Non-invasive transcriptomic analysis using mRNAs in skin surface lipids obtained from children with mild-to-moderate atopic dermatitis.

BACKGROUND: Specimens for analysing the molecular pathology of skin disease are generally obtained through invasive methods, such as biopsy. However, less burdensome methods are desirable for paediatric patients. We recently established a method that comprehensively analyses RNA present in sebum (skin surface lipid-RNAs: SSL-RNAs) using a next-generation sequencer. Using this method, biological information can be obtained from the skin in a completely non-invasive manner. OBJECTIVES: To verify the applicability of the SSL-RNA method for analysis of paediatric skin and analyse the molecular pathology of mild-to-moderate atopic dermatitis (AD) in children. METHODS: We collected sebum specimens from the whole faces of 23 healthy children and 16 children with mild-to-moderate AD (eczema area and severity index (EASI) score: 5.9 ± 2.6) ranging in age from 6 months to 5 years, using an oil-blotting film. We then extracted SSL-RNAs from the samples and performed an AmpliSeq transcriptomic analysis. RESULTS: The expressions of genes related to keratinization (LCE, PSORS1C2, IVL and KRT17), triglyceride synthesis and storage (PLIN2, DGAT2 and CIDEA), wax synthesis (FAR2), ceramide synthesis (GBA2, SMPD3 and SPTLC3), antimicrobial peptides (DEFB1) and intercellular adhesion (CDSN), all of which are related to the skin barrier, are lower in children with AD than in healthy children. The children with AD also have higher expression of CCL17, a Th2-cytokine and an increased Th2-immune response as demonstrated by a gene set variation analysis. Moreover, KRT17 and CCL17 expression levels are significantly correlated with the EASI score. CONCLUSIONS: Molecular changes associated with abnormal immune responses and the epidermal barrier in children with mild-to-moderate AD can be determined using the SSL-RNA method. This non-invasive method could therefore be a useful means for understanding the molecular pathology of paediatric AD.

Management of bone metastasis and cancer treatment-induced bone loss during the COVID-19 pandemic: An international perspective and recommendations.

Optimum management of patients with cancer during the COVID-19 pandemic has proved extremely challenging. Patients, clinicians and hospital authorities have had to balance the risks to patients of attending hospital, many of whom are especially vulnerable, with the risks of delaying or modifying cancer treatment. Those whose care has been significantly impacted include patients suffering from the effects of cancer on bone, where delivering the usual standard of care for bone support has often not been possible and clinicians have been forced to seek alternative options for adequate management. At a virtual meeting of the Cancer and Bone Society in July 2020, an expert group shared experiences and solutions to this challenge, following which a questionnaire was sent internationally to the symposium's participants, to explore the issues faced and solutions offered. 70 respondents, from 9 countries (majority USA, 39%, followed by UK, 19%) included 50 clinicians, spread across a diverse range of specialties (but with a high proportion, 64%, of medical oncologists) and 20 who classified themselves as non-clinical (solely lab-based). Spread of clinician specialty across tumour types was breast (65%), prostate (27%), followed by renal, myeloma and melanoma. Analysis showed that management of metastatic bone disease in all solid tumour types and myeloma, adjuvant bisphosphonate breast cancer therapy and cancer treatment induced bone loss, was substantially impacted. Respondents reported delays to routine CT scans (58%), standard bone scans (48%) and MRI scans (46%), though emergency scans were less affected. Delays in palliative radiotherapy for bone pain were reported by 31% of respondents with treatments often involving only a single dose without fractionation. Delays to, or cancellation of, prophylactic surgery for bone pain were reported by 35% of respondents. Access to treatments with intravenous bisphosphonates and subcutaneous denosumab was a major problem, mitigated by provision of drug administration at home or in a local clinic, reduced frequency of administration or switching to oral bisphosphonates taken at home. The questionnaire also revealed damaging delays or complete stopping of both clinical and laboratory research. In addition to an analysis of the questionnaire, this paper presents a rationale and recommendations for adaptation of the normal guidelines for protection of bone health during the pandemic.

L-ascorbic acid: A true substrate for HIF prolyl hydroxylase?

