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Anti-proliferative and pro-apoptotic effects induced by simultaneous inactivation of HER1 and HER2 through endogenous polyclonal antibodies.

ABSTRACT: The human epidermal growth factor receptor (HER1) and its partner HER2 are extensively described oncogenes and validated targets for cancer therapy. However, the effectiveness of monospecific therapies targeting these receptors is hampered by resistance emergence, which is frequently associated with the upregulation of other members of HER family. Combined therapies using monoclonal antibodies or tyrosine kinase inhibitors have been suggested as a promising strategy to circumvent this resistance mechanism. We propose an alternative approach based on simultaneous inactivation of HER1 and HER2 by multi-epitope blockade with specific polyclonal antibodies induced by vaccination. Elicited antibodies impaired both receptors activation and induced their degradation, which caused the inhibition of down-signaling cascades. This effect was translated into cell cycle arrest and apoptosis induction of human tumor cells. Elicited antibodies were able to reduce the viability of a panel of human tumor lines with differential expression levels of HER1 and HER2. The most significant effects were obtained in the tumor lines with lower expression levels of both receptors. These new insights would contribute to the rational design of HER receptors targeting multivalent vaccines, as an encouraging approach for the treatment of cancer patients.

SUBMITTER: Suarez NG

PROVIDER: S-EPMC5669935 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:PurposeTo evaluate the potential of anti-human epidermal growth factor receptor (HER)1- and anti-HER2-targeted radiolabeled antibodies and magnetic resonance (MR) imaging for imaging of orthotopic malignant pleural mesothelioma (MPM) in mouse models.Materials and methodsAnimal studies with 165 mice were performed in accordance with National Institutes of Health guidelines for the humane use of animals, and all procedures were approved by the institutional Animal Care and Use Committee. Flow cytometry studies were performed to evaluate HER1 and HER2 expression in NCI-H226 and MSTO-211H mesothelioma cells. Biodistribution and single photon emission computed tomography (SPECT)/computed tomography (CT) imaging studies were performed in mice (four or five per group, depending on tumor growth) bearing subcutaneous and orthotopic MPM tumors by using HER1- and HER2-targeted indium 111 ((111)In)- and iodine 125 ((125)I)-labeled panitumumab and trastuzumab, respectively. Longitudinal MR imaging over 5 weeks was performed in three mice bearing orthotopic tumors to monitor tumor growth and metastases. SPECT/CT/MR imaging studies were performed at the final time point in the orthotopic models (n = 3). The standard unpaired Student t test was used to compare groups.ResultsOrthotopic tumors and pleural effusions were clearly visualized at MR imaging 3 weeks after tumor cell inoculation. At 2 days after injection, the mean (111)In-panitumumab uptake of 29.6% injected dose (ID) per gram ± 2.2 (standard error of the mean) was significantly greater than the (111)In-trastuzumab uptake of 13.6% ID/g ± 1.0 and the (125)I-panitumumab uptake of 7.4% ID/g ± 1.2 (P = .0006 and P = .0001, respectively). MR imaging fusion with SPECT/CT provided more accurate information about (111)In-panitumumab localization in the tumor, as the tumor was poorly visualized at CT alone.ConclusionThis study demonstrates the utility of radiolabeled anti-HER1 antibodies in the imaging of MPM in preclinical models.Supplemental materialhttp://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12121021/-/DC1.

Project description:IntroductionSustained HER2 signaling at the cell surface is an oncogenic mechanism in a significant proportion of breast cancers. While clinically effective therapies targeting HER2 such as mAbs and tyrosine kinase inhibitors exist, tumors overexpressing HER2 eventually progress despite treatment. Thus, abrogation of persistent HER2 expression at the plasma membrane to synergize with current approaches may represent a novel therapeutic strategy.MethodsWe generated polyclonal anti-HER2 antibodies (HER2-VIA) by vaccinating mice with an adenovirus expressing human HER2, and assessed their signaling effects in vitro and anti-tumor effects in a xenograft model. In addition, we studied the signaling effects of human HER2-specific antibodies induced by vaccinating breast cancer patients with a HER2 protein vaccine.ResultsHER2-VIA bound HER2 at the plasma membrane, initially activating the downstream kinases extracellular signal-regulated protein kinase 1/2 and Akt, but subsequently inducing receptor internalization in clathrin-coated pits in a HER2 kinase-independent manner, followed by ubiquitination and degradation of HER2 into a 130 kDa fragment phosphorylated at tyrosine residues 1,221/1,222 and 1,248. Following vaccination of breast cancer patients with the HER2 protein vaccine, HER2-specific antibodies were detectable and these antibodies bound to cell surface-expressed HER2 and inhibited HER2 signaling through blocking tyrosine 877 phosphorylation of HER2. In contrast to the murine antibodies, human anti-HER2 antibodies induced by protein vaccination did not mediate receptor internalization and degradation.ConclusionThese data provide new insight into HER2 trafficking at the plasma membrane and the changes induced by polyclonal HER2-specific antibodies. The reduction of HER2 membrane expression and HER2 signaling by polyclonal antibodies induced by adenoviral HER2 vaccines supports human clinical trials with this strategy for those breast cancer patients with HER2 therapy-resistant disease.

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Anti-proliferative and pro-apoptotic effects induced by simultaneous inactivation of HER1 and HER2 through endogenous polyclonal antibodies.

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