A pan-cancer analysis of the role of argininosuccinate synthase 1 in human tumors.

Aim: There is accumulating evidence indicating that ASS1 is closely related to tumors. No pan-cancer analysis of ASS1 was available. Methods: Here we explored the gene expression and survival analysis of ASS1 across thirty-three tumors based on the datasets of the TCGA (Cancer Genome Atlas), the GEO (Gene Expression Omnibus), and the GEPIA2 (Gene Expression Profiling Interactive Analysis, version 2). Results: ASS1 is highly expressed in most normal tissues and is related to the progression of some tumors. We also report ASS1 genetic alteration and their association with tumor prognosis and report differences in ASS1 phosphorylation sites between tumors and control normal tissues. ASS1 expression was associated with the infiltration of cancer-associated fibroblasts (CAFs) for the TCGA tumors of BRCA (Breast invasive carcinoma), CESC (Cervical squamous cell carcinoma and endocervical adenocarcinoma), COAD (Colon adenocarcinoma), ESCA (Esophageal carcinoma), SKCM (Skin cutaneous melanoma), SKCM-Metastasis, TGCT (Testicular germ cell tumors), and endothelial cell for the tumors of BRCA, BRCA-Basal, CESC, ESCA, KIRC (Kidney renal clear cell carcinoma), LUAD (Lung adenocarcinoma), LUSC (Lung squamous cell carcinoma), SKCM, SKCM-Metastasis, SKCM-Primary, STAD (Stomach adenocarcinoma), and TGCT. The KEGG and GO analysis were used to analyze ASS1-related signaling pathways. Finally, we used Huh7 cell line to verify the function of ASS1 in vitro. After ASS1 knockdown using small interfering RNA (siRNA), the proliferation and invasion of Huh7 were enhanced, cyclin D1 was up-regulated, and anti-apoptotic protein bax was down-regulated, suggesting that ASS1 is a tumor suppressor gene in hepatocellular carcinoma. Conclusion: Our first pan-cancer study offers a relatively comprehensive understanding of the roles of ASS1 in different tumors.

Abnormal expression pattern of lncRNA H19 participates in multiple myeloma bone disease by unbalancing osteogenesis and osteolysis.

BACKGROUND: Accumulating genetic and epigenetic alterations in multiple myeloma (MM) have been demonstrated to be closely associated with osteolytic bone disease, generally characterized as increased osteoclast formation and decreased osteoblast activity. Previously, serum long non-coding RNA (lncRNA) H19 has been proved to be a biomarker for the diagnosis of MM. Whereas, its role in MM-associated bone homeostasis remains largely elusive. METHODS: A cohort of 42 MM patients and 40 healthy volunteers were enrolled for evaluating differential expressions of H19 and its downstream effectors. The proliferative capacity of MM cells was monitored by CCK-8 assay. Alkaline phosphatase (ALP) staining and activity detection, either with Alizarin red staining (ARS) were employed to assess osteoblast formation. Osteoblast- or osteoclast-associated gene were detected using qRT-PCR and western blot analysis. Bioinformatics analysis, RNA pull-down, RNA immunoprecipitation (RIP), and chromatin immunoprecipitation (ChIP) were subjected to verify H19/miR-532-3p/E2F7/EZH2 axis, which was accounted for epigenetic suppression of PTEN. The functional role of H19 on MM development through unbalancing osteolysis and osteogenesis was also confirmed in the murine MM model. RESULTS: Upregulation of serum H19 was observed in MM patients, suggesting its positive correlation with the poor prognosis of MM patients. Loss of H19 dramatically weakened cell proliferation of MM cells, promoted osteoblastic differentiation, and impaired osteoclast activity. While reinforced H19 exhibited the opposite effects. Akt/mTOR signaling plays an indispensable role in H19-mediated osteoblast formation and osteoclastgenesis. Mechanistically, H19 served as a sponge for miR-532-3p to upregulate E2F7, a transcriptional activator of EZH2, thereby accounting for modulating epigenetic suppression of PTEN. The in vivo experiments further validated that H19 exerted important impacts on tumor growth through breaking the balance between osteogenesis and osteolysis via Akt/mTOR signaling. CONCLUSION: Collectively, increased enrichment of H19 in MM cells exhibits an essential role in MM development by disturbing bone homeostasis.

