[Antitumor effects of redox-responsive nanoparticles containing platinum（Ⅳ）in ovarian cancer]

Objectives: To explore the antitumor effects of redox-responsive nanoparticles containing platinum(Ⅳ)-NP@Pt(Ⅳ) in ovarian cancer. Methods: Redox-responsive polymer carriers were synthesized. Polymer carriers and platinum(Ⅳ)-Pt(Ⅳ) can self-assemble into NP@Pt(Ⅳ). Inductively coupled plasma mass spectrometry was performed to detect the platinum release from NP@Pt(Ⅳ) in reducing environment and the platinum content in ovarian cancer cells ES2 treated with cisplatin, Pt(Ⅳ) and NP@Pt(Ⅳ). The proliferation ability of the ovarian cancer cells were detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cellular apoptosis was assessed by flow cytometry. Collection of primary ovarian cancer tissues from patients with primary high-grade serous ovarian cancer who were surgically treated at the Cancer Hospital of the Chinese Academy of Medical Sciences from October to December 2022. The high-grade serous ovarian cancer patient-derived xenograft (PDX) mice were intravenously injected with Cy7.5 labeled NP@Pt(Ⅳ) followed by in vivo imaging system. Mice were treated with PBS, cisplatin and NP@Pt(Ⅳ). Tumor volume and weight were measured in each group. Necrosis, apoptosis and cell proliferation of tumor tissues were detected by hematoxylin-eosin (HE) staining, TUNEL fluorescence staining and Ki-67 immunohistochemistry staining. Body weight and HE staining of heart, liver, spleen, lung and kidney of mice in each group were measured. Results: The platinum release of NP@Pt(Ⅳ) after 48 hours in reducing environment was 76.29%, which was significantly higher than that of 26.82% in non-reducing environment (P<0.001). The platinum content in ES2 cells after 4 hours and 7 hours of treatment with NP@Pt(Ⅳ) (308.59, 553.15 ng/million cells) were significantly higher than those of Pt(Ⅳ) (100.21, 180.31 ng/million cells) and cisplatin (43.36, 50.36 ng/million cells, P＜0.05). The half inhibitory concentrations of NP@Pt(Ⅳ) in ovarian cancer cells ES2, A2780, A2780DDP were 1.39, 1.42 and 4.62 μmol/L, respectively, which were lower than those of Pt(IV) (2.89, 7.27, and 16.74 μmol/L) and cisplatin (5.21, 11.85, and 71.98 μmol/L). The apoptosis rate of ES2 cells treated with NP@Pt(Ⅳ) was (33.91±3.80)%, which was significantly higher than that of Pt(Ⅳ) [(16.28±2.41)%] and cisplatin [(15.01±1.17)%, P＜0.05]. In high-grade serous ovarian cancer PDX model, targeted accumulation of Cy7.5 labeled NP@Pt(Ⅳ) at tumor tissue could be observed. After the treatment, the tumor volume of mice in NP@Pt(IV) group was (130±98) mm3, which was significantly lower than those in control group [(1 349±161) mm3, P<0.001] and cisplatin group [(715±293) mm3, P=0.026]. The tumor weight of mice in NP@Pt(IV) group was (0.17±0.09)g, which was significantly lower than those in control group [(1.55±0.11)g, P<0.001] and cisplatin group [(0.82±0.38)g, P=0.029]. The areas of tumor necrosis and apoptosis in mice treated with NP@Pt(Ⅳ) were higher than those in mice treated with cisplatin. Immunohistochemical staining revealed that there were low expressions of Ki-67 at tumor tissues of mice treated with NP@Pt(Ⅳ) compared with cisplatin. The change in body weight of mice in NP@Pt(Ⅳ) group was not significantly different from that of the control group [(18.56±2.04)g vs.(20.87±0.79)g, P=0.063]. Moreover, the major organs of the heart, liver, spleen, lung, and kidney were also normal by HE staining. Conclusion: Redox-responsive NP@Pt(Ⅳ), produced in this study can enhance the accumulation of cisplatin in ovarian cancer cells and improve the efficacy of ovarian cancer chemotherapy.

