Aptamer Targeting the ERBB2 Receptor Tyrosine Kinase for Applications in Tumor Therapy

Aptamers are an emerging class of molecules in cancer therapy. They can be easily synthesized and are considered cost-effective drug candidates. In this book chapter we describe the selection and characterization of DNA aptamers specific to the human epidermal growth factor receptor 2 (ERBB2/HER2), an oncogenic tyrosine kinase. First, a DNA aptamer library is applied and ERBB2-specific aptamers are selected using SELEX. Binders are subcloned into a pGEM-T vector, sequenced, and characterized using biochemical and cell biological techniques. By multimerizing the selected ERBB2 aptamers, it might be possible to significantly increase their avidity. For example, we could show that a trimeric ERBB2-specific aptamer could efficiently internalize membranal ERBB2. Furthermore, the receptor assembled in cytoplasmic puncta and was finally degraded by the lysosome. In addition, the selected, trimeric aptamer inhibited proliferation in an XTT assay in comparison to a control sequence. Aptamers selected using the protocol we describe might exert anticancer effect. In our example of a trimeric anti-HER2 aptamer, we could report that a human gastric xenograft mouse model demonstrated pharmacological value of the selected aptamer in vivo. This chapter should enable the interested reader to replicate selection of DNA aptamers specific to oncogenic cell surface. We would like to particularly emphasize some experimental approaches which were used to further characterize selected aptamer sequen...
Source: Springer protocols feed by Cancer Research - Category: Cancer & Oncology Source Type: news

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We present the case of a patient diagnosed with a de novo metastatic gastric cancer who experienced an extraordinary long response to multiple lines of chemotherapy (FOLFOX6, paclitaxel plus ramucirumab, FOLFIRI, rechallenge with FOLFOX6).Key Message: Gastric cancer therapy should be considered as the result of a strategy based on the patient ’s condition, and tolerance and response to various therapies. The emerging evidence of the role of subsequent lines of therapy, along with the recognition of the pivotal role of nutritional support and the availability of new drugs, should help clinicians in the management of p...
Source: Gastrointestinal Tumors - Category: Gastroenterology Source Type: research
In conclusion, trastuzumab plus doublet cytotoxic backbone containing oxaliplatin is preferable over the ToGA regimen with cisplatin. S‐1 can substitute capecitabine or 5‐FU when specific toxicities are encountered.
Source: International Journal of Cancer - Category: Cancer & Oncology Authors: Tags: Cancer Therapy and Prevention Source Type: research
Conclusions: Taken together, the results provide insight into the biological and clinical potential of targeted AMO-21 and 5-Fu co-delivery using modified trastuzumab for GC treatment.Cell Physiol Biochem 2017;44:2158 –2173
Source: Cellular Physiology and Biochemistry - Category: Cytology Source Type: research
In conclusion, the efficacy of DS‐8201a as a treatment for patients with T‐DM1‐resistant breast or gastric cancer merits investigation.
Source: International Journal of Cancer - Category: Cancer & Oncology Authors: Tags: Cancer Therapy and Prevention Source Type: research
Abstract HER2 is a receptor tyrosine kinase, which is amplified and overexpressed in a subset of human cancers including breast and gastric cancers, and is indicated in its involvement in progression of cancer. Although its specific ligand(s) has not been detected, HER2 homodimerization, which is critical for its activation, is considered to be dependent on its expression levels. Here, we demonstrate a significant role of HER2 methylation by protein lysine methyltransferase SMYD3 in HER2 homodimerization. We found that SMYD3 trimethylates HER2 protein at lysine 175. HER2 homodimerization was enhanced in the presence of SMY...
Source: Cancer Medicine - Category: Cancer & Oncology Authors: Tags: Original Research Source Type: research
In this study, we analyzed CTCs of patients with gastric cancer (GC) to find thos e who were likely to benefit from trastuzumab therapies. We developed an imaging-based method that enabled CTC identification simultaneously with evaluation ofHER2 gene amplification (the 3D –IF-FISH method). Then we performed a study enrolling 101 GC patients in whom we analyzed CTCs by both 3D–IF-FISH and an FDA-approved CellSearch system. As compared with the CellSearch system, 3D–IF-FISH methods identified a higher number of patients whose primary tumors were HER2- but who hadHER2+ CTCs, suggesting that the 3D –IF-...
Source: Targeted Oncology - Category: Cancer & Oncology Source Type: research
Abstract Accurate measurement of Human epidermal growth factor receptor (HER2) gene expression is central for breast or stomach cancer therapy orientation and prognosis. The current standards testing methods for HER2 expression are immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). In the current study, we explored the use of quantitative real time reverse transcription-PCR (RT-qPCR) as a potential method for the accurate relative quantification of the HER2 gene using formalin fixed paraffin embedded (FFPE) breast cancer biopsy samples. The main aim of the current study is to measure the lev...
Source: Gene - Category: Genetics & Stem Cells Authors: Tags: Gene Source Type: research
Septins are a family of cytoskeletal GTP-binding proteins that assemble into membrane-associated hetero-oligomers and organize scaffolds for recruitment of cytosolic proteins or stabilization of membrane proteins. Septins have been implicated in a diverse range of cancers, including gastric cancer, but the underlying mechanisms remain unclear. The hypothesis tested here is that septins contribute to cancer by stabilizing the receptor tyrosine kinase ErbB2, an important target for cancer treatment. Septins and ErbB2 were highly over-expressed in gastric cancer cells. Immunoprecipitation followed by MS analysis identifi...
Source: Biochemical Journal - Category: Biochemistry Authors: Tags: Research articles Source Type: research
Abstract Septins are a family of cytoskeletal GTP-binding proteins that assemble into membrane-associated hetero-oligomers and organize scaffolds for recruitment of cytosolic proteins or stabilization of membrane proteins. Septins have been implicated in a diverse range of cancers, including gastric cancer, but the underlying mechanisms remain unclear. The hypothesis tested here is that septins contribute to cancer by stabilizing the receptor tyrosine kinase ErbB2, an important target for cancer treatment. Septins and ErbB2 were highly over-expressed in gastric cancer cells. Immunoprecipitation followed by ma...
Source: The Biochemical Journal - Category: Biochemistry Authors: Tags: Biochem J Source Type: research
In this study, we investigated the anticancer effect of KU004, a novel dual EGFR and HER2 inhibitor in vitro and in vivo. In vitro, KU004 preferentially inhibited the growth of HER2-overexpressing breast and gastric cell lines and HER2 expression level significantly correlated with response to KU004. It blocked activation of EGFR, HER2 and downstream Akt and Erk and induced G0/G1 arrest which was associated with downregulation of p53, p21, cyclin D1 and CDK4 along with increase of p27 and dephosphorylation of pRb. Apoptosis occurred in a caspase-dependent manner mainly via the extrinsic apoptotic pathway after KU004 treatm...
Source: Apoptosis - Category: Molecular Biology Source Type: research
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