Cytoplasmic and/or nuclear accumulation of the beta-catenin protein is a frequent event in human osteosarcoma

LncRNAs as potential prognosis/diagnosis markers and factors driving drug resistance of osteosarcoma, a review

Osteosarcoma is a common malignancy that often occurs in children, teenagers and young adults. Although the treatment strategy has improved, the results are still poor for most patients with metastatic or recurrent osteosarcomas. Therefore, it is necessary to identify new and effective prognostic biomarkers and therapeutic targets for diseases. Human genomes contain lncRNAs, transcripts with limited or insufficient capacity to encode proteins. They have been implicated in tumorigenesis, particularly regarding the onset, advancement, resistance to treatment, recurrence and remote dissemination of malignancies. Aberrant lncRNA expression in osteosarcomas has been reported by numerous researchers; lncRNAs have the potential to exhibit either oncogenic or tumor-suppressing behaviors and thus, to govern the advancement of this skeletal cancer. They are suspected to influence osteosarcoma cell growth, replication, invasion, migration, remote dissemination and programmed cell death. Additionally, they have been recognized as clinical markers, and may participate in the development of multidrug resistance. Therefore, the study of lncRNAs in the growth, metastasis, treatment and prognosis of osteosarcoma is very important for the active prevention and treatment of osteosarcoma. Consequently, this work reviews the functions of lncRNAs.

Identifying Genetic Signatures Associated with Oncogene-Induced Replication Stress in Osteosarcoma and Screening for Potential Targeted Drugs

Osteosarcoma is the most common type of primary malignant bone tumor. Due to the lack of selectivity and sensitivity of chemotherapy drugs to tumor cells, coupled with the use of large doses, chemotherapy drugs often have systemic toxicity. The use of modern sequencing technology to screen tumor markers in a large number of tumor samples is a common method for screening highly specific and selective anti-tumor drugs. This study aims to identify potential biomarkers using the latest reported gene expression signatures of oncogene-induced replication stress (ORS) in aggressive cancers, and potential anti-osteosarcoma drugs were screened in different drug databases. In this study, we obtained 89 osteosarcoma-related samples in the TARGET database, all of which included survival information. According to the median expression of each of six reported ORS gene markers (NAT10/DDX27/ZNF48/C8ORF33/MOCS3/MPP6), we divided 89 osteosarcoma gene expression datasets into a high expression group and a low expression group and then performed a differentially expressed gene (DEG) analysis. The coexisting genes of 6 groups of DEGs were used as replication stress-related genes (RSGs) of osteosarcoma. Then, key RSGs were screened using LASSO regression, a Cox risk proportional regression prognostic model and a tenfold cross-validation test. GSE21257 datasets collected from the Gene Expression Omnibus (GEO) database were used to verify the prognostic model. The final key RSGs selected were used in the L1000PWD and DGIdb databases to mine potential drugs. After further validation by the prognostic model, we identified seven genes associated with ORS in osteosarcoma as key RSGs, including transcription factor 7 like 2 (TCF7L2), solute carrier family 27 member 4 (SLC27A4), proprotein convertase subtilisin/kexin type 5 (PCSK5), nucleolar protein 6 (NOL6), coiled-coil-coil-coil-coil-helix domain containing 4 (CHCHD4), eukaryotic translation initiation factor 3 subunit B (EIF3B), and synthesis of cytochrome C oxidase 1 (SCO1). Then, we screened the seven key RSGs in two drug databases and found six potential anti-osteosarcoma drugs (D GIdb database: repaglinide, tacrolimus, sirolimus, cyclosporine, and hydrochlorothiazide; L1000PWD database: the small molecule VU-0365117-1). Seven RSGs (TCF7L2, SLC27A4, PCSK5, NOL6, CHCHD4, EIF3B, and SCO1) may be associated with the ORS gene signatures in osteosarcoma. Repaglinide, tacrolimus, sirolimus, cyclosporine, hydrochlorothiazide and the small molecule VU-0365117-1 are potential therapeutic drugs for osteosarcoma.

Clinicopathological significance of SOX9 and β-catenin expression in pre-neoadjuvant chemotherapy cases of osteosarcoma: molecular and immunohistochemical study

The molecular pathogenesis of osteosarcoma (OS), the most frequent primary malignant bone tumor of all age groups, is still obscure. Since multidrug chemotherapeutic regimens were introduced in the 1970s, survival rates have been stationary. The Wnt-β-catenin signaling cascade and SOX9 have a significant contribution to skeletal growth, development, and tumorigenesis. In the present work, an attempt was made to examine the role and clinicopathological significance of β-catenin and SOX9 in 46 cases of pre-neoadjuvant chemotherapy OS tissues compared to 10 cases of non-neoplastic bone. The mRNA levels of both markers were assessed by qRT-PCR, and protein levels of β-catenin were analyzed by immunohistochemistry. The results were correlated with different clinicopathological parameters. SOX9 mRNA levels were significantly elevated in OS compared to non-neoplastic bone, and higher levels were significantly associated with the occurrence of fluid-fluid levels (indicating blood-containing cystic spaces) and osteolytic radiological pattern. Although β-catenin mRNA and protein levels were higher in OS compared to non-neoplastic bone, only the protein levels reached statistical significance. Higher β-catenin mRNA levels were significantly associated with tumor size, while higher protein levels were significantly associated with the histologic subtype, mitotic count, and radiological pattern. No significant association was noted with any of the other evaluated parameters. OS showing higher SOX9 mRNA expression and lower β-catenin mRNA and protein expression exhibited longer estimated overall survival times approaching statistical significance. To conclude, while high expression of β-catenin and SOX9 suggests their possible involvement in OS development, their prognostic role may need further research.

Zinc oxide nanoparticles inhibit osteosarcoma metastasis by downregulating β-catenin via HIF-1α/BNIP3/LC3B-mediated mitophagy pathway

Osteosarcoma (OS) therapy faces many challenges, especially the poor survival rate once metastasis occurs. Therefore, it is crucial to explore new OS treatment strategies that can efficiently inhibit OS metastasis. Bioactive nanoparticles such as zinc oxide nanoparticles (ZnO NPs) can efficiently inhibit OS growth, however, the effect and mechanisms of them on tumor metastasis are still not clear. In this study, we firstly prepared well-dispersed ZnO NPs and proved that ZnO NPs can inhibit OS metastasis-related malignant behaviors including migration, invasion, and epithelial-mesenchymal transition (EMT). RNA-Seqs found that differentially expressed genes (DEGs) in ZnO NP-treated OS cells were enriched in wingless/integrated (Wnt) and hypoxia-inducible factor-1 (HIF-1) signaling pathway. We further proved that Zn²⁺ released from ZnO NPs induced downregulation of β-catenin expression via HIF-1α/BNIP3/LC3B-mediated mitophagy pathway. ZnO NPs combined with ICG-001, a β-catenin inhibitor, showed a synergistic inhibitory effect on OS lung metastasis and a longer survival time. In addition, tissue microarray (TMA) of OS patients also detected much higher β-catenin expression which indicated the role of β-catenin in OS development. In summary, our current study not only proved that ZnO NPs can inhibit OS metastasis by degrading β-catenin in HIF-1α/BNIP3/LC3B-mediated mitophagy pathway, but also provided a far-reaching potential of ZnO NPs in clinical OS treatment with metastasis.

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Zn²⁺ released from bioactive ZnO NPs trigger OS metastasis inhibition.

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ZnO NPs inhibit OS metastasis through degrading β-catenin expression via HIF-1α/BNIP3/LC3B-mediated mitophagy pathway.

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Tissue microarray of OS patients detected higher β-catenin expression which confirmed the potential of ZnO NPs in clinical.