L-Ascorbate (L-Asc), but not D-isoascorbate (D-Asc) and N-acetylcysteine (NAC) suppress HIF1 ODD-luc reporter activation induced by various inhibitors of HIF prolyl hydroxylase (PHD). The efficiency of suppression by L-Asc was sensitive to the nature of HIF PHD inhibitor chosen for reporter activation. In particular, the inhibitors developed to compete with alpha-ketoglutarate (αKG), were less sensitive to suppression by the physiological range of L-Asc (40-100 µM) than those having a strong iron chelation motif. Challenging those HIF activators in the reporter system with D-Asc demonstrated that the D-isomer, despite exhibiting the same reducing potency with respect to ferric iron, had almost no effect compared to L-Asc. Similarly, no effect on reporter activation was observed with cell-permeable reducing agent NAC up to 1 mM. Docking of L-Asc and D-Asc acid into the HIF PHD2 crystal structure showed interference of Tyr310 with respect to D-Asc. This suggests that L-Asc is not merely a reducing agent preventing enzyme inactivation. Rather, the overall results identify L-Asc as a co-substrate of HIF PHD that may compete for the binding site of αKG in the enzyme active center. This conclusion is in agreement with the results obtained recently in cell-based systems for TET enzymes and jumonji histone demethylases, where L-Asc has been proposed to act as a co-substrate and not as a reducing agent preventing enzyme inactivation.

TGFß1 synergizes with FLT3 ligand to induce chemoresistant quiescence in acute lymphoblastic leukemia with MLL gene rearrangements.

Fms-like tyrosine kinase 3 (FLT3) is highly expressed in mixed-lineage leukemia (MLL) gene-rearranged acute lymphoblastic leukemia (MLL+ALL) with a dismal prognosis. We previously reported that FLT3 ligand (FL) stimulation induced cell cycle arrest in MLL+ALL cells leading to resistance against anti-leukemic agents. Given that FL stimulation enhanced transforming growth factor (TGF)ß1 mRNA levels in MLL+ALL cells, we extensively examined the effect of TGFß1 on the cell cycle progression and chemosensitivity in MLL+ALL cells, and found that TGFß1 stimulation induced MLL+ALL cells into cell cycle arrest resistant to arabinosyl cytosine; its effect was markedly enhanced in synergy with FL. Thus, it is likely that TGFß1 and FL, both abundantly produced by bone marrow stromal cells, function in a coordinated manner to render MLL+ALL cells chemoresistant, which should lead to the development of minimal residual disease (MRD) resulting in relapse. The use of inhibitors against FLT3 and TGFß1 may become a useful strategy for eradicating MRD in MLL+ALL.

Investigation of SO3 absorption line for in situ gas detection inside combustion plants using a 4-µm-band laser source.

We have investigated 4-µm-band SO3 absorption lines for in situSO3 detection using a mid-infrared laser source based on difference frequency generation in a quasi-phase-matched LiNbO3 waveguide. In the wavelength range of 4.09400-4.10600 µm, there were strong SO3 absorption lines. The maximum absorption coefficient at a concentration of 170 ppmv was estimated to be about 3.2×10-5 cm-1 at a gas temperature of 190°C. In coexistence with H2O, the reduction of the SO3 absorption peak height was observed, which was caused by sulfuric acid formation. We discuss a method of using an SO3 equilibrium curve to derive the total SO3 molecule concentration.

Tofacitinib, an oral Janus kinase inhibitor, for the treatment of chronic plaque psoriasis: results from two randomized, placebo-controlled, phase III trials.

BACKGROUND: Tofacitinib is an oral Janus kinase inhibitor being investigated for psoriasis. OBJECTIVES: To determine the 16-week efficacy and safety of two oral tofacitinib doses vs. placebo in patients with moderate-to-severe chronic plaque psoriasis. METHODS: Patients in two similarly designed phase III studies (OPT Pivotal 1, NCT01276639, n = 901; OPT Pivotal 2, NCT01309737, n = 960) were initially randomized 2 : 2 : 1 to tofacitinib 10 or 5 mg or placebo, twice daily. Coprimary efficacy end points (week 16) included the proportion of patients achieving Physician's Global Assessment (PGA) of 'clear' or 'almost clear' (PGA response) and the proportion achieving ≥ 75% reduction in Psoriasis Area and Severity Index (PASI 75). RESULTS: Across OPT Pivotal 1 and OPT Pivotal 2, 745 patients received tofacitinib 5 mg, 741 received tofacitinib 10 mg and 373 received placebo. At week 16, a greater proportion of patients achieved PGA responses with tofacitinib 5 and 10 mg twice daily vs. placebo (OPT Pivotal 1, 41·9% and 59·2% vs. 9·0%; OPT Pivotal 2, 46·0% and 59·1% vs. 10·9%; all P < 0·001). Higher PASI 75 rates were observed with tofacitinib vs. placebo (OPT Pivotal 1, 39·9%, 59·2% and 6·2%, respectively, for tofacitinib 5 and 10 mg twice daily and placebo; OPT Pivotal 2, 46·0%, 59·6% and 11·4%; all P < 0·001 vs. placebo). Adverse event (AE) rates appeared generally similar across groups; rates of serious AEs, infections, malignancies and discontinuations due to AEs were low. Twelve patients reported herpes zoster across the tofacitinib treatment groups in both studies vs. none in the respective placebo groups. The most common AE across groups was nasopharyngitis. CONCLUSIONS: Oral tofacitinib demonstrated significant efficacy vs. placebo during the initial 16 weeks of treatment in patients with moderate-to-severe psoriasis. Safety findings were consistent with prior studies.