The novel HLA-C*03:621 allele, identified by Sanger dideoxy nucleotide sequencing in a Chinese individual.

HLA-C*03:621 differs from HLA-C*03:04:01:01 by one nucleotide in exon 1.

A pan-cancer analysis of the role of hexokinase II (HK2) in human tumors.

More and more evidence show that HK2 is closely related to tumors. But no pan-cancer analysis is available. This paper aimed to explore the potential roles of HK2 across thirty-three tumors based on the datasets of the cancer genome Atlas (TCGA) and gene expression omnibus. HK2 is highly expressed in most tumors and related to the progression of some tumors. HK2 expression was associated with the infiltration of T follicular helper cells for the TCGA tumors of uveal melanoma, breast invasive carcinoma (BRCA), breast invasive carcinoma-luminalA (BRCA-LumA), head and neck squamous cell carcinoma (HNSC), head and neck squamous cell carcinoma with HPV positive (HNSC-HPV+), and cancer-associated fibroblasts for the tumors of brain lower grade glioma and stomach adenocarcinoma. Our first pan-cancer study offers a relatively comprehensive understanding of the roles of HK2 in different tumors.

A transgene-encoded truncated human epidermal growth factor receptor for depletion of anti- B-cell maturation antigen CAR-T cells.

BACKGROUND: Chimeric antigen receptor T cells (CAR-T) against B-cell maturation antigen (BCMA) has been used to treat multiple myeloma (MM). CAR-T cells co-expressing a truncated human EGFR (tEGFR) has been proposed for in vivo cell ablation. METHODS: We designed and tested a novel anti-BCMA CAR. We transduced T cells with retroviral vectors encoding CAR and tEGFR. The anti-BCMA-CAR-transduced T cells were evaluated for the functions including cytokine production, proliferation, cytotoxicity, and in vivo tumor eradication of BCMA. Cetuximab was used for in vivo cell ablation. RESULTS: The CAR-T cells could specifically recognize BCMA, and anti-BCMA CAR-T cells could exhibit interferon-γ and cytotoxicity specifically produced by BCMA and eradicate tumor in vivo. Cetuximab could mediate antibody-dependent cellular cytotoxicity and in vivo elimination. CONCLUSIONS: We confirm that BCMA is a suitable target for CAR- T cells and tEGFR is a effective tool for cellular ablation.

Expression and role of fibroblast activation protein α in acute myeloid leukemia.

Currently, the prognosis of acute myeloid leukemia (AML) is poor. In the AML microenvironment, bone marrow (BM) mesenchymal stem cells (BMMSCs) serve an important role in protecting AML cells from chemotherapy­induced apoptosis. The present study aimed to evaluate the expression of fibroblast activation protein α (FAPα) in BMMSCs and BM biopsy samples via flow cytometry, reverse transcription­quantitative PCR and immunohistochemistry, as well as to identify the correlation between the expression of FAPα in BM with clinical parameters and survival of newly diagnosed patients with AML. Subsequently, the protective effect of FAPα on Cytosine arabinoside (Ara­C)­induced apoptosis in Kasumi­1 cells was investigated via small interfering (si)RNA, and its underlying mechanism was examined by western blotting. The results demonstrated significant differences in FAPα expression in BMMSCs and BM biopsy samples between patients with AML and healthy donors. Furthermore, BMMSCs protected Ara­C­induced Kasumi­1 cells from apoptosis, and knockdown of FAPα using siRNA decreased this protection. It was found that Kasumi­1 cells expressed ß­catenin, which could be inhibited by Ara­C, and ß­catenin expression was significantly activated when co­cultured with BMMSCs, even in the presence of Ara­C. Knockdown of FAPα with siRNA significantly suppressed the expression of ß­catenin. The present results indicated that FAPα serves an important role in the AML BM microenvironment, and that increased expression of FAPα in BM may be a poor prognostic factor in patients with AML. Moreover, the current findings demonstrated that BMMSCs protected AML cells from apoptosis, which was in part contributed by FAPα, and may occur via the ß­catenin signaling pathway.

