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We previously demonstrated that a subset of acute myeloid leukemia (AML) patients with concurrent RAS pathway and TP53 mutations have an extremely poor prognosis and that most of these TP53 mutations are missense mutations. Here, we report that, in contrast to the mixed AML and T cell malignancy that developed in [Nras.sup.G12D/+] [p53.sup.-/-] ([NP.sup.-/- ]) mice, [Nras.sup.G120/+] [p53.sup.R172H/+] ([NP.sup.mut]) mice rapidly developed inflammation-associated AML. Under the inflammatory conditions, [NP.sup.mut] hematopoietic stem and progenitor cells (HSPCs) displayed imbalanced myelopoiesis and lymphopoiesis and mostly normal cell proliferation despite MEK/ERK hyperactivation. RNA-Seq analysis revealed that oncogenic NRAS signaling and mutant p53 synergized to establish an [NP.sup.mut]-AML transcriptome distinct from that of [NP.sup.-/-] cells. The [NP.sup.mut]-AML transcriptome showed GATA2 downregulation and elevated the expression of inflammatory genes, including those linked to NF-[kappa]B signaling. NF- [kappa]B was also upregulated in human NRAS TP53 AML. Exogenous expression of GATA2 in human [NP.sup.mut] KY821 AML cells downregulated inflammatory gene expression. Mouse and human [NP.sup.mut] AML cells were sensitive to MEK and NF- [kappa]B inhibition in vitro. The proteasome inhibitor bortezomib stabilized the NF-KB-inhibitory protein iKBa, reduced inflammatory gene expression, and potentiated the survival benefit of a MEK inhibitor in [NP.sup.mut] mice. Our study demonstrates that a p53 structural mutant synergized with oncogenic NRAS to promote AML through mechanisms distinct from p53 loss., Introduction Acute myeloid leukemia (AML) is an aggressive and devastating hematologic malignancy characterized by the accumulation of partially differentiated myeloid blast cells ([greater than or equal to]20%) in bone marrow [...]

* Autoimmune lymphoproliferative syndrome (ALPS) is an inherited nonmalignant lymphoproliferative disorder characterized by heterozygous mutations within the first apoptosis signal receptor (FAS) signaling pathway. Defects in FAS-mediated apoptosis cause an expansion and accumulation of autoreactive [CD4.sup.-] and [CD8.sup.-] (double-negative) T cells, leading to cytopenias, splenomegaly, lymphadenopathy, autoimmune disorders, and a greatly increased lifetime risk of lymphoma. The differential diagnosis of ALPS includes infection, other inherited immunodeficiency disorders, primary and secondary autoimmune syndromes, and lymphoma. The most consistent pathologic feature is a florid paracortical expansion of double-negative T cells in lymph nodes. A presumptive clinical diagnosis can be made from symptoms and a constellation of laboratory test results. However, a definitive diagnosis requires ancillary testing and enables disease subclassification. Recognition of ALPS is critical, as treatment with immunosuppressive therapies can effectively reduce or ameliorate symptoms for most patients. (Arch Pathol Lab Med. 2020;144:245-251; doi: 10.5858/arpa.2018-0190-RS), The first apoptosis signal receptor (FAS) pathway regulates apoptosis and is critical for proper development and functioning of the immune system. (1) Autoimmune lymphoproliferative syndrome (ALPS) is an inherited lymphoproliferative [...]