Role of Periostin Expression in Canine Osteosarcoma Biology and Clinical Outcome

Periostin is a matricellular protein important in regulating bone, tooth, and cardiac development. In pathologic conditions, periostin drives allergic and fibrotic inflammatory diseases and is also overexpressed in certain cancers. Periostin signaling in tumors has been shown to promote angiogenesis, metastasis, and cancer stem cell survival in rodent models, and its overexpression is associated with poor prognosis in human glioblastoma. However, the role of periostin in regulating tumorigenesis of canine cancers has not been evaluated. Given its role in bone development, we sought to evaluate mRNA and protein expression of periostin in canine osteosarcoma (OS) and assess its association with patient outcome. We validated an anti-human periostin antibody cross-reactive to canine periostin via western blot and immunohistochemistry and evaluated periostin expression in microarray data from 49 primary canine OS tumors and 8 normal bone samples. Periostin mRNA was upregulated greater than 40-fold in canine OS tumors compared to normal bone and was significantly correlated with periostin protein expression based on quantitative image analysis. However, neither periostin mRNA nor protein expression were associated with time to metastasis in this cohort. Gene Set Enrichment Analysis demonstrated significant enhancement of pro-tumorigenic pathways including canonical WNT signaling, epithelial-mesenchymal transition, and angiogenesis in periostin-high tumors, while periostin-low tumors demonstrated evidence of heightened antitumor immune responses. Overall, these data identify a novel antibody that can be used as a tool for evaluation of periostin expression in dogs and suggest that investigation of Wnt pathway-targeted drugs in periostin overexpressing canine OS may be a potential therapeutic target.

An Immunohistochemical Study of β-catenin Expression and Immune Cell Population in Metastatic Carcinoma to the Liver

The liver is the commonest site of cancer metastasis. In this study, we asked whether the immune tumor microenvironment in liver metastases was governed by the β-catenin activation status of the tumor. To this end, we analyzed CD8 and FoxP3 immunohistochemical expression against β-catenin expression status of the tumor in a cohort of 52 liver samples with metastatic carcinoma. The results showed that colorectal primary constituted the largest proportion of metastatic carcinoma showing β-catenin overexpression. Intra-tumoral CD8 count was lower and FoxP3 count was higher when compared with the non-tumoral liver parenchyma. β-catenin overexpression was associated with a lower CD8 count in the tumor region (p = 0.003). In summary, our findings are in support of an altered immune tumor microenvironment vs. the non-tumor liver tissues in the metastatic site. Suppression of CD8 count was associated with activated Wnt/β-catenin signaling in the metastatic tumor.

Pathogenesis and Current Treatment of Osteosarcoma: Perspectives for Future Therapies

Osteosarcoma is the most common primary malignant bone tumor in children and young adults. The standard-of-care curative treatment for osteosarcoma utilizes doxorubicin, cisplatin, and high-dose methotrexate, a standard that has not changed in more than 40 years. The development of patient-specific therapies requires an in-depth understanding of the unique genetics and biology of the tumor. Here, we discuss the role of normal bone biology in osteosarcomagenesis, highlighting the factors that drive normal osteoblast production, as well as abnormal osteosarcoma development. We then describe the pathology and current standard of care of osteosarcoma. Given the complex heterogeneity of osteosarcoma tumors, we explore the development of novel therapeutics for osteosarcoma that encompass a series of molecular targets. This analysis of pathogenic mechanisms will shed light on promising avenues for future therapeutic research in osteosarcoma.

Unraveling the chaotic genomic landscape of primary and metastatic canine appendicular osteosarcoma with current sequencing technologies and bioinformatic approaches

Osteosarcoma is a rare disease in children but is one of the most common cancers in adult large breed dogs. The mutational landscape of both the primary and pulmonary metastatic tumor in two dogs with appendicular osteosarcoma (OSA) was comprehensively evaluated using an automated whole genome sequencing, exome and RNA-seq pipeline that was adapted for this study for use in dogs. Chromosomal lesions were the most common type of mutation. The mutational landscape varied substantially between dogs but the lesions within the same patient were similar. Copy number neutral loss of heterozygosity in mutant TP53 was the most significant driver mutation and involved a large region in the middle of chromosome 5. Canine and human OSA is characterized by loss of cell cycle checkpoint integrity and DNA damage response pathways. Mutational profiling of individual patients with canine OSA would be recommended prior to targeted therapy, given the heterogeneity seen in our study and previous studies.

Usefulness of β-catenin expression in the differential diagnosis of osteosarcoma, osteoblastoma, and chondroblastoma

The aim of this study is to assess the usefulness of beta-catenin immunohistochemical expression in the differential diagnosis of osteoid-producing primary tumors of bone. Seventy cases of osteoid-producing tumors of bone (24 conventional osteosarcomas, 18 osteoblastomas, 13 osteoblastoma-like osteosarcomas, 10 chondroblastomas, and 5 chondroblastoma-like osteosarcomas) diagnosed at Istituto Ortopedico Rizzoli were reviewed and evaluated for the intensity, extension, and subcellular distribution of immunohistochemical expression of beta-catenin. A majority of cases (73%, 51 cases) exhibited cytoplasmic and/or membranous positivity in varied degrees of intensity and proportion of positive cells, in the absence of nuclear staining. Fifteen cases (21%) were completely negative, including two osteoblastomas, five chondroblastomas, three conventional osteosarcomas, four osteoblastoma-like osteosarcomas, and one chondroblastoma-like osteosarcoma. A minority of cases (6%) including three osteoblastoma-like osteosarcomas and one osteoblastoma showed focal nuclear beta-catenin positivity with or without concomitant cytoplasmic staining. In the current series, beta-catenin showed not to be useful in the differential diagnosis of osteoid-producing primary bone tumors.

Long non-coding RNA (LncRNA) HOTAIR regulates BMP9-induced osteogenic differentiation by targeting the proliferation of mesenchymal stem cells (MSCs)

Long non-coding RNAs are important regulators of biological processes, but their roles in the osteogenic differentiation of mesenchymal stem cells (MSCs) remain unclear. Here we investigated the role of murine HOX transcript antisense RNA (mHotair) in BMP9-induced osteogenic differentiation of MSCs using immortalized mouse adipose-derived cells (iMADs). Touchdown quantitative polymerase chain reaction analysis found increased mHotair expression in bones in comparison with most other tissues. Moreover, the level of mHotair in femurs peaked at the age of week-4, a period of fast skeleton development. BMP9 could induce earlier peak expression of mHotair during in vitro iMAD osteogenesis. Silencing mHotair diminished BMP9-induced ALP activity, matrix mineralization, and expression of osteogenic, chondrogenic and adipogenic markers. Cell implantation experiments further confirmed that knockdown of mHotair attenuated BMP9-induced ectopic bone formation and mineralization of iMADs, leading to more undifferentiated cells. Crystal violet staining and cell cycle analysis revealed that silencing of mHotair promoted the proliferation of iMAD cells regardless of BMP9 induction. Moreover, ectopic bone masses developed from mHotair-knockdown iMAD cells exhibited higher expression of PCNA than the control group. Taken together, our results demonstrated that murine mHotair is an important regulator of BMP9-induced MSC osteogenesis by targeting cell cycle and proliferation.