[Signal transducer and activator of transcription 3 and cancer associated fibroblasts jointly generate chemo-resistance and affect prognosis in epithelial ovarian cancer]

Objective: To investigate the mechanism of signal transducer and activator of transcription 3 (STAT3) and cancer associated fibroblasts (CAF) jointly generate chemo-resistance in epithelial-ovarian cancer and their effect on prognosis. Methods: A total of 119 patients with high-grade ovarian serous cancer who received surgery in Cancer Hospital of Chinese Academy of Medical Sciences from September 2009 to October 2017 were collected. The clinico-pathological data and follow-up data were complete. Multivariate Cox regression model was used to analyze the prognostic factors. Ovarian cancer tissue chips of patients in our hospital were prepared. EnVision two-step method immunohistochemistry was used to detect the protein expression levels of STAT3, the specific markers of CAF activation, fibroblast activating protein (FAP), and type Ⅰ collagen (COL1A1) secreted by CAF. The relationship between the expression of STAT3, FAP, COL1A1 protein and drug resistance and prognosis of ovarian cancer patients was analyzed, and the correlation between the expression of three proteins was analyzed. These results were verified through the gene expression and prognostic information of human ovarian cancer tissues collected in the GSE26712 dataset of gene expression omnibus (GEO) database. Results: (1) Multivariate Cox regression model analysis showed that chemotherapy resistance was an independent risk factor for overall survival (OS) of ovarian cancer (P<0.001). (2) The expression levels of STAT3, FAP, and COL1A1 proteins in chemotherapy resistant patients were significantly higher than those in chemotherapy sensitive patients (all P<0.05). Patients with high expression of STAT3, FAP, and COL1A1 had significantly shorter OS than those with low expression (all P<0.05). According to the human ovarian cancer GSE26712 dataset of GEO database, patients with high expression of STAT3, FAP, and COL1A1 also showed shorter OS than patients with low expression (all P<0.05), the verification results were consistent with the detection results of ovarian cancer patients in our hospital. (3) Correlation analysis showed that the protein level of STAT3 was positively correlated with FAP and COL1A1 in our hospital's ovarian cancer tissue chips (r=0.47, P<0.001; r=0.30, P=0.006), the analysis of GEO database GSE26712 dataset showed that the expression of STAT3 gene and FAP, COL1A1 gene were also significantly positively correlated (r=0.31, P<0.001; r=0.52, P<0.001). Conclusion: STAT3 and CAF could promote chemotherapy resistance of ovarian cancer and lead to poor prognosis.

Abstract P2-09-07: Elevated Pretreatment Serum CA9 (CAIX) (Carbonic Anhydrase 9) Predicts Reduced Progression-Free and Overall Survival in Trastuzumab-Treated Metastatic Breast Cancer

Background: Approximately one-half of HER2-positive breast cancer patients will respond to first-line trastuzumab-containing therapy. However, in those patients with an initial trastuzumab response, most will progress within a year with acquired resistance. Since trastuzumab treatment is also now used in the HER2-positive adjuvant breast cancer setting, trastuzumab resistance will continue to be a vexing clinical problem, and better predictive and prognostic biomarkers are urgently needed. Methods: Serum HER2, tissue inhibitor of metalloproteinase-1 (TIMP-1), urokinase-type plasminogen activator (uPA), CA9, Insulin-like growth factor-1 receptor (IGF-1R), VEGF-165, and endoglin were measured using ELISA assays in 60 metastatic breast cancer patients before starting first-line trastuzumab-containing therapy. The HER2, TIMP-1, uPA, CA9, IGF-IR, and VEGF-165 ELISAs were from Oncogene Science/Siemens Healthcare Diagnostics, Cambridge, MA; and the endoglin ELISA was from R&D Systems, Minneapolis, MN. Progression-free survival (PFS) and overall survival (OS) were analyzed using the Kaplan-Meier method and Cox modeling with continuous pretreatment serum biomarker variables.

