-2 (6%) strongly stained. No difference in BRCA1 and IGF-IR staining intensity was noted between BRCA1/2 mutation carriers and noncarriers. Metastatic tumors stained more intensely for BRCA1 than did the primary tumor site (P = 0.041) and with borderline significance for IGF-IR (P = 0.069). BRCA1 and IGF-IR staining did not correlate to survival. BRCA1 expression led to 35% and 54% reduction in IGF-IR promoter activity in the USPC1 and USCP2 cell lines, respectively. Western immunoblotting showed a decline in phosphorylated IGF-IR and phosphorylated AKT in both transiently and stably transfected cells. BRCA1 and IGF-IR are highly expressed in USC tumors. BRCA1 suppresses IGF-IR gene expression and activity. These findings suggest a possible biological link between the BRCA1 and the IGF-I signaling pathways in USC. The clinical implications of this association need to be explored.

Downregulation of membrane complement inhibitors CD55 and CD59 by siRNA sensitises uterine serous carcinoma overexpressing Her2/neu to complement and antibody-dependent cell cytotoxicity in vitro: implications for trastuzumab-based immunotherapy

Background:We evaluated the expression of CD46, CD55 and CD59 membrane-bound complement-regulatory proteins (mCRPs) in primary uterine serous carcinoma (USC) and the ability of small interfering RNA (siRNA) against these mCRPs to sensitise USC to complement-dependent cytotoxicity (CDC) and antibody (trastuzumab)-dependent cellular cytotoxicity (ADCC) in vitro.Methods:Membrane-bound complement-regulatory proteins expression was evaluated using real-time PCR (RT–PCR) and flow cytometry, whereas Her2/neu expression and c-erbB2 gene amplification were assessed using immunohistochemistry, flow cytometry and fluorescent in-situ hybridisation. The biological effect of siRNA-mediated knockdown of mCRPs on HER2/neu-overexpressing USC cell lines was evaluated in CDC and ADCC 4-h chromium-release assays.Results:High expression of mCRPs was found in USC cell lines when compared with normal endometrial cells (P<0.05). RT–PCR and FACS analyses demonstrated that anti-mCRP siRNAs were effective in reducing CD46, CD55 and CD59 expression on USC (P<0.05). Baseline complement-dependent cytotoxicity (CDC) against USC cell lines was low (mean±s.e.m.=6.8±0.9%) but significantly increased upon CD55 and CD59 knockdown (11.6±0.8% and 10.7±0.9%, respectively, P<0.05). Importantly, in the absence of complement, both CD55 and CD59, but not CD46, knockdowns significantly augmented ADCC against USC overexpressing Her2/neu.Conclusion:Uterine serous carcinoma express high levels of the mCRPs CD46, CD55 and CD59. Small interfering RNA inhibition of CD55 and CD59, but not CD46, sensitises USC to both CDC and ADCC in vitro, and if specifically targeted to tumour cells, may significantly increase trastuzumab-mediated therapeutic effect in vivo.

P53 Regulates insulin-like growth factor-I receptor gene expression in uterine serous carcinoma and predicts responsiveness to an insulin-like growth factor-I receptor-directed targeted therapy

The role of the insulin-like growth factors (IGF) in endometrial cancer has been well established. The IGF-I receptor (IGF-IR), which mediates the biological actions of IGF-I, is usually overexpressed in endometrial tumours. Uterine serous carcinoma (USC) constitutes a defined histological category among endometrial cancers. Mutation of the p53 gene appears early in the course of the disease and is considered a key event in the initiation of USC. The aim of the present study was to evaluate the potential interactions between p53 and the IGF-IR in USC. In addition, we investigated the role of p53 as a biomarker in IGF-IR targeted therapies. Immunohistochemical analysis in a collection of 35 USC specimens revealed that IGF-IR is highly expressed in primary and metastatic USC. Likewise, p53 was expressed in 85.7% of primary tumours and 100% of metastases. A significant negative correlation between p53 expression and survival was noticed. In addition, using USC-derived cell lines we provide evidence that p53 regulates IGF-IR gene expression via a mechanism that involves repression of the IGF-IR promoter. We show that the mechanism of action of p53 involves interaction with zinc finger protein Sp1, a potent transactivator of the IGF-IR gene. Finally, we demonstrate that USC tumours overexpressing p53 are more likely to benefit from anti-IGF-IR therapies. In summary, we provide evidence that p53 regulates IGF-IR gene expression in USC cells via a mechanism that involves repression of the IGF-IR promoter. The interplay between the p53 and IGF-I signalling pathways is of major basic and translational relevance.

Her2/neu extracellular domain shedding in uterine serous carcinoma: implications for immunotherapy with trastuzumab

Background:We evaluated shedding of epidermal growth factor type II receptor (Her2/neu) extracellular domain (ECD) in primary uterine serous carcinoma (USC) cell lines and in the serum of USC patients and its biological effects in experiments of trastuzumab-induced cytotoxicity in vitro.Methods:Her2/neu expression was evaluated by immunohistochemistry (IHC), real-time PCR and flow cytometry, while c-erbB2 gene amplification was assessed using fluorescent in situ hybridisation (FISH). Her2/neu ECD levels in the supernatants of USC cell lines and in the serum of 38 USC patients and 19 controls were tested using ELISA. The biologic effect of Her2/neu ECD on trastuzumab-induced antibody-dependent cell-mediated cytotoxicity (ADCC) was evaluated in 5-h chromium-release assays.Results:Five out of ten USC cell lines overexpressed Her2/neu by IHC and showed amplification of the c-erbB2 gene. High levels of Her2/neu ECD were found in supernatants of all FISH-positive tumours. In contrast, FISH-negative USC was negative for Her2/neu ECD shedding. Serum Her2/neu ECD levels in patients harbouring 3+Her2/neu tumours were higher than those found in healthy women (P=0.02) or USC patients with 2+ or 1+/negative Her2/neu expression (P=0.02). In cytotoxicity experiments, trastuzumab-mediated ADCC was significantly decreased by the addition of Her2/neu ECD-containing supernatants (P=0.01).Conclusion:FISH-positive c-erbB2 USC cell lines shed high levels of Her2/neu ECD. High levels of Her2/neu ECD in USC patients may reduce trastuzumab-mediated ADCC in vitro and potentially neutralise its therapeutic effect in vivo.

Development and characterization of a human single-chain antibody fragment against claudin-3: a novel therapeutic target in ovarian and uterine carcinomas

The purpose of this study was to develop and characterize a human antibody in a single-chain antibody fragment format (scFv) that is directed specifically against claudin-3 (CLDN3). The synthetic ETH-2 Gold human antibody phage display library was used to select scFv specific against CLDN3. scFv binding properties were analyzed by surface plasmon resonance; specificity was confirmed with enzyme-linked immunosorbent assay, immunofluorescence, and flow cytometry on a panel of ovarian and uterine serous carcinoma cell lines. Surface plasmon resonance studies indicated scFv H6 to be the clone with the highest affinity against CLDN3 (K(D) of 23.60 nmol/L). scFv H6 efficiently stained CLDN3-expressing cells and recognized its epitope in enzyme-linked immunosorbent assay that was performed with uterine serous papillary carcinoma native protein extract, which suggested that a conformational epitope is recognized by this antibody. Cell surface immunofluorescence with laser scanning confocal microscopy confirmed the specific binding to the native membrane CLDN3. scFv H6 may represent a novel antitumor agent against chemotherapy-resistant ovarian and serous papillary carcinomas and other human malignancies that overexpress CLDN3.