The inhibition of BRAF activity sensitizes chemoresistant human ovarian cancer cells to paclitaxel-induced cytotoxicity and tumor growth inhibition

Ovarian cancer is one of the most common cancers in women and the second most common cause of gynecologic cancer death in women worldwide. While ovarian cancer is highly heterogeneous in histological subtypes and molecular genetic makeup, epithelial ovarian cancer is the most common subtype. The clinical outcomes of ovarian cancer largely depend on early detection and access to appropriate surgery and systemic therapy. While combination therapy with platinum-based drugs and paclitaxel (PTX) remains the first-line systemic therapy for ovarian cancer, many patients experience recurrence and die of progressive chemoresistance. Thus, there is an unmet clinical need to overcome recurrent disease due to resistance to chemotherapies of ovarian cancer. Here, we investigated whether BRAF inhibitors (BRAFi) could sensitize PTX-resistant ovarian cancer cells to PTX, and thus would overcome the resistance to chemotherapies. We found that BRAF and several members of the RAS/MAPK pathways were upregulated upon PTX treatment in ovarian cancer cells, and that BRAF expression was significantly elevated in the PTX-resistant ovarian cancer cells. While the BRAFi vemurafenib (VEM) alone did not cause any significant cytotoxicity in PTX-resistant ovarian cancer cells, VEM significantly enhanced PTX-induced growth inhibition and apoptosis in a dose-dependent manner. Furthermore, VEM and PTX were shown to synergistically inhibit tumor growth and cell proliferation of PTX-resistant human ovarian cancer cells in vivo. Collectively, these findings strongly suggest that BRAFi may be exploited as synergistic sensitizers of paclitaxel in treating chemoresistant ovarian cancer.

The Wnt/β-Catenin Pathway is Activated as a Novel Nucleolar Stress Response

Ribosomes are mandatory for growth and survival. The complex process of ribosome biogenesis is located in nucleoli and requires action of the RNA polymerases I-III, together with a multitude of processing factors involved in rRNA cleavage and maturation. Impaired ribosome biogenesis and loss of nucleolar integrity triggers nucleolar stress, which classically stabilizes the tumor suppressor p53 and induces cell cycle arrest and apoptosis. Nucleolar stress is implemented in modern anti-cancer therapies, however, also emerges as contributor to diverse pathological conditions. These include ribosomopathies, such as the Shwachman Bodian Diamond Syndrome (SBDS), which are not only characterized by nucleolar stress, but paradoxically also increased cancer incidence. Wnt signaling is tightly coupled to cell proliferation and is constitutively activated in various tumor types. In addition, the Wnt/β-Catenin pathway regulates ribosome formation. Here, we demonstrate that induction of nucleolar stress by different strategies stimulates the Wnt/β-Catenin pathway. We show that depletion of the key ribosomopathy factor SBDS, or the nucleolar factors Nucleophosmin (NPM), Pescadillo 1 (PES1) or Peter Pan (PPAN) by si RNA-mediated knockdown or CRISPR/Cas9 strategy activates Wnt/β-Catenin signaling in a β-Catenin-dependent manner and stabilizes β-Catenin in human cancer cells. Moreover, triggering nucleolar stress by the chemotherapeutic agents Actinomycin D or the RNA polymerase I inhibitor CX-5461 stimulates expression of Wnt/β-Catenin targets, which is followed by the p53 target CDKN1A (p21). As PPAN expression is induced by Wnt/β-Catenin signaling, our data establish a novel feedback mechanism and reveal that nucleolar stress over-activates the Wnt/β-Catenin pathway, which most likely serves as compensatory mechanism to sustain ribosome biogenesis.

Blockade of IGF/IGF-1R signaling axis with soluble IGF-1R mutants suppresses the cell proliferation and tumor growth of human osteosarcoma

Primary bone tumor, also known as osteosarcoma (OS), is the most common primary malignancy of bone in children and young adults. Current treatment protocols yield a 5-year survival rate of near 70% although approximately 80% of patients have metastatic disease at the time of diagnosis. However, long-term survival rates have remained virtually unchanged for nearly four decades, largely due to our limited understanding of the disease process. One major signaling pathway that has been implicated in human OS tumorigenesis is the insulin-like growth factor (IGF)/insulin-like growth factor-1 receptor (IGF1R) signaling axis. IGF1R is a heterotetrameric α2β2 receptor, in which the α subunits comprise the ligand binding site, whereas the β subunits are transmembrane proteins containing intracellular tyrosine kinase domains. Although numerous strategies have been devised to target IGF/IGF1R axis, most of them have failed in clinical trials due to the lack of specificity and/or limited efficacy. Here, we investigated whether a more effective and specific blockade of IGF1R activity in human OS cells can be accomplished by employing dominant-negative IGF1R (dnIGF1R) mutants. We engineered the recombinant adenoviruses expressing two IGF1R mutants derived from the α (aa 1-524) and β (aa 741-936) subunits, and found that either dnIGF1Rα and/or dnIGF1Rβ effectively inhibited cell migration, colony formation, and cell cycle progression of human OS cells, which could be reversed by exogenous IGF1. Furthermore, dnIGF1Rα and/or dnIGF1Rβ inhibited OS xenograft tumor growth in vivo, with the greatest inhibition of tumor growth shown by dnIGF1Rα. Mechanistically, the dnIGF1R mutants down-regulated the expression of PI3K/AKT and RAS/RAF/MAPK, BCL2, Cyclin D1 and most EMT regulators, while up-regulating pro-apoptotic genes in human OS cells. Collectively, these findings strongly suggest that the dnIGF1R mutants, especially dnIGF1Rα, may be further developed as novel anticancer agents that target IGF signaling axis with high specificity and efficacy.

The effect of baicalein on Wnt/β-catenin pathway and miR-25 expression in Saos-2 osteosarcoma cell line

Background/aim

Osteosarcoma is the most common primary bone malignancy that occurs frequently in children and adolescents. Baicalein, a flavonoid that has attracted great attention in recent years with its strong antitumor activity, shows a wide range of biological and pharmaceutical effects.MicroRNAs have been found to be involved in many critical processes in cancers. This study aimed to investigate the effect of baicalein and miR-25 on Wnt/β-catenin signaling pathway of osteosarcoma cell line Saos-2.

Materials and methods

Cell viability was assessed, and qRT-PCR and Western blot were performed to study the effects of baicalein on expression of Wnt/β-catenin signaling pathway-realted genes (β-catenin, GSK-3β, and Axin2) of Saos-2 cells.

Results

Our results indicated that baicalein can inhibit the proliferation (IC50 value 35 μM), regulate Wnt/β-catenin pathway and also increase miR-25 expression of Saos-2. Baicalein and also miR-25 decreased the expression of β-catenin and Axin2, while increasing the expression of GSK-3β. Down regulation of miR-25 decreased the expression of GSK-3β, while β-catenin and Axin2 expression increased.

Conclusion

These findings demonstrate that baicalein may target genes related to the Wnt/β-catenin pathway by regulating miR-25 expression and may be a potential Wnt/β-catenin pathway inhibitor for osteosarcoma therapy.

The multiple function of long noncoding RNAs in osteosarcoma progression, drug resistance and prognosis

Osteosarcoma is a bone tumor prevalent in children and young adults. LncRNAs are a family of non-protein-coding transcripts longer than 200 nucleotides. The tumor-related pathological functions of lncRNAs include proliferation, migration, and chemotherapy resistance, all of which have been widely acknowledged in research on osteosarcoma. In addition, compelling evidence suggests that lncRNAs could serve as diagnostic indicators, prognostic biomarkers, and targets for disease treatment. In this review, we systematically summarize how lncRNAs regulate tumorigenesis, invasion and therapeutic resistance. By deepening our knowledge of the relationship between lncRNAs and osteosarcoma, we hope to translate research findings into clinical applications as soon as possible.

Prognostic Significance of β-Catenin Expression in Osteosarcoma: A Meta-Analysis

Background: β-catenin plays a crucial role in the progression of osteosarcoma. However, the clinical significance of β-catenin over-expression in osteosarcoma still remains unclear. Thus, we performed a meta-analysis of studies that evaluated the impact of β-catenin on metastasis and overall survival (OS) in osteosarcoma.

Methods: We searched PubMed, The Cochrane Library, Embase, Springer, Science Direct, OVID, Weipu, Wanfang and China National Knowledge Internet (CNKI) databases from their start year up to Aug.2019. Individual hazard ratios (HRs) and 95% confidence intervals (CIs) were extracted and pooled HRs with 95% CIs or odd ratio (OR) were used to evaluate the relationships between β-catenin over-expression and metastasis and overall survival in osteosarcoma.

