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Abstract Background Multiple myeloma (MM) is a hematopoietic malignancy for which proteasome inhibitors have become available in recent years. However, many patients develop resistance to these drugs during treatment. Therefore, it is important to elucidate the mechanisms underlying resistance acquisition by proteasome inhibitors. Side population (SP) cells, which have a high drug efflux capacity and hypoxic responses in the microenvironment have both provided important insights into drug resistance in MM; however, little is known about the characteristics of SP cells in hypoxic microenvironments. Methods We performed cDNA microarray analysis for SP and non‐SP obtained from RPMI‐8226 and KMS‐11 cell lines cultured for 48 h in normoxic and hypoxic conditions (1% O2). Genes specifically upregulated in hypoxic SP were examined. Results Our comprehensive gene expression analysis identified HMOX1, BACH2, and DUX4 as protein‐coding genes that are specifically highly expressed in SP cells under hypoxic conditions. We have shown that HMOX1/heme oxygenase‐1 (HMOX1/HO‐1) is induced by hypoxia‐inducible reactive oxygen species (ROS) and reduces ROS levels. Furthermore, we found that HMOX1 contributes to hypoxia‐induced resistance to proteasome inhibitors in vitro and in vivo. Excessive ROS levels synergistically enhance bortezomib sensitivity. In clinical datasets, HMOX1 had a strong and significantly positive correlation with MAFB but not MAF. Interestingly, hypoxic stimulation increased MAFB/MafB expression in myeloma cells; in addition, the knockdown of MAFB under hypoxic conditions suppressed HMOX1 expression. Conclusion These results suggest that the hypoxia‐ROS‐HMOX1 axis and hypoxia‐induced MafB may be important mechanisms of proteasome inhibitor resistance in hypoxic microenvironments.

Abstract Background Peripheral T‐cell lymphoma (PTCL) represents a heterogeneous and rare subgroup of aggressive lymphomas that generally demonstrate poor clinical outcomes with conventional treatment. Since the prognosis of PTCL is heterogeneous, more accurate risk assessment, and risk‐adapted treatment strategies are required. In this study, we examined whether interim positron emission tomography (iPET)‐computed tomography (PET/CT) results can be combined with baseline volume‐based metabolic assessments including total metabolic tumor volume (TMTV) and total lesion glycolysis (TLG) for risk stratification in PTCL. Methods The data of 63 patients with nodal PTCL, who had analyzable baseline PET/CT and iPET, were retrospectively reviewed. We calculated the baseline TMTV and TLG values. All iPET responses were analyzed using the Deauville 5‐point scale. Results On univariate analysis, a prognostic index for PTCL (PIT) higher than 2 (hazard ratio [HR], 2.03; P = .026), high TMTV (>389 cm3; HR, 2.24; P = .01), high TLG (>875; HR, 3.77; P = .0005), and positive iPET (HR, 2.18; P = .009) were significantly associated with poorer progression‐free survival (PFS). On multivariate analysis, only high TLG and positive iPET independently predicted both poorer overall survival (OS) and PFS. A model combining TLG and iPET showed that patients with low TLG and negative iPET had superior outcomes, with a 5‐year PFS and OS of 72% and 90%, respectively. Conversely, both 5‐year PFS and OS for those with high TLG and positive iPET were 0%. Conclusions In summary, TLG combined with iPET predicted survival in PTCL more accurately. This information may help in the development of risk‐adapted treatment strategies for PTCL.

Abstract We retrospectively analyzed bone marrow (BM) infiltration pattern in consecutive 30 intravascular large B‐cell lymphoma (IVLBCL) patients diagnosed by random skin biopsy (RSB). BM infiltration of lymphoma was observed in 18 patients (60.0%), including five patients with the intrasinusoidal pattern with minimal extravasation, eight patients with the mixed of intrasinusoidal and scattered/interstitial or nodular infiltration, and five patients with the nodular/diffuse pattern. Twelve patients were negative for lymphoma infiltration. BM histology of patients with IVLBCL were diverse and frequently discordant with those of other site of IVLBCL lesions. BM biopsy had a poorer diagnostic performance for detecting intravascular features.

Abstract Renal impairment (RI) is a common clinical presentation in patients with multiple myeloma (MM). Despite treatment with novel agents or management strategies that focus on the disease response, some patients develop irreversible RI. This study aimed to determine the influencing, clinical variables of renal reversibility in patients with RI treated with novel drugs. We analyzed 244 patients newly diagnosed with MM retrospectively. Maximum renal response was assessed according to the criteria for the definition of renal response proposed by the International Myeloma Working Group. Major renal response was defined as the occurrence of complete renal response or partial renal response. RI (a glomerular filtration rate 25 mIU/mL (P 25 mIU/mL and urinary albumin ≤25%. The estimated 6‐month rates of major renal responses of patients with scores of 2, 1, and 0 were 78.6%, 30.6%, and 0%, respectively (P 25 mIU/mL is an independent predictive factor for major renal response and may predict renal reversibility more accurately when urinary albumin level is congruently ≤25%.

