Down-regulation of osteopontin mediates a novel mechanism underlying the cytostatic activity of TGF-β

Enhancement of differentiation and mineralization of human dental pulp stem cells via TGF-β signaling in low-level laser therapy using Er:YAG lasers

OBJECTIVES

Low-level laser therapy (LLLT) using an erbium-doped yttrium aluminum garnet (Er:YAG) laser provides a non-invasive approach applicable to various dental treatments. Here, we investigated the effects of Er:YAG laser irradiation on human dental pulp stem cells (hDPSCs) in an in vitro experiment.

METHODS

The hDPSCs were categorized into four groups: laser-irradiated with activators (VLT: activated vitamin D3, bone morphogenetic protein receptor inhibitor, and transforming growth factor-beta (TGF-β)) (LLLT(+)VLT), laser-irradiated without activators (LLLT(+)-only), non-irradiated with activators (LLLT(-)VLT), and non-irradiated without activators (control). Cell proliferation, hard tissue differentiation, TGF-β signaling pathway activity, mineralization induction, and gene expression levels were assessed using several approaches, including cell proliferation assays, ALP assays, western blotting, Alizarin Red S staining, X-ray diffraction, and quantitative polymerase chain reaction.

RESULTS

Cell proliferation was similar between the LLLT(+)-only and control groups. The ALP activity was significantly higher in LLLT(+)VLT group than in LLLT(-)VLT group (p < 0.05); however, it was suppressed by TGF-β signaling inhibitors. Western blotting showed enhanced SMAD3 phosphorylation in the LLLT(+)VLT group. The mineralization nodules and mRNA levels of matrix vesicle marker genes were significantly higher in LLLT(+)VLT group, and the nodules were partially composed of hydroxyapatite. The hard tissue formation marker gene expression in LLLT(+)VLT group was significantly higher (p < 0.05) than that in the LLLT(+)-only and control groups; however, it was unchanged or suppressed compared with that in LLLT(-)VLT group.

CONCLUSIONS

LLLT using an Er:YAG laser, combined with VLT, may promote the differentiation of hDPSCs into hard tissue-forming cells and enhance mineralization.

BET inhibitor suppresses melanoma progression via the noncanonical NF-κB/SPP1 pathway

Background: Bromodomain and extra-terminal domain (BET) inhibitors have shown profound efficacy against hematologic malignancies and solid tumors in preclinical studies. However, the underlying molecular mechanism in melanoma is not well understood. Here we identified secreted phosphoprotein 1 (SPP1) as a melanoma driver and a crucial target of BET inhibitors in melanoma. Methods: Bioinformatics analysis and meta-analysis were used to evaluate the SPP1 expression in normal tissues, primary melanoma, and metastatic melanoma. Real-time PCR (RT-PCR) and Western blotting were employed to quantify SPP1 expression in melanoma cells and tissues. Cell proliferation, wound healing, and Transwell assays were carried out to evaluate the effects of SPP1 and BET inhibitors in melanoma cells in vitro. A xenograft mouse model was used to investigate the effect of SPP1 and BET inhibitors on melanoma in vivo. Chromatin immunoprecipitation (ChIP) assay was performed to evaluate the regulatory mechanism of BET inhibitors on SPP1. Results: SPP1 was identified as a melanoma driver by bioinformatics analysis, and meta-analysis determined it to be a diagnostic and prognostic biomarker for melanoma. SPP1 overexpression was associated with poor melanoma prognosis, and silencing SPP1 suppressed melanoma cell proliferation, migration, and invasion. Through a pilot drug screen, we identified BET inhibitors as ideal therapeutic agents that suppressed SPP1 expression. Also, SPP1 overexpression could partially reverse the suppressive effect of BET inhibitors on melanoma. We further demonstrated that bromodomain-containing 4 (BRD4) regulated SPP1 expression. Notably, BRD4 did not bind directly to the SPP1 promoter but regulated SPP1 expression through NFKB2. Silencing of NFKB2 resembled the phenotype of BET inhibitors treatment and SPP1 silencing in melanoma. Conclusion: Our findings highlight SPP1 as an essential target of BET inhibitors and provide a novel mechanism by which BET inhibitors suppress melanoma progression via the noncanonical NF-κB/SPP1 pathway.

Osteopontin as a Link between Inflammation and Cancer: The Thorax in the Spotlight

The glycoprotein osteopontin (OPN) possesses multiple functions in health and disease. To this end, osteopontin has beneficial roles in wound healing, bone homeostasis, and extracellular matrix (ECM) function. On the contrary, osteopontin can be deleterious for the human body during disease. Indeed, osteopontin is a cardinal mediator of tumor-associated inflammation and facilitates metastasis. The purpose of this review is to highlight the importance of osteopontin in malignant processes, focusing on lung and pleural tumors as examples.