Results: Eight related studies involving 521 patients were qualified for this meta-analysis. Results showed that over-expression of β-catenin was significantly correlated with metastasis (OR = 3.31, 95% CI = 2.08–5.24, P < 0.001) and overall survival (HR = 2.32, 95% CI = 1.48–363, P = 0.02).

Conclusion: The meta-analysis revealed that over-expression of β-catenin might be associated with distant metastasis and overall survival in osteosarcoma, which reminds that β-catenin acts as a prognostic biomarker and it can guide the clinical therapy in osteosarcoma patients.

Activated Signaling Pathways and Targeted Therapies in Desmoid-Type Fibromatosis: A Literature Review

Desmoid-type fibromatosis (DTF) is a rare, soft tissue tumor of mesenchymal origin which is characterized by local infiltrative growth behavior. Besides “wait and see,” surgery and radiotherapy, several systemic treatments are available for symptomatic patients. Recently, targeted therapies are being explored in DTF. Unfortunately, effective treatment is still hampered by the limited knowledge of the molecular mechanisms that prompt DTF tumorigenesis. Many studies focus on Wnt/β-catenin signaling, since the vast majority of DTF tumors harbor a mutation in the CTNNB1 gene or the APC gene. The established role of the Wnt/β-catenin pathway in DTF forms an attractive therapeutic target, however, drugs targeting this pathway are still in an experimental stage and not yet available in the clinic. Only few studies address other signaling pathways which can drive uncontrolled growth in DTF such as: JAK/STAT, Notch, PI3 kinase/AKT, mTOR, Hedgehog, and the estrogen growth regulatory pathways. Evidence for involvement of these pathways in DTF tumorigenesis is limited and predominantly based on the expression levels of key pathway genes, or on observed clinical responses after targeted treatment. No clear driver role for these pathways in DTF has been identified, and a rationale for clinical studies is often lacking. In this review, we highlight common signaling pathways active in DTF and provide an up-to-date overview of their therapeutic potential.

Osteosarcoma progression is associated with increased nuclear levels and transcriptional activity of activated β-Catenin

Osteosarcoma (OS) is an aggressive primary bone malignancy that has peak incidence in children and young adults <25 years of age. Despite current multimodal treatments, no significant change in patient outcome has been observed in two decades. Presently, there is a lack of established, reliable baseline prognostic markers for aggressive OS, other than extent and site of disease involvement. The canonical Wnt/β-catenin pathway controls multiple cellular processes, and is known to be a critical pathway in OS progression. This pathway regulates cellular levels of β-catenin, which is a significant player in the oncogenesis and progression of many cancers. We investigated the relationship between β-catenin, more specifically, the transcriptionally active form of β-catenin, Activated β-Catenin (ABC), and OS progression. Using an in vitro model, we observed that cellular/nuclear ABC levels, but not cellular/nuclear β-catenin levels, increase with the degree of aggressiveness in OS. Our results demonstrate a strong association between nuclear-ABC levels and aggressive OS in vitro. Furthermore, we observed significant correlation between positive nuclear-ABC and patient age and tumor stage. Our results support the potential use of ABC as a predictive marker for risk stratification in OS.

β-catenin and PPAR-γ levels in bone marrow of myeloproliferative neoplasm: an immunohistochemical and ultrastructural study

In accordance with increased proliferation in myeloproliferative neoplasm (MPN), the goal is to evaluate the immunoexpression of: β-catenin, PPAR-γ and Ki67 protein, to compare them with bone marrow ultrastructural characteristics in patients with MPN. Immunoexpression and electron microscopy of bone marrow was analyzed in 30 Ph-negative MPN patients, including per 10 patients with polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF). The quantity of β-catenin immunoreactive cells was significantly higher in PV then in ET (p < 0.01) or PMF group of patients (p < 0.01) and also in ET versus PMF group of patients (p < 0.01). Erythroid lineage showed absent β-catenin staining without immunoreactivity in nucleus. In contrast, immunoreactivity for PPAR-γ was localized mostly in megakaryocytes and the highest number of PPAR-γ immunopositive cells was detected in PMF group of patients. In addition, the proliferative Ki67 index was significantly increased in the PMF and PV patients compared to patients with ET. Also, the megakaryocytes showed abnormal maturation in PMF group of patients as determined by ultrastructural analysis. These results indicated that PV dominantly expressed β-catenin and proliferation marker Ki67 in bone marrow, while PMF is linked preferentially to PPAR-γ immunopositive megakaryocytes characterized by abnormal maturation.

Monensin inhibits cell proliferation and tumor growth of chemo-resistant pancreatic cancer cells by targeting the EGFR signaling pathway

Pancreatic ductal adenocarcinoma (PDAC) is one of the most deadly malignancies with <5% five-year survival rate due to late diagnosis, limited treatment options and chemoresistance. There is thus an urgent unmet clinical need to develop effective anticancer drugs to treat pancreatic cancer. Here, we study the potential of repurposing monensin as an anticancer drug for chemo-resistant pancreatic cancer. Using the two commonly-used chemo-resistant pancreatic cancer cell lines PANC-1 and MiaPaCa-2, we show that monensin suppresses cell proliferation and migration, and cell cycle progression, while solicits apoptosis in pancreatic cancer lines at a low micromole range. Moreover, monensin functions synergistically with gemcitabine or EGFR inhibitor erlotinib in suppressing cell growth and inducing cell death of pancreatic cancer cells. Mechanistically, monensin suppresses numerous cancer-associated pathways, such as E2F/DP1, STAT1/2, NFkB, AP-1, Elk-1/SRF, and represses EGFR expression in pancreatic cancer lines. Furthermore, the in vivo study shows that monensin blunts PDAC xenograft tumor growth by suppressing cell proliferation via targeting EGFR pathway. Therefore, our findings demonstrate that monensin can be repurposed as an effective anti-pancreatic cancer drug even though more investigations are needed to validate its safety and anticancer efficacy in pre-clinical and clinical models.

A blockade of PI3Kγ signaling effectively mitigates angiotensin II-induced renal injury and fibrosis in a mouse model

Chronic kidney disease (CKD) poses a formidable challenge for public healthcare worldwide as vast majority of patients with CKD are also at risk of accelerated cardiovascular disease and death. Renal fibrosis is the common manifestation of CKD that usually leads to end-stage renal disease although the molecular events leading to chronic renal fibrosis and eventually chronic renal failure remain to be fully understood. Nonetheless, emerging evidence suggests that an aberrant activation of PI3Kγ signaling may play an important role in regulating profibrotic phenotypes. Here, we investigate whether a blockade of PI3Kγ signaling exerts any beneficial effect on alleviating kidney injury and renal fibrosis. Using a mouse model of angiotensin II (Ang II)-induced renal damage, we demonstrate that PI3Kγ inhibitor AS605240 effectively mitigates Ang II-induced increases in serum creatinine and blood urea nitrogen, renal interstitial collagen deposition, the accumulation of ECM proteins and the expression of α-Sma and fibrosis-related genes in vivo. Mechanistically, we reveal that AS605240 effectively inhibits Ang II-induced cell proliferation and phosphorylation of Akt in fibroblast cells. Furthermore, we demonstrate that Ang II-upregulated expression of IL-6, Tnf-α, IL-1β and Tgf-β1 is significantly attenuated in the mice treated with AS605240. Taken together, our results demonstrate that PI3Kγ may function as a critical mediator of Ang II-induced renal injury and fibrosis. It is thus conceivable that targeted inhibition of PI3Kγ signaling may constitute a novel therapeutic approach to the clinical management of renal fibrosis, renal hypertension and/or CKD.

