Development and characterization of a preclinical ovarian carcinoma model to investigate the mechanism of acquired resistance to trastuzumab

Abstract

Trastuzumab (Herceptin®) is a humanized monoclonal antibody designed to bind and inhibit the function of the human epidermal growth factor receptor 2 (HER2)/erbB2 receptor. Trastuzumab has demonstrated clinical activity in several types of HER2-overexpressing epithelial tumors, such as breast and metastatic gastric or gastroesophageal junction cancer. Relapse and therapeutic resistance, however, still occur in a subset of patients treated with regimens including trastuzumab, despite significant improvements in response rates, survival and quality of life. To investigate the potential mechanisms of acquired therapeutic resistance to trastuzumab, we developed a preclinical model of human ovarian cancer cells, SKOV-3 Herceptin-resistant (HR), and examined the corresponding changes in gene expression profiles. SKOV-3 HR cells were developed by in vivo serial passaging of parental trastuzumab-sensitive SKOV-3 cells. Following four rounds of serial transplantation of 'break-through' xenograft tumors under trastuzumab treatment, significant and reproducible differences in the effects of trastuzumab treatment between SKOV-3 HR and SKOV-3 cells in vivo and in vitro were revealed. SKOV-3 HR cells retained HER2 protein expression but were unaffected by the antiproliferative effects of trastuzumab. The trastuzumab binding affinity for SKOV-3 HR cells was diminished, despite these cells having more binding sites for trastuzumab. Microarray expression profiling (MEP) was performed to determine the genes involved in the resistance mechanism. Functional analysis revealed the differential expression of genes potentially involved in angiogenesis, metastasis, differentiation and proliferation, such as mucin1 (MUC1). Immunohistochemical staining of SKOV-3 HR cells demonstrated a marked overexpression of MUC1. Based on these data, we hypothesize that the overexpression of MUC1 may hinder trastuzumab binding to HER2 receptors, abrogating the antitumor effects of trastuzumab and thus could contribute to resistance to therapy. Moreover, the resultant MEP preclinical gene signature in this preclinical model system may provide the basis for further investigation of potential clinical mechanisms of resistance to trastuzumab.

Quantifying Cellular Internalization with a Fluorescent Click Sensor

“…The labeled proteins were incubated with SKOV-3 cells, an ovarian cancer cell line that overexpresses HER2 . 2D3 was added at double the molar concentration of trastuzumab to account for the differences in the number of binding sites between the two proteins.…”

“…The labeled proteins were incubated with SKOV-3 cells, an ovarian cancer cell line that overexpresses HER2. 52 2D3 was added at double the molar concentration of trastuzumab to account for the differences in the number of binding sites between the two proteins. When the proteins were bound to the cell surface at 4 °C, a quenching efficiency of ∼79% for 2D3 and ∼71% for trastuzumab was observed (Figure 5a).…”

Bispecific radioimmunoconjugates exploit receptor heterogeneity for positron emission tomography of tumors expressing HER2 and/or EGFR

“… 24 By combining ISH and IHC staining, two patterns of HER2 heterogeneity were defined: i) “genetic heterogeneity” consisting of a mixture of HER2-positive and HER2-negative cells due to corresponding HER2- amplification or non- HER2 gene amplification, and ii) “non-genetic heterogeneity” consisting of a mixture of HER2-positive and HER2-negative cells by ICH despite homogeneous HER2 gene amplification. 24 SK-OV-3 cells are HER2 gene-amplified 25 while MDA-MB-468 cells are not amplified for the HER2 gene, thus the pattern of HER2 heterogeneity in tumors formed of a mixture of SK-OV-3 and MDA-MB-468 cells in our study could be classified as “genetic heterogeneity.” It should be noted that in patients with HER2-positive BC, besides intratumoral HER2 heterogeneity, there may be interlesional HER2 heterogeneity. The ZEPHIR trial investigated PET imaging with [ 89 Zr]Zr-DFO-trastuzumab to predict response to treatment with trastuzumab emtansine (T-DM1) in patients with HER2-positive BC.…”

Exploring the role and diversity of mucins in health and disease with special insight into non-communicable diseases

“…Therefore, in cancer transformations, during progression and even in drug response mucin molecule plays an important role [47] thus considered as diagnostic marker [33] and drug target for cancer detection and therapies [48]. Functional analysis of drug resistant cancer cells revealed the differential expression of mucin potentially involved in angiogenesis, metastasis, differentiation and proliferation [49,50]. Abnormal expression of the mucins are said to be reported in various cancers [51,52], such as pancreatic adenocarcinomas, colon carcinomas [53], Breast cancer [48,54] and cancers associated with other organs (Fig.…”