GDF11 exhibits tumor suppressive properties in hepatocellular carcinoma cells by restricting clonal expansion and invasion

Growth differentiation factor 11 (GDF11) has been characterized as a key regulator of differentiation in cells that retain stemness features, despite some controversies in age-related studies. GDF11 has been poorly investigated in cancer, particularly in those with stemness capacity, such as hepatocellular carcinoma (HCC), one of the most aggressive cancers worldwide. Here, we focused on investigating the effects of GDF11 in liver cancer cells. GDF11 treatment significantly reduced proliferation, colony and spheroid formation in HCC cell lines. Consistently, down-regulation of CDK6, cyclin D1, cyclin A, and concomitant upregulation of p27 was observed after 24 h of treatment. Interestingly, cell viability was unchanged, but cell functionality was compromised. These effects were potentially induced by the expression of E-cadherin and occludin, as well as Snail and N-cadherin repression, in a time-dependent manner. Furthermore, GDF11 treatment for 72 h induced that cells were incapable of sustaining colony and sphere capacity in the absent of GDF11, up to 5 days, indicating that the effect of GDF11 on self-renewal capacity is not transient. Finally, in vivo invasion studies revealed a significant decrease in cell migration of hepatocellular carcinoma cells treated with GDF11 associated to a decreased proliferation judged by Ki67 staining. Data show that exogenous GDF11 displays tumor suppressor properties in HCC cells.

Microcalcification and BMP-2 in breast cancer: correlation with clinicopathological features and outcomes

Background

Microcalcification is a very important diagnostic information in breast cancer. The purpose of this study was to determine the relationship of clinicopathological features and prognosis of breast cancer with microcalcification and to detect biomarkers related to the possible mechanisms of microcalcifications.

Patients and methods

All 529 subjects with microcalcifications were selected from patients who had been examined using breast mammography. The control group did not have detectable microcalcifications, and was matched in a ratio of 1:3. The clinicopathological factors, progression-free survival (PFS), and overall survival were evaluated by SPSS.

Results

There was a significant difference in tumor size between the two groups, with larger tumors in the calcification group than the control group, and the proportion of patients in the calcification group with tumors of >5 cm was 20.4% vs 17.2% in the control group (P=0.041). The proportion of patients with lymph node metastasis in the calcification group was higher than that of the control group (35% vs 27.9%, P=0.027). The recurrence rate in ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) patients with microcalcification was higher than that in the control group (P=0.035 and 0.044). BMP-2 expression was higher in breast cancer tissues, especially in breast cancer tissues with microcalcifications. The recurrence rate in the BMP-2(+) group was higher than that in the BMP-2(-) group both in DCIS and IDC (P=0.044 and 0.049). Microcalcifications and the positive expression of BMP-2 were independent factors affecting the PFS of the breast cancer patients.

Conclusion

Through the analysis of this study, it was found that the prognosis of the patients with microcalcification was relatively poor. BMP-2 was highly expressed in the breast cancer with microcalcification and was associated with poor prognosis.

Transforming growth factor β suppresses peroxisome proliferator-activated receptor γ expression via both SMAD binding and novel TGF-β inhibitory elements

Transforming growth factor β (TGF-β) contributes to wound healing and, when dysregulated, to pathological fibrosis. TGF-β and the anti-fibrotic nuclear hormone receptor peroxisome proliferator-activated receptor γ (PPARγ) repress each other's expression, and such PPARγ down-regulation is prominent in fibrosis and mediated, via previously unknown SMAD-signaling mechanisms. Here, we show that TGF-β induces the association of SMAD3 with both SMAD4, needed for translocation of the complex into the nucleus, and the essential context-sensitive co-repressors E2F4 and p107. The complex mediates TGF-β-induced repression by binding to regulatory elements in the target promoter. In the PPARG promoter, we found that the SMAD3-SMAD4 complex binds both to a previously unknown consensus TGF-β inhibitory element (TIE) and also to canonical SMAD-binding elements (SBEs). Furthermore, the TIE and SBEs independently mediated the partial repression of PPARG transcription, the first demonstration of a TIE and SBEs functioning within the same promoter. Also, TGF-β-treated fibroblasts contained SMAD complexes that activated a SMAD target gene in addition to those repressing PPARG transcription, the first finding of such dual activity within the same cell. These findings describe in detail novel mechanisms by which TGF-β represses PPARG transcription, thereby facilitating its own pro-fibrotic activity.

Induction of Osteopontin by Dengue Virus-3 Infection in THP-1 Cells: Inhibition of the Synthesis by Brefelamide and Its Derivative

Osteopontin (OPN) is a multifunctional matricellular protein produced by a broad range of cells including osteoclasts, macrophages, T cells, endothelial cells, and vascular smooth muscle cells. OPN modulates various physiological and pathological events such as inflammation, wound healing, and bone formation and remodeling. Dengue virus (DENV) infection causes an increase in plasma OPN levels, which is correlated with the severity of symptoms and coagulation abnormalities. DENV infection also induces OPN gene expression in human macrophages. This study investigated the inhibitory effects of brefelamide and its methyl ether derivative on DENV-3 by measuring changes in OPN levels in human THP-1 and 293T cell lines infected at different multiplicities of infection and post-infection time points. OPN mRNA expression and viral RNA were detected by reverse transcriptase quantitative real-time PCR, whereas protein level was determined by enzyme-linked immunosorbent assay. We found that viral copy number was higher in 293T than in THP-1 cells. However, THP-1 constitutively expressed higher levels of OPN mRNA and protein, which were enhanced by DENV-3 infection. Brefelamide and its derivative suppressed OPN production in DENV-3 infected THP-1 cells; the effective doses of these compounds had no effect on uninfected cells, indicating low cytotoxicity. These results suggest that brefelamide and its methyl ether derivative have therapeutic effects in preventing inflammation, coagulopathy, and fibrinolysis caused by OPN upregulation induced by DENV-3 infection.