Development of a closed CAR-T manufacturing process

The field of immunotherapy has emerged as a promising new type of treatment for cancer with the approval of the first two CAR-T therapies. The clinical success of T-cell based immunotherapies necessitates a robust manufacturing process for these products to be consistently produced at commercial scale. Our CAR-T workflow combines unit operation specific solutions for thaw of an apheresis unit, wash, CD3 selection, T-cell activation, lentiviral transduction, incubator- and reactor-based expansion culture, harvest, formulation, cryopreservation and thaw of CAR-T product. We have evaluated the impact of both serum-containing and xeno-free culture media, commercially available T-cell selection and activation reagents, closed small-scale culture vessel options, alternative solutions to enhance transduction, and the specific timing of process steps to develop a modular platform process that is robust and flexible for the varied needs of CAR-T developers. Frozen apheresis units are processed using the SmartWash protocol on the SepaxTM 2 and T-cells are isolated with EasySepTM Release CD3 Positive Selection Kit. The cells are then activated with ImmunoCult CD3/CD28/CD2 T-cell activator before being transduced 24 hours later using the SepaxTM 2. Expansion of Tcells are carried out in two stages: incubator-based culture before going into the XuriTM Cell Expansion System W25 with a perfusion feeding regime. Cultured cells are then harvested and washed in Plasmalyte-A with human serum albumin and formulated with CryoStor® CS10 using the FlexCell protocol on the Sefia™ Cell Processing System. The final cell products are cryopreserved using the VIA Freeze controlled-rate freezer. We have also accessed a point-of-care thawing strategy using the VIA Thaw. Our CAR-T process achieves greater than 1.0E10 expanded T-cells with \u3e80% eGFP transduction efficiency across an 8-day manufacturing process

Histone deacetylase inhibitor regulation of gene expression

Histone deacetylase inhibitors (HDIs) are a group of chemo-preventive and chemo-therapeutic agents that have generated significant attention in clinical trials, given their ability to selectively induce cell cycle arrest, differentiation and/or apoptosis of tumor cells. Presently, these agents are proposed to function by altering gene expression levels, primarily by promoting histone hyperacetylation and gene transcription. However, in this thesis, HDIs are reported to control the expression of genes from the c-Src kinase family and p21WAF1 by means other than transcriptional activation. Overexpression and activation of c-Src, a 60kDa non-receptor tyrosine kinase, has been implicated in the development, growth, progression, and metastasis of several human cancers, especially those of the colon. Butyrate and the more specific histone deacetylase inhibitor trichostatin A (TSA) were both found to effectively inhibit the expression of c-Src mRNA and protein in a number of tumor cell lines, including those of the colon, liver and breast. Expression of the SRC oncogene is alternatively regulated by the SRC1A and SRC1α promoters. HDIs were shown to repress c-Src expression by inhibiting transcription of both of these promoters, independent of any new protein synthesis. Furthermore, butyrate and TSA similarly regulated the expression of the c-Src family kinase (SFK) members Yes, Fyn, Lyn and Lck in human colon cancer cell lines. In addition, TATA binding protein (TBP) associated factor 1 (TAF1) was shown to be necessary for basal transcription of the SRC1A, YES and LYN promoters, but was not required for HDI mediated repression. Induction of the potent cyclin dependent kinase inhibitor p21WAF1 has been identified to be a key feature of HDI mediated cell cycle arrest. The level of p21WAF1 expression has been extensively reported to be directly upregulated by HDIs in a p53 independent manner that requires Sp family binding sites in the p21WAF1 proximal promoter to induce transcription. However, HDIs were shown to be capable of inducing p21WAF1 gene expression, dependent on new protein synthesis, by increasing mRNA stability. To date, p21WAF1 mRNA stability has been extensively studied and a number of cis-acting elements in the 3’ untranslated region (UTR) of the p21WAF1 mRNA have been implicated in the regulation of mRNA stability, such as AU rich elements (AREs) and a 42 nucleotide HuD/Elav binding element. Similarly, in this work, two novel cis-acting elements were identified in the 3’ UTR of p21WAF1 and were shown to facilitate basal and HDI induced post-transcriptional regulation of p21WAF1 mRNA stability in HepG2 cells. Collectively, these studies highlight the intricacy of HDI mediated effects and challenge the preconceptions regarding the molecular mechanism of these anti-tumor agents

How Tets and Cytoskeleton Dynamics MET in Reprogramming

International audienceTwo studies by Sakurai et al. (2014) and Hu et al. (2014) in this issue of Cell Stem Cell add a new level of understanding to the mesenchymal-to-epithelial transition taking place during reprogramming, showing how this morphological transformation is promoted by Tet enzymes and blocked by kinase-dependent cytoskeletal organization

GCN5 Regulates FGF Signaling and Activates Selective MYC Target Genes during Early Embryoid Body Differentiation

Summary: Precise control of gene expression during development is orchestrated by transcription factors and co-regulators including chromatin modifiers. How particular chromatin-modifying enzymes affect specific developmental processes is not well defined. Here, we report that GCN5, a histone acetyltransferase essential for embryonic development, is required for proper expression of multiple genes encoding components of the fibroblast growth factor (FGF) signaling pathway in early embryoid bodies (EBs). Gcn5−/− EBs display deficient activation of ERK and p38, mislocalization of cytoskeletal components, and compromised capacity to differentiate toward mesodermal lineage. Genomic analyses identified seven genes as putative direct targets of GCN5 during early differentiation, four of which are cMYC targets. These findings established a link between GCN5 and the FGF signaling pathway and highlighted specific GCN5-MYC partnerships in gene regulation during early differentiation

PTEN regulates cilia through Dishevelled

Cilia are hair-like cellular protrusions important in many aspects of eukaryotic biology. For instance, motile cilia enable fluid movement over epithelial surfaces, while primary (sensory) cilia play roles in cellular signalling. The molecular events underlying cilia dynamics, and particularly their disassembly, are not well understood. Phosphatase and tensin homologue (PTEN) is an extensively studied tumour suppressor, thought to primarily act by antagonizing PI3-kinase signalling. Here we demonstrate that PTEN plays an important role in multicilia formation and cilia disassembly by controlling the phosphorylation of Dishevelled (DVL), another ciliogenesis regulator. DVL is a central component of WNTsignalling that plays a role during convergent extension movements, which we show here are also regulated by PTEN. Our studies identify a novel protein substrate for PTEN that couples PTEN to regulation of cilia dynamics and WNT signalling, thus advancing our understanding of potential underlying molecular etiologies of PTEN-related pathologies