LINGO3 regulates mucosal tissue regeneration and promotes TFF2 dependent recovery from colitis.

Aim: Recovery of damaged mucosal surfaces following inflammatory insult requires diverse regenerative mechanisms that remain poorly defined. Previously, we demonstrated that the reparative actions of Trefoil Factor 3 (TFF3) depend upon the enigmatic receptor, leucine rich repeat and immunoglobulin-like domain containing nogo receptor 2 (LINGO2). This study examined the related orphan receptor LINGO3 in the context of intestinal tissue damage to determine whether LINGO family members are generally important for mucosal wound healing and maintenance of the intestinal stem cell (ISC) compartment needed for turnover of mucosal epithelium.Methods and Results: We find that LINGO3 is broadly expressed on human enterocytes and sparsely on discrete cells within the crypt niche, that contains ISCs. Loss of function studies indicate that LINGO3 is involved in recovery of normal intestinal architecture following dextran sodium sulfate (DSS)-induced colitis, and that LINGO3 is needed for therapeutic action of the long acting TFF2 fusion protein (TFF2-Fc), including a number of signaling pathways critical for cell proliferation and wound repair. LINGO3-TFF2 protein-protein interactions were relatively weak however and LINGO3 was only partially responsible for TFF2 induced MAPK signaling suggesting additional un-identified components of a receptor complex. However, deficiency in either TFF2 or LINGO3 abrogated budding/growth of intestinal organoids and reduced expression of the intestinal ISC gene leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5), indicating homologous roles for these proteins in tissue regeneration, possibly via regulation of ISCs in the crypt niche.Conclusion: We propose that LINGO3 serves a previously unappreciated role in promoting mucosal wound healing.

The combination of hypomethylating agents and histone deacetylase inhibitors produce marked synergy in preclinical models of T-cell lymphoma.

T-cell lymphomas (TCL) are aggressive lymphomas usually treated with CHOP (cyclophsophamide, doxorubicin, vincristine, prednisolone)-like regimens upfront. Recent data suggest that TCL are driven by epigenetic defects, potentially rendering them sensitive to epigenetic therapies. We explored the therapeutic merits of a combined epigenetic platform using histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors (DNMT) in in vitro and in vivo models of TCL. The 50% inhibitory concentration (IC50 ) values revealed romidepsin was the most potent HDACI, with an IC50 in the low nanomolar range. The combination with a hypomethylating agent produced synergy across all cell lines, which was confirmed in cytotoxicity and apoptosis assays. An in vivo xenograft study demonstrated inhibition of tumour growth in the combination cohort compared to the single agent. Gene expression array and global methylation profiling revealed differentially expressed genes and modulated pathways for each of the single treatment conditions and the combination. Most of the effects induced by the single agent treatment were maintained in the combination group. In total, 944 unique genes were modulated by the combination treatment, supporting the hypothesis of molecular synergism. These data suggest combinations of hypomethylating agents and HDACIs are synergistic in models of TCL, which is supported at the molecular level.

NPM-ALK-Induced Reprogramming of Mature TCR-Stimulated T Cells Results in Dedifferentiation and Malignant Transformation.

Fusion genes including NPM-ALK can promote T-cell transformation, but the signals required to drive a healthy T cell to become malignant remain undefined. In this study, we introduce NPM-ALK into primary human T cells and demonstrate induction of the epithelial-to-mesenchymal transition (EMT) program, attenuation of most T-cell effector programs, reemergence of an immature epigenomic profile, and dynamic regulation of c-Myc, E2F, and PI3K/mTOR signaling pathways early during transformation. A mutant of NPM-ALK failed to bind several signaling complexes including GRB2/SOS, SHC1, SHC4, and UBASH3B and was unable to transform T cells. Finally, T-cell receptor (TCR)-generated signals were required to achieve T-cell transformation, explaining how healthy individuals can harbor T cells with NPM-ALK translocations. These findings describe the fundamental mechanisms of NPM-ALK-mediated oncogenesis and may serve as a model to better understand factors that regulate tumor formation. SIGNIFICANCE: This investigation into malignant transformation of T cells uncovers a requirement for TCR triggering, elucidates integral signaling complexes nucleated by NPM-ALK, and delineates dynamic transcriptional changes as a T cell transforms.See related commentary by Spasevska and Myklebust, p. 3160.

The novel kinesin spindle protein (KSP) inhibitor SB-743921 exhibits marked activity in in vivo and in vitro models of aggressive large B-cell lymphoma.

The kinesin spindle protein (KSP) is a mitotic protein essential for cell cycle control and motility. SB-743921 (hereafter SB-921) is an inhibitor that selectively targets the ATP-binding domain of the KSP. The preclinical activity of SB-921 was evaluated in models of diffuse large B-cell lymphoma (DLBCL). The cytotoxicity of SB-921 was evaluated in a series of germinal center (GC-DLBCL) and post-germinal center (ABC-DLBCL) DLBCL cell lines and a murine lymphoma xenograft model. GC-DLBCL lines generally demonstrated greater sensitivity to SB-921. IC50 values ranged between 1 nM and 900 nM for GC-DLBCL compared to 1 nM to 10 µM for ABC lines. SB-921 demonstrated marked activity in a xenograft model of Ly-1 (GC-DLBCL). While SB-921 was relatively more active in GC derived cell lines, ABC-derived lines still underwent apoptosis at higher concentrations. These results demonstrate that SB-921 inhibits proliferation and induces apoptosis in both GC-DLBCL and ABC-DLBCL.

