AAA-ATPase TRIP13 is one of the chromosome instability gene recently established in multiple myeloma (MM), the second most common and incurable hematological malignancy. However, the specific function of TRIP13 in MM is largely unknown. Using sequential gene expression profiling, we demonstrated that high TRIP13 expression levels were positively correlated with progression, disease relapse, and poor prognosis in MM patients. Overexpressing human TRIP13 in myeloma cells prompted cell growth and drug resistance, and overexpressing murine TRIP13, which shares 93% sequence identity with human TRIP13, led to colony formation of NIH/3T3 fibroblasts in vitro and tumor formation in vivo. Meanwhile, the knockdown of TRIP13 inhibited myeloma cell growth, induced cell apoptosis, and reduced tumor burden in xenograft MM mice. Mechanistically, we observed that the overexpression of TRIP13 abrogated the spindle checkpoint and induced proteasome-mediated degradation of MAD2 primarily through the Akt pathway. Thus, our results demonstrate that TRIP13 may serve as a biomarker for MM disease development and prognosis, making it a potential target for future therapies.

Recent findings demonstrate that aberrant downregulation of the iron-exporter protein, ferroportin (FPN1), is associated with poor prognosis and osteoclast differentiation in multiple myeloma (MM). Here, we show that FPN1 was downregulated in MM and that clustered regularly interspaced short palindromic repeat (CRISPR)-mediated FPN1 knockout promoted MM cell growth and survival. Using a microRNA target-scan algorithm, we identified miR-17-5p as an FPN1 regulator that promoted cell proliferation and cell cycle progression, and inhibited apoptosis—both in vitro and in vivo. miR-17-5p inhibited retarded tumor growth in a MM xenograft model. Moreover, restoring FPN1 expression at least partially abrogated the biological effects of miR-17-5p in MM cells. The cellular iron concentration regulated the expression of the iron-regulatory protein (IRP) via the 5′-untranslated region of IRP messenger RNA and modulated the post-transcriptional stability of FPN1. Bioinformatics analysis with subsequent chromatin immunoprecipitation-polymerase chain reaction and luciferase activity experiments revealed that the transcription factor Nrf2 drove FPN1 transcription through promoter binding and suppressed miR-17-5p (which also increased FPN1 expression). Nrf2-mediated FPN1 downregulation promoted intracellular iron accumulation and reactive oxygen species. Our study links FPN1 transcriptional and post-transcriptional regulation with MM cell growth and survival, and validates the prognostic value of FPN1 and its utility as a novel therapeutic target in MM.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma (NHL). Pterostilbene, a natural dimethylated analog of resveratrol, has been shown to possess diverse pharmacological activities, including anti-inflammatory, antioxidant and anticancer properties. However, to the best of our knowledge, there has been no study of the effects of pterostilbene upon hematological malignancies. Herein, we report the antitumor activity and mechanism of pterostilbene against DLBCL cells both in vitro and in vivo. We found that pterostilbene treatment resulted in a dose-dependent inhibition of cell viability. In addition, pterostilbene exhibited a strong cytotoxic effect, as evidenced not only by reductions of mitochondrial membrane potential (MMP) but also by increases in cellular apoptotic index and reactive oxygen species (ROS) levels, leading to arrest in the S-phase of the cell cycle. Furthermore, pterostilbene treatment directly up-regulated p-p38MAPK and down-regulated p-ERK1/2. In vivo, intravenous administration of pterostilbene inhibited tumor development in xenograft mouse models. Overall, the results suggested that pterostilbene is a potential anti-cancer pharmaceutical against human DLBCL by a mechanism involving the suppression of ERK1/2 and activation of p38MAPK signaling pathways.

The AAA-ATPase TRIP13 drives multiple myeloma progression. Here, we present the crystal structure of wild-type human TRIP13 at a resolution of 2.6 Å. A small-molecule inhibitor targeting TRIP13 was identified on the basis of the crystal structure. The inhibitor, designated DCZ0415, was confirmed to bind TRIP13 using pull-down, nuclear magnetic resonance spectroscopy, and surface plasmon resonance-binding assays. DCZ0415 induced antimyeloma activity in vitro, in vivo, and in primary cells derived from drug-resistant patients with myeloma.The inhibitor impaired nonhomologous end joining repair and inhibited NF-kB activity. Moreover, combining DCZ0415 with the multiple myeloma chemotherapeutic melphalan or the HDAC inhibitor panobinostat induced synergistic antimyeloma activity. Therefore, targeting TRIP13 may be an effective therapeutic strategy for multiple myeloma, particularly refractory or relapsed multiple myeloma.Significance: These findings identify TRIP13 as a potentially new therapeutic target in multiple myeloma.