Abstract CML is a myeloproliferative disorder characterized by unregulated growth of predominantly myeloid cells, and their subsequent accumulation in the bone marrow and peripheral blood. CML originates in hematopoietic stem cells (HSCs) with t(9;22)(q34;q11.2) translocation, which causes the constitutively expression of the BCR-ABL kinase driving the expansion of leukemic progeny. Ex vivo cultures of CML-derived cell lines and primary CML cells, ectopic expression of BCR-ABL in CD34+ cells and mouse models have provided important insights into CML pathogenesis and led to the development of targeted therapy for this neoplastic disease with BCR-ABL thyrosine kinase inhibitor (TKI), imatinib. Despite these achievements, in many cases CML remains incurable because of innate resistance of CML leukemia stem cells (LSCs) to TKI. Thus, a definitive cure for leukemia requires identifying novel therapeutic targets to eradicate LSCs. However, the rarity of LSCs within the pool of malignant cells remains a major limiting factor for their study in humans. Recently we generated transgene-free iPSCs from the bone marrow mononuclear cells of a patient in the chronic phase of CML (CML15 iPSCs and CML17 iPSCs) and showed that these iPSCs capture the entire genome of neoplastic cells, including the unique 4-way translocation between chromosomes 1, 9, 22, and 11 that was present in the patient bone marrow (BM) (Hu et al., Blood 2011). By differentiating CML iPSCs back to the blood we were able to generate iCD34+ primitive hematopoietic cells with typical LSC properties, including HSC phenotype (lin-CD34+CD45+CD90+CD117+CD45RA-RholowALDHhigh), adhesion defect, increased long-term survival and proliferation, and innate resistance to TKI imatinib. By analyzing transcriptome of CML and normal BM iCD34+ cells treated or non-treated with imatinib we discovered OLFM4 as top-ranking gene, which is selectively upregulated by imatinib in CML, but not normal BM iCD34+ cells. Using siRNA, we demonstrated that OLFM4 knockdown potentiate imatinib-induced apoptosis and suppression of CFCs in iCD34+ cells, thereby indicating that OLFM4 is involved in regulation of imatinib resistance and survival of de novo generated primitive CML cells. To find out whether findings obtained using iCD34+ cells can be translated to somatic cells, we evaluated the expression and functional role of OLFM4 in CD34+ cells obtained from parental bone marrow and bone marrow from the several other CML patients in the chronic phase. Using immunohistochemistry and RT-PCR we confirmed OLFM4 expression in lin-CD34+ and CD34- bone marrow cells from patients. Knockdown OLFM4 with siRNA in somatic CML lin-CD34+ potentiated imatininb-induced CFC suppression, abrogated LTC-ICs and engraftment of lin-CD34+ cells in NSGW41 mice, thereby indicating that OLFM4 is critical for survival of CML LSCs. In summary, we showed that reprogramming leukemia cells to pluripotency and then differentiating them back into blood cells can be used as a novel approach to produce an unlimited number of primitive hematopoietic cells with LSC properties and identify of novel LSC survival factors and drug targets. We validated this approach by demonstrating the successful application of the iPSC-based platform to discover OLFM4 as a novel LSC survival factor in patients in the chronic phase of CML. Disclosures Thomson: CDI: Consultancy, Equity Ownership. Slukvin:CDI: Consultancy, Equity Ownership; Cynata: Consultancy, Equity Ownership, Research Funding.

Aim and background: Combined endocyclophotocoagulation and phacoemulsification (ECP/Phaco) are uncommonly associated with complications. We present the first case of a rare complication following ECP/Phaco. Case description: A 72-year-old patient with dense nuclear sclerotic cataracts and primary open-angle glaucoma (POAG) underwent bilateral surgery uneventfully. He experienced a brief episode of postoperative elevated intraocular pressure (IOP), but only one eye with a lower baseline IOP developed a dilated pupil. No pupillary response was observed after applying 4% pilocarpine. The fixed mydriasis persisted without reaction to light or near stimulus, and the best-corrected vision (BCVA) was 20/30 in the affected eye. Conclusion: This case reports a possible rare complication when undergoing ECP/Phaco therapy. The pathogenesis of Urrets-Zavalia syndrome is unknown, but we hypothesized that eyes with more pronounced increases in IOP from baseline may be more susceptible to ischemic injury to the pupillary sphincter, resulting in a chronically dilated pupil. Clinical significance: Even a modest transient rise in postoperative IOP in a glaucomatous eye with normal baseline IOP could result in a chronically dilated pupil. [ABSTRACT FROM AUTHOR]

Abstract Background The proteasome inhibitor bortezomib can inhibit activation of the transcription factor NF-κB, a mechanism implicated in its anti-neoplastic effects observed in mantle cell lymphoma (MCL). However, NF-κB can be activated through many distinct mechanisms, including proteasome independent pathways. While MCL cells have been shown to harbor constitutive NF-κB activity, what fraction of this activity in primary MCL samples is sensitive or resistant to inhibition by bortezomib remains unclear. Results Proteasome activity in the EBV-negative MCL cell lines Jeko-1 and Rec-1 is inhibited by greater than 80% after exposure to 20 nM bortezomib for 4 hours. This treatment decreased NF-κB activity in Jeko-1 cells, but failed to do so in Rec-1 cells when assessed by electrophoretic mobility shift assay (EMSA). Concurrently, Rec-1 cells were more resistant to the cytotoxic effects of bortezomib than Jeko-1 cells. Consistent with a proteasome inhibitor resistant pathway of activation described in mouse B-lymphoma cells (WEHI231) and a breast carcinoma cell line (MDA-MB-468), the bortezomib-resistant NF-κB activity in Rec-1 cells is inhibited by calcium chelators, calmodulin inhibitors, and perillyl alcohol, a monoterpene capable of blocking L-type calcium channels. Importantly, the combination of perillyl alcohol and bortezomib is synergistic in eliciting Rec-1 cell cytotoxicity. The relevance of these results is illuminated by the additional finding that a considerable fraction of primary MCL samples (8 out of 10) displayed bortezomib-resistant constitutive NF-κB activity. Conclusion Our findings show that bortezomib-resistant NF-κB activity is frequently observed in MCL samples and suggest that this activity may be relevant to MCL biology as well as serve as a potential therapeutic target.