Evolving Therapeutic Strategies for the Classic Philadelphia-Negative Myeloproliferative Neoplasms

AbstractDespite the emergence of JAK inhibitors, there is a need for disease-modifying treatments for Philadelphia-negative myeloproliferative neoplasms (MPNs). JAK inhibitors ameliorate symptoms and address splenomegaly, but because of the heterogeneous contributors to the disease process, JAK inhibitor monotherapy incompletely addresses the burden of disease. The ever-growing understanding of MPN pathogenesis has provided the rationale for testing novel and targeted therapeutic agents, as monotherapies or in combination, in preclinical and clinical settings. A number of intriguing options have emerged, and it is hoped that further progress will lead to significant changes in the natural history of MPNs

Activation of Rac1 and the p38 Mitogen-activated Protein Kinase Pathway in Response to All-trans-retinoic Acid

Several signaling pathways are activated by all-trans-retinoic acid (RA) to mediate induction of differentiation and apoptosis of malignant cells. In the present study we provide evidence that the p38 MAP kinase pathway is activated in a RA-dependent manner in the NB-4, acute pro-myelocytic leukemia, and the MCF-7, breast carcinoma, cell lines. RA treatment of cells induces a time- and dose-dependent phosphorylation of p38, and such phosphorylation results in activation of its catalytic domain. p38 activation is not inducible by RA in a variant NB-4 cell line, NB-4.007/6, which is resistant to the effects of RA, suggesting a role for this pathway in the induction of RA responses. Our data also demonstrate that the small G-protein Rac1 is activated by RA and functions as an upstream regulator of p38 activation, whereas the MAPKAPK-2 serine kinase is a downstream effector for the RA-activated p38. To obtain information on the functional role of the Rac1/p38/MAPKAPK-2 pathway in RA signaling, the effects of pharmacological inhibition of p38 on RA-induced gene transcription and cell differentiation were determined. Our results indicate that treatment of cells with the SB203580 inhibitor does not inhibit RA-dependent gene transcription via retinoic acid response elements or induction of Stat1 protein expression. However, treatment with SB203580 or SB202190 strongly enhances RA-dependent induction of cell differentiation and RA-regulated growth inhibitory responses. Altogether, our findings demonstrate that the Rac1/p38 MAP kinase pathway is activated in a RA-dependent manner and exhibits negative regulatory effects on the induction of differentiation

Cross-talk between NFkB and the PI3-Kinase/AKT pathway can be targeted in primary effusion lymphoma (PEL) cell lines for efficient apoptosis

Background: A number of constitutively activated signaling pathways play critical roles in the survival and growth of primary effusion lymphoma cells (PELs) including NFkB and PI3/AKT kinase cascades. NFkBis constitutively activated in a number of malignancies, including multiple myeloma, Burkitt’s lymphoma and diffuse large cell B-cell lymphoma. However, its role in primary effusion lymphoma has not been fully explored. Methodology/Principal Findings: We used pharmacological inhibition and gene silencing to define the role of NFkB in growth and survival of PEL cells. Inhibition of NFkB activity by Bay11-7085 resulted in decreased expression of p65 in the nuclear compartment as detected by EMSA assays. In addition, Bay11-7085 treatment caused de-phosphorylation of AKT and its downstream targets suggesting a cross-talk between NFkB and the PI3-kinase/AKT pathway. Importantly, treatment of PEL cells with Bay11-7085 led to inhibition of cell viability and induced apoptosis in a dose dependent manner. Similar apoptotic effects were found when p65 was knocked down using specific small interference RNA. Finally, co-treatment of PEL cells with suboptimal doses of Bay11-7085 and LY294002 led to synergistic apoptotic responses in PEL cells.Conclusion/Significance: These data support a strong biological-link between NFkB and the PI3-kinase/AKT pathway in the modulation of anti-apoptotic effects in PEL cells. Synergistic targeting of these pathways using NFKB- and PI3-kinase/AKT- inhibitors may have a therapeutic potential for the treatment of PEL and possibly other malignancies with constitutive activation of these pathway

Central nervous system immune interactome is a function of cancer lineage, tumor microenvironment, and STAT3 expression.

BACKGROUNDImmune cell profiling of primary and metastatic CNS tumors has been focused on the tumor, not the tumor microenvironment (TME), or has been analyzed via biopsies.METHODSEn bloc resections of gliomas (n = 10) and lung metastases (n = 10) were analyzed via tissue segmentation and high-dimension Opal 7-color multiplex imaging. Single-cell RNA analyses were used to infer immune cell functionality.RESULTSWithin gliomas, T cells were localized in the infiltrating edge and perivascular space of tumors, while residing mostly in the stroma of metastatic tumors. CD163+ macrophages were evident throughout the TME of metastatic tumors, whereas in gliomas, CD68+, CD11c+CD68+, and CD11c+CD68+CD163+ cell subtypes were commonly observed. In lung metastases, T cells interacted with CD163+ macrophages as dyads and clusters at the brain-tumor interface and within the tumor itself and as clusters within the necrotic core. In contrast, gliomas typically lacked dyad and cluster interactions, except for T cell CD68+ cell dyads within the tumor. Analysis of transcriptomic data in glioblastomas revealed that innate immune cells expressed both proinflammatory and immunosuppressive gene signatures.CONCLUSIONOur results show that immunosuppressive macrophages are abundant within the TME and that the immune cell interactome between cancer lineages is distinct. Further, these data provide information for evaluating the role of different immune cell populations in brain tumor growth and therapeutic responses.FUNDINGThis study was supported by the NIH (NS120547), a Developmental research project award (P50CA221747), ReMission Alliance, institutional funding from Northwestern University and the Lurie Comprehensive Cancer Center, and gifts from the Mosky family and Perry McKay. Performed in the Flow Cytometry & Cellular Imaging Core Facility at MD Anderson Cancer Center, this study received support in part from the NIH (CA016672) and the National Cancer Institute (NCI) Research Specialist award 1 (R50 CA243707). Additional support was provided by CCSG Bioinformatics Shared Resource 5 (P30 CA046592), a gift from Agilent Technologies, a Research Scholar Grant from the American Cancer Society (RSG-16-005-01), a Precision Health Investigator Award from University of Michigan (U-M) Precision Health, the NCI (R37-CA214955), startup institutional research funds from U-M, and a Biomedical Informatics & Data Science Training Grant (T32GM141746)