Abstract
The effects of standard clinical therapies including surgery and chemotherapy are poor in advanced gallbladder cancer (GBC). There are a few reported cases of human epidermal growth factor receptor 2 (HER2)-positive GBC that responded well to trastuzumab. But trastuzumab has not yet been used to treat HER2-negative GBC. In this study, we investigated the cytotoxic effects of different combined therapies with trastuzumab and gemcitabine and/or 5-fluorouracil on HER2-negative GBC cell lines in vitro and in vivo. Trastuzumab alone showed almost no cytotoxicity to GBC cells with originally low HER2 gene amplification. Sequential therapy with chemotherapy followed by trastuzumab showed superiority over reverse sequential chemotherapy (P<0.05), concurrent combined chemotherapy (P<0.05), chemotherapy alone (P<0.05), and trastuzumab alone (P<0.05) in terms of cytotoxicity. Sequential therapy with chemotherapy followed by trastuzumab nearly completely inhibited cell viability in HER2-negative GBC cells. Similar results were observed with regard to apoptosis. Western blot analysis showed that gemcitabine/5-fluorouracil increased the expressions of total and phosphorylated forms of HER2, thus enhancing the cytotoxicity of trastuzumab. In vivo study verified the results of in vitro study by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay and immunohistochemical analysis. Moreover, not only the lightest tumor bearing but also the best survival state was detected in sequential therapy with chemotherapy followed by trastuzumab group compared with other groups. Our in vivo and in vitro data suggest that sequential therapy with gemcitabine/5-fluorouracil followed by trastuzumab represents a novel and promising therapeutic strategy against HER2-negative GBC. The upregulation of phosphorylated HER2 and phosphorylated-AKT induced by gemcitabine/5-fluorouracil treatment shows that HER2/AKT pathway is triggered.
Highlights
Gallbladder cancer (GBC), the most common biliary tract malignancy and the sixth most common digestive tract cancer worldwide [1], is a highly fatal disease with poor prognosis [2]
For the sequential therapy with chemotherapy followed by trastuzumab group, GBC cells were incubated in Dulbecco’s modified Eagle medium (DMEM) containing GEM (NOZ, 345 μg/mL and GB-D1, 2258 μg/mL) and/or 5-Fu (NOZ, 0.024 μg/mL and GB-D1, 123 μg/mL) for 48 h first, washed with phosphate buffered saline (PBS), and treated with trastuzumab (NOZ, 40 μg/mL, and GB-D1, 0.44 μg/mL) for 48 h
For the sequential therapy with trastuzumab followed by chemotherapy group, GBC cells that were pretreated with trastuzumab were further treated with chemotherapeutic drugs
Summary
Gallbladder cancer (GBC), the most common biliary tract malignancy and the sixth most common digestive tract cancer worldwide [1], is a highly fatal disease with poor prognosis [2]. Human epidermal growth factor receptor 2 (HER2) is a transmembrane glycoprotein with tyrosine kinase receptor activity It provides signal transduction for cell proliferation, adhesion, migration, apoptosis, and differentiation [6,7,8] and plays a role in the development of breast [9] and gastric cancers [10]. The application of trastuzumab in combination with chemotherapeutic drugs in the treatment of patients with HER2-positive breast or gastric cancer is more effective than standard chemotherapy [10, 15]. The present study was undertaken to investigate whether combined therapy with chemotherapy and trastuzumab in HER2-negative GBC cell lines in vitro and in vivo could improve cytotoxicity, and which combination would achieve the best efficacy. Differences in apoptosis, cell cycle, and HER2/protein kinase B (AKT) signaling pathway were analyzed to demonstrate the reasons behind different effects
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
