SUMMARYBMP activity is essential for many steps of neural development, including the initial role in neural induction and the control of progenitor identities along the dorsal-ventral axis of the neural tube. Taking advantage of chick in ovo electroporation, we show a novel role for BMP7 at the time of neurogenesis initiation in the spinal cord. Using in vivo loss-of-function experiments, we show that BMP7 activity is required for the generation of three discrete subpopulations of dorsal interneurons: dI1-dI3-dI5. Analysis of the BMP7 mouse mutant shows the conservation of this activity in mammals. Furthermore, this BMP7 activity appears to be mediated by the canonical Smad pathway, as we demonstrate that Smad1 and Smad5 activities are similarly required for the generation of dI1-dI3-dI5. Moreover, we show that this role is independent of the patterned expression of progenitor proteins in the dorsal spinal cord, but depends on the BMP/Smad regulation of specific proneural proteins, thus narrowing this BMP7 activity to the time of neurogenesis. Together, these data establish a novel role for BMP7 in primary neurogenesis, the process by which a neural progenitor exits the cell cycle and enters the terminal differentiation pathway.
Patients with hepatocellular carcinoma (HCC) have a poor prognosis and limited therapeutic options. Alpha‐fetoprotein (AFP) is often expressed at high levels in HCC and is an established clinical biomarker of the disease. Expression of AFP in nonmalignant liver can occur, particularly in a subset of progenitor cells and during chronic inflammation, at levels typically lower than in HCC. This cancer‐specific overexpression indicates that AFP may be a promising target for immunotherapy. We verified expression of AFP in normal and diseased tissue and generated an affinity‐optimized T‐cell receptor (TCR) with specificity to AFP/HLA‐A*02+ tumors. Expression of AFP was investigated using database searches, by qPCR, and by immunohistochemistry (IHC) analysis of a panel of human tissue samples, including normal, diseased, and malignant liver. Using in vitro mutagenesis and screening, we generated a TCR that recognizes the HLA‐A*02‐restricted AFP158‐166 peptide, FMNKFIYEI, with an optimum balance of potency and specificity. These properties were confirmed by an extension of the alanine scan (X‐scan) and testing TCR‐transduced T cells against normal and tumor cells covering a variety of tissues, cell types, and human leukocyte antigen (HLA) alleles. Conclusion: We have used a combination of physicochemical, in silico, and cell biology methods for optimizing a TCR for improved affinity and function, with properties that are expected to allow TCR‐transduced T cells to differentiate between antigen levels on nonmalignant and cancer cells. T cells transduced with this TCR constitute the basis for a trial of HCC adoptive T‐cell immunotherapy.
Neuroblastoma is an embryonic tumor derived from cells of the neural crest. Taking advantage of a newly developed neural crest lineage tracer and based on the hypothesis that the molecular mechanisms that mediate neural crest delamination are also likely to be involved in the spread of neuroblastoma, we were able to identify genes that are active both in neural crest development and neuroblastoma tumor formation. A subsequent search of the neuroblastoma gene server for human orthologues of genes differentially expressed in the chick embryo neural crest screen retrieved the LIM domain only protein 4 (LMO4), which was expressed in both cell types analyzed. Functional experiments in these two model systems revealed that LMO4 activity is required for neuroblastoma cell invasion and neural crest delamination. Moreover, we identified LMO4 as an essential cofactor in Snail2-mediated cadherin repression and in the epithelial-tomesenchymal transition of both neural crest and neuroblastoma cells. Together, our results suggest that the association of high levels of LMO4 with aggressive neuroblastomas is dependent on LMO4 regulation of cadherin expression and hence, tumor invasiveness.
The DNA methyl transferase inhibitors 5-aza-2’-deoxycytidine (decitabine or DECI) and 5-azacytidine (azacitidine or AZA) have recently been approved for the treatment of a variety of hematologic malignancies. These cytidine analogues remove repressive epigenetic DNA methyl marks and induce the transcription of numerous genes normally silenced during the processes of cellular differentiation or transformation. DNMTis have a net anti-neoplastic activity through the up-regulation of tumor-suppressor genes involved in the induction of apoptosis, cellular differentiation and cell cycle arrest. In addition, DNMTis promote the expression of several cancer testis antigens (CTAs) by tumor cells, including NY-ESO and MAGE-A1/A3. These observations suggest that the combination of DNMTis with immunotherapeutic modalities may provide some clinical benefit. Adoptive immunotherapies using autologous CD4+ and CD8+ T cells expressing an affinity optimized NY-ESO TCR are in clinical trials and show robust clinical responses in patients across several indications including synovial sarcoma, multiple myeloma or melanoma. DNMTis were previously shown to induce the expression of NY-ESO in antigen-low or -negative tumor cells and consequently enable the activation of NY-ESO-specific T-cells. While there is compelling evidence for the combination of DNMTis with T cells containing engineered affinity-enhanced TCRs recognizing NY-ESO-1, safety data supporting this approach are lacking. Initial tests into the safety of combining these treatments investigated the effects of DECI and AZA on NY-ESO and LAGE-1 expression in a panel of primary adult human cells of different tissue origins. Our data demonstrate that treatment with either compound resulted in a significant up-regulation of NY-ESO transcription in a subset of primary cells tested. The magnitude of increase in transcript expression varied between cell types and, in some cases, was sufficient to activate T cells expressing an affinity-optimized NY-ESO-specific TCR. These findings raise important safety concerns with regards to the potential combination of DNMTi compounds with NY-ESO T-cell therapy and suggest that such co-therapies may result in on-target off-tumor toxicities. Citation Format: Bruno Laugel, Alexandra Sevko, Karen Howe, Zoltan Ferjentsik, Tiago Ferronha, Miguel Maroto, Joanna Brewer, Bent Jakobsen, Gwendolyn Binder-Scholl. DNA methyl transferase inhibitors (DNMTis) upregulate NY-ESO expression in several human primary cells: implications for co-therapy with engineered adoptive T-cell therapies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2281.
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