Advances in the pathogenesis of multiple myeloma bone disease. / å¤šå‘æ€§éª¨é«“ç˜¤éª¨ç— å‘ç— æœºåˆ¶çš„ç ”ç©¶è¿›å±•.

Multiple myeloma (MM) is a clonal proliferative malignant tumor of plasma cells in bone marrow. With the aging of population in China, the incidence of MM is on the rise. Multiple myeloma bone disease (MBD) is one of the common clinical manifestations of MM, and 80%-90% of MM patients are accompanied by osteolytic lesions at the time of their first visit to the clinic. MBD not only increases the disability rate of patients, but also severely reduces the physical function of patients due to skeletal lesions and bone-related events. Currently available drugs for treating of MBD are ineffective and associated with side effects. Therefore, it is important to find new therapeutic approaches for the treatment of MBD. It is generally believed that the increased osteoclast activity and suppressed osteoblast function are the main pathologic mechanisms for MBD. However, more and more studies have suggested that soluble molecules in the bone marrow microenvironment, including cytokines, extracellular bodies, and metabolites, play an important role in the development of MBD. Therefore, exploring the occurrence and potential molecular mechanisms for MBD from multiple perspectives, and identifying the predictive biomarkers and potential therapeutic targets are of significance for the clinical treatment of MBD.

Phosphoglycerate dehydrogenase promotes proliferation and bortezomib resistance through increasing reduced glutathione synthesis in multiple myeloma.

The serine synthesis pathway (SSP) is active in multiple cancers. Previous study has shown that bortezomib (BTZ) resistance is associated with an increase in the SSP in multiple myeloma (MM) cells; however, the underlying mechanisms of SSP-induced BTZ resistance remain unclear. In this study, we found that phosphoglycerate dehydrogenase (PHGDH), the first rate-limiting enzyme in the SSP, was significantly elevated in CD138+ cells derived from patients with relapsed MM. Moreover, high PHGDH conferred inferior survival in MM. We also found that overexpression of PHDGH in MM cells led to increased cell growth, tumour formation, and resistance to BTZ in vitro and in vivo, while inhibition of PHGDH by short hairpin RNA or NCT-503, a specific inhibitor of PHGDH, inhibited cell growth and BTZ resistance in MM cells. Subsequent mechanistic studies demonstrated PHGDH decreased reactive oxygen species (ROS) through increasing reduced glutathione (GSH) synthesis, thereby promoting cell growth and BTZ resistance in MM cells. Furthermore, adding GSH to PHGDH silenced MM cells reversed S phase arrest and BTZ-induced cell death. These findings support a mechanism in which PHGDH promotes proliferation and BTZ resistance through increasing GSH synthesis in MM cells. Therefore, targeting PHGDH is a promising strategy for MM therapy.

High COX-2 expression in cancer-associated fibiroblasts contributes to poor survival and promotes migration and invasiveness in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) has the highest rate of metastasis among head and neck cancers, and distant metastasis is the major reason for treatment failure. We have previously shown that high cyclooxygenase-2 (COX-2) expression is associated with a poor prognosis of patients with NPC and inhibits chemotherapy-induced senescence in NPC cells. In this study, we found that COX-2 was upregulated in cancer-associated fibroblasts (CAFs) derived from NPC by RNA-Seq. Furthermore, elevated COX-2 expression in CAF was detected in NPC patients with poor survival and distant metastasis by using immunohistochemistry. Then, we identified that COX-2 is highly expressed in CAF at the distant metastasis site in seven paired NPC patients. High expression of COX-2 and secretion of prostaglandin E2, a major product catalyzed by COX-2 in fibroblasts, promotes migration and invasiveness of NPC cells in vitro. On the contrary, inhibition of COX-2 has the opposite effect in vitro as well as in the COX-2-/- mouse with the lung metastasis model in vivo. Mechanistically, we discovered that COX-2 elevates tumor necrosis factor-α expression in CAF to promote NPC cell migration and invasiveness. Overall, our results identified a novel target in CAF promoting NPC metastasis. Our findings suggested that high expression of COX-2 in CAF may serve as a new prognostic indicator for NPC metastasis and provide the possibility of targeting CAF for treating advanced NPC.

