Metformin and FTY720 Synergistically Induce Apoptosis in Multiple Myeloma Cells.

BACKGROUND/AIMS: Patients with multiple myeloma (MM) invariably relapse with chemotherapy-resistant disease, underscoring the need for new therapeutic options that bypass these resistance mechanisms. Metformin is a widely prescribed antidiabetic drug with direct antitumor activity against various tumor cell lines. FTY720, also known as fingolimod, is an immune-modulating agent approved by the FDA as oral medication to treat the relapsing form of multiple sclerosis (MS). In recent years, FTY720 has attracted attention due to its anti-tumor activity. To explore an optimized combinational therapy, interactions between metformin and FTY720 were examined in MM cells. METHODS: MTT assays were employed to assess the viability of MM cells. An apoptotic nucleosome assay was employed to measure apoptosis. Loss of mitochondrial membrane potential (MMP, ΔΨm) and cellular levels of ROS were measured by flow cytometry. qRT-PCR was used to analyze the expression of mRNAs. Western blotting assays were applied to measure the levels of proteins involved in different signaling pathways. RESULTS: Coadministration of metformin and FTY720 synergistically inhibited the proliferation of MM cells. Increased levels of apoptosis, activation of caspase-3 and cleavage of PARP were detected after cotreatment with metformin and FTY720. These events were associated with modulation of Bcl-2 proteins, loss of MMP, ER stress induction, and inhibition of the PI3K/AKT/mTOR signaling pathway. The metformin/FTY720 regimen markedly induced ROS generation; moreover, apoptosis, ER stress and inhibition of PI3K/AKT/ mTOR were attenuated by the ROS scavenger NAC. CONCLUSIONS: Exposure to metformin in combination with FTY720 potently induces apoptosis in MM cells in a ROS-dependent manner, suggesting that a strategy combining these agents warrants further investigation in MM.

TRIM21 enhances bortezomib sensitivity in multiple myeloma by halting prosurvival autophagy.

Bortezomib (bort) is an effective therapeutic agent for patients with multiple myeloma (MM); however, most patients develop drug resistance. Autophagy, a highly conserved process that recycles cytosol or entire organelles via lysosomal activity, is essential for the survival, homeostasis, and drug resistance in MM. Growing evidence has highlighted that E3 ligase tripartite motif-containing protein 21 (TRIM21) not only interacts with multiple autophagy regulators but also participates in drug resistance in various cancers. However, to date, the direct substrates and additional roles of TRIM21 in MM remain unexplored. In this study, we demonstrated that low TRIM21 expression is a factor for relapse in MM. TRIM21 knockdown (KD) made MM cells more resistant to bort, whereas TRIM21 overexpression (OE) resulted in increased MM sensitivity to bort. Proteomic and phosphoproteomic studies of TRIM21 KD MM cells showed that bort resistance was associated with increased oxidative stress and elevated prosurvival autophagy. Our results showed that TRIM21 KD MM cell lines induced prosurvival autophagy after bort treatment, suppressing autophagy by 3-methyladenine treatment or by the short hairpin RNA of autophagy-related gene 5 (ATG5)-restored-bort sensitivity. Indeed, ATG5 expression was increased and decreased by TRIM21 KD and OE, respectively. TRIM21 affected autophagy by ubiquitinating ATG5 through K48 for proteasomal degradation. Importantly, we confirmed that TRIM21 could potentiate the antimyeloma effect of bort through in vitro and in vivo experiments. Overall, our findings define the key role of TRIM21 in MM bort resistance and provide a foundation for a novel targeted therapeutic approach.

CUDC-101 as a dual-target inhibitor of EGFR and HDAC enhances the anti-myeloma effects of bortezomib by regulating G2/M cell cycle arrest. / EGFR和HDAC双靶点抑制剂CUDC-101通过调控G2/M期阻滞增强硼替佐米抗骨髓瘤的作用.

CUDC-101, an effective and multi-target inhibitor of epidermal growth factor receptor (EGFR), histone deacetylase (HDAC), and human epidermal growth factor receptor 2 (HER2), has been reported to inhibit many kinds of cancers, such as acute promyelocytic leukemia and non-Hodgkin's lymphoma. However, no studies have yet investigated whether CUDC-101 is effective against myeloma. Herein, we proved that CUDC-101 effectively inhibits the proliferation of multiple myeloma (MM) cell lines and induces cell apoptosis in a time- and dose-dependent manner. Moreover, CUDC-101 markedly blocked the signaling pathway of EGFR/phosphoinositide-3-kinase (PI3K) and HDAC, and regulated the cell cycle G2/M arrest. Moreover, we revealed through in vivo experiment that CUDC-101 is a potent anti-myeloma drug. Bortezomib is one of the important drugs in MM treatment, and we investigated whether CUDC-101 has a synergistic or additive effect with bortezomib. The results showed that this drug combination had a synergistic anti-myeloma effect by inducing G2/M phase blockade. Collectively, our findings revealed that CUDC-101 could act on its own or in conjunction with bortezomib, which provides insights into exploring new strategies for MM treatment.