Results: Pretreatment serum HER2 (p= 0.008), TIMP-1 (p&lt; 0.0001), uPA (p= 0.006), endoglin (p= 0.010), and CA9 (p &lt;0.0001) were all significant as univariate continuous biomarkers for predicting PFS to first-line trastuzumab-containing therapy, but VEGF (p=0.94) and IGF-IR (p=0.11) were not. In multivariate analysis for PFS with all 7 biomarkers, only serum CA9 (p= 0.002) was a significant independent covariate. For OS, pretreatment serum HER2 (p= 0.018), TIMP-1 (P&lt;0.0001), uPA (P&lt;0.0001), endoglin (0.006), CA9 (P&lt;0.0001) were all significant as univariate continuous biomarkers for prognosis, but VEGF (p=0.69) and IGF-IR (p=0.098) were not. In multivariate analysis for OS with all 7 biomarkers, only serum CA9 was a significant independent prognostic covariate (p=0.001), and TIMP-1 trended significant (p=0.069). Conclusions: Elevated pretreatment serum CA9 (a marker of hypoxia) predicts reduced progression-free survival and overall survival in metastatic breast cancer patients treated with first-line trastuzumab-containing therapy. These serum biomarkers deserve further study in larger trials of HER2-targeted breast cancer treatment. Supported by a grant from Komen for the Cure.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-09-07.

Use of pretreatment serum CA9 (carbonic anhydrase 9) to predict PFS and survival in trastuzumab-treated metastatic breast cancer

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Background: Approximately half of HER2-positive breast cancer patients will respond to first-line trastuzumab-containing therapy. However, in those patients with an initial trastuzumab response, most will progress within a year with acquired resistance. Since trastuzumab treatment is also now used in the HER2-positive adjuvant breast cancer setting, trastuzumab resistance will continue to be a vexing clinical problem, and better predictive and prognostic biomarkers are urgently needed. Methods: Serum HER2, tissue inhibitor of metalloproteinase-1 (TIMP-1), urokinase-type plasminogen activator (uPA), CA9, VEGF-165, and endoglin were measured using ELISA assays in 66 metastatic breast cancer patients before starting first-line trastuzumab-containing therapy. The HER2, TIMP-1, uPA, CA9, and VEGF-165 ELISAs were from Oncogene Science/Siemens Healthcare Diagnostics, Cambridge, MA; and the endoglin ELISA was from R&D Systems, Minneapolis, MN. Progression-free (PFS) and overall survival (OS) were analyzed using the Kaplan-Meier method and Cox modeling with continuous pretreatment serum biomarker variables. Results: Pretreatment serum HER2 (p= 0.005), TIMP-1 (p< 0.0001), uPA (p= 0.006), endoglin (p= 0.008), and CA9 (p <0.0001) were all significant as univariate continuous biomarkers for predicting PFS to first-line trastuzumab-containing therapy, but VEGF was not. In multivariate analysis for PFS with all six biomarkers, only serum CA9 (p= 0.002) was a significant independent covariate. For OS, pretreatment serum HER2 (p= 0.018), TIMP-1 (p< 0.0001), uPA (p< 0.0001), endoglin (p= 0.002), and CA9 (p< 0.0001) were all significant as univariate continuous biomarkers for prognosis, but serum VEGF was not. In multivariate analysis for OS with all six biomarkers, only serum CA9 was a significant independent prognostic covariate (p= 0.001). Conclusions: Elevated pretreatment serum CA9 (a marker of hypoxia) predicts reduced progression-free survival and overall survival in metastatic breast cancer patients treated with first-line trastuzumab-containing therapy. These serum biomarkers deserve further study in larger trials of HER2-targeted breast cancer treatment. Supported by a grant from Komen for the Cure.

[Table: see text]

[The sub-cellular distribution of beta-catenin in the neural differentiation of RA induced P19 EC cells]

Wnt signals have been shown to play an important role in the development of the central nervous system (CNS) of mouse. In our previous work, it was demonstrated that Wnt signal could initiate differentiation of P19 EC cells. In the present investigation, it was examined with RT-PCR whether expression of beta-catenin, a downstream gene of Wnt in its signal transduction pathway, is regulated. It was found that the level of protein or transcript beta-catenin during P19 neuronal differentiation was not changed. However, immunostaining data showed that beta-catenin was translocalized into nuclei after retinoic acid induced P19 cell aggregates were trypsinized and cultured in serum free N2 medium for 2 and 4 d. In this period, transcription of En-2, a downstream target gene of Wnt signal, increased evidently. The above data suggest that Wnt signals are involved in the early stage of neuronal differentiation process of P19 cell. Meanwhile, the distribution of beta-catenin on the neurites indicates that this protein may also be involved in neuritis outgrowth process.