Leptin improves fatty liver independently of insulin sensitization and appetite suppression in hepatocyte-specific Pten-deficient mice with insulin hypersensitivity.

Nonalcoholic fatty liver disease (NAFLD) is recognized as the hepatic component of the metabolic syndrome. Although NAFLD is a major cause of cirrhosis and cancer of the liver of unknown cause, no established pharmacological treatment for NAFLD has been established yet. It has been reported that leptin treatment improved fatty liver dramatically as well as insulin resistance and hyperphagia in patients with lipodystrophy. However, it is unclear whether leptin improves fatty liver independently of these metabolic improvements. We investigated the liver effect of leptin independently of insulin sensitization and appetite suppression using hepatocyte-specific Pten-deficient (AlbCrePtenff) mouse, a model of severe fatty liver with insulin hypersensitivity. Male AlbCrePtenff mice were infused subcutaneously with leptin (20 ng/g/h) for 2 weeks using osmotic minipumps. Leptin infusion effectively reduced liver weight, liver triglyceride content, and glutamate pyruvate transaminase (GPT) concentrations as well as food intake and body weight without the change of plasma insulin concentration in AlbCrePtenff mice. Pair-feeding also reduced body weight but not liver triglyceride content. Pair feeding reduced α1 and α2 AMP-activated protein kinase (AMPK) activities and PGC1α gene expression in the liver, while leptin infusion unchanged them. The present study clearly demonstrated that leptin improve fatty liver independently of insulin sensitization and suppression of food intake. It was suggested that leptin improves fatty liver by stimulation of ß-oxidation in the liver. The present study might provide a further understanding on the mechanism of metabolic effect of leptin.

Pim-2 kinase is an important target of treatment for tumor progression and bone loss in myeloma.

Pim-2 kinase is overexpressed in multiple myeloma (MM) cells to enhance their growth and survival, and regarded as a novel therapeutic target in MM. However, the impact of Pim-2 inhibition on bone disease in MM remains unknown. We demonstrated here that Pim-2 expression was also upregulated in bone marrow stromal cells and MC3T3-E1 preosteoblastic cells in the presence of cytokines known as the inhibitors of osteoblastogenesis in MM, including interleukin-3 (IL-3), IL-7, tumor necrosis factor-α, transforming growth factor-ß (TGF-ß) and activin A, as well as MM cell conditioned media. The enforced expression of Pim-2 abrogated in vitro osteoblastogenesis by BMP-2, which suggested Pim-2 as a negative regulator for osteoblastogenesis. Treatment with Pim-2 short-interference RNA as well as the Pim inhibitor SMI-16a successfully restored osteoblastogenesis suppressed by all the above inhibitory factors and MM cells. The SMI-16a treatment potentiated BMP-2-mediated anabolic signaling while suppressing TGF-ß signaling. Furthermore, treatment with the newly synthesized thiazolidine-2,4-dione congener, 12a-OH, as well as its prototypic SMI-16a effectively prevented bone destruction while suppressing MM tumor growth in MM animal models. Thus, Pim-2 may have a pivotal role in tumor progression and bone loss in MM, and Pim-2 inhibition may become an important therapeutic strategy to target the MM cell-bone marrow interaction.

Survivin modulates genes with divergent molecular functions and regulates proliferation of hematopoietic stem cells through Evi-1.

