Probes for HER2

Objective:
To investigate in situ mRNA expression of HER 2 oncogene in breast cancers with equivocal immunohistochemical results , and to explore the potential feasibility of RNAscope technique in evaluating HER2 status in breast cancers .Methods Sixty-nine FFPE samples of invasive ductal breast cancer with equivocal HER 2 immunohistochemistry results ( IHC 2+) were collected from surgical excisions from Peking Union Medical College Hospital between June 2010 and June 2013.HER2 status and in situ mRNA expression were tested by fluorescence in situ hybridization ( FISH) and RNAscope respectively using tissue microarray constructed from tumor paraffin blocks .The results of HER2 mRNA expression were scored 0 to 4 ( from low to high levels ) according to mRNA expression in 100 cancer cells .HER2 mRNA expression was evaluated in two groups of patients , with positive and negative FISH results .Results Twenty-three of the 69 samples were FISH positive, including 16 samples that were scored 4 by RNAscope (70%,16/23), 6 samples were scored 3 ( 26%,6/23 ) and one sample was scored 2 ( 4%,1/23 ) .High in situ mRNA expression (score 4 or 3) were observed in 96%of HER2 FISH positive samples.All of samples that were scored 4 by RNAscope were FISH positive .Forty-six samples were FISH negative , including 17 samples that were scored 3 by RNAscope (37%,17/46), 25 samples were scored 2 (54%,25/46), and 4 samples were scored 1 (9%,4/46).Conclusions Breast cancer with HER2 IHC 2 +could be further classified according to in situ mRNA expression status .Among them, RNAscope score of 4 could be one of the interpretation criteria for re-testing IHC 2+samples.In situ detection of HER2 mRNA may be an additional candidate method of confirmation for HER 2 gene amplification or protein overexpression , and has potential clinical utility.

The androgen receptor (AR) is a nuclear steroid receptor that binds to testosterone and dihydrotestosterone and regulates the transcription of genes leading to cell growth, differentiation and survival. AR serves as an important oncogenic signal in prostate cancers and apocrine breast cancers. Salivary duct carcinoma (SDC) is a rare subtype of head and neck cancer that is defined by an apocrine phenotype, with AR positivity by immunohistochemistry (IHC) in up to 98% of cases [1]. A recent clinical trial with leuprorelin acetate and bicalutamide has shown promising activity with an overall response rate of 42% in AR-positive salivary gland cancers, but further analyses of clinicopathological factors or biomarkers including AR expression intensity, HER2 expression, EGFR expression and HRAS mutation did not show any significant association with outcomes [2].

Development of resistance causes failure of drugs targeting receptor tyrosine kinase (RTK) networks and represents a critical challenge for precision medicine. Here, we show that PHLDA1 downregulation is critical to acquisition and maintenance of drug resistance in RTK-driven cancer. Using fibroblast growth factor receptor (FGFR) inhibition in endometrial cancer cells, we identify an Akt-driven compensatory mechanism underpinned by downregulation of PHLDA1. We demonstrate broad clinical relevance of our findings, showing that PHLDA1 downregulation also occurs in response to RTK-targeted therapy in breast and renal cancer patients, as well as following trastuzumab treatment in HER2+ breast cancer cells. Crucially, knockdown of PHLDA1 alone was sufficient to confer de novo resistance to RTK inhibitors and induction of PHLDA1 expression re-sensitized drug-resistant cancer cells to targeted therapies, identifying PHLDA1 as a biomarker for drug response and highlighting the potential of PHLDA1 reactivation as a means of circumventing drug resistance.

Abstract