The addition of granulocyte-colony stimulating factor shifts the dose limiting toxicity and markedly increases the maximum tolerated dose and activity of the kinesin spindle protein inhibitor SB-743921 in patients with relapsed or refractory lymphoma: results of an international, multicenter phase I/II study.

This was a phase I study of SB-743921 (SB-921) in patients with relapsed/refractory lymphoma. Previous studies established that neutropenia was the only dose limiting toxicity (DLT). The primary objective was to determine the DLT, maximum tolerated dose (MTD) and efficacy of SB-921 with and without granulocyte-colony stimulating factor (G-CSF). Sixty-eight patients were enrolled, 42 without G-CSF, 26 with G-CSF. In the cohort without G-CSF, SB-921 doses ranged from 2 to 7 mg/m(2), with 6 mg/m(2) being the MTD. In the cohort with G-CSF support, doses of 6-10 mg/m(2) were administered, with 9 mg/m(2) being the MTD, representing a 50% increase in dose density. Fifty-six patients were evaluable for efficacy. Four of 55 patients experienced a partial response (three in Hodgkin lymphoma and one in non-Hodgkin lymphoma, all at doses ≥ 6 mg/m(2)); 19 patients experienced stable disease, 33 patients developed progression of disease. G-CSF shifted the DLT from neutropenia to thrombocytopenia, allowing for a 50% increase in dose density. Responses were seen at higher doses with G-CSF support.

Aurora A Kinase Inhibition Selectively Synergizes with Histone Deacetylase Inhibitor through Cytokinesis Failure in T-cell Lymphoma.

PURPOSE: Aurora A kinase (AAK) is expressed exclusively during mitosis, and plays a critical role in centrosome duplication and spindle formation. Alisertib is a highly selective AAK inhibitor that has demonstrated marked clinical activity of alisertib across a spectrum of lymphomas, though particularly in patients with T-cell lymphoma (TCL). We sought to compare and contrast the activity of alisertib in preclinical models of B-cell lymphoma (BCL) and TCL, and identify combinations worthy of clinical study. High-throughput screening of pralatrexate, the proteasome inhibitor (ixazomib), and the histone deacetylase (HDAC) inhibitor (romidepsin) revealed that only romidepsin synergized with alisertib, and only in models of TCL. We discovered that the mechanism of synergy between AAK inhibitors and HDAC inhibitors appears to be mediated through cytokinesis failure. EXPERIMENTAL DESIGN: A high-throughput screening approach was used to identify drugs that were potentially synergistic in combination with alisertib. Live-cell imaging was used to explore the mechanistic basis for the drug: drug interaction between alisertib and romidepsin. An in vivo xenograft TCL model was used to confirm in vitro results. RESULTS: In vitro, alisertib exhibited concentration-dependent cytotoxicity in BCL and TCL cell lines. Alisertib was synergistic with romidepsin in a T-cell-specific fashion that was confirmed in vivo. Live-cell imaging demonstrated that the combination treatment resulted in profound cytokinesis failure. CONCLUSIONS: These data strongly suggest that the combination of alisertib and romidepsin is highly synergistic in TCL through modulation of cytokinesis and merits clinical development.

Preclinical pharmacologic evaluation of pralatrexate and romidepsin confirms potent synergy of the combination in a murine model of human T-cell lymphoma.

PURPOSE: T-cell lymphomas (TCL) are aggressive diseases, which carry a poor prognosis. The emergence of new drugs for TCL has created a need to survey these agents in a rapid and reproducible fashion, to prioritize combinations which should be prioritized for clinical study. Mouse models of TCL that can be used for screening novel agents and their combinations are lacking. Developments in noninvasive imaging modalities, such as surface bioluminescence (SBL) and three-dimensional ultrasound (3D-US), are challenging conventional approaches in xenograft modeling relying on caliper measurements. The recent approval of pralatrexate and romidepsin creates an obvious combination that could produce meaningful activity in TCL, which is yet to be studied in combination. EXPERIMENTAL DESIGN: High-throughput screening and multimodality imaging approach of SBL and 3D-US in a xenograft NOG mouse model of TCL were used to explore the in vitro and in vivo activity of pralatrexate and romidepsin in combination. Corresponding mass spectrometry-based pharmacokinetic and immunohistochemistry-based pharmacodynamic analyses of xenograft tumors were performed to better understand a mechanistic basis for the drug:drug interaction. RESULTS: In vitro, pralatrexate and romidepsin exhibited concentration-dependent synergism in combination against a panel of TCL cell lines. In a NOG murine model of TCL, the combination of pralatrexate and romidepsin exhibited enhanced efficacy compared with either drug alone across a spectrum of tumors using complementary imaging modalities, such as SBL and 3D-US. CONCLUSIONS: Collectively, these data strongly suggest that the combination of pralatrexate and romidepsin merits clinical study in patients with TCLs.