The Mechanism Of Trastuzumab Resistance In Breast Carcinomas With HER-2 Mutation Factors Influencing Non-sentinel Lymph Nodes Metastases Of Breast Cancer And Implications For Treatment

Background:Around 15-20%breast cancers have HER-2-gene amplifications or protein/mRNA over-expressions.Deregulations of HER-2-gene,through over-expressions or gene’s amplifications,have been demonstrated of importance in cancer’s tumorigenesis or proliferation.Trastuzumab is an effective drug for the treatment of HER-2-positive breast cancer.HER-2 oncoprotein is one of the class-1 transmembrane-receptors with tyrosine-kinase activities and plays important roles in the oncogenic activations of lots of signaling-pathways,like the phosphoinositide 3-kinase(PI3K)pathway and mitogen-activated protein kinase(MAPK)pathway.The mechanism of trastuzumab resistance is relatively complex.The mutation of HER-2 gene was discovered in the past research and researchers believed that HER-2 mutation may have important effect on the treatment of trastuzumab.An important reason of resistance to trastuzumab.The present work aims to explore the mechanism of trastuzumab resistance caused by HER-2 mutation in breast carcinomas.Methods:Firstly,the HER-2 WT and HER-2 mutant(HER-2 Q429R,HER-2 Q429H and HER-2 T798M are the commonest 3 types of mutations)MCF7 cell lines were established.Cell proliferation inhibition was then assessed by the Cell Counting Kit-8(CCK8)assay and BrdU assay.Transwell invasion assays were also conducted to investigate the metastatic potential influenced by the HER-2 mutation.Furthermore,western blotting and Co-Immunoprecipitation were conducted to detect protein levels and the physical interaction of HER-2 and trastuzumab.Results:The results showed that the mutant MCF7 cells were less sensitive to trastuzumab than the wild-type MCF7 cells.The mutation of HER-2 almost had no influence on the expression of HER-2 and the interaction of HER-2 and trastuzumab.Finally,the mutation of HER-2 weakened the inhibition of trastuzumab in the PI3K/Akt pathways.In addition,the inhibition of PI3K/Akt signaling-pathway increased the trastuzumab-sensitivity of HER-2-mutant MCF7 cells.Conclusions:Taken together,our findings showed that dysregulation of the PI3K/Akt signaling pathway was one of the major mechanisms leading to the resistance to trastuzumab in HER-2 mutant breast cancer cells.Our study provides a theoretical basis for further improving the effect of trastuzumab targeted breast cancer treatment.Background:Globally,breast cancer is the most frequently diagnosed cancer and the leading cause of cancer death in women.Sentinel lymph node biopsy is one of the main methods to assess the status of patients’ axillary lymph nodes during breast cancer treatment.Historically,patients with any nodal metastasis underwent axillary lymph node dissection.However,only approximately 40 percent of patients with a positive sentinel lymph node had metastatic disease;the rest derived no benefit from the addition axillary lymph node dissection.The ACSOG Z0011 and IBCSG 23-01 studies have published a 10-year follow-up results that further confirms the disease-free survival and overall survival between sentinel lymph node biology group and axillary lymph node dissection group in patients with micro-metastasis and isolated tumor cells in sentinel lymph nodes.However,there are few studies on whether a patient with a sentinel lymph node metastasis needs to undergo axillary lymph node dissection.Previous studies have shown a certain bias because of including a lot of patients with micro-metastasis and isolated tumor cell metastasis.This study was to analyze the influential factors of non-sentinel lymph node metastasis in breast cancer patients with sentinel lymph node macro-metastasis,to establish a predictive model for predicting non-sentinel lymph node metastasis and to analyze its implications for clinical treatment.Methods:This retrospective study enrolled 719 breast cancer patients with SLNs macro-metastases who underwent ALND in the primary cohort between January 2012 and December 2016.Chi-square and multivariate logistic regression tests were used to find factors that influenced NSLNs metastases,then a predictive nomogram was formulated by using the rms package in R version 3.3.3 and obtained its area under the curve.An independent validation cohort containing 94 patients was then tested from January 2017 to June 2017.Results:A predictive nomogram was developed that included six factors(tumor pathologic invasion size,lympho-vascular invasion,number of identified SLNs,number of positive SLNs,ALN status on imaging and surgical method)according to the result of primary cohort by multivariate analysis.The area under the curve of the primary and validation cohorts were all 0.72.Conclusion:We developed a predictive nomogram to assess the risk of non-SLN metastases in Chinese breast cancer patients with SLNs macro-metastases and analyze the clinical significance of the influencing factors.