Zhouting Zhu

Checkpoint inhibitors have achieved durable responses and long-lasting immunologic memory in cancer patients. However, the initial and acquired resistance remains an unsolved problem. It’s urgent to learn the molecular mechanisms causing resistance. microRNAs (miRNAs) are short transcripts that regulate many pathophysiological processes. Here, we investigated the miRNAs expression changes after GVAX combined with monoclonal PD-1 antibody treatment in the murine melanoma B16F10 tumors and identified microRNAs down-regulated in responsive tumors. Deletion of this family member in three different syngeneic mouse tumors did not affect their in vitro nor in vivo proliferation but sensitized anti-PD1 immunotherapy. The miRNA deletion with anti-PD1 therapy increased total CD45+ leukocyte infiltration with all types of hematopoietic cells except macrophages. Both tumor bulk RNA sequencing and …

N6‐methyladenosine (m6A), the most abundant internal modification in eukaryotic mRNA, plays important roles in many physiological and pathological processes, including the development and progression of cancer. RNA modification by m6A is regulated by methyltransferases, demethylases, and m6A‐binding proteins that function in large part by regulating mRNA expression and function. Here, we investigate the expression of m6A regulatory proteins in breast cancer. We find that expression of KIAA1429/VIRMA, a component of the m6A methyltransferase complex, is upregulated in breast cancer tissue and correlates positively with poor survival. KIAA1429/VIRMA is mislocalized to the cytosol of breast cancer tissues and cell lines, and shRNA‐mediated knockdown inhibits breast cancer cell proliferation, migration, and invasion. Mechanistically, KIAA1429/VIRMA is shown to bind to the m6A‐dependent RNA …

Although immune checkpoint inhibitors targeting T-cell immunoregulatory proteins have revolutionized cancer treatment, they are effective only in a limited number of patients, and new strategies are needed to enhance tumor responses to immunotherapies. Deletion of protein tyrosine phosphatase non-receptor type 2 (Ptpn2), a regulator of growth factor and cytokine signaling pathways, has been shown to sensitize murine B16F10 melanoma cells to IFNγ and anti-PD-1 immunotherapy. Here, we investigated the potential therapeutic utility of small-molecule PTPN2 inhibitors. Ten inhibitors were synthesized on the basis of in silico modeling and structure-based design and functionally tested in vitro and in vivo. We show that the inhibitors had little effect on B16F10 cells alone, but effectively sensitized the tumor cells to IFNγ treatment in vitro and to anti-PD-1 therapy in vivo. Under both conditions, Ptpn2 inhibitor …

Adenosine N6‐methylation (m6A) and N6,2′‐O‐dimethylation (m6Am) are regulatory modifications of eukaryotic mRNAs. m6Am formation is catalyzed by the methyl transferase phosphorylated CTD‐interacting factor 1 (PCIF1); however, the pathophysiological functions of this RNA modification and PCIF1 in cancers are unclear. Here, we show that PCIF1 expression is upregulated in colorectal cancer (CRC) and negatively correlates with patient survival. CRISPR/Cas9‐mediated depletion of PCIF1 in human CRC cells leads to loss of cell migration, invasion, and colony formation in vitro and loss of tumor growth in athymic mice. Pcif1 knockout in murine CRC cells inhibits tumor growth in immunocompetent mice and enhances the effects of anti‐PD‐1 antibody treatment by decreasing intratumoral TGF‐β levels and increasing intratumoral IFN‐γ, TNF‐α levels, and tumor‐infiltrating natural killer cells. We further …