Long Noncoding RNA H19 Promotes Tumorigenesis of Multiple Myeloma by Activating BRD4 Signaling by Targeting MicroRNA 152-3p.

Multiple myeloma (MM) accounts for over twenty percent of hematological cancer-related death worldwide. Long noncoding RNA (lncRNA) H19 is associated with multiple tumorigenesis and is increased in MM, but the underlying mechanism of H19 in MM is unclear. In this study, the expression of H19, microRNA 152-3p (miR-152-3p), and BRD4 in MM patients was evaluated by quantitative real-time PCR (qRT-PCR) and Western blotting. Colony formation and flow cytometry analysis were used to determine the effects of H19 and miR-152-3p on MM cell proliferation, apoptosis, and cell cycle. A luciferase reporter assay was conducted to confirm the interaction among H19, miR-152-3p, and BRD4. A nude mouse xenograft model was established, and the cell proliferation and apoptosis were evaluated by immunohistochemistry (IHC) staining and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling assay. We found that levels of H19 and BRD4 were upregulated and the expression of miR-152-3p was downregulated in MM patients. Dual luciferase reporter assay showed H19 targeted miR-152-3p to promote BRD4 expression. Knockdown of H19 repressed proliferation and enhanced apoptosis and cell cycle G1 arrest by upregulating miR-152-3p in MM cells. Furthermore, H19 knockdown suppressed the growth of xenograft tumor, reduced Ki-67 and BRD4 levels, and increased cell apoptosis in xenograft tumor tissues. Taking these results together, H19 knockdown suppresses MM tumorigenesis via inhibiting BRD4-mediated cell proliferation through targeting miR-152-3p, implying that H19 is a promising biomarker and drug target for MM.

Ibrutinib in CLL/SLL: From bench to bedside (Review).

B-cell receptor (BCR) signaling is important for the development and maturation of normal B-cells and plays a key role in B-cell malignancies. Bruton's tyrosine kinase (BTK), a crucial terminal kinase enzyme in BCR signaling, has emerged as an attractive target and has been successfully applied in the treatment of hematological malignancies. Ibrutinib, a BTK inhibitor, has demonstrated marked efficacy and tolerability in treatment-naïve, relapsed/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and mantle cell lymphoma (MCL). Ibrutinib has been approved by the Food and Drug Administration (FDA) for the treatment of CLL/SLL, MCL, marginal zone lymphoma and Waldenström macroglobulinemia and by the China FDA for the treatment of CLL/SLL and MCL. Clinical trials of ibrutinib, as a single agent or combined with chemoimmunotherapy and other promising novel agents in the treatment of B-cell malignancy therapy, such as diffuse large B-cell lymphoma, follicular lymphoma, multiple myeloma, primary and secondary CNS lymphoma and acute lymphoblastic leukemia, T-cell lymphoma and myelodysplastic syndrome, are ongoing (https://clinicaltrials.gov/). The aim of the present review was mainly to cover the clinical developments regarding the use of ibrutinib in the treatment of CLL/SLL, as well as its safety and toxicity profile.

The potential therapeutic benefit of resveratrol on Th17/Treg imbalance in immune thrombocytopenic purpura.