NEDD4L binds the proteasome and promotes autophagy and bortezomib sensitivity in multiple myeloma.

Multiple myeloma (MM) remains an incurable plasma cell cancer characterized by abnormal secretion of monoclonal immunoglobulins. The molecular mechanism that regulates the drug sensitivity of MM cells is being intensively studied. Here, we report an unexpected finding that the protein encoded by neural precursor cell-expressed developmentally downregulated gene 4L (NEDD4L), which is a HECT E3 ligase, binds the 19S proteasome, limiting its proteolytic function and enhancing autophagy. Suppression of NEDD4L expression reduced bortezomib (Bor) sensitivity in vitro and in vivo, mainly through autophagy inhibition mediated by low NEDD4L expression, which was rescued by an autophagy activator. Clinically, elevated expression of NEDD4L is associated with a considerably increased probability of responding to Bor, a prolonged response duration, and improved overall prognosis, supporting both the use of NEDD4L as a biomarker to identify patients most likely to benefit from Bor and the regulation of NEDD4L as a new approach in myeloma therapy.

High-Order Fiber Mode Beam Parameter Optimization for Transport and Rotation of Single Cells.

Optical tweezers are becoming increasingly important in biomedical applications for the trapping, propelling, binding, and controlled rotation of biological particles. These capabilities enable applications such as cell surgery, microinjections, organelle extraction and modification, and preimplantation genetic diagnosis. In particular, optical fiber-based tweezers are compact, highly flexible, and can be readily integrated into lab-on-a-chip devices. Taking advantage of the beam structure inherent in high-order modes of propagation in optical fiber, LP11, LP21, and LP31 fiber modes can generate structured radial light fields with two or more concentrations in the cross-section of a beam, forming multiple traps for bioparticles with a single optical fiber. In this paper, we report the dynamic modeling and optimization of single cell manipulation with two to six optical traps formed by a single fiber, generated by either spatial light modulation (SLM) or slanted incidence in laser-fiber coupling. In particular, we focus on beam size optimization for arbitrary target cell sizes to enable trapped transport and controlled rotation of a single cell, using a point matching method (PMM) of the T-matrix to compute trapping forces and rotation torque. Finally, we validated these optimized beam sizes experimentally for the LP21 mode. This work provides a new understanding of optimal optical manipulation using high-order fiber modes at the single-cell level.

DMAMCL exerts antitumor effects on hepatocellular carcinoma both in vitro and in vivo.

Hepatocellular carcinoma (HCC) is a common malignancy with a poor prognosis. Dimethylaminomicheliolide (DMAMCL) is a novel antitumor agent that has been tested in phase I clinical trials; however, little is known regarding its effects in HCC. In this study, we found that DMAMCL reduces the viability of HCC cells in a dose- and time-dependent manner. In addition, DMAMCL causes cell cycle arrest at the G2/M phase and inhibits cell invasion and epithelial-mesenchymal transition (EMT). DMAMCL treatment also induces apoptosis via the intrinsic apoptotic pathway in HCC cells, which could be blocked by the pan-caspase inhibitor zVAD-fmk and silencing of Bax/Bak or overexpression of Bcl-2. Furthermore, DMAMCL treatment inactivates the PI3K/Akt pathway and leads to the generation of reactive oxygen species (ROS), which regulate apoptosis and inhibition of PI3K/Akt induced by DMAMCL. In vivo, DMAMCL inhibits tumor growth in mice bearing xenograft HCC tumors without noticeable toxicity. In summary, DMAMCL exerts antitumor effects both in vitro and in vivo and therefore may be applied as a potential therapeutic agent for HCC.

Camalexin Induces Apoptosis via the ROS-ER Stress-Mitochondrial Apoptosis Pathway in AML Cells.

Camalexin is a phytoalexin that accumulates in various cruciferous plants upon exposure to environmental stress and plant pathogens. It was shown that camalexin has potent antitumor properties, but its underlying mechanisms are still elusive. In the present study, we evaluated the effects of camalexin on human leukemic cells and normal polymorph nuclear cells. CCK-8 assay was used to determine cell viability after camalexin treatment. Apoptosis, intracellular reactive oxygen species (ROS) levels, and loss of mitochondrial membrane potential (MMP) were measured by flow cytometry. The activity of SOD, catalase, and ratio of GSH/GSSG were assayed. ER stress and apoptotic signaling pathway was examined by Western blot. Xenograft mice were used to verify the effect of camalexin in vivo. Our results indicated that camalexin inhibited viability of leukemic but not normal polymorph nuclear cells. Furthermore, camalexin induces apoptosis via the mitochondrial pathway in a caspase-dependent manner. We also observed ER stress is located upstream of apoptosis induced by camalexin. Besides, ROS levels, SOD activity, CAT activity, and GSSG levels were significantly enhanced while the GSH level was decreased after treatment of camalexin. In addition, the generation of ROS is critical for the ER stress and apoptosis induced by camalexin. Finally, administration of camalexin suppresses xenograft tumor graft growth without obvious toxicity. Taken together, this study indicates that camalexin exerts antitumor effects against leukemia cells via the ROS-ER stress-mitochondrial apoptosis pathway.