Thermoresponsive Citrate-Based Graphene Oxide Scaffold Enhances Bone Regeneration from BMP9-Stimulated Adipose-Derived Mesenchymal Stem Cells

Effective bone tissue engineering is important to overcome the unmet clinical challenges as more than 1.6 million bone grafts are done annually in the United States. Successful bone tissue engineering needs minimally three critical constituents: osteoprogenitor cells, osteogenic factors, and osteoinductive/osteoconductive scaffolds. Osteogenic progenitors are derived from multipotent mesenchymal stem cells (MSCs), which can be prepared from numerous tissue sources, including adipose tissue. We previously showed that BMP9 is the most osteogenic BMP and induces robust bone formation of immortalized mouse adipose-derived MSCs entrapped in a citrate-based thermoresponsive hydrogel referred to as PPCNg. As graphene and its derivatives emerge as promising biomaterials, here we develop a novel thermosensitive and injectable hybrid material by combining graphene oxide (GO) with PPCNg (designated as GO-P) and characterize its ability to promote bone formation. We demonstrate that the thermoresponsive behavior of the hybrid material is maintained while effectively supporting MSC survival and proliferation. Furthermore, GO-P induces early bone-forming marker alkaline phosphatase (ALP) and potentiates BMP9-induced expression of osteogenic regulators and bone markers as well as angiogenic factor VEGF in MSCs. In vivo studies show BMP9-transduced MSCs entrapped in the GO-P scaffold form well-mineralized and highly vascularized trabecular bone. Thus, these results indicate that GO-P hybrid material may function as a new biocompatible, injectable scaffold with osteoinductive and osteoconductive activities for bone regeneration.

The miR-17-92 cluster/QKI2/β-catenin axis promotes osteosarcoma progression

Quaking(QKI) is an RNA binding protein, and it has been shown to serve as a tumor suppressor. However, the expression and functions of QKI in osteosarcoma progression remain poorly understood. In this study, we aimed to explore the expression of QKI2 in osteosarcoma tissues and to determine the mechanisms underlying aberrant QKI2 expression and the effect of QKI2 on osteosarcoma progression. We found that QKI2 was significantly down-regulated in osteosarcoma tissues compared with adjacent normal bone tissues. Using a series of molecular biological techniques, we demonstrated that all members of the miR-17-92 cluster were up-regulated and contributed to the down-regulation of QKI2 expression in osteosarcoma. Functional examination showed that QKI2 inhibited the proliferation, migration and invasion of osteosarcoma cells via decreasing the expression of β-catenin. Conclusively, we revealed that the regulatory axis consisting of the miR-17-92 cluster/QKI2/β-catenin plays a crucial role in the development and progression of osteosarcoma.

Retracted Article: Overexpression of PCDH8 inhibits proliferation and invasion, and induces apoptosis in papillary thyroid cancer cells

Protocadherin8 (PCDH8), a member of the protocadherin (PCDH) family, is involved in the progression of several types of cancers. However, the expression and biological roles of PCDH8 in papillary thyroid carcinoma (PTC) remain largely unknown. Therefore, in the present study, we detected the expression of PCDH8 in human PTC tissues and cell lines, and evaluated its role in PTC cells. Our results demonstrated that PCDH8 was lowly expressed in human PTC tissues and cell lines. In addition, ectopic expression of PCDH8 efficiently inhibited the proliferation, migration and invasion of PTC cells, as well as prevented the epithelial-mesenchymal transition (EMT) phenotype in PTC cells. Furthermore, PCDH8 efficiently induced apoptosis and autophagy in PTC cells. Mechanistically, overexpression of PCDH8 significantly prevented the activation of the Wnt/β-catenin pathway in PTC cells. Taken together, these findings showed that overexpression of PCDH8 inhibits proliferation and migration/invasion, and induces apoptosis of PTC cells through the Wnt/β-catenin signaling pathway.

Protocadherin8 (PCDH8), a member of the protocadherin (PCDH) family, is involved in the progression of several types of cancers.

Anthelmintic mebendazole enhances cisplatin's effect on suppressing cell proliferation and promotes differentiation of head and neck squamous cell carcinoma (HNSCC)

Head and neck squamous cell carcinoma (HNSCC) is one of the most common and aggressive types of human cancers worldwide. Nearly a half of HNSCC patients experience recurrence within five years of treatment and develop resistance to chemotherapy. Thus, there is an urgent clinical need to develop safe and novel anticancer therapies for HNSCC. Here, we investigate the possibility of repurposing the anthelmintic drug mebendazole (MBZ) as an anti-HNSCC agent. Using the two commonly-used human HNSCC lines CAL27 and SCC15, we demonstrate MBZ exerts more potent anti-proliferation activity than cisplatin in human HNSCC cells. MBZ effectively inhibits cell proliferation, cell cycle progression and cell migration, and induces apoptosis of HNSCC cells. Mechanistically, MBZ can modulate the cancer-associated pathways including ELK1/SRF, AP1, STAT1/2, MYC/MAX, although the regulatory outcomes are context-dependent. MBZ also synergizes with cisplatin in suppressing cell proliferation and inducing apoptosis of human HNSCC cells. Furthermore, MBZ is shown to promote the terminal differentiation of CAL27 cells and keratinization of CAL27-derived xenograft tumors. Our results are the first to demonstrate that MBZ may exert its anticancer activity by inhibiting proliferation while promoting differentiation of certain HNSCC cancer cells. It's conceivable the anthelmintic drug MBZ can be repurposed as a safe and effective agent used in combination with other frontline chemotherapy drugs such as cisplatin in HNSCC treatment.

Degalactotigonin, a Natural Compound from Solanum nigrum L., Inhibits Growth and Metastasis of Osteosarcoma through GSK3β Inactivation-Mediated Repression of the Hedgehog/Gli1 Pathway

Purpose: Agents extracted from natural sources with antitumor property have attracted considerable attention from researchers and clinicians because of their safety, efficacy, and immediate availability. Degalactotigonin (DGT), extracted from Solanum nigrum L, has anticancer properties without serious side effects. Here, we explored whether DGT can inhibit the growth and metastasis of osteosarcoma.Experimental Design: MTT, colony formation, and apoptosis assays were performed to analyze the effects of DGT on osteosarcoma cell viability in vitro The migration and invasion abilities were measured using a Transwell assay. Animal models were used to assess the roles of DGT in both tumor growth and metastasis of osteosarcoma. Gli1 expression and function were measured in osteosarcoma cells and clinical samples. After DGT treatment, Gli1 activation and the phosphorylation status of multiple cellular kinases were measured with a luciferase reporter and phospho-kinase antibody array.Results: DGT inhibited proliferation, induced apoptosis, and suppressed migration and invasion in osteosarcoma cells. DGT, injected intraperitoneally after tumor inoculation, significantly decreased the volume of osteosarcoma xenografts and dramatically diminished the occurrence of osteosarcoma xenograft metastasis to the lungs. Mechanistically, DGT inhibited osteosarcoma growth and metastasis through repression of the Hedgehog/Gli1 pathway, which maintains malignant phenotypes and is involved in the prognosis of osteosarcoma patients. DGT decreased the activity of multiple intracellular kinases that affect the survival of osteosarcoma patients, including GSK3β. In addition, DGT represses the Hedgehog/Gli1 pathway mainly through GSK3β inactivation.Conclusions: Our studies provide evidence that DGT can suppress the growth and metastasis of human osteosarcoma through modulation of GSK3β inactivation-mediated repression of the Hedgehog/Gli1 pathway. Clin Cancer Res; 24(1); 130-44. ©2017 AACR.

