Mara P. Steinkamp

Auranofin Synergizes with Cisplatin in Reducing Tumor Burden of NOTCH-Dependent Ovarian Cancer

Abstract The NOTCH pathway regulates cell proliferation, differentiation, and stem cell maintenance. Thus, aberrant NOTCH activation plays a key role in cancer initiation, progression, and chemoresistance. Mutations and amplification of NOTCH pathway genes have been identified in high-grade serous ovarian cancers and are associated with poor clinical outcomes. Among the four NOTCH receptors, NOTCH3 alterations were strongly correlated with poor overall survival. Previously, we identified auranofin, an oral gold salt therapeutic compound, as a novel NOTCH pathway inhibitor that disrupts the DNA binding of RBPJ, the major downstream transcriptional effector of the NOTCH pathway. In this study, we surveyed the response of eight ovarian cancer cell lines to auranofin and found IC50 values ranging from 1.7 to 12 μmol/L, with NOTCH3-negative SKOV3 cells having the highest IC50 value. In NOTCH-dependent OVCAR3 cells, auranofin synergized with cisplatin to enhance cell death. Importantly, auranofin treatment led to a dose-dependent decrease in RBPJ occupancy at the NOTCH-dependent promoters, HES1 and HES4. Furthermore, knocking down NOTCH3 in OVCAR3 cells significantly decreased sensitivity to auranofin, further supporting the notion that NOTCH3 signaling is a major target of auranofin. Moreover, auranofin increased cisplatin efficacy in an OVCAR3-derived xenograft mouse model. Using eight patient-derived cancer organoid models, we found that auranofin increased cisplatin efficacy in killing cancer organoids generated from clinically platinum-sensitive patients but also restored platinum response in a subset of organoid models developed from platinum-resistant patients. These studies underscore the potential of auranofin to improve platinum-based cancer therapy, particularly in NOTCH3-expressing cancers. Significance: NOTCH signaling underlies cancer initiation, progression, and chemoresistance. Our study revealed the potential of auranofin as a NOTCH pathway inhibitor to enhance the efficacy of platinum-based ovarian cancer therapy.

Patient-derived ovarian cancer models demonstrate the influence of tumor-associated macrophages on therapeutic response

While most ovarian cancer (OC) patients respond to front-line platinum/taxane chemotherapy and surgical debulking, the majority will develop platinum-resistance and recur. Our study investigated how tumor-associated macrophages (TAMs) within the tumor microenvironment (TME) affect chemotherapy outcomes using OC patient-derived organoids and humanized patient-derived xenografts (huPDX).

Humanized Patient-derived Xenograft Models of Disseminated Ovarian Cancer Recapitulate Key Aspects of the Tumor Immune Environment within the Peritoneal Cavity

Abstract The importance of the immune microenvironment in ovarian cancer progression, metastasis, and response to therapies has become increasingly clear, especially with the new emphasis on immunotherapies. To leverage the power of patient-derived xenograft (PDX) models within a humanized immune microenvironment, three ovarian cancer PDXs were grown in humanized NBSGW (huNBSGW) mice engrafted with human CD34+ cord blood–derived hematopoietic stem cells. Analysis of cytokine levels in the ascites fluid and identification of infiltrating immune cells in the tumors demonstrated that these humanized PDX (huPDX) established an immune tumor microenvironment similar to what has been reported for patients with ovarian cancer. The lack of human myeloid cell differentiation has been a major setback for humanized mouse models, but our analysis shows that PDX engraftment increases the human myeloid population in the peripheral blood. Analysis of cytokines within the ascites fluid of huPDX revealed high levels of human M-CSF, a key myeloid differentiation factor as well as other elevated cytokines that have previously been identified in ovarian cancer patient ascites fluid including those involved in immune cell differentiation and recruitment. Human tumor-associated macrophages and tumor-infiltrating lymphocytes were detected within the tumors of humanized mice, demonstrating immune cell recruitment to tumors. Comparison of the three huPDX revealed certain differences in cytokine signatures and in the extent of immune cell recruitment. Our studies show that huNBSGW PDX models reconstitute important aspects of the ovarian cancer immune tumor microenvironment, which may recommend these models for preclinical therapeutic trials. Significance: huPDX models are ideal preclinical models for testing novel therapies. They reflect the genetic heterogeneity of the patient population, enhance human myeloid differentiation, and recruit immune cells to the tumor microenvironment.