Argarose gel electrophoresis may be employed effectively for the detection and preliminary characterization of plasmid deoxyribonucleic acid (DNA) present in clinical isolates and laboratory strains of gram-negative microorganisms. The method is sensitive and does not require radioisotopes or ultracentrifugation. The estimation of plasmid mass from the extent of DNA migration in gels compares favorably with results obtained by electron microscopy of plasmid DNA purified by equilibrium density centrifugation. The method has proved to be a useful tool for survey work and the epidemiological investigation of plasmid dissemination, as well as an important adjunct to the genetic analysis of plasmids.

ImportanceCutaneous disease in dermatomyositis has no standardized treatment approach and so presents a challenging task for patients and clinicians.ObjectiveTo study the efficacy and safety of apremilast as an add-on therapy in patients with recalcitrant cutaneous dermatomyositis.Design, Setting, and ParticipantsThis phase 2a, open-label, single-arm nonrandomized controlled trial was conducted at a single center from June 2018 to June 2021. Participants were 8 patients with recalcitrant cutaneous dermatomyositis, defined by a cutaneous disease activity severity index (CDASI) score greater than 5 despite treatment with steroids, steroid-sparing agents, or both. Data were analyzed from June 2018 to June 2021.InterventionsApremilast 30 mg orally twice daily was added to ongoing treatment regimens.Main Outcomes and MeasuresThe primary outcome was the overall response rate (ORR) at 3 months. Key secondary outcomes were the safety and toxicity of apremilast and the durability of response at 6 months. The CDASI, muscle score, dermatology life quality index (DLQI), and depression assessments were performed at baseline and regularly until month 7. Skin biopsies were performed at baseline and 3 months after apremilast (defined as 3 months into active apremilast therapy) and tested for gene expression profiling and immunohistochemical stains. Adverse events were assessed using the Common Terminology Criteria for Adverse Events version 5.0.ResultsAmong 8 patients with recalcitrant cutaneous dermatomyositis (all women; mean [SD] age, 54 [15.9] years), a response was found at 3 months after apremilast among 7 patients (ORR, 87.5%). The mean (SD) decrease in CDASI was 12.9 (6.3) points at 3 months (P < .001). Apremilast was well tolerated, with no grade 3 or higher adverse events. Sequencing of RNA was performed on skin biopsies taken from 7 patients at baseline and at 3 months after therapy. Appropriate negative (ie, no primary antibody) and positive (ie, tonsil and spleen) controls were stained in parallel with each set of slides studied. Of 39 076 expressed genes, there were 195 whose expression changed 2-fold or more at P < .01 (123 downregulated and 72 upregulated genes). Gene set enrichment analysis identified 13 pathways in which apremilast was associated with downregulated expression, notably signal transducers and activators of transcription 1 (STAT1), STAT3, interleukin 4 (IL-4), IL-6, IL-12, IL-23, interferon γ (IFNγ), and tumor necrosis factor α (TNFα) pathways. In immunohistochemical staining, there was a mean (SD) decrease in phosphorylation levels STAT1 (22.3% [28.3%] positive cells) and STAT3 (13.4% [11.6%] positive cells) at the protein level, a downstream signaling pathway for the downregulated cytokines.Conclusions and RelevanceThese findings suggest that apremilast was a safe and efficacious add-on treatment in recalcitrant dermatomyositis, with an overall response rate of 87.5% and associations with downregulation of multiple inflammatory pathways.Trial RegistrationClinicalTrials.gov Identifier: NCT03529955

Long interspersed element ‐1 (LINE‐1) is a mobile element, or jumping gene, which employs a “copy and paste” method called retrotransposition to insert itself into the human genome. This retrotransposition mechanism utilizes an enzyme called the L1 endonuclease to initiate the double strand breaks necessary for LINE‐1 insertion. Studies have found that a significant portion of the human genome is composed of mobile elements, which have likely played a crucial evolutionary role in the current genetic variability observed in humans. However, in some instances the mutations that have arisen from increased LINE‐1 retrotransposition, have been linked to genetic diseases such as colon cancer, breast cancer, and have been linked to genome instability due to increased double strand breaks. Previous research suggests that heavy metals such as Ni2+, Co2+, and Cd2+, which occur in our industrialized environment as pollutants, potentially affect levels of LINE‐1 retrotransposition. These toxic metals have been observed to compete with Mg2+ as cofactors for proteins, and have been observed to inhibit essential reactions in DNA repair. Competition with Mg as a cofactor suggests these heavy metals likely have an effect on levels of LINE‐1 endonuclease activity in vitro since it also utilizes Mg2+ as a cofactor for enzymatic activity. We focused on the effects that the heavy metals cobalt and cadmium have on the LINE‐1 endonuclease activity to determine whether or not these metals also influence levels of double strand breaks in vitro. Preliminary results indicate that the metal cobalt does not prevent LINE‐1 endonuclease activity at doses up to 100uM.Support or Funding InformationThis work was funded by an Institutional Development Award (IDeA) from the NIGMS under grant number P20GM103424 and from the Louisiana Cancer Research Consortium, the NIH‐RCMI grant #8G12MD007595‐05.