Abstract: We aimed to determine the clinical and prognostic significance of medullary abnormalities detected by low-dose whole-body multidetector computed tomography (MDCT) in the appendicular skeleton (AS) of patients with newly diagnosed symptomatic multiple myeloma (MM). One hundred ninety-six patients underwent low-dose whole-body MDCT as an initial workup. Patients were categorized into 3 groups based on the medullary pattern of the AS: fatty (36.3%), focal (43.4%), and diffuse (20.4%). Medullary abnormalities were associated with Durie-Salmon and revised International Scoring System stage 3, creatinine levels >2.0 mg/dL, and the proportion of bone marrow plasma cells. The median follow-up was 35.4 months. Patients with fatty, focal, and diffuse patterns had a median survival of not reached, 56 months, and 38 months, respectively. Overall survival (OS) was associated with age, Durie-Salmon stage 3, creatinine levels >2.0 mg/dL, ineligibility for autologous stem cell transplantation, and focal and diffuse patterns on univariate analysis. Multivariate analysis showed that age and diffuse pattern (hazard ratio [HR], 1.92; 95% confidence interval [CI], 1.12-3.31; P = .018) were independent predictors of progression-free survival. Age and focal (HR, 2.51; 95% CI, 1.14-5.56; P = .023) and diffuse (HR, 4.12; 95% CI, 1.74-9.77; P = .001) patterns were also independent predictors of OS. The addition of marrow pattern to preexisting risk factors was associated with a net reclassification improvement for predicting OS (to 0.37, P = .015). Medullary abnormalities in the AS (detected by low-dose whole-body MDCT) are associated with a poor prognosis, independent of other clinical variables.

Abstract Background Patients with anorexia nervosa (AN) often present with pancytopenia. In most cases described in the literature, AN with pancytopenia demonstrates gelatinous marrow transformation (GMT), which is a typical bone marrow feature of malnutrition. Differentiation of AN-associated pancytopenia from other types of pancytopenia, especially idiopathic aplastic anemia (IAA), has not been studied. We encountered a case of pancytopenia in a patient with AN and relatively poor nutritional status, whose hematological findings mimicked those of IAA, specifically fatty bone marrow and absence of GMT. Case presentation The patient was a 32-year-old woman with poorly controlled AN. At 31 years of age, her body mass index (BMI) had fallen from 17.0 kg/m2 to below 13.8 kg/m2. The patient presented with ongoing fatigue and thus was examined by a hematologist. Hematological findings were consistent with IAA: peripheral blood tests revealed pancytopenia, whereas the bone marrow displayed fatty replacement without GMT. Despite the absence of bone marrow features typically seen in malnutrition, the patient’s hematological abnormalities had manifested after a decrease in body weight. Thus, although the bone marrow findings indicated IAA, we considered that the nutritional etiology of pancytopenia could not be thoroughly ruled out. Using nutritional therapy alone, the hematological abnormalities improved as BMI increased to 16.5 kg/m2. The final diagnosis was pancytopenia secondary to malnutrition because pancytopenia and fatty bone marrow improved after implementation of nutritional therapy alone. Conclusions The present case is the first documented case of AN with pancytopenia for which bone marrow examination confirmed fatty marrow without any evidence of GMT. IAA and pancytopenia secondary to malnutrition can present the same clinical findings. This case is significant because it suggests a need to differentiate between malnutrition and IAA.

Abstract: In multiple myeloma (MM), the bone marrow (BM) microenvironment may contain a myeloma cell fraction that has acquired treatment resistance by undergoing an epigenetic gene expression change. Hypoxic stress is an important factor in the BM microenvironment. Recently, we demonstrated that miR-210 was upregulated in hypoxia and downregulated IRF4, which is known as an essential factor in myeloma oncogenesis in normoxia. In the study, we demonstrated that myeloma cells still showed a strong antiapoptotic phenotype despite IRF4 downregulation, suggesting that another antiapoptotic factor might be involved under hypoxic stress. To determine the factor or factors, we conducted gene expression analysis on myeloma cells (primary samples and cell lines) that were exposed to chronic hypoxia and observed upregulation of glycolytic genes and genes encoding H3K9 demethylases in myeloma cells with hypoxia. Among these, KDM3A was most significantly upregulated in all examined cells, and its knockdown induced apoptosis of myeloma cells in chronic hypoxia. Expression of KDM3A was dependent on HIF-1α, which is a transcription factor specifically upregulated in hypoxia. We further demonstrated that an essential target of KDM3A was a noncoding gene, MALAT1, whose upregulation contributed to acquisition of an antiapoptotic phenotype by accumulation of HIF-1α, leading to upregulation of glycolytic genes under hypoxia. This process was independent from IRF4. These results led us to conclude that the hypoxia-inducible HIF-1α-KDM3A-MALAT1 axis also contributes to acquisition of the antiapoptotic phenotype via upregulation of glycolysis-promoting genes. Thus, this axis is a promising therapeutic target against myeloma cells in the BM microenvironment.

