Resistance to trastuzumab and concomitantly distal metastasis are leading causes of mortality in HER2-positive breast cancers, the molecular basis of which remains largely unknown. Here, we generated trastuzumab-resistant breast cancer cells with increased tumorigenicity and invasiveness compared with parental cells, and observed robust epithelial-mesenchymal transition (EMT) and consistently elevated TGF-b signaling in these cells. which Breast cancers remain the most common malignancies in women with one million newly diagnosed cases and 400,000 deaths worldwide per year.1 The vast majority of these deaths are attributed to distal metastasis and resistance to available therapeutics.

No abstract

Despite the successful use of the humanized monoclonal antibody trastuzumab (Herceptin) in the clinical treatment of human epidermal growth factor receptor 2 (HER2)-overexpressing breast cancer, the frequently occurring drug resistance remains to be overcome. The regulatory mechanisms of trastuzumab-elicited immune response in the tumor microenvironment remain largely uncharacterized. Here, we found that the nonclassical histocompatibility antigen HLA-G desensitizes breast cancer cells to trastuzumab by binding to the natural killer (NK) cell receptor KIR2DL4. Unless engaged by HLA-G, KIR2DL4 promotes antibody-dependent cell-mediated cytotoxicity and forms a regulatory circuit with the interferon-γ (IFN-γ) production pathway, in which IFN-γ upregulates KIR2DL4 via JAK2/STAT1 signaling, and then KIR2DL4 synergizes with the Fcγ receptor to increase IFN-γ secretion by NK cells. Trastuzumab treatment of neoplastic and NK cells leads to aberrant cytokine production characterized by excessive tumor growth factor-β (TGF-β) and IFN-γ, which subsequently reinforce HLA-G/KIR2DL4 signaling. In addition, TGF-β and IFN-γ impair the cytotoxicity of NK cells by upregulating PD-L1 on tumor cells and PD-1 on NK cells. Blockade of HLA-G/KIR2DL4 signaling improved the vulnerability of HER2-positive breast cancer to trastuzumab treatment in vivo. These findings provide novel insights into the mechanisms underlying trastuzumab resistance and demonstrate the applicability of combined HLA-G and PD-L1/PD-1 targeting in the treatment of trastuzumab-resistant breast cancer.

No abstract

RNF2, also known as RING1b or RING2, is identified as the catalytic subunit of polycomb repressive complex 1 (PRC1), which mediates the mono-ubiquitination of histone H2A. RNF2 has been proved to have oncogenic function in many kinds of cancers, but the function of RNF2 in prostate cancer (PCa) has not been evaluated. Here we show that PCa tissues showed higher RNF2 expression than the benign prostatic hyperplasia (BPH) tissues. Knockdown of RNF2 in PCa cells resulted in cell cycle arrest, increased apoptosis and inhibited cell proliferation, and the growth of RNF2 knockdown PCa xenografts were obviously inhibited in nude mice. Gene microarray analysis was performed and tumor suppressor gene TXNIP was found to be significantly increased in RNF2 knockdown cells. Simultaneously knockdown of RNF2 and TXNIP can partially rescue the arrested cell cycle, increased apoptosis and inhibited cell proliferation in RNF2 single knockdown cells. Furthermore, ChIP assay result showed that RNF2 enriched at the TXNIP promoter, and the enrichment of RNF2 and ubiquitination of H2A in TXNIP promoter was obviously inhibited in RNF2 knockdown cells. In conclusion, our results demonstrate that RNF2 functions as an oncogene in PCa and RNF2 may regulate the progression of PCa through the inhibition of TXNIP.