Despite a central role for B-cell receptor precursor (pre-BCR) pathway in precursor B-cell acute lymphoblastic leukemia (B-ALL), there is limited available data on therapies that aim to disrupt this pathway. Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is a para-caspase required for BCR-mediated NF-κB activation. We recently showed that targeting MALT1 with the small molecule inhibitor MI2 is effective in CLL, including drug-resistant clones (Saba Can Res 2017). We sought to examine the role of MALT1 in B-ALL and determine the biological consequences of inhibiting its activity. First, we tested MALT1 expression by immunoblot in B-ALL using 17 cell lines representing the disease spectrum (7 pro-B: REH, SEMK2, TOM1, RS4;11, NALM21, Z119, BV173; 8 pre-B: HB11;19, NALM6, RCH-ACV, SMS-SB, 697, KASUMI2, KOPN8, HPB-NULL; and 2 mature/Burkitt: 2F7, RAJI), and found that MALT1 was expressed in all cell lines at different levels. To determine sensitivity to MALT1 inhibition we used two molecules: Z-VRPR-fmk, a highly selective MALT1 blocking peptide, and MI2, a small molecule MALT1 inhibitor. Z-VRPR-fmk resulted in a dramatic cell growth inhibition in most of our B-ALL cell lines, with appropriate positive (TMD8) and negative (K562) controls, independent of the cell-of-origin (pro, pre, mature) or the presence of the Philadelphia chromosome. We did not observe a clear correlation between MALT1 level and degree of sensitivity to Z-VRPR-fmk. Interestingly, the two ibrutinib-resistant cell lines RS4;11 and 697, were amongst the top sensitive cell lines to MALT1 inhibition. A similar pattern of cell sensitivity was observed when these cell lines were treated with MI2, resulting in an IC50 at 48h of 0.2 µM in RS4;11 and < 0.5 µM in other sensitive cell lines, which is consistent with published data in sensitive DLBCL cell lines (IC50, 0.2-0.5 µM), and our data on the CLL cell line MEC1 (IC50, 0.2 µM). We then tested freshly collected PBMCs from patients with various blood cancers presenting with a leukemic phase against serial dilutions of MI2 for 48h (7 B-ALL, 24 CLL, and 4 CML). In addition, we included normal B-cells collected from five volunteers. Interestingly, B-ALL samples showed the highest sensitivity to MI2, followed by CLL, while the rest were resistant. The proteolytic activity of MALT1 can be studied by measuring its ability to cleave its targets such as A20, CYLD, BCL10, Roquin, Regnase and RelB. Surprisingly, with the exception of the Burkitt cell line 2F7, we did not detect cleavage of these targets at baseline, nor after proteasomal inhibition with MG-132 or following crosslinking of pre-BCR with anti-IgM in pre-B ALL, the latter successfully increased AKT phosphorylation. The constitutive activation of MALT1 in 2F7 was effectively inhibited by Z-VRPR-fmk as determined by a marked reduction in targets cleavage concomitant with an increase in full length proteins. We are expanding the mature B-ALL cell line cohort to include TANOUE, BALL-1, DAUDI, GA-10, and NC-37 cell lines to further explore to role of MALT1 in this disease subset. Collectively, these data highly suggest distinct roles for MALT1 in B-ALL: pro and pre-B-ALL vs. mature B-ALL. To explore the possibility of distinct role for MALT1 in B-ALL, arguably independent of BTK and of signaling through BCR, we used RNA sequencing to determine the changes in gene expression profiling following a 24h treatment with Z-VRPR-fmk in 3 highly sensitive B-ALL cell lines (RS4;11, HPB-NULL, and 697). Out of 39,514 tested genes, there were 160 genes whose expression changed ≥ 2-fold at P < 0.05 (84 down- and 76 up-regulated). Gene Set Enrichment Analysis (GSEA) identified 34 Hallmark and Oncogenic Signatures gene sets relevant to B-ALL that were all downregulated by Z-VRPR-fmk (FDR < 10%, and normalized enrichment score (NES) ≥ 1.50). Among those gene sets, mTOR-S6K and TANK-binding kinase 1 (TBK1)-dependent gene signatures stood out as the most affected. MALT1 was shown to be involved in the ribosomal protein S6 phosphorylation through activation of mTOR/AKT signaling. Indeed, treatment with MI2 and Z-VRPR resulted in a significant decrease in S6 phosphorylation in RS4;11 and SEMK2. In conclusion, MALT1 plays a critical role in B-ALL survival likely through a novel mechanism that involves mTOR-S6K pathway, independently from pre-BCR/BCR signaling. Supported by a grant from the Ladies Leukemia League, Inc., of the Gulf South Region. Disclosures Saba: Kyowa Kirin: Consultancy; AbbVie: Consultancy; Janssen: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Speakers Bureau. Melnick:Epizyme: Consultancy; Janssen: Research Funding; Constellation: Consultancy. Wiestner:Merck: Research Funding; Nurix: Research Funding; Pharmayclics: Research Funding; Acerta: Research Funding. Burger:AstraZeneca: Honoraria; Aptose Biosciences, Inc: Research Funding; Gilead Sciences: Research Funding; Janssen Pharmaceuticals: Consultancy, Honoraria; Pharmacyclics, an AbbVie company: Research Funding; BeiGene: Research Funding. Safah:Celgene: Speakers Bureau; Incyte: Speakers Bureau; Verastem: Honoraria, Speakers Bureau; Jazz: Speakers Bureau; Amgen: Honoraria, Speakers Bureau.