The inhibitor of apoptosis protein Survivin regulates hematopoiesis, although its mechanisms of regulation of hematopoietic stem cells (HSCs) remain largely unknown. While investigating conditional Survivin deletion in mice, we found that Survivin was highly expressed in phenotypically defined HSCs, and Survivin deletion in mice resulted in significantly reduced total marrow HSCs and hematopoietic progenitor cells. Transcriptional analysis of Survivin(-/-) HSCs revealed altered expression of multiple genes not previously linked to Survivin activity. In particular, Survivin deletion significantly reduced expression of the Evi-1 transcription factor indispensable for HSC function, and the downstream Evi-1 target genes Gata2, Pbx1 and Sall2. The loss of HSCs following Survivin deletion and impaired long-term HSC repopulating function could be partially rescued by ectopic Evi-1 expression in Survivin -/- HSCs. These data demonstrate that Survivin partially regulates HSC function by modulating the Evi-1 transcription factor and its downstream targets and identify new genetic pathways in HSCs regulated by Survivin.

Susceptibility quantitative trait loci for pathogenic leucocytosis in SCG/Kj mice, a spontaneously occurring crescentic glomerulonephritis and vasculitis model.

The spontaneous crescentic glomerulonephritis-forming/Kinjoh (SCG/Kj) mouse, a model of human crescentic glomerulonephritis (CrGN) and systemic vasculitis, is characterized by the production of myeloperoxidase-specific anti-neutrophil cytoplasmic autoantibody (MPO-ANCA) and marked leucocytosis. This study was performed to identify the specific populations of leucocytes associated with CrGN and susceptibility loci for pathogenic leucocytosis. Four hundred and twenty female (C57BL/6 × SCG/Kj) F2 intercross mice were subjected to serial flow cytometry examination of the peripheral blood (PB). Kidney granulocytes and monocytes were examined histopathologically. Linkage analyses were performed with 109 polymorphic microsatellite markers. Correlation studies revealed that increase of the granulocytes, F4/80(+) cells, CD3(+) CD4(-) CD8(-) T cells and dendritic cells (DCs) in peripheral blood (PB) were associated significantly with glomerulonephritis, crescent formation and vasculitis. In kidney sections, F4/80(low) cells were observed in crescent, while F4/80(high) cells were around the Bowman's capsules and in the interstitium. Numbers of F4/80(+) cells in crescents correlated significantly with F4/80(+) cell numbers in PB, but not with numbers of F4/80(+) cells in the interstitium. Genome-wide quantitative trait locus (QTL) mapping revealed three SCG/Kj-derived non-Fas QTLs for leucocytosis, two on chromosome 1 and one on chromosome 17. QTLs on chromosome 1 affected DCs, granulocytes and F4/80(+) cells, but QTL on chromosome 17 affected DCs and granulocytes. We found CrGN-associated leucocytes and susceptibility QTLs with their positional candidate genes. F4/80(+) cells in crescents are considered as recruited inflammatory macrophages. The results provide information for leucocytes to be targeted and genetic elements in CrGN and vasculitis.

Statins inhibit tumor progression via an enhancer of zeste homolog 2-mediated epigenetic alteration in colorectal cancer.

While statin intake has been proven to reduce the risk of colorectal cancer (CRC), the mechanism of antitumor effects and clinical significance in survival benefits remain unclear. Statin-induced antiproliferative effects and its underlying mechanism were examined using six CRC cell lines. Statins except pravastatin showed antiproliferative effects (simvastatin ≥ fluvastatin > atorvastatin) even though both of simvastatin and pravastatin could activate mevalonate pathways, suggesting the statin-mediated antiproliferative effects depended on non-mevalonate pathway. Indeed, statin induced p27(KIP1) expression by downregulation of histone methyltransferase enhancer of zeste homolog 2 (EZH2), which acts as an epigenetic gene silencer. Additionally, the use of simvastatin plus classII histone deacetylase (HDAC) inhibitor (MC1568) induced further overexpression of p27(KIP1) by inhibiting HDAC5 induction originated from downregulated EZH2 in CRC cells and synergistically led to considerable antiproliferative effects. In the clinical setting, Statin intake (except pravastatin) displayed the downregulated EZH2 expression and inversely upregulated p27(KIP1) expression in the resected CRC by immunohistochemical staining and resulted in the significantly better prognoses both in overall survival (p = 0.02) and disease free survival (p < 0.01) compared to patients without statin intake. Statins may inhibit tumor progression via an EZH2-mediated epigenetic alteration, which results in survival benefits after resected CRC. Furthermore, statin plus classII HDAC inhibitor could be a novel anticancer therapy by their synergistic effects in CRC.

Particle therapy using carbon ions or protons as a definitive therapy for patients with primary sacral chordoma.

