Graphical Abstract Highlights d Homozygous UBQLN4 germline mutations lead to a genome instability syndrome d UBQLN4 removes ubiquitylated MRE11 from damaged chromatin to curtail DSB resection d UBQLN4 overexpression represses HRR and promotes the use of NHEJ for DSB repair d UBQLN4 overexpression in tumors promotes PARP1 inhibitor sensitivity SUMMARY Genomic instability can be a hallmark of both human genetic disease and cancer. We identify a deleterious UBQLN4 mutation in families with an autosomal recessive syndrome reminiscent of genome instability disorders. UBQLN4 deficiency leads to increased sensitivity to genotoxic stress and delayed DNA double-strand break (DSB) repair. The proteasomal shuttle factor UBQLN4 is phosphorylated by ATM and interacts with ubiquitylated MRE11 to mediate early steps of homologous recombination-mediated DSB repair (HRR). Loss of UBQLN4 leads to chromatin retention of MRE11, promoting non-physiological HRR activity in vitro and in vivo. Conversely, UBQLN4 overexpression represses HRR and favors non-homologous end joining. Moreover, we find UBQLN4 overexpressed in aggressive tumors. In line with an HRR defect in these tumors, UBQLN4 overexpression is associated with PARP1 inhibitor sensitivity. UBQLN4 therefore curtails HRR activity through removal of MRE11 from damaged chromatin and thus offers a therapeutic window for PARP1 inhibitor treatment in UBQLN4overexpressing tumors.of selected pairs defined in a contrast matrix using the R library multcomp. Error bars represent SD of the mean for 3 replicate wells analyzed in one experiment. Each experiment was carried out twice. *p < 0.05. (N) Quantification of the relative comet tail moment (n = 100) derived from the neutral comet assays at the indicated time points. Error bars represent SD of the mean of the relative comet tail moment analyzed in n = 3 experiments.

Deciphering the evolution of cancer cells under therapeutic pressure is a crucial step to understand the mechanisms that lead to treatment resistance. To this end, we analyzed whole-exome sequencing data of eight chronic lymphocytic leukemia (CLL) patients that developed resistance upon BCL2-inhibition by venetoclax. Here, we report recurrent mutations in BTG1 (2 patients) and homozygous deletions affecting CDKN2A/B (3 patients) that developed during treatment, as well as a mutation in BRAF and a high-level focal amplification of CD274 (PD-L1) that might pinpoint molecular aberrations offering structures for further therapeutic interventions.

Hodgkin lymphoma (HL) has become one of the best curable cancers. However, better biomarkers are needed for outcome prediction that would allow protecting patients from over-or under-dosing of treatment. Thymus and activation-regulated chemokine/CCL17 (TARC) is highly and specifically elevated in this disease and has been proposed as possible biomarker in HL patients. In this study, we show that pretreatment TARC levels were associated with established clinical risk factors and predictive for response to treatment in a large cohort of HL patients treated in clinical trials by the German Hodgkin Study Group. Moreover, TARC levels also significantly contributed to a novel multivariate model predicting treatment response. These data clearly suggest an important role for this chemokine as biomarker in HL. Am. J. Hematol. 88:113-115, 2013. V

Here, we use a large-scale cell line-based approach to identify cancer cell-specifi c mutations that are associated with DNA-dependent protein kinase catalytic subunit (DNA-PKcs) dependence. For this purpose, we profi led the mutational landscape across 1,319 cancerassociated genes of 67 distinct cell lines and identifi ed numerous genes involved in homologous recombination-mediated DNA repair, including BRCA1 , BRCA2 , ATM , PAXIP , and RAD50 , as being associated with non-oncogene addiction to DNA-PKcs. Mutations in the mismatch repair gene MSH3 , which have been reported to occur recurrently in numerous human cancer entities, emerged as the most signifi cant predictors of DNA-PKcs addiction. Concordantly, DNA-PKcs inhibition robustly induced apoptosis in MSH3 -mutant cell lines in vitro and displayed remarkable single-agent effi cacy against MSH3 -mutant tumors in vivo . Thus, we here identify a therapeutically actionable synthetic lethal interaction between MSH3 and the non-homologous end joining kinase DNA-PKcs. Our observations recommend DNA-PKcs inhibition as a therapeutic concept for the treatment of human cancers displaying homologous recombination defects. SIGNIFICANCE:We associate mutations in the MSH3 gene, which are frequently detected in microsatellite-instable colon cancer (∼40%), with a therapeutic response to specifi c DNA-PKcs inhibitors. Because potent DNA-PKcs inhibitors are currently entering early clinical trials, we offer a novel opportunity to genetically stratify patients who may benefi t from a DNA-PKcs-inhibitory therapy. Cancer Discov; 4(5);[592][593][594][595][596][597][598][599][600][601][602][603][604][605]

MYC paralogs are frequently activated in small cell lung cancer (SCLC) but represent poor drug targets. Thus, a detailed mapping of MYC -paralog-specific vulnerabilities may help to develop effective therapies for SCLC patients. Using a unique cellular CRISPR activation model, we uncover that, in contrast to MYCN and MYCL, MYC represses BCL2 transcription via interaction with MIZ1 and DNMT3a. The resulting lack of BCL2 expression promotes sensitivity to cell cycle control inhibition and dependency on MCL1. Furthermore, MYC activation leads to heightened apoptotic priming, intrinsic genotoxic stress and susceptibility to DNA damage checkpoint inhibitors. Finally, combined AURK and CHK1 inhibition substantially prolongs the survival of mice bearing MYC-driven SCLC beyond that of combination chemotherapy. These analyses uncover MYC -paralog-specific regulation of the apoptotic machinery with implications for genotype-based selection of targeted therapeutics in SCLC patients.

