Natural killer (NK) cells are primary defenders against cancer precursors, but cancer cells can persist by evading immune surveillance. To investigate the genetic mechanisms underlying this evasion, we perform a genome-wide CRISPR screen using B lymphoblastoid cells. SPPL3, a peptidase that cleaves glycosyltransferases in the Golgi, emerges as a top hit facilitating evasion from NK cytotoxicity. SPPL3-deleted cells accumulate glycosyltransferases and complex N-glycans, disrupting not only binding of ligands to NK receptors but also binding of rituximab, a CD20 antibody approved for treating B cell cancers. Notably, inhibiting N-glycan maturation restores receptor binding and sensitivity to NK cells. A secondary CRISPR screen in SPPL3-deficient cells identifies B3GNT2, a transferase-mediating poly-LacNAc extension, as crucial for resistance. Mass spectrometry confirms enrichment of N-glycans bearing poly-LacNAc upon SPPL3 loss. Collectively, our study shows the essential role of SPPL3 and poly-LacNAc in cancer immune evasion, suggesting a promising target for cancer treatment.
Published by Elsevier Inc.

Advanced-stage cutaneous T-cell lymphoma (CTCL) is usually a fatal malignancy despite optimal use of currently available treatments. In this preclinical study of novel CTCL therapy, we performed in vitro and ex vivo experiments to determine the efficacy of combination treatment with a panel of BET bromodomain inhibitors (BETi) (JQ1, OTX015, CPI-0610, I-BET762) and HDAC inhibitors (HDACi) (SAHA/Vorinostat, Romidepsin). BETi/HDACi combinations were synergistic (combination index <1) against cell viability and induced G0/G1 cell cycle arrest. Apoptosis was uniformly enhanced. From a mechanistic standpoint, proliferative drivers c-Myc, Cyclin D1, NFkB, and IL-15Rα were reduced. Inhibitory CDKN1A was increased. CDKN1B, IL-7R, IL-17Rα, STAT3, and STAT5 alterations varied. There were significant increases in extrinsic apoptotic pathway death receptors and ligands (FasL, DR4, DR5, TRAIL, and TNFR1). At clinically tolerable levels of single agents, Romidepsin (1 nM) + OTX015 (125 nM) induced the greatest apoptosis (60%_80%) at 96 hours. Ex vivo studies of leukemic CTCL cells obtained from patients with Sezary syndrome also showed higher levels of apoptosis (about 60%-90%) in response to combination treatments relative to single agents. In contrast, combination treatment of normal CD4+ T cells induced only minimal apoptosis (<10%). Our findings show that the mechanism of action of BETi/HDACi therapy in CTCL involves induction of both cell cycle arrest and apoptosis with reduced proliferative drivers and enhanced expression of apoptotic extrinsic pathway death receptors and ligands. Relative to single agents, the superior anti-CTCL effects of BETi/HDACi combinations in vitro and ex vivo provide a rationale for clinical trials exploring their efficacy as therapy for CTCL.
Published by Elsevier Inc.

To characterize peripheral blood natural killer (NK) cells phenotypes by flow cytometry as potential biomarker of liver fibrosis in human immunodeficiency virus (HIV)/hepatitis C virus (HCV) coinfected patients.
Peripheral mononuclear cells from 24 HIV/HCV (HBV negative) coinfected and 5 HIV/HCV/HBV seronegative individuals were evaluated. HIV/HCV coinfected patients were divided in to groups: G1, patients with METAVIR F0-F2 and G2, patients with METAVIR F3-F4. NK surface cell staining was performed with: Anti-CD3(APC/Cy7), anti-CD56(PE/Cy5), anti-CD57(APC), anti-CD25(PE), anti-CD69(FITC), anti-NKp30(PE), anti-NKp46(PE/Cy7), anti-NKG2D(APC), anti-DNAM(FITC); anti-CD62L (PE/Cy7), anti-CCR7(PE), anti-TRAIL(PE), anti-FasL(PE), anti CD94(FITC). Flow cytometry data acquisition was performed on BD FACSCanto, analyzed using FlowJo software. Frequency of fluorescence was analyzed for all single markers. Clinical records were reviewed, and epidemiological and clinical data were obtained.
Samples from 11 patients were included in G1 and from 13 in G2. All patients were on ARV, with undetectable HIV viral load. Liver fibrosis was evaluated by transient elastography in 90% of the patients and with biopsy in 10% of the patients. Mean HCV viral load was (6.18 ± 0.7 log10). Even though, no major significant differences were observed between G1 and G2 regarding NK surface markers, it was found that patients with higher liver fibrosis presented statistically lower percentage of NK cells than individual with low to mild fibrosis and healthy controls (G2: 5.4% ± 2.3%, G1: 12.6% ± 8.2%, P = 0.002 and healthy controls 12.2% ± 2.7%, P = 0.008). It was also found that individuals with higher liver fibrosis presented lower CD4 LT count than those from G1 (G2: 521 ± 312 cells/μL, G1: 770 ± 205 cells/μL; P = 0.035).
Higher levels of liver fibrosis were associated with lower percentage of NK cells and LTCD4+ count; and they may serve as noninvasive biomarkers of liver damage.

Extracellular vesicles (EVs) are lipid membrane-enclosed nanoparticles released by cells. They mediate intercellular communication by transferring biological molecules and therefore have potential as innovative drug delivery vehicles. TNF-related apoptosis-inducing ligand (TRAIL) selectively induces apoptosis of cancer cells. Unfortunately, the clinical application of recombinant rTRAIL has been hampered by its low bioavailability and resistance of cancer cells. EV-mediated TRAIL delivery may circumvent these problems. Mesenchymal stromal cells (MSCs) produce EVs and could be a good source for therapeutic EV production. We investigated if TRAIL could be expressed in MSC-derived EVs and examined their cancer cell-killing efficacy. EVs were isolated by ultracentrifugation and were membranous particles of 50-70 nm in diameter. Both MSC- and TRAIL-expressing MSC (MSCT)-derived EVs express CD63, CD9 and CD81, but only MSCT-EVs express surface TRAIL. MSCT-EVs induced apoptosis in 11 cancer cell lines in a dose-dependent manner but showed no cytotoxicity in primary human bronchial epithelial cells. Caspase activity inhibition or TRAIL neutralisation blocked the cytotoxicity of TRAIL-positive EVs. MSCT-EVs induced pronounced apoptosis in TRAIL-resistant cancer cells and this effect could be further enhanced using a CDK9 inhibitor. These data indicate that TRAIL delivery by MSC-derived EVs is an effective anticancer therapy.