OBJECTIVE: This study retrospectively evaluated the efficacy and toxicity of particle therapy using carbon ions or protons for primary sacral chordomas. METHODS: We evaluated 23 patients with primary sacral chordoma treated with carbon ion therapy (CIT) or proton therapy (PT) between July 2005 and June 2011 at the Hyogo Ion Beam Medical Center, Hyogo, Japan. The median patient age was 72 years. 14 patients were treated with 70.4 Gy equivalents (GyE) in 16 fractions and 9 were treated with 70.4 GyE in 32 fractions. CIT was used for 16 patients, and PT was used for 7 patients. RESULTS: The median follow-up period was 38 months. At 3 years, local control (LC), overall survival (OS) and progression-free survival (PFS) for all patients were 94%, 83% and 68%, respectively. The log-rank test revealed that male sex was significantly related to better PFS (p=0.029). No other factors, including dose fractionation and ion type, were significant for LC, OS or PFS. In nine patients, ≥ Grade 3 acute dermatitis was observed, and ≥ Grade 3 late toxicities were observed in nine patients. The 32-fraction protocol reduced severe toxicities in both the acute and late phases compared with the 16-fraction protocol. CONCLUSION: Particle therapy for patients with sacral chordoma showed favourable LC and OS. Severe toxicities were successfully reduced by modifying the dose fractionation and treatment planning in the later treatment era. Thus, this therapeutic modality should be considered useful and safe. ADVANCES IN KNOWLEDGE: This is the first study including both CIT and PT for sacral chordomas.

Phytohemagglutinin-induced IL2 mRNA in whole blood can predict bortezomib-induced peripheral neuropathy for multiple myeloma patients.

The proteasome inhibitor bortezomib has revolutionized the treatment of multiple myeloma. However, bortezomib-induced peripheral neuropathy (BiPN) is a serious complication that compromises clinical outcome. If patients with a risk of developing BiPN could be predicted, physicians might prefer weekly, reduced-dose, or subcutaneous approaches. To seek biomarkers for BiPN, we conducted a multicenter prospective study using a simple and unique system. Multiple myeloma patients received twice-weekly or weekly 1.3 mg/m(2) bortezomib intravenously, and a 2-ml sample of whole blood was obtained before treatment and 2-3 days and 1-3 weeks after the first dose. Induction of gene expression was then quantified by real-time PCR. Of a total of 64 enrolled patients, 53 patient samples qualified for mRNA analysis. The BiPN grade was associated with phytohemagglutinin-induced IL2, IFNG and TNFSF2, as well as with lipopolysaccharide-induced IL6 levels. More importantly, of the 19 patients showing a 3-fold increase in phytohemagglutinin-induced IL2, 14 did not suffer from BiPN (73.7% prediction), whereas of the 34 patients with a <3-fold increase, 23 experienced BiPN (67.6% prediction). Therefore, we concluded that pretreatment of phytohemagglutinin-induced IL2 mRNA levels in whole blood serve as a promising biomarker for predicting BiPN, and this finding warrants validation in a larger study.

Histopathological and immunohistochemical evaluation of malignant potential in canine aortic body tumours.

In order to verify the malignant potential of aortic body tumours (ABTs) in dogs, 13 cases of canine ABT were studied histopathologically and immunohistochemically. The cases were divided into two groups according to the presence or absence of metastases to other organs at necropsy examination (metastasis group [n = 9] and non-metastasis group [n = 4]). The mean tumour weight:body weight ratio (TW:BW; g/kg) in the metastasis group (9.3 ± 6.7) was significantly higher than that in the non-metastasis group (1.5 ± 1.7) (P <0.05). In both groups, the neoplastic cells had malignant features including pleomorphism, anisocytosis and anisokaryosis, and mononuclear giant cells were present, showing invasion through the capsule and into the vascular lumen and other adjacent tissues. The mitotic index (MI), mean nuclear area (NA) for size value and coefficient of variation of the nuclear area (CVNA) for anisonucleosis did not differ significantly between the two groups. These findings show that anaplastic characteristics are present regardless of the tumour size or the presence or absence of metastases, suggesting that these tumours are generally malignant or potentially malignant. Immunohistochemical analysis using neuroendocrine markers including neuron-specific enolase, chromogranin A and S100 revealed no obvious differences in labelling intensity of neoplastic cells related to the presence or absence of metastases or associated with the mean TW:BW, MI, NA or CVNA value, indicating that immunohistochemistry has no practical value for determining the tumour grade of canine ABTs.

A whole-genome association study of major determinants for allopurinol-related Stevens-Johnson syndrome and toxic epidermal necrolysis in Japanese patients.

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are severe, cutaneous adverse drug reactions that are rare but life threatening. Genetic biomarkers for allopurinol-related SJS/TEN in Japanese were examined in a genome-wide association study in which Japanese patients (n=14) were compared with ethnically matched healthy controls (n=991). Associations between 890 321 single nucleotide polymorphisms and allopurinol-related SJS/TEN were analyzed by the Fisher's exact test (dominant genotype mode). A total of 21 polymorphisms on chromosome 6 were significantly associated with allopurinol-related SJS/TEN. The strongest association was found at rs2734583 in BAT1, rs3094011 in HCP5 and GA005234 in MICC (P=2.44 × 10(-8); odds ratio=66.8; 95% confidence interval, 19.8-225.0). rs9263726 in PSORS1C1, also significantly associated with allopurinol-related SJS/TEN, is in absolute linkage disequilibrium with human leukocyte antigen-B*5801, which is in strong association with allopurinol-induced SJS/TEN. The ease of typing rs9263726 makes it a useful biomarker for allopurinol-related SJS/TEN in Japanese.

Human papillomavirus type 56-associated Bowen disease.

BACKGROUND: Some cases of human papillomavirus (HPV) type 56 infection in Bowen disease have been reported. However, the incidence and clinical characteristics are still unclear. OBJECTIVE: To clarify the prevalence of HPV type 56-positive Bowen disease in our department and to characterize the clinical manifestations. METHODS: Sixty-eight specimens of Bowen disease were examined by polymerase chain reaction using HPV consensus primers, and the amplified products were subjected to DNA sequence analyses. Moreover, positive samples were investigated by in situ hybridization. These findings were used to clarify the clinical characteristics of HPV-positive Bowen disease. RESULTS: Eight out of 68 specimens (12%) of Bowen disease were HPV-positive, of which six specimens were HPV type 56-positive. The HPV type 56-positive lesions were characterized by a longitudinal melanonychia or a deeply pigmented keratotic lesion. The remaining two specimens were genital Bowen disease in which HPV type 16 was detected. In situ hybridization demonstrated the positive cells in the upper layer of epidermis. The HPV type 56 detected in the samples of longitudinal melanonychia can be divided into at least into two types. CONCLUSIONS: This study determined the prevalence of HPV type 56-positive Bowen disease. Longitudinal melanonychia is the most characteristic manifestation of HPV type 56-associated Bowen disease.

Compton spectroscopy for rotation-mode computed tomography.

In computed tomography (CT) systems, it is desirable to know the X-ray energy spectra for various applications, including medical CT imaging, and diagnostic field and heavy ion therapy. However, because of the restricted space, the only practical solution is to use Compton spectroscopy, where the incident spectrum is inferred from the scattered spectrum. The geometry of the scatterer and its position within the CT can affect the spectrum of the secondary beam, making it difficult to determine the primary spectrum during operation of the CT system. A modified Compton spectrometer is described that allows measurement of the X-ray energy spectra during operation, and most importantly, in rotation mode. The geometry of the scatterer was optimized to reduce the energy broadening of the secondary beam. The performance of the system was evaluated by comparing the reconstructed exposure to that measured directly using an ion chamber.

Small molecule antibody targeting HLA class I inhibits myeloma cancer stem cells by repressing pluripotency-associated transcription factors.

Cancer stem cells have been proposed to be responsible for tumorigenesis and recurrence in various neoplastic diseases, including multiple myeloma (MM). We have previously reported that MM cells specifically express HLA class I at high levels and that single-chain Fv diabody against this molecule markedly induces MM cell death. Here we investigated the effect of a new diabody (C3B3) on cancer stem cell-like side population (SP) cells. SP fraction of MM cells highly expressed ABCG2 and exhibited resistance to chemotherapeutic agents; however, C3B3 induced cytotoxicity in both SP cells and main population (MP) cells to a similar extent. Moreover, C3B3 suppressed colony formation and tumorigenesis of SP cells in vitro and in vivo. Crosslinking of HLA class I by C3B3 mediated disruption of lipid rafts and actin aggregation, which led to inhibition of gene expression of ß-catenin and pluripotency-associated transcription factors such as Sox2, Oct3/4 and Nanog. Conversely, knockdown of Sox2 and Oct3/4 mRNA reduced the proportion of SP cells, suggesting that these factors are essential in maintenance of SP fraction in MM cells. Thus, our findings reveal that immunotherapeutic approach by engineered antibodies can overcome drug resistance, and provide a new basis for development of cancer stem cell-targeted therapy.