High NEK2 confers to poor prognosis and contributes to cisplatin-based chemotherapy resistance in nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a common malignant tumor in southern China and Southeast Asia, but the molecular mechanism of its pathogenesis is poorly understood. Our previous work demonstrated that NEK2 is overexpressed in multiple cancers. However, how NEK2 involves in NPC development remains to be elucidated. In this study, we firstly identified NEK2, located at +1q32-q33, a late event in NPC pathogenesis, overexpressed in the stage III-IV and paired sequential recurrent patients with NPC by immunohistochemistry. Furthermore, Kaplan-Meier analysis indicated high NEK2 conferred an inferior overall survival in NPC. In addition, cisplatin experiments with cell counting kit-8, colony formation, and a xenograft mice model of NPC demonstrated that NEK2 contributed to proliferation and cisplatin resistance in vitro and in vivo. On the contrary, downregulation of NEK2 by short hairpin RNA inhibited NPC cell growth and increased the sensitivity of cisplatin treatment in vitro. Thus, increased expression of NEK2 protein could not be predicted for poor survival but used as a novel biomarker for recurrence of NPC. Targeting NEK2 has the potential to eradicate the cisplatin-based chemotherapy resistant NPC cells.

ARHGEF19 interacts with BRAF to activate MAPK signaling during the tumorigenesis of non-small cell lung cancer.

Rho guanine nucleotide exchange factors (RhoGEFs) are proteins that activate Rho GTPases in response to extracellular stimuli and regulate various biologic processes. ARHGEF19, one of RhoGEFs, was reported to activate RhoA in the Wnt-PCP pathway controlling convergent extension in Xenopus gastrulation. The goal of our study was to identify the role and molecular mechanisms of ARHGEF19 in the tumorigenesis of non-small cell lung cancer (NSCLC). ARHGEF19 expression was significantly elevated in NSCLC tissues, and ARHGEF19 levels were significantly associated with lymph node status, distant metastasis and TNM stage; Patients with high ARHGEF19 levels had poor overall survival (OS) and progression-free survival (PFS). Our investigations revealed that ARHGEF19 overexpression promoted the cell proliferation, invasion and metastasis of lung cancer cells, whereas knockdown of this gene inhibited these processes. Mechanistically, ARHGEF19 activated the mitogen-activated protein kinase (MAPK) pathway in a RhoA-independent manner: ARHGEF19 interacted with BRAF and facilitated the phosphorylation of its downstream kinase MEK1/2; both the Dbl homology (DH) and Pleckstrin homology (PH) domains of ARHGEF19 were indispensable for the phosphorylation of MEK1/2. Furthermore, downregulation of miR-29b was likely responsible for the increased expression of ARHGEF19 in lung cancer tissues and, consequently, the abnormal activation of MAPK signaling. These findings suggest that ARHGEF19 upregulation, due to the low expression of miR-29 in NSCLC tissues, may play a crucial role in NSCLC tumorigenesis by activating MAPK signaling. ARHGEF19 could serve as a negative prognostic marker as well as a therapeutic target for NSCLC patients.

Excessive serine from the bone marrow microenvironment impairs megakaryopoiesis and thrombopoiesis in Multiple Myeloma.

