Anti-PTPN11 monoclonal antibody, clone Z588 Knockout Validated

Redirecting CD8 T cell immunity with self/tumor-specific affinity-matured T cell receptors (TCRs) is a promising approach for clinical adoptive T cell therapy, with the aim to improve treatment efficacy. Despite numerous functional-based studies, little is known about the characteristics of TCR signaling (i.e., intensity, duration, and amplification) and the regulatory mechanisms underlying optimal therapeutic T cell responses. Using a panel of human SUP-T1 and primary CD8 T cells engineered with incremental affinity TCRs against the cancer-testis antigen NY-ESO-1, we found that upon activation, T cells with optimal-affinity TCRs generated intense and sustained proximal (CD3 zeta, LCK) signals associated with distal (ERK1/2) amplification-gain and increased function. In contrast, in T cells with very high affinity TCRs, signal initiation was rapid and strong yet only transient, resulting in poor MAPK activation and low proliferation potential even at high antigen stimulation dose. Under resting conditions, the levels of surface TCR/CD3e, CD8 beta, and CD28 expression and of CD3. phosphorylation were significantly reduced in those hypo-responsive cells, suggesting the presence of TCR affinity-related activation thresholds. We also show that SHP phosphatases were involved along the TCR affinity gradient, but displayed spatially distinct regulatory roles. While PTPN6/SHP-1 phosphatase activity controlled TCR signaling initiation and subsequent amplification by counteracting CD3. and ERK1/2 phosphorylation, PTPN11/SHP-2 augmented MAPK activation without affecting proximal TCR signaling. Together, our findings indicate that optimal TCR signaling can be finely tuned by TCR affinity-dependent SHP-1 and SHP-2 activity, and this may readily be determined at the TCR/CD3 complex level. We propose that these TCR affinity-associated regulations represent potential protective mechanisms preventing high affinity TCR-mediated autoimmune diseases.

Protein tyrosine phosphatases (PTP) are exciting and novel targets for cancer drug discovery that work in concert with protein tyrosine kinases (PTK) in controlling cellular homeostasis. Given the activating role that some PTKs play in initiating growth factor-mediated cellular processes, PTPs are usually perceived as the negative regulators of these events and therefore tumor suppressive in nature. However, mounting evidence indicate that PTPs do not always antagonize the activity of PTKs in regulating tyrosine phosphorylation, but can also play dominant roles in the initiation and progression of signaling cascades that regulate cell functions. It follows, therefore, that PTP malfunction can actively contribute to a host of human disorders, in particular, cancer, metabolic syndromes, and autoimmune diseases. The Src homology domain containing phosphatase 2 (SHP2) and the three-membered family of phosphatases of regenerating liver (PRL) are infamously oncogenic members of the PTP superfamily. Both are established regulators of major cancer pathways such as Ras/ERK1/2, Src, JAK/STAT, JNK, NF-kappa B, and PTEN/PI3K/AKT. Furthermore, upregulation, mutation, or other dysregulation of these PTPs has been positively correlated with cancer initiation and progression. This review will provide topical coverage of target validation and drug discovery efforts made in targeting these oncogenic PTPs as compelling candidates for cancer therapy. (C) 2017 AACR.