Adenocarcinoma of the posterior segment of the gastrointestinal tract in dogs - clinical, endoscopic, histopathological and immunohistochemical findings

Of all the tumours in dogs, three percent are located in the intestines, and 36-60% of those tumours affect the large intestine. Adenocarcinomas of the intestines account for 20-35% of the gastrointestinal tumours and for almost 60% of the large intestine tumours. The aim of the study was to analyze clinical disorders and endoscopic, histopathological and immunohistochemical changes in colorectal adenocarcinomas in dogs with the use of the E-cadherin, β-catenin, cytokeratin 20 (CK20), Ki-67 and minichromosome maintenance 3 (MCM-3). The study comprised 11 dogs of both genders and of different breeds diagnosed with adenocarcinoma of the large intestine. They were from 4 to 11 years old. The large intestine adenocarcinoma was diagnosed in all the patients. 72.7% cases were diagnosed with a rectal adenocarcinoma, and 27.3% were found to have a colonic adenocarcinoma. All the studied proteins were expressed at different levels and, together with the histological findings, indicated different levels of malignancy (G). The statistical analysis revealed no statistically significant differences between the expression of E-cadherin and β-catenin in the studied tissues (p=0.79) and between the expression of Ki-67 andMCM-3 (p=0.39). A strong positive correlation was found between the expression of E-cadherin and β-catenin (r=0.86; p<0.05). The diagnosis of adenocarcinomas of the large intestine may be facilitated by the introduction of immunohistochemical studies using appropriate cell markers. They may also aid in the accurate evaluation of the biological character of the tumours, their origin, the connections between tumour cells and the mitotic index. That, in turn, may help determine the malignancy and the choice of treatment.

Tetrahydrocurcumin induces mesenchymal-epithelial transition and suppresses angiogenesis by targeting HIF-1α and autophagy in human osteosarcoma

Human osteosarcoma is considered a malignant tumor with poor prognosis that readily metastasizes. Tetrahydrocurcumin (THC) has been reported to have anti-tumor activity in numerous tumors. In addition, hypoxia-inducible factor-1α (HIF-1α) has been demonstrated to be associated with tumor metastasis by regulating epithelial-mesenchymal transition (EMT). However, the role of THC in osteosarcoma remains uncertain. Therefore, this study aimed to elucidate the potential mechanisms. We found that THC significantly reduced the growth of osteosarcoma cells and suppressed migration and invasion, as tested in a nude mouse lung metastasis model. Additionally, the mesenchymal-epithelial transition (MET) process was facilitated by THC. Mechanistically, our study showed that HIF-1α had a pivotal role in the anti-metastatic effect of THC. Importantly, HIF-1α expression was downregulated by THC by inhibiting Akt/mTOR and p38 MAPK pathways. Moreover, THC exhibited a remarkable inhibitory effect on HIF-1α expression and angiogenesis under hypoxic conditions. Furthermore, THC activated autophagy and induced MET and suppressed angiogenesis in a HIF-1α-related manner. Taken together, our findings suggest that THC suppresses metastasis and invasion and this may be associated with HIF-1α and autophagy, which would potentially provide therapeutic strategies for human osteosarcoma.

Osteosarcoma: Molecular Pathogenesis and iPSC Modeling

Rare hereditary disorders provide unequivocal evidence of the importance of genes in human disease pathogenesis. Familial syndromes that predispose to osteosarcomagenesis are invaluable in understanding the underlying genetics of this malignancy. Recently, patient-derived induced pluripotent stem cells (iPSCs) have been successfully utilized to model Li-Fraumeni syndrome (LFS)-associated bone malignancy, demonstrating that iPSCs can serve as an in vitro disease model to elucidate osteosarcoma etiology. We provide here an overview of osteosarcoma predisposition syndromes and review recently established iPSC disease models for these familial syndromes. Merging molecular information gathered from these models with the current knowledge of osteosarcoma biology will help us to gain a deeper understanding of the pathological mechanisms underlying osteosarcomagenesis and will potentially aid in the development of future patient therapies.

RNA sequencing identifies gene expression profile changes associated with β-estradiol treatment in U2OS osteosarcoma cells

This study was conducted to identify gene expression profile changes associated with β-estradiol (E2) treatment in U2OS osteosarcoma cells by high-throughput RNA sequencing (RNA-seq). Two U2OS cell samples treated with E2 (15 μmol/L) and two untreated control U2OS cell samples were subjected to RNA-seq. Differentially expressed genes (DEGs) between the groups were identified, and main biological process enrichment was performed using gene ontology (GO) analysis. A protein–protein interaction (PPI) network was constructed using Cytoscape based on the Human Protein Reference Database. Finally, NFKB1 expression was confirmed by quantitative real-time polymerase chain reaction (qRT-PCR). The map ratios of the four sequenced samples were >65%. In total, 128 upregulated and 92 downregulated DEGs were identified in E2 samples. After GO enrichment, the downregulated DEGs, such as AKT1, were found to be mainly enriched in cell cycle processes, whereas the upregulated DEGs, such as NFKB1, were involved in the regulation of gene expression. Moreover, AKT1 (degree =117) and NFKB1 (degree =72) were key nodes with the highest degrees in the PPI network. Similarly, the results of qRT-PCR confirmed that E2 upregulated NFKB1 expression. The results suggest that E2 upregulates the expression of NFKB1, ATF7IP, and HDAC5, all of which are involved in the regulation of gene expression and transcription, but downregulates that of TCF7L2, ALCAM, and AKT, which are involved in Wnt receptor signaling through β-catenin and morphogenesis in U2OS osteosarcoma cells.

Involvement of c-Fos in cell proliferation, migration, and invasion in osteosarcoma cells accompanied by altered expression of Wnt2 and Fzd9

Osteosarcoma (OS) is an aggressive bone tumor, and proto-oncogene c-Fos is involved in this lethal disease. However, the role and molecular mechanism of c-Fos in the development and progression of OS remain enigmatic. As one of the Wnt family members, Wnt2 is closely associated with the development of several malignant tumors. In the present study, the expression of c-Fos, Wnt2, and its receptor Fzd9 in human OS tissues, MG63 OS cell line, and human osteoblast hFOB 1.19 cell line was detected by Western blot analysis, immunohistochemical staining, or reverse transcription-polymerase chain reaction. The role of c-Fos in the OS was clarified by treating MG63 cells with small interfering RNA to knockdown c-Fos. Then, cell migration and invasion were assayed by transwell assays and wound healing assay; cell proliferation was assayed by MTS method and 5-ethynyl-2'-deoxyuridine DNA proliferation in vitro detection; cell apoptosis was assayed by flow cytometric method. Co-immunoprecipitation kit was used to confirm the relationship between c-Fos and Wnt2/Fzd9. We found that the expression of c-Fos, Wnt2, and Fzd9 protein was distinctly higher in human OS tissues than that in the adjacent non-cancerous tissues, and their expression in the MG63 OS cell line was markedly increased compared with that in the human osteoblast hFOB 1.19 cell line. Knockdown of c-Fos inhibited the proliferation, migration, and invasion of MG63 cells, and promoted the apoptosis of MG63 cells. Moreover, knockdown of c-Fos inhibited the expression of Wnt2 and Fzd9 mRNA and protein. Our data enforced the evidence that knockdown of c-Fos inhibited cell proliferation, migration, and invasion, and promoted the apoptosis of OS cells accompanied by altered expression of Wnt2 and Fzd9. These findings offer new clues for OS development and progression, and c-Fos may be a potential therapeutic target for OS.

Knockdown of SALL4 Inhibits Proliferation, Migration, and Invasion in Osteosarcoma Cells

Sal-like protein 4 (SALL4) is a zinc finger transcription factor that has been reported to be aberrantly expressed in several human malignancies and identified as an oncogene. However, the potential role of SALL4 in osteosarcoma remains to be elucidated. In this study, we explored the biological functions of SALL4 in osteosarcoma. We found that SALL4 was overexpressed in osteosarcoma tissues and cell lines. Knockdown of SALL4 inhibited osteosarcoma cell proliferation, migration, and invasion in vitro. In addition, SALL4 knockdown suppressed osteosarcoma growth and metastasis in vivo. We also showed that SALL4 knockdown decreased the protein expression of Wnt3a and β-catenin in osteosarcoma cells. Taken together, our study showed that SALL4 plays an important role in regulating the proliferation, migration, and invasion of osteosarcoma cells. Thus, SALL4 may represent a potential therapeutic target in the treatment of osteosarcoma.