Multiple myeloma (MM) is the second most common malignancy in the hematologic system, which is characterized by accumulation of plasma cells in bone marrow. Pterostilbene (PTE) is a natural dimethylated analog of resveratrol, which has anti-oxidant, anti-inflammatory and anti-tumor properties. In the present study, we examined the anti-tumor effect of PTE on MM cell lines both in vitro and in vivo using the cell counting kit (CCK)-8, apoptosis assays, cell cycle analysis, reactive oxygen species (ROS) generation, JC-1 mitochondrial membrane potential assay, Western blotting and tumor xenograft models. The results demonstrated that PTE induces apoptosis in the H929 cell line and causes cell cycle arrest at G0/G1 phase by enhancing ROS generation and reducing mitochondrial membrane potential. The anti-tumor effect of PTE may be caused by the activation of the extracellular regulated protein kinases (ERK) 1/2 and c-Jun N-terminal kinase (JNK) signaling pathways. Additionally, mice treated with PTE by intraperitoneal injection demonstrated reduced tumor volume. Taken together, the results of this study indicate that the anti-tumor effect of PTE on MM cells may provide a new therapeutic option for MM patients.

Pterostilbene is a natural 3,5-dimethoxy analog of trans-resveratrol that has been reported to have antitumor, antioxidant, and anti-inflammatory effects. T-cell leukemia/lymphoma is one of the more aggressive yet uncommon non-Hodgkin lymphomas. Although there has been increasing research into T-cell leukemia/lymphoma, the molecular mechanisms of the antitumor effects of pterostilbene against this malignancy are still largely unknown. The aim of this study is to confirm the effects of pterostilbene in T-cell leukemia/lymphoma. Jurkat and Hut-78 cells treated with pterostilbene were evaluated for cell proliferation using Cell Counting Kit-8, and apoptosis, cell cycle progression, reactive oxygen species generation, and mitochondrial membrane potential were analyzed using flow cytometry. The level of protein expression was detected by western blot. The results demonstrated that pterostilbene significantly inhibited the growth of T-cell leukemia/lymphoma cell lines in vitro and induced apoptosis in a dose- and time-dependent manner. Moreover, pterostilbene treatment markedly induced S-phase cell cycle arrest, which was accompanied by downregulation of cdc25A, cyclin A2, and CDK2. Pterostilbene also induced the generation of reactive oxygen species and the loss of mitochondrial membrane potential and inhibited ERK1/2 phosphorylation. Taken together, our study demonstrated the potential of pterostilbene to be an effective treatment for T-cell leukemia/lymphoma.

We previously showed that the proteasome inhibitor carfilzomib and the histone deacetylase inhibitor (HDACI) vorinostat cooperated to induce cell apoptosis in one T-cell leukemia cell line in vitro, implying the possibility of the combination treatment of carfilzomib and vorinostat as a potential therapeutic strategy in human T-cell leukemia/lymphoma. Here we report that combination treatment of carfilzomib and vorinostat enhanced cell apoptosis and induced a marked increase in G2-M arrest, reactive oxygen species (ROS) generation, and activated the members of mitogen-activated protein kinases (MAPK) family, including the stress-activated kinases JNK, p38MAPK, and ERK1/2. Carfilzomib/vorinostat-mediated apoptosis was blocked by the ROS scavenger N-acetylcysteine (NAC). The JNK inhibitor SP600125 and the p38MAPK inhibitor SB203580 but not the MEK1/2 inhibitor U0126 significantly attenuated carfilzomib/vorinostat-induced apoptosis, suggesting that p38MAPK and JNK activation contribute to carfilzomib and vorinostat-induced apoptosis. This was further confirmed via short hairpin (shRNA) RNA knockdown of p38MAPK and JNK. Interestingly, the ROS scavenger NAC attenuated carfilzomib/vorinostat-mediated activation of p38MAPK and JNK. However, p38MAPK shRNA but not JNK shRNA diminished carfilzomib/vorinostat-mediated ROS generation. In contrast, overexpression of p38MAPK significantly increased carfilzomib/vorinostat-mediated ROS generation, suggesting that an amplification loop exists between ROS and p38MAPK pathway. Combination treatment of carfilzomib and vorinostat enhanced their individual antitumor activity in both a human xenograft model as well as human primary T-cell leukemia/lymphoma cells. These data suggest the potential clinical benefit and underlying molecular mechanism of combining carfilzomib with vorinostat in the treatment of human T-cell leukemia/lymphoma.

No abstract