BACKGROUND: Immune thrombocytopenic purpura (ITP) is an autoimmune disease characterized by the restrained production of new platelets and the persistent reduction of existing platelets. An imbalance between Th17 and Treg cells is associated with a decrease in platelets. However, few therapeutic strategies aim to modulate this imbalance between Th17 and Treg cells in ITP. METHODS: ITP patients and healthy controls were enrolled in this study. Quantitative real-time PCR (qRT-PCR) and Western blotting were performed to measure the expression of the aryl hydrocarbon receptor (AhR), cytochrome P450 family 1 member A1 (CYP1A1), RAR-related orphan receptor gamma t (ROR-γt) and forkhead-box P3 (Foxp3). ELISA was employed to measure the secretion of IL-17A, IL-22 and IL-10. Flow cytometry was used to assess the proportion of Th17 and Treg cells. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to measure cell viability. RESULTS: The proportion of Th17 cells and the secretion of the pro-inflammatory cytokines IL-17A and IL-22 were both elevated, whereas the proportion of Treg cells and the production of the anti-inflammatory cytokine IL-10 were both reduced in ITP patients compared to healthy controls. The ratio of Th17/Treg cells and the expression of IL-17A and IL-22 displayed a positive correlation with the severity of ITP. Low and moderate concentrations of resveratrol did not affect the viability of CD4+ T cells from ITP patients but repressed Th17 differentiation and promoted Treg differentiation. Moreover, resveratrol could markedly downregulate the production of IL-17A and IL-22 and upregulate the secretion of IL-10 in CD4+ T cells in a time- and concentration-dependent manner. Mechanistic studies revealed that resveratrol exerted its beneficial function mainly through suppressing the AhR pathway, which led to the impaired expression of ROR-γt and reduced secretion of IL-17A and IL-22, as well as enhanced expression of Foxp3 and augmented secretion of IL-10. The induction of AhR by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in CD4+ T cells led to a Th17/Treg imbalance and the upregulation of IL-17A and IL-22, an effect that could be reversed by resveratrol treatment. CONCLUSION: This study revealed that resveratrol reversed the Th17/Treg imbalance by a mechanism involving the suppression of the AhR pathway. Since ITP is characterized by a Th17/Treg imbalance, resveratrol might be beneficial for the treatment of this condition.

I-BET151 suppresses osteoclast formation and inflammatory cytokines secretion by targetting BRD4 in multiple myeloma.

Background: Multiple myeloma (MM) is an incurable hematologic cancer, accompanied by excessive osteoclast formation and inflammatory cytokine secretion. The mechanisms by which bromodomain and extra-terminal domain (BET) protein inhibitor I-BET151 regulates osteoclast differentiation and inflammatory cytokine secretion in MM are largely unknown. Methods: The isolated peripheral blood mononuclear cells from normal or patients with MM were treated with receptor activator of NF-κB ligand (RANKL) and M-CSF to induce osteoclast differentiation. RAW 264.7 cells were treated with RANKL. I-BET151 was applied to investigate the effects of BRD4 inhibition on osteoclast formation and inflammatory cytokine secretion. Osteoclast formation was determined by tartrate-resistant acid phosphatase (TRACP) staining. The expression of osteoclast-specific genes TRACP, matrix metalloproteinase-9 (MMP-9), cathepsin K (Ctsk), and c-Src was tested using quantitative real-time PCR. And the level of inflammatory cytokines TNF-α, IL-1ß, and IL-6 was assessed by ELISA. Tumor necrosis factor receptor-associated factor 6 (TRAF6), BRD4, nuclear and cytoplasm p65, IκB-α, nuclear factor of activated T cells cytoplasmic (NFATc1), and osteoprotegerin (OPG) expression were measured by Western blotting. RNAi technology was applied to knock down BET family member BRD4. Results: I-BET151 dose-dependently suppressed osteoclast formation, inhibited the levels of osteoclast-specific genes TRACP, MMP-9, Ctsk, and c-Src and inflammatory cytokines TNF-α, IL-1ß, and IL-6 secretion in peripheral blood mononuclear cells and RAW 264.7. I-BET151 inhibited the protein levels of BRD4 and NFATc1, increased OPG expression, and suppressed IκB-α degradation and p65 nuclear translocation. Further, the effects of I-BET151 on osteoclast formation, osteoclast-specific genes expression, inflammatory cytokine secretion, and NF-κB inhibition were promoted by BRD4 knockdown. Conclusion: I-BET151 inhibits osteoclast formation and inflammatory cytokine secretion by targetting BRD4-mediated RANKL-NF-κB signal pathway and BRD4 inhibition might be beneficial for MM treatment.

Role of interleukin-32 in cancer biology.