Pediatric Chondromyxoid Fibroma-Like Osteosarcoma

Chondromyxoid fibroma-like osteosarcoma (CMF-OS) is a low-grade osteosarcoma, often misdiagnosed on initial biopsy as a benign lesion, with five cases previously described. We report a 13-year-old male with an intramedullary lytic CMF-OS of the right tibial proximal metaphysis with cortical destruction and soft tissue extension. Diagnosis was based on malignant new bone formation, increased mitotic figures, lamellar bone permeation with bony destruction, and correlation with imaging studies. There were no metastasis at presentation and the tumor showed good response to standard chemotherapy with >95% necrosis.

RASSF4 Overexpression Inhibits the Proliferation, Invasion, EMT, and Wnt Signaling Pathway in Osteosarcoma Cells

RASSF4, a member of the RASSF family, is broadly expressed in normal tissues but often inactivated in human cancers. Despite various studies on RASSF4, its role in osteosarcoma remains unclear. Therefore, in this study, we investigated the effects of RASSF4 expression on osteosarcoma cells and explored the underlying mechanism. The results of our study showed that RASSF4 was lowly expressed in osteosarcoma tissues and cells. RASSF4 overexpression significantly inhibited proliferation, migration, and invasion as well as the EMT process in osteosarcoma cells. Meanwhile, we found that RASSF4 overexpression markedly decreased the protein expression of β-catenin, cyclin D1, and c-Myc in osteosarcoma cells. In conclusion, our findings showed that RASSF4 overexpression inhibits proliferation, invasion, EMT, and Wnt signaling pathway in osteosarcoma cells. Thus, RASSF4 may be considered a novel target for osteosarcoma treatment.

Ursolic acid inhibits proliferation and induces apoptosis by inactivating Wnt/β-catenin signaling in human osteosarcoma cells

Although multiple chemotherapeutic agents have been used for osteosarcoma (OS) treatment, their mechanisms need further study. Ursolic acid (UA), a pentacyclic triterpenoid, can reduce cell proliferation and induce apoptosis in various cancer cells, such as OS. However, the exact mechanism underlying this function remains unclear. In this study, we investigated the anti‑proliferative effect of UA in human OS 143B cells and dissected the possible molecular mechanism underlying this effect. We demonstrated that UA can reduce cell proliferation, induce apoptosis and arrest cell cycle in 143B cells, as well as inhibit OS tumor growth in a mouse xenograft model. Using a luciferase reporter assay, we found that the Wnt/β‑catenin signaling is inhibited by UA in 143B cells. Correspondingly, the expression level and nuclear translocation of β‑catenin are both decreased by UA. Exogenous expression of β‑catenin attenuates the anticancer effect of UA in 143B cells, while knockdown of β‑catenin enhances this effect. UA increases the expression level of p53 in a concentration‑dependent manner, and inhibition of p53 reduces the anticancer effect of UA in 143B cells. Moreover, inhibition of p53 partly reverses the UA‑induced downregulation of β‑catenin, as do the targets of Wnt/β‑catenin signaling, such as c‑Myc and cyclin D1. Our findings indicated that UA can inhibit the proliferation of 143B OS cells through inactivation of Wnt/β-catenin signaling, which may be mediated partly by upregulating the expression of p53.

The canonical Wnt/β-catenin pathway: From the history of its discovery to clinical application

The Wnt/β signaling pathway (Wnt-SP) is a phylogenetically ancient mechanism that regulates development and maintains tissue homeostasis through the control of cell proliferation, differentiation, migration, and apoptosis. The accurate regulation of the canonical Wnt/β-catenin signaling pathway (Wnt-SP) is critical for embryogenesis and postnatal development; and impaired signal transduction at one of its stages leads to various diseases, including organ malformations, cancers, metabolic and neurodegenerative disorders. The literature review discusses the biological role of the canonical Wnt-SP in the development of the skeleton and in the remodeling of bone tissue. The Wnt signal transmission changes observed during genetic mutations cause various human skeletal diseases. Understanding the functional mechanism involved in the development of bone abnormality could open new horizons in the treatment of osteoporosis, by affecting the Wnt-SP. The design of antibodies to sclerostin, a Wnt-SP inhibitor, is most promising now. The paper summarizes the studies that have investigated the canonical Wnt-SP and designed drugs to treat osteoporosis.

miR-200c and phospho-AKT as prognostic factors and mediators of osteosarcoma progression and lung metastasis

Lung metastasis is the major cause of death in osteosarcoma patients. However, molecular mechanisms underlying this metastasis remain poorly understood. To identify key molecules related with pulmonary metastasis of pediatric osteosarcomas, we analyzed high-throughput miRNA expression in a cohort of 11 primary tumors and 15 lung metastases. Results were further validated with an independent cohort of 10 primary tumors and 6 metastases. In parallel, we performed immunohistochemical analysis of activated signaling pathways in 36 primary osteosarcomas. Only phospho-AKT associated with lower overall survival in primary tumors, supporting its role in osteosarcoma progression. CTNNB1 expression also associated with lower overall survival but was not strong enough to be considered an independent variable. Interestingly, miR-200c was overexpressed in lung metastases, implicating an inhibitory feed-back loop to PI3K-AKT. Moreover, transfection of miR200c-mimic in U2-OS cells reduced phospho-AKT levels but increased cellular migration and proliferation. Notably, miR-200c expression strongly correlated with miR-141 and with the osteogenic inhibitor miR-375, all implicated in epithelial to mesenchymal transition. These findings contrast epithelial tumors where reduced miR-200c expression promotes metastasis. Indeed, we noted that osteosarcoma cells in the lung also expressed the epithelial marker CDH1, revealing a change in their mesenchymal phenotype. We propose that miR-200c upregulation occurs late in osteosarcoma progression to provide cells with an epithelial phenotype that facilitates their integration in the metastatic lung niche. Thus, our findings identify phospho-AKT in the primary tumor and miR-200c later during tumor progression as prognostic molecules and potential therapeutic targets to prevent progression and metastasis of pediatric osteosarcomas.

Plumbagin exhibits an anti-proliferative effect in human osteosarcoma cells by downregulating FHL2 and interfering with Wnt/β-catenin signalling

Plumbagin, a naphthoquinone constituent of Plumbago zeylanica L. (Plumbaginaceae) is widely used in traditional Chinese medicine as an antifungal, antibacterial and anti-inflammatory agent. Plumbagin is known to exhibit proapoptotic, antiangiogenic and antimetastatic effects in cancer cells. The transcriptional co-factor four and a half LIM domains 2 (FHL2) is a multifunctional adaptor protein that is involved in the regulation of gene expression, signal transduction and cell proliferation and differentiation, and also acts as a tumor suppressor or oncoprotein depending on the tissue microenvironment. The present study investigated the effect of plumbagin on FHL2 expression, Wnt/β-catenin signalling and its anti-proliferative activity in various human osteosarcoma cell lines, including SaOS2, MG63, HOS and U2OS. The cells were exposed to plumbagin and the expression of FHL2 was evaluated using western blot analysis. Furthermore, the anti-proliferative effect of plumbagin was evaluated using a 3-(4,5 dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. In addition, since FHL2 is involved in Wnt/β-catenin signaling, the effect of plumbagin on β-catenin and its primary target genes, including v-myc avian myelocytomatosis viral oncogene homolog (c-Myc) and WNT1 inducible signaling pathway protein-1 (WISP-1), was evaluated using western blot analysis. It was observed that plumbagin suppressed the expression of FHL2 and exhibited significant anti-proliferative activity in osteosarcoma cells. It also attenuated Wnt/β-catenin signalling by downregulating β-catenin and its target genes, including c-Myc and WISP-1. In conclusion, plumbagin demonstrated anti-proliferative activity in osteosarcoma cells by downregulating FHL2 and interfering with Wnt/β-catenin signalling.