In the seminiferous tubules of mouse testes, a population of glial cell line-derived neurotrophic factor family receptor alpha 1 (GFRα1)-positive spermatogonia harbors the stem cell functionality and supports continual spermatogenesis, likely independent of asymmetric division or definitive niche control. Here, we show that activation of Wnt/β-catenin signaling promotes spermatogonial differentiation and reduces the GFRα1+ cell pool. We further discovered that SHISA6 is a cell-autonomous Wnt inhibitor that is expressed in a restricted subset of GFRα1+ cells and confers resistance to the Wnt/β-catenin signaling. Shisa6+ cells appear to show stem cell-related characteristics, conjectured from the morphology and long-term fates of T (Brachyury)+ cells that are found largely overlapped with Shisa6+ cells. This study proposes a generic mechanism of stem cell regulation in a facultative (or open) niche environment, with which different levels of a cell-autonomous inhibitor (SHISA6, in this case) generates heterogeneous resistance to widely distributed differentiation-promoting extracellular signaling, such as WNTs.

Histone deacetylase inhibitors are promising agents for various T-cell lymphomas, including cutaneous T-cell lymphoma, peripheral T-cell lymphoma, and adult T-cell lymphoma/leukemia. CCR4 is an important therapeutic target molecule because mogamulizumab, an anti-CCR4 antibody, has shown promising efficacy against various T-cell lymphomas. In this study, we examined the in vitro synergistic effects of mogamulizumab and histone deacetylase inhibitors against various T-cell lymphomas. First, we examined the expression of CCR4 mRNA and surface CCR4 in various T-cell lymphoma cell lines and found that it was downregulated upon treatment with vorinostat, a pan-histone deacetylase inhibitor. Next, we used isoform-specific histone deacetylase inhibitors and short-interfering RNA to determine the histone deacetylase isoform involved in the regulation of CCR4, and demonstrated that romidepsin, a class I selective histone deacetylase inhibitor, reduced CCR4 most efficiently. Moreover, among class I histone deacetylases, histone deacetylase 2 knockdown led to a reduction of CCR4 in lymphoma cells, suggesting that CCR4 expression is mainly regulated by histone deacetylase 2. When we examined the CCR4 expression in skin samples from primary cutaneous T-cell lymphoma, obtained from the same patients before and after vorinostat treatment, we found that CCR4 expression was greatly reduced after treatment. Finally, when we conducted an antibody-dependent cell-mediated cytotoxicity assay with mogamulizumab by using various lymphoma cells, we found that the efficacy of mogamulizumab was significantly reduced by pretreatment with vorinostat. Altogether, our results suggest that the primary use of histone deacetylase inhibitors before treatment with mogamulizumab might not be suitable to obtain synergistic effects. Moreover, these results have potential implications for optimal therapeutic sequences in various CCR4-positive T-cell lymphomas.

The transcription factor MAFB is an important regulator of the development and differentiation of various organs and tissues. Previous studies have shown that MAFB is expressed in embryonic and adult mouse testes and is expected to act as the downstream target of retinoic acid (RA) to initiate spermatogenesis. However, its exact localization and function remain unclear. Here, we localized MAFB expression in embryonic and adult testes and analyzed its gene function using Mafb-deficient mice. We found that MAFB and c-MAF are the only large MAF transcription factors expressed in testes, while MAFA and NRL are not. MAFB was localized in Leydig and Sertoli cells at embryonic day (E) 18.5 but in Leydig cells, Sertoli cells, and pachytene spermatocytes in adults. Mafb-deficient testes at E18.5 showed fully formed seminiferous tubules with no abnormal structure or differences in testicular somatic cell numbers compared with those of control wild-type mice. Additionally, the expression levels of genes related to development and function of testicular cells were unchanged between genotypes. In adults, the expression of MAFB in Sertoli cells was shown to be stage specific and induced by RA. By generating Mafbfl/fl CAG-CreER™ (Mafb-cKO) mice, in which Cre recombinase was activated upon tamoxifen treatment, we found that the neonatal cKO mice died shortly upon Mafb deletion, but adult cKO mice were alive upon deletion. Adult cKO mice were fertile, and spermatogenesis maintenance was normal, as indicated by histological analysis, hormone levels, and germ cell stage-specific markers. Moreover, there were no differences in the proportion of seminiferous stages between cKO mice and controls. However, RNA-Seq analysis of cKO Sertoli cells revealed that the down-regulated genes were related to immune function and phagocytosis activity but not spermatogenesis. In conclusion, we found that MAFB is dispensable for fetal testis morphogenesis and spermatogenesis maintenance in adult mice, despite the significant gene expression in different cell types, but MAFB might be critical for phagocytosis activity of Sertoli cells.