Thrombocytopenia is a major complication in a subset of patients with multiple myeloma (MM). However, little is known about its development and significance during MM. Here, we show thrombocytopenia is linked to poor prognosis in MM. In addition, we identify serine, which is released from MM cells into the bone marrow microenvironment, as a key metabolic factor that suppresses megakaryopoiesis and thrombopoiesis. The impact of excessive serine on thrombocytopenia is mainly mediated through the suppression of megakaryocyte (MK) differentiation. Extrinsic serine is transported into MKs through SLC38A1 and downregulates SVIL via SAM-mediated tri-methylation of H3K9, ultimately leading to the impairment of megakaryopoiesis. Inhibition of serine utilization or treatment with TPO enhances megakaryopoiesis and thrombopoiesis and suppresses MM progression. Together, we identify serine as a key metabolic regulator of thrombocytopenia, unveil molecular mechanisms governing MM progression, and provide potential therapeutic strategies for treating MM patients by targeting thrombocytopenia.

Intestinal Klebsiella pneumoniae Contributes to Pneumonia by Synthesizing Glutamine in Multiple Myeloma.

Pneumonia accounts for a significant cause of morbidity and mortality in multiple myeloma (MM) patients. It has been previously shown that intestinal Klebsiella pneumonia (K. pneumonia) enriches in MM and promotes MM progression. However, what role the altered gut microbiota plays in MM with pneumonia remains unknown. Here, we show that intestinal K. pneumonia is significantly enriched in MM with pneumonia. This enriched intestinal K. pneumonia links to the incidence of pneumonia in MM, and intestinal colonization of K. pneumonia contributes to pneumonia in a 5TGM1 MM mice model. Further targeted metabolomic assays reveal the elevated level of glutamine, which is consistently increased with the enrichment of K. pneumonia in MM mice and patients, is synthesized by K. pneumonia, and leads to the elevated secretion of TNF-α in the lung normal fibroblast cells for the higher incidence of pneumonia. Inhibiting glutamine synthesis by establishing glnA-mutated K. pneumonia alleviates the incidence of pneumonia in the 5TGM1 MM mice model. Overall, our work proposes that intestinal K. pneumonia indirectly contributes to pneumonia in MM by synthesizing glutamine. Altogether, we unveil a gut-lung axis in MM with pneumonia and establish a novel mechanism and a possible intervention strategy for MM with pneumonia.

COX2 confers bone marrow stromal cells to promoting TNFα/TNFR1ß-mediated myeloma cell growth and adhesion.

PURPOSE: Bone marrow stromal cells (BMSCs) have been implicated in multiple myeloma (MM) progression. However, the underlying mechanisms remain largely elusive. Therefore, we aimed to explore key factors in BMSCs that contribute to MM development. METHODS: RNA-sequencing was used to perform gene expression profiling in BMSCs. Enzyme-linked immunosorbent assays (ELISAs) were performed to determine the concentrations of PGE2 and TNFα in sera and conditioned media (CM). Western blotting, qRT-PCR and IHC were used to examine the expression of cyclooxygenase 2 (COX2) in BMSCs and to analyze the regulation of TNFα by COX2. Cell growth and adhesion assays were employed to explore the function of COX2 in vitro. A 5T33MMvt-KaLwRij mouse model was used to study the effects of COX2 inhibition in vivo. RESULTS: COX2 was found to be upregulated in MM patient-derived BMSCs and to play a critical role in BMSC-induced MM cell proliferation and adhesion. Administration of PGE2 to CM derived from BMSCs promoted MM cell proliferation and adhesion. Conversely, inhibition of COX2 in BMSCs greatly compromised BMSC-induced MM cell proliferation and adhesion. PCR array-based analysis of inflammatory cytokines indicated that COX2 upregulates the expression of TNFα. Subsequent rescue assays showed that an anti-TNFα monoclonal antibody could antagonize COX2-mediated MM cell proliferation and adhesion. Administration of NS398, a specific COX2 inhibitor, inhibited in vivo tumor growth and improved the survival of 5TMM mice. CONCLUSIONS: Our results indicate that COX2 contributes to BMSC-induced MM proliferation and adhesion by increasing the secretion of PGE2 and TNFα. Targeting COX2 in BMSCs may serve as a potential therapeutic approach of treating MM.

NEK2 induces autophagy-mediated bortezomib resistance by stabilizing Beclin-1 in multiple myeloma.

NEK2 is associated with drug resistance in multiple cancers. Our previous studies indicated that high NEK2 confers inferior survival in multiple myeloma (MM); thus, a better understanding of the mechanisms by which NEK2 induces drug resistance in MM is required. In this study, we discovered that NEK2 enhances MM cell autophagy, and a combination of autophagy inhibitor chloroquine (CQ) and chemotherapeutic bortezomib (BTZ) significantly prevents NEK2-induced drug resistance in MM cells. Interestingly, NEK2 was found to bind and stabilize Beclin-1 protein but did not affect its mRNA expression and phosphorylation. Moreover, autophagy enhanced by NEK2 was significantly prevented by knockdown of Beclin-1 in MM cells, suggesting that Beclin-1 mediates NEK2-induced autophagy. Further studies demonstrated that Beclin-1 ubiquitination is decreased through NEK2 interaction with USP7. Importantly, knockdown of Beclin-1 sensitized NEK2-overexpressing MM cells to BTZ in vitro and in vivo. In conclusion, we identify a novel mechanism whereby autophagy is activated by the complex of NEK2/USP7/Beclin-1 in MM cells. Targeting the autophagy signaling pathway may provide a promising therapeutic strategy to overcome NEK2-induced drug resistance in MM.

SUV39H2 promotes colorectal cancer proliferation and metastasis via tri-methylation of the SLIT1 promoter.

Suppressor of variegation 3-9 homolog 2 (SUV39H2) is a member of the SUV39H subfamily of lysine methyltransferases. Its role in colorectal cancer (CRC) proliferation and metastasis has remained unexplored. Here, we determined that SUV39H2 was upregulated in CRC tissues compared with that in adjacent non-neoplastic tissues. Further statistical analysis revealed that high SUV39H2 expression was strongly associated with distant metastasis (P = 0.016) and TNM stage (P = 0.038) and predicted a shorter overall survival (OS; P = 0.018) and progression-free survival (PFS; P = 0.018) time for CRC patients. Both in vitro and in vivo assays demonstrated that ectopically expressed SUV39H2 enhanced CRC proliferation and metastasis, while SUV39H2 knockdown inhibited CRC proliferation and metastasis. A molecular screen of SUV39H2 targets found that SUV39H2 negatively regulated the expression of SLIT guidance ligand 1 (SLIT1). Moreover, rescue assays suggested that SLIT1 could antagonize the function of SUV39H2 in CRC. Mechanistic studies indicated that SUV39H2 can directly bind to the SLIT1 promoter, suppressing SLIT1 transcription by catalyzing histone H3 lysine 9 (H3K9) tri-methylation. In summary, we propose that SUV39H2 can predict CRC patient prognosis and stimulate CRC malignant phenotypes via SLIT1 promoter tri-methylation.

BST2 confers cisplatin resistance via NF-κB signaling in nasopharyngeal cancer.

Concurrent/adjuvant cisplatin-based chemoradiotherapy is regarded as the standard of treatment for locoregionally advanced nasopharyngeal carcinoma (NPC). However, patients who do not respond to cisplatin suffer, rather than benefit, from chemotherapy treatment. The goal of this study was to identify molecules involved in cisplatin resistance and to clarify their molecular mechanisms, which would help in the discovery of potential therapeutic targets and in developing a personalized and precise treatment approach for NPC patients. We previously generated a cisplatin-sensitive NPC cell line, S16, from CNE2 cells and found that eIF3a, ASNS and MMP19 are upregulated in S16 cells, which contributes to their cisplatin sensitivity. In this study, we found that BST2 is downregulated in cisplatin-sensitive S16 cells compared with CNE2 cells. Knockdown of BST2 in NPC cells sensitized their response to cisplatin and promoted cisplatin-induced apoptosis, whereas exogenous overexpression of BST2 increased their cisplatin resistance and inhibited cisplatin-induced apoptosis. Further investigation demonstrated that BST2-mediated cisplatin resistance depended on the activation of the NF-κB signaling pathway and consequent upregulation of anti-apoptotic genes, such as Bcl-XL and livin. Moreover, an analysis of clinical data revealed that a high BST2 level might serve as an independent indicator of poor prognosis in patients with locally advanced NPC treated with platinum-based chemoradiotherapy. These findings suggest that BST2 likely mediates platinum resistance in NPC, offering guidance for personalized and precise treatment strategies for patients with NPC.

The loss-of-function mutations and down-regulated expression of ASB3 gene promote the growth and metastasis of colorectal cancer cells.

BACKGROUND: Ankyrin repeat and SOCS box protein 3 (ASB3) is a member of ASB family and contains ankyrin repeat sequence and SOCS box domain. Previous studies indicated that it mediates the ubiquitination and degradation of tumor necrosis factor receptor 2 and is likely involved in inflammatory responses. However, its effects on oncogenesis are unclear. This study aimed to investigate the effects of ASB3 on the growth and metastasis of colorectal cancer (CRC). METHODS: We used next-generation sequencing or Sanger sequencing to detect ASB3 mutations in CRC specimens or cell lines, and used real-time quantitative polymerase chain reaction, Western blotting, and immunohistochemical or immunofluorescence assay to determine gene expression. We evaluated cell proliferation by MTT and colony formation assays, tested cell cycle distribution by flow cytometry, and assessed cell migration and invasion by transwell and wound healing assays. We also performed nude mouse experiments to evaluate tumorigenicity and hepatic metastasis potential of tumor cells. RESULTS: We found that ASB3 gene was frequently mutated (5.3%) and down-regulated (70.4%) in CRC cases. Knockdown of endogenous ASB3 expression promoted CRC cell proliferation, migration, and invasion in vitro and facilitated tumorigenicity and hepatic metastasis in vivo. Conversely, the ectopic overexpression of wild-type ASB3, but not that of ASB3 mutants that occurred in clinical CRC tissues, inhibited tumor growth and metastasis. Further analysis showed that ASB3 inhibited CRC metastasis likely by retarding epithelial-mesenchymal transition, which was characterized by the up-regulation of ß-catenin and E-cadherin and the down-regulation of transcription factor 8, N-cadherin, and vimentin. CONCLUSION: ASB3 dysfunction resulted from gene mutations or down-regulated expression frequently exists in CRC and likely plays a key role in the pathogenesis and progression of CRC.

High expression of XPA confers poor prognosis for nasopharyngeal carcinoma patients treated with platinum-based chemoradiotherapy.

In this study, we tried to explore if xeroderma pigmentosum complementation group-A (XPA) expression is likely a prognostic prediction factor for locally advanced nasopharyngeal carcinoma (NPC) patients treated with platinum-based chemoradiotherapy, which was considered to bring chemotherapy-related severe toxicity compared with radiotherapy alone. Firstly, MTT assay revealed that downregulating XPA expression in NPC HONE1 and CNE1 cells decreased IC50 of cisplatin and sensitized cells to cisplatin. XPA expression was detected by immunohistochemistry in cancer tissues from locally advanced NPC patients treated with platinum-based chemoradiotherapy. The relationships between XPA expression and clinicopathologic features, overall survival and progression-free survival of patients were evaluated. The results showed that XPA expression was not associated with clinicopathologic parameters, but was likely an independent prognostic factor for patient survival. High XPA level predicts a poor prognosis, and the prediction values were higher in subgroups of younger, higher EBV antibody titer, or treated with concurrent chemoradiotherapy. Combining XPA levels and T/N classifications, we successfully classified these patients into low, medium and high risk groups for platinum-based chemoradiotherapy. These findings suggest that XPA levels may be a potential predictor of prognosis in locally advanced NPC patients treated with platinum-based chemoradiotherapy, and helpful for selecting patients likely to need and benefit from this treatment in future.