Proteomic analysis of an induced pluripotent stem cell model reveals strategies to treat Juvenile Myelomonocytic Leukaemia

Juvenile myelomonocytic leukemia (JMML) is an aggressive myeloproliferative neoplasm of early childhood with a poor survival rate, thus there is a requirement for improved treatment strategies. Induced pluripotent stem cells offer the ability to model disease and develop new treatment strategies. JMML is frequently associated with mutations in PTPN11. Children with Noonan syndrome, a development disorder, have an increased incidence of JMML associated with specific germline mutations in PTPN11. We undertook a proteomic assessment of myeloid cells derived from induced pluripotent stem cells obtained from Noonan syndrome patients with PTPN11 mutations, either associated or not associated with an increased incidence of JMML. We report that the proteomic perturbations induced by the leukemia-associated PTPN11 mutations are associated with TP53 and NF-Kκb signaling. We have previously shown that MYC is involved in the differential gene expression observed in Noonan syndrome patients associated with an increased incidence of JMML. Thus, we employed drugs to target these pathways and demonstrate differential effects on clonogenic hematopoietic cells derived from Noonan syndrome patients, who develop JMML and those who do not. Further, we demonstrated these small molecular inhibitors, JQ1 and CBL0137, preferentially extinguish primitive hematopoietic cells from sporadic JMML patients as opposed to cells from healthy individuals

The atypical chemokine receptor CCX-CKR regulates metastasis of mammary carcinoma via an effect on EMT

Over the last decade, the significance of the homeostatic CC chemokine receptor-7 and its ligands CC chemokine ligand-19 (CCL19) and CCL21, in various types of cancer, particularly mammary carcinoma, has been highlighted. The chemokine receptor CCX-CKR is a high-affinity receptor for these chemokine ligands but rather than inducing classical downstream signalling events promoting migration, it instead sequesters and targets its ligands for degradation, and appears to function as a regulator of the bioavailability of these chemokines in vivo. Therefore, in this study, we tested the hypothesis that local regulation of chemokine levels by CCX-CKR expressed on tumours alters tumour growth and metastasis in vivo. Expression of CCX-CKR on 4T1.2 mouse mammary carcinoma cells inhibited orthotopic tumour growth. However, this effect could not be correlated with chemokine scavenging in vivo and was not mediated by host adaptive immunity. Conversely, expression of CCX-CKR on 4T1.2 cells resulted in enhanced spontaneous metastasis and haematogenous metastasis in vivo. In vitro characterisation of the tumourigenicity of CCX-CKR-expressing 4T1.2 cells suggested accelerated epithelial-mesenchymal transition (EMT) revealed by their more invasive and motile character, lower adherence to the extracellular matrix and to each other, and greater resistance to anoikis. Further analysis of CCX-CKR-expressing 4T1.2 cells also revealed that transforming growth factor (TGF)-β1 expression was increased both at mRNA and protein levels leading to enhanced autocrine phosphorylation of Smad 2/3 in these cells. Together, our data show a novel function for the chemokine receptor CCX-CKR as a regulator of TGF-β1 expression and the EMT in breast cancer cells