Deciphering signaling networks in osteosarcoma pathobiology

Osteosarcoma is the most frequent type of primary bone tumors among children and adolescents. During the past years, little progress has been made regarding prognosis of osteosarcoma patients, especially for those with metastatic disease. Genomic instability and gene alterations are common, but current data do not reveal a consistent and repeatable pattern of osteosarcoma development, thus paralleling the tumor's high heterogeneity. Critical signal transduction pathways have been implicated in osteosarcoma pathobiology and are being evaluated as therapeutic targets, including receptor activator for nuclear factor-κB (RANK), Wnt, Notch, phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin, and mechanotransduction pathways. Herein, we recapitulate and discuss recent advances in the context of molecular mechanisms and signaling networks that contribute to osteosarcoma progression and metastasis, towards patient-tailored and novel-targeted treatments.

A thermoresponsive polydiolcitrate-gelatin scaffold and delivery system mediates effective bone formation from BMP9-transduced mesenchymal stem cells

Successful bone tissue engineering requires at the minimum sufficient osteoblast progenitors, efficient osteoinductive factors, and biocompatible scaffolding materials. We previously demonstrated that bone morphogenetic protein 9 (BMP9) is one of the most potent factors in inducing osteogenic differentiation of mesenchymal stem cells (MSCs). Here, we investigated the potential use of a biodegradable citrate-based thermosensitive macromolecule, poly(polyethyleneglycol citrate-co-N-isopropylacrylamide) (PPCN) mixed with gelatin (PPCNG) as a scaffold for the delivery of BMP9-stimulated MSCs to promote localized bone formation. The addition of gelatin to PPCN effectively enhanced the cell adhesion and survival properties of MSCs entrapped within the gel in 3D culture. Using the BMP9-transduced MSC line immortalized mouse embryonic fibroblasts (iMEFs), we found that PPCNG facilitated BMP9-induced osteogenic differentiation of iMEFs in vivo and promoted the formation of well-ossified and vascularized trabecular bone-like structures in a mouse model of ectopic bone formation. Histologic evaluation revealed that vascularization of the bony masses retrieved from the iMEFs  +  PPCNG group was significantly more pronounced than that of the direct cell injection group. Accordingly, vascular endothelial growth factor (VEGF) expression was shown to be significantly higher in the bony masses recovered from the iMEFs  +  PPCNG group. Taken together, our results suggest that PPCNG may serve as a novel biodegradable and injectable scaffold and carrier for gene and cell-based bone tissue engineering.

Over-expression of Sox4 and β-catenin is associated with a less favorable prognosis of osteosarcoma

The purpose of this study was to examine the association of the expression of Sox4 and β-catenin with the prognosis of osteosarcoma. A total of 108 cases of conventional osteosarcoma were involved in this study and 28 cases of osteochondroma served as controls. The expression of Sox4 and β-catenin was detected by using immunohistochemical staining and Western blotting. The results showed that Sox4 and β-catenin were over-expressed in 67 (62.03%) and 62 (57.41%) of 108 osteosarcoma cases, while in only 3 (10.71%) and 5 (17.86%) of 28 controls, respectively (P<0.05 for all). The expression of Sox4 and β-catenin was associated with the distant metastasis, pathological grade and Enneking stage of patients with osteosarcoma (P<0.05 for all). The mean overall survival time and the 5-year-survival rate in osteosarcoma patients with Sox4 and β-catenin over-expressed were significantly reduced as compared with those in Sox4 and β-catenin low-expression group (P<0.05 for all). Cox multifactor regression analysis revealed that the distant metastasis, Enneking stage, and the expression of Sox4 and β-catenin were independent risk factors of patients with osteosarcoma (P<0.05 for all). The findings indicated that overexpression of Sox4 and β-catenin is associated with a poor prognosis of osteosarcoma.

Lentivirus-Mediated Knockdown of CTHRC1 Inhibits Osteosarcoma Cell Proliferation and Migration

Collagen triple helix repeat containing-1 (CTHRC1), a secreted protein, is transiently expressed in the arterial wall in response to injury, indicating that it may contribute to vascular remodeling by limiting collagen matrix deposition and promoting cell migration. Recent studies showed that it is aberrantly upregulated in most human solid tumors, yet its role in osteosarcoma remains unclear. In this study, the authors investigated the role of CTHRC1 in human osteosarcoma tumorigenesis. The authors used lentivirus-mediated short hairpin RNA (shRNA) against CTHRC1 to limit its endogenous expression in U2OS and SW1353 cells. Interestingly, they found that depletion of CTHRC1 significantly inhibited cell proliferation and colony formation in U2OS and SW1353 cells. Flow cytometry assay showed that knockdown of CTHRC1 increased the cell percentage of G0/G1 phase, resulting in cell cycle arrest in U2OS cells. Moreover, CTHRC1 silencing induced the cell cycle arrest by a decrease in the cell percentage in G0/G1 phase and increased in G2/M phase in SW1353 cells. In addition, crystal violet staining suggested CTHRC1 silencing inhibited migration of U2OS and SW1353 cells. These results demonstrated that CTHRC1 might play an important role in osteosarcoma progression.

The evolving roles of canonical WNT signaling in stem cells and tumorigenesis: implications in targeted cancer therapies

The canonical WNT/β-catenin signaling pathway governs a myriad of biological processes underlying the development and maintenance of adult tissue homeostasis, including regulation of stem cell self-renewal, cell proliferation, differentiation, and apoptosis. WNTs are secreted lipid-modified glycoproteins that act as short-range ligands to activate receptor-mediated signaling pathways. The hallmark of the canonical pathway is the activation of β-catenin-mediated transcriptional activity. Canonical WNTs control the β-catenin dynamics as the cytoplasmic level of β-catenin is tightly regulated via phosphorylation by the 'destruction complex', consisting of glycogen synthase kinase 3β (GSK3β), casein kinase 1α (CK1α), the scaffold protein AXIN, and the tumor suppressor adenomatous polyposis coli (APC). Aberrant regulation of this signaling cascade is associated with varieties of human diseases, especially cancers. Over the past decade, significant progress has been made in understanding the mechanisms of canonical WNT signaling. In this review, we focus on the current understanding of WNT signaling at the extracellular, cytoplasmic membrane, and intracellular/nuclear levels, including the emerging knowledge of cross-talk with other pathways. Recent progresses in developing novel WNT pathway-targeted therapies will also be reviewed. Thus, this review is intended to serve as a refresher of the current understanding about the physiologic and pathogenic roles of WNT/β-catenin signaling pathway, and to outline potential therapeutic opportunities by targeting the canonical WNT pathway.

Downregulation of tumor suppressing STF cDNA 3 promotes epithelial-mesenchymal transition and tumor metastasis of osteosarcoma by the Wnt/GSK-3β/β-catenin/Snail signaling pathway

Epithelial to mesenchymal transition (EMT) has received considerable attention as a conceptual paradigm for explaining the invasive and metastatic behavior of cells during cancer progression. Our previous study showed that loss of expression of TSSC3 is positively associated with osteosarcoma malignancy and progression. However, whether TSSC3 mediates EMT in osteosarcoma is poorly understood. In the present study, we determined that TSSC3 downregulation induced cell migration and invasion ability and promoted mesenchymal transition of osteosarcoma cells by upregulating mesenchymal markers and inhibiting the epithelial markