BRD9 Degradation Disrupts Ribosome Biogenesis in Multiple Myeloma.

PURPOSE: BRD9 is a defining component of the noncanonical SWI/SNF complex, which regulates gene expression by controlling chromatin dynamics. Although recent studies have found an oncogenic role for BRD9 in multiple cancer types including multiple myeloma, its clinical significance and oncogenic mechanism have not yet been elucidated. Here, we sought to identify the clinical and biological impact of BRD9 in multiple myeloma, which may contribute to the development of novel therapeutic strategies. EXPERIMENTAL DESIGN: We performed integrated analyses of BRD9 in vitro and in vivo using multiple myeloma cell lines and primary multiple myeloma cells in established preclinical models, which identified the molecular functions of BRD9 contributing to multiple myeloma cell survival. RESULTS: We found that high BRD9 expression was a poor prognostic factor in multiple myeloma. Depleting BRD9 by genetic (shRNA) and pharmacologic (dBRD9-A; proteolysis-targeting chimera; BRD9 degrader) approaches downregulated ribosome biogenesis genes, decreased the expression of the master regulator MYC, and disrupted the protein-synthesis maintenance machinery, thereby inhibiting multiple myeloma cell growth in vitro and in vivo in preclinical models. Importantly, we identified that the expression of ribosome biogenesis genes was associated with the disease progression and prognosis of patients with multiple myeloma. Our results suggest that BRD9 promotes gene expression by predominantly occupying the promoter regions of ribosome biogenesis genes and cooperating with BRD4 to enhance the transcriptional function of MYC. CONCLUSIONS: Our study identifies and validates BRD9 as a novel therapeutic target in preclinical models of multiple myeloma, which provides the framework for the clinical evaluation of BRD9 degraders to improve patient outcome.

Prolyl-tRNA synthetase as a novel therapeutic target in multiple myeloma.

Multiple myeloma (MM) is a plasma cell malignancy characterised by aberrant production of immunoglobulins requiring survival mechanisms to adapt to proteotoxic stress. We here show that glutamyl-prolyl-tRNA synthetase (GluProRS) inhibition constitutes a novel therapeutic target. Genomic data suggest that GluProRS promotes disease progression and is associated with poor prognosis, while downregulation in MM cells triggers apoptosis. We developed NCP26, a novel ATP-competitive ProRS inhibitor that demonstrates significant anti-tumour activity in multiple in vitro and in vivo systems and overcomes metabolic adaptation observed with other inhibitor chemotypes. We demonstrate a complex phenotypic response involving protein quality control mechanisms that centers around the ribosome as an integrating hub. Using systems approaches, we identified multiple downregulated proline-rich motif-containing proteins as downstream effectors. These include CD138, transcription factors such as MYC, and transcription factor 3 (TCF3), which we establish as a novel determinant in MM pathobiology through functional and genomic validation. Our preclinical data therefore provide evidence that blockade of prolyl-aminoacylation evokes a complex pro-apoptotic response beyond the canonical integrated stress response and establish a framework for its evaluation in a clinical setting.

Sodium-glucose cotransporter 2 inhibitor canagliflozin attenuates lung cancer cell proliferation in vitro.

Cancer is a major cause of death in patients with type 2 diabetes mellitus (T2DM) and lung cancer is one of the most prevalent cancers in patients with T2DM. In the present study, we examined the anti-cancer effect of the Sodium-glucose cotransporter 2 (SGLT2) inhibitor, canagliflozin, using a lung cancer model. In lung cancer tissues from non-T2DM human subjects, SGLT2 was detected by immunohistochemistry. SGLT2 mRNA and protein were also detected in A549, H1975 and H520 lung cancer cell lines by RT-PCR and immunohistochemistry, respectively. Canagliflozin at 1-50 µM significantly suppressed the growth of A549 cells in a dose-dependent manner. In BrdU assays, canagliflozin attenuated the proliferation of A549 cells, but did not induce apoptosis. In cell cycle analysis, S phase entry was attenuated by canagliflozin in A549 cells. In in vivo experiments, a xenograft model of athymic mice implanted with A549 lung cancer cells was treated with low and high dose oral canagliflozin. Despite the results of the in vitro experiments, tumor weight was not decreased by canagliflozin. In addition, the serum insulin level, but not body weight or blood glucose level, was decreased by canagliflozin. The number of cells positive for Ki67 was slightly decreased by canagliflozin, but this was not statistically significant. In conclusion, SGLT2 is expressed in human lung cancer tissue and cell lines, and the SGLT2 inhibitor, canagliflozin, attenuated proliferation of A549 lung cancer cells by inhibiting cell cycle progression in vitro but not in vivo.

Harnessing the Immune System Against Multiple Myeloma: Challenges and Opportunities.

Multiple myeloma (MM) is an incurable malignancy of plasma cells that grow within a permissive bone marrow microenvironment (BMM). The bone marrow milieu supports the malignant transformation both by promoting uncontrolled proliferation and resistance to cell death in MM cells, and by hampering the immune response against the tumor clone. Hence, it is expected that restoring host anti-MM immunity may provide therapeutic benefit for MM patients. Already several immunotherapeutic approaches have shown promising results in the clinical setting. In this review, we outline recent findings demonstrating the potential advantages of targeting the immunosuppressive bone marrow niche to restore effective anti-MM immunity. We discuss different approaches aiming to boost the effector function of T cells and/or exploit innate or adaptive immunity, and highlight novel therapeutic opportunities to increase the immunogenicity of the MM clone. We also discuss the main challenges that hamper the efficacy of immune-based approaches, including intrinsic resistance of MM cells to activated immune-effectors, as well as the protective role of the immune-suppressive and inflammatory bone marrow milieu. Targeting mechanisms to convert the immunologically "cold" to "hot" MM BMM may induce durable immune responses, which in turn may result in long-lasting clinical benefit, even in patient subgroups with high-risk features and poor survival.

Transposition of pulmonary veins for mobilization of residual right middle and lower lobes after carinal right upper lobectomy: a unique pulmonary hilar mobilization technique for safe tension-free airway anastomosis.

Unique right hilar mobilization was performed by pulmonary venous transposition of the right middle and lower lobe veins to the opening of the right upper pulmonary vein to achieve tension-free airway anastomosis after carinal right upper lobectomy for a patient with adenoid cystic carcinoma. The right middle and lower lobes were reconstructed safely thereafter by side-to-end anastomosis between the side of the lower trachea and intermediate bronchus with acceptable suturing tension.

Prognostic Significance of BMI-1 But Not MEL-18 Expression in Pulmonary Squamous Cell Carcinoma.

AIM: We investigated the possibility of BMI-1 and MEL-18 to predict survival in patients with pulmonary squamous cell carcinoma. MATERIALS AND METHODS: One hundred and ninety-nine patients underwent surgery in our Institute between 1995 and 2005. We used immunohistochemical (IHC) analysis to determine the expressions of BMI-1 and MEL-18 and compared them with clinicopathological factors and survival. RESULTS: Forty-one of 199 cases (21%) were BMI-1-positive. No correlation was found between BMI-1 and MEL-18 expression by IHC and clinicopathological factors. Five-year overall survival in the BMI-1-positive group (66.8%), but not MEL-18, was significantly better than that in the negative group (45.5%, p=0.04). In multivariate analysis, positive BMI-1 was a better prognostic factor of overall survival (hazard ratio (HR)=0.561, 95% confidence interval (CI)=0.271-1.16, p=0.12). CONCLUSION: BMI-1 expression, but not MEL-18, is associated with a favorable prognosis and is a possible prognostic factor of pulmonary squamous cell carcinoma.