NKG2D, an activating receptor expressed on NK cells and T cells, is critically involved in tumor immunosurveillance. In this study, we explored the potential therapeutic utility of the NKG2D ligand ULBP2 for the treatment of colon carcinoma. To this end we designed a fusion protein consisting of human ULBP2 and an antibody-derived single chain targeting the tumor carcinoembryonic antigen (CEA). The bispecific recombinant fusion protein re-directed NK cells towards malignant cells by binding to both, tumor cells and NK cells, and triggered NK cell-mediated target cell killing in vitro. Moreover, tumor growth was significantly delayed in a syngeneic colon carcinoma mouse model in response to immunoligand treatment. The anti-tumor activity could be attributed to the stimulation of immune cells with an elevated expression of the activation marker CD69 on NK, T and NKT cells and the infiltration of CD451 immune cells into the solid tumor. In summary, it was demonstrated that immunoligands provide specific tumor targeting by NK cells and exert anti-tumor activity in vitro and in vivo. This technology represents a novel immunotherapeutic strategy for solid tumors with the potential to be further developed for clinical applications.Colorectal cancer is fatal in advanced stages of the disease. Curative treatment options are commonly reserved for tumors not yet metastasized or with resectable metastasis. Colorectal cancer is susceptible to chemotherapy from the onset, but due to therapeutic pressure cancer cells usually become resistant to the standard therapies. In addition, the standard therapies are frequently associated with severe side effects. Thus, there is a high demand for targeted therapies. Most recently developed antibody-based immunotherapies including cetuximab, bevacizumab and the fully human antibody panitumumab have not only added new impulses to colorectal cancer therapy, but essentially improved clinical outcome. 1 They have shown to overcome resistance to conventional chemotherapy and have clearly demonstrated that colorectal carcinoma is accessible to antibody therapy.The potential of immune modulation as well as the role of antibody therapy to enhance a cell-based immunotherapy is currently evaluated. 2-4 Increasing attention has been drawn onto NK cells, which are part of the innate immune system and can attack malignant cells without prior antigen stimulation. 5,6 Numerous ways of tumor cell recognition by NK cells have been described. NK cell cytotoxicity against tumors can be triggered by cells lacking expression of self-recognized MHC class I molecules. This mechanism has been referred to as the "missing-self"-hypothesis and is controlled through a group of inhibitory receptors on the NK cell surface. 7 In addition, an anti-tumor immune response can be induced by the upregulation of ligands for triggering NK cell receptors on the surface of tumor cells. 8 This mechanism has been referred to as "induced-self" and provokes an effective immune response even in the presence of inhibitory signalling....

Cancer that might develop as host natural killer (NK) cells fail to detect ligands for their activating NK receptors. Immunoligands represent promising immunotherapeutic tools to overcome this deficit. These are fusion proteins containing a single-chain antibody fragment (scFv) to target an available tumor antigen and ULBP2 to activate host NK cells by targeting the activatory receptor NKG2D. Prostate-specific membrane antigen (PSMA) is an integral non-shed type 2 membrane protein that is highly and specifically expressed on prostate epithelial cells and strongly upregulated in prostate cancer. Here, we compare the impact of various anti-PSMA immunoligand formats on the therapeutic efficacy against prostate carcinoma cells by activating NK cells via NKG2D. Shortening of the linker separating the heavy and light chain antibody domain leads to the formation of dimers, trimers, and higher molecular mass oligomers. NK cells are most efficiently activated by multimeric immunoligands, thus showing an altered cytokine release pattern. The high avidity format is also superior in in vitro NK-mediated tumor cell targeting as shown in cytotoxicity assays. Finally, the efficacy of a multimeric immunoligand is shown in a prostate carcinoma mouse xenograft model showing a strong activity against advanced established tumors. Mol Cancer Ther; 10(6); 1036-45. Ó2011 AACR.

Genomic profiling revealed the identity of at least 5 subtypes of DLBCL, including the MCD/C5 cluster characterized by aberrations in MYD88, BCL2, PRDM1 and/or SPIB. We generated mouse models harboring B cell-specific Prdm1 or Spib aberrations on the background of oncogenic Myd88 and Bcl2 lesions. We deployed whole exome sequencing, transcriptome, flow- and mass cytometry analyses to demonstrate that Prdm1- or Spib-altered lymphomas display molecular features consistent with pre-memory B cells and light zone B cells, whereas lymphomas lacking these alterations were enriched for late light-zone and plasmablast-associated gene sets. Consistent with the phenotypic evidence for increased B cell receptor signaling activity in Prdm1-altered lymphomas, we demonstrate that combined BTK/BCL2 inhibition displays therapeutic activity in mice and in five out of six relapsed/refractory DLBCL patients. Moreover, Prdm1-altered lymphomas were immunogenic upon transplantation into immuno-competent hosts, displayed an actionable PD-L1 surface expression and were sensitive to anti-murine-CD19-CAR-T cell therapy, in vivo.