Interleukin-32 (IL-32), a novel proinflammatory cytokine, is highly expressed in various cancer tissues and in established cancer cell lines. IL-32 has been revealed to serve a crucial role in human cancer development, including tumour initiation, proliferation and maintenance. The expression of IL-32 is regulated by numerous factors, including genetic variations, hypoxia and acidosis in the tumour microenvironment. Understanding the underlying mechanisms of IL-32 expression and its function are critical for the discovery of novel therapeutic strategies that target IL-32. This is a review of the current literature on the regulation and function of IL-32 in cancer progression, focusing on the molecular pathways linking IL-32 and tumour development.

Metformin and cancer: An existing drug for cancer prevention and therapy.

Metformin is a standard clinical drug used to treat type 2 diabetes mellitus (T2DM) and polycystic ovary syndrome. Recently, epidemiological studies and meta-analyses have revealed that patients with T2DM have a lower incidence of tumor development than healthy controls and that patients diagnosed with cancer have a lower risk of mortality when treated with metformin, demonstrating an association between metformin and tumorigenesis. In vivo and in vitro studies have revealed that metformin has a direct antitumor effect, which may depress tumor proliferation and induce the apoptosis, autophagy and cell cycle arrest of tumor cells. The mechanism underpinning the antitumor effect of metformin has not been well established. Studies have demonstrated that reducing insulin and insulin-like growth factor levels in the peripheral blood circulation may lead to the inhibition of phosphoinositide 3-kinase/Akt/mechanistic target of rapamycin (mTOR) signaling or activation of AMP-activated protein kinase, which inhibits mTOR signaling, a process that may be associated with the antitumor effect of metformin. The present review primarily focuses on the recent progress in understanding the function of metformin in tumor development.

Interleukin-32α promotes the proliferation of multiple myeloma cells by inducing production of IL-6 in bone marrow stromal cells.

Multiple myeloma (MM) is a malignant plasma disease closely associated with inflammation. In MM bone marrow microenvironment, bone marrow stromal cells (BMSCs) are the primary source of interleukin-6 (IL-6) secretion, which promotes the proliferation and progression of MM cells. However, it is still unknown how the microenvironment stimulates BMSCs to secrete IL-6. Interleukin-32 (IL-32) is a newly identified pro-inflammatory factor. It was reported that in solid tumors, IL-32 induces changes in other inflammatory factors including IL-6, IL-10, and TNF-α. The aim of this study was to investigate the expression of IL-32 and the role of IL-32 in the MM bone marrow microenvironment. Our data illustrate that MM patients have higher expression of IL-32 than healthy individuals in both bone marrow and peripheral blood. We used ELISA and qRT-PCR to find that malignant plasma cells are the primary source of IL-32 production in MM bone marrow. ELISA and Western blot analysis revealed that recombinant IL-32α induces production of IL-6 in BMSCs by activating NF-κB and STAT3 signaling pathways, konckdown of IL-32 receptor PR3 inhibit this process. Knockdown of IL-32 by shRNA decreased the proliferation in MM cells that induced by BMSCs. In conclusion, IL-32 secreted from MM cells has paracrine effect to induce production of IL-6 in BMSCs, thus feedback to promote MM cells growth.

I­BET151 inhibits osteoclastogenesis via the RANKL signaling pathway in RAW264.7 macrophages.

Excessive bone resorption mediated by osteoclasts may lead to the risk of various lytic bone diseases. In the present study, the effects of I­BET151, a bromodomain and extra terminal domain protein inhibitor, on osteoclastogenesis in RAW264.7 cells and the underlying mechanism of this process was investigated. Cells were divided into 6 groups, including the control group, receptor activator of nuclear factor­κB ligand (RANKL) group and 4 other groups containing RANKL and I­BET151 at different concentrations. Tartrate­resistant acid phosphatase (TRACP) staining was used to observe the effect of I­BET151 on osteoclastogenesis and the number of TRACP positive multinucleated cells was calculated. Western blotting was used to evaluate the expression of tumor necrosis factor receptor associated factor (TRAF6), nuclear factor of activated T­cells cytoplasmic 1 (NFATcl), transcription factor p65 (p65), nuclear factor of κ light polypeptide gene enhancer in B­cells inhibitor­α (IκB­α), extracellular signal­regulated kinase, Jun N­terminal kinase (JNK) and p38. mRNA expression levels of osteoclast specific genes TRACP, matrix metalloproteinase­9 (MMP9), cathepsin K (CtsK) and proto­oncogene tyrosine­protein kinase Src (c­Src) were measured using the reverse transcription­quantitative polymerase chain reaction (RT­qPCR). TRACP staining results demonstrated that I­BET151 inhibited osteoclastogenesis induced by RANKL and the inhibition was dose dependent. TRACP multinucleated positive cells were significantly decreased when treated with I­BET151 compared with the RANKL group. The inhibitory effect on TRAF6 was significant when concentrations of 100 and 200 nM I­BET151 were used, and NFATcl was significantly inhibited when a concentration of 200 nM was used compared with the RANKL group, in a dose-dependent manner. Nuclear translocation of p65 was significantly inhibited by I­BET151 at all concentrations. The degradation of IκB­α, and phosphorylation of JNK and p38 were also significantly inhibited by I­BET151, with the exception of the expression of IκB­α following treatment with 50 nM I­BET151. The RT­qPCR results revealed that osteoclast­specific genes TRACP, MMP9, CtsK and c­Src were all dose­dependently inhibited by I­BET151, except for CtsK. In conclusion, I­BET151 may significantly suppress the osteoclastogenesis of RAW264.7 cells via the RANKL signaling pathway.

Quercetin induces cell apoptosis of myeloma and displays a synergistic effect with dexamethasone in vitro and in vivo xenograft models.

Quercetin, a kind of dietary flavonoid, has shown its anticancer activity in many kinds of cancers including hematological malignancies (acute myelogenous leukemia, chronic myelogenous leukemia, chronic lymphocytic leukemia, and MM) in vitro and in vivo. However, its effects on MM need further investigation. In this study, MM cell lines were treated with quercetin alone or in combination with dexamethasone. In order to observe the effects in vivo, a xenograft model of human myeloma was established. Quercetin inhibited proliferation of MM cells (RPMI8226, ARP-1, and MM.1R) by inducing cell cycle arrest in the G2/M phase and apoptosis. Western blot showed that quercetin downregulated c-myc expression and upregulated p21 expression. Quercetin also activated caspase-3, caspase-9, and poly(ADP-ribose)polymerase 1. Caspase inhibitors partially blocked apoptosis induced by quercetin. Furthermore, quercetin combined with dexamethasone significantly increased MM cell apoptosis. In vivo xenograft models, quercetin obviously inhibited tumor growth. Caspase-3 was activated to a greater extent when quercetin was combined with dexamethasone. In conclusion, quercetin alone or in combination with dexamethasone may be an effective therapy for MM.

Fibroblast activation protein α in tumor microenvironment: recent progression and implications (review).

Accumulated evidence has demonstrated that the microenvironment of a given tumor is important in determining its drug resistance, tumorigenesis, progression and metastasis. These microenvironments, like tumor cells, are vital targets for cancer therapy. The cross-talk between tumor cells and cancer-associated fibroblasts (CAFs, alternatively termed activated fibroblasts) is crucial in regulating the drug resistance, tumorigenesis, neoplastic progression, angiogenesis, invasion and metastasis of a tumor. Fibroblast activation protein α (FAPα) is a transmembrane serine protease and is highly expressed on CAFs present in >90% of human epithelial neoplasms. FAPα activity, alongside that of gelatinase and type I collagenase, has become increasingly important in cancer therapy due to its effectiveness in modulating tumor behavior. In this review, recent progression in the knowledge of the role of FAPα in tumor microenvironments is discussed.

Metformin displays anti-myeloma activity and synergistic effect with dexamethasone in in vitro and in vivo xenograft models.

Epidemiologic studies and meta-analyses have suggested that patients with type 2 diabetes mellitus (T2DM) have a higher incidence of malignancies, including myeloma. Metformin is a widely prescribed antidiabetic drug. Recently, researchers have shown that metformin has direct anticancer activity against many tumor cell lines, mainly through activating AMP-activated protein kinase (AMPK) or reducing the blood insulin level. In the present study, we investigated whether metformin exerts an anti-myeloma effect in in vitro and in vivo xenograft models and explored the underlying mechanism. We found that metformin can inhibit proliferation of MM cells by inducing apoptosis and cell cycle arrest in the G0/G1 phase. Western blot showed that metformin activated caspase 3, caspase 9, PARP-1, Bak, and p21 and inactivated Mcl-1, HIAP-1, cyclin D1, CDK4, and CDK6. Metformin inhibited the expression of insulin growth factor-I receptor (IGF-IR), and phosphatidyl inositol 3-kinase (PI3K), protein kinase B (PKB/AKT) and the downstream mammalian target of rapamycin (mTOR). IGF-I blocked metformin-induced MM cell apoptosis and reactivation of the PI3K/AKT/mTOR signaling pathway. Metformin also demonstrated synergistic activity with dexamethasone but not bortezomib to eradicate MM cells in vitro and in vivo, especially in MM.1S cells. We conclude that metformin inhibits MM cell proliferation through the IGF-1R/PI3K/AKT/mTOR signaling pathway. Metformin and dexamethasone combination therapy may be an option for MM treatment.

Fibroblast activation protein protects bortezomib-induced apoptosis in multiple myeloma cells through ß-catenin signaling pathway.

Multiple myeloma (MM) is a malignant plasma cells proliferative disease. The intricate cross-talk of myeloma cells with bone marrow microenvironment plays an important role in facilitating growth and survival of myeloma cells. Bone marrow mesenchymal stem cells (BMMSCs) are important cells in MM microenvironment. In solid tumors, BMMSCs can be educated by tumor cells to become cancer-associated fibroblasts (CAFs) with high expression of fibroblast activation protein (FAP). FAP was reported to be involved in drug resistance, tumorigenesis, neoplastic progression, angiogenesis, invasion, and metastasis of tumor cells. However, the expression and the role of FAP in MM bone marrow microenvironment are still less known. The present study is aimed to investigate the expression of FAP, the role of FAP, and its relevant signaling pathway in regulating apoptosis induced by bortezomib in MM cells. In this study, our data illustrated that the expression levels of FAP were not different between the cultured BMMSCs isolated from MM patients and normal donors. The expression levels of FAP can be increased by tumor cells conditioned medium (TCCM) stimulation or coculture with RPMI8226 cells. FAP has important role in BMMSCs mediated protecting MM cell lines from apoptosis induced by bortezomib. Further study showed that this process may likely through ß-catenin signaling pathway in vitro. The activation of ß-catenin in MM cell lines was dependent on direct contact with BMMSCs other than separated by transwell or additional condition medium from BMMSCs and cytokines.

TLR4 inactivation protects from graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

Graft-versus-host disease (GVHD) is the most common complication after hematopoietic stem cell transplantation. To clarify the role of Toll-like receptor 4 (TLR4), which is a major receptor for bacterial lipopolysaccharides (LPS), in the development of acute GVHD, we used a TLR4-knockout (TLR4(-/-)) mouse GVHD model and analyzed the underlying immunological mechanisms. When TLR4(-/-) mice were used as bone marrow and splenocyte cell graft donors or recipients, GVHD symptom occurrence and mortality were delayed compared to wild-type (TLR4(+/+)) mice. In addition, histopathological analyses revealed that in TLR4(-/-)→BALB/c chimeras, liver and small intestine tissue damage was reduced with minimal lymphocytic infiltration. In contrast to TLR4(+/+), TLR4(-/-) mice dendritic cells did not express CD80, CD86, CD40, MHC-II or IL-12 during LPS induction and remained in an immature state. Furthermore, the ability of TLR4(-/-) mice spleen dendritic cells to promote allogeneic T-cell proliferation and, in particular, T-helper cell 1 (Th1) development was obviously attenuated compared with TLR4(+/+) mice dendritic cells, and the levels of interferon-γ (IFN-γ) and IL-10, Th2-cell specific cytokines, were significantly higher in the serum of TLR4(-/-)→BALB/c than in TLR4(+/+)→BALB/c chimeric mice. Overall, our data revealed that TLR4 may play a role in the pathogenesis of GVHD and that targeted TLR4 gene therapy might provide a new treatment approach to reduce the risk of GVHD.