Project description:The major histocompatibility complex class II (MHC II) is important for the adaptive immune response because it presents processed antigens to CD4-positive T-cells. Conventional chemotherapeutic agents (e.g., melphalan, adriamycin, hydroxyurea) induce tumor cell death by causing DNA double strand breaks (DSBs), which are crucial for anti-tumor effects. However, the cellular response induced at low doses of these agents that do not cause immediate cell death is unclear. We have employed microarray expression profiling to identify genes which are induced by low dose of chemotherapeutic agents. Multiple myeloma cell line KMS12PE was treated with vehicle, 2 μM melphalan, or 50 nM adriamycin. These agents transcriptionally induced the major histocompatibility complex class II (MHC II) genes. They also increased the expressions of MHC class II transactivator (CIITA), the master regulator of MHC II genes and interferon regulatory factor 1 (IRF1), a transcription factor for CIITA.
Project description:Expression profiling of rat major histocompatibility complex and natural killer complex genes in skin explant assays reveals genes that are regulated in graft versus host disease. The major histocompatibility complex (MHC) is the most important genomic region that contributes to the genetic risk of graft rejection and graft versus host disease (GVHD) after haematopoietic stem cell transplantation. Therefore, MHC matching is most essential for the success of clinical transplantations. However, the MHC contains in addition to MHC class I and class II genes that are genotyped for selection of donors further so far unidentified genes that also contribute significantly to the risk to develop acute GVHD. It is difficult to identify these MHC genes by genetic association studies alone due to linkage disequilibrium in this region. Therefore, we aimed to identify MHC genes that might be involved in the pathohysiology of GVHD by expression profiling. To reduce the complexity of our model, we used genetically well-defined inbred rat strains (PVG and BN) and skin explant assays, an in-vitro-model of graft versus host reaction (GVHR), to analyse the expression of MHC and natural killer complex (NKC) genes in a cutaneous GVHR by a custom microarray. A higher percentage of genes in these immunologically highly important genomic regions were regulated than in the rest of the genome. We observed a statistically significant regulation of 25 MHC and 6 NKC genes and 168 other genes (i.e., 4.9%, 14.0%, and 6.6%, respectively) in rat skin explants cultured in the presence of pre-stimulated allogeneic lymphocytes compared to control samples cultured in the presence of syngeneic lymphocytes. Seven MHC and 3 NKC genes were selected for analysis by quantitative real-time polymerase chain reaction PCR. Most of the results of the microarray were confirmed in the same experimental set that was used for the microarray analysis and in a second independent experimental set of skin explant samples. In addition, GVHD-affected skin lesions of transplanted rats were analysed and similar regulations of most of the selected MHC and NKC genes were observed. Thus, our skin explant model of GVHR is informative for the gene regulation during GVHD. Interestingly, the human homologues of several of the regulated genes are polymorphic and could therefore contribute to the genetic risk of GVHD. These genes include RT1-Dmb, C2, Aif1, Spr1, Ubd, and Olr1. The human homologues of these genes might be useful for risk assessment and diagnosis of GVHD in patients. Two-condition experiment, Stimulated vs. NonSimulated cells. 12 Biological replicates, 2 Technical Replicates (Dye Swap) per Biological Replicate.
Project description:There is increasing recognition of the prognostic significance of tumor cell major histocompatibility complex (MHC) class II expression in anti-cancer immunity. Relapse of acute myeloid leukemia (AML) following allogeneic stem cell transplantation (alloSCT) has recently been linked to MHC class II silencing in leukemic blasts; however, the regulation of MHC class II expression remains incompletely understood. Utilizing unbiased CRISPR-Cas9 screens, we identify that the C-terminal binding protein (CtBP) complex transcriptionally represses MHC class II pathway genes, while the E3 ubiquitin ligase complex component FBXO11 mediates degradation of CIITA, the principal transcription factor regulating MHC class II expression. Targeting these repressive mechanisms selectively induces MHC class II upregulation across a range of AML cell lines. Functionally, MHC class II+ leukemic blasts stimulate antigen-dependent CD4+ T cell activation and potent anti-tumor immune responses, providing fundamental insights into the graft-versus-leukemia effect. These findings establish the rationale for therapeutic strategies aimed at restoring tumor-specific MHC class II expression to salvage AML relapse post-alloSCT and also potentially to enhance immunotherapy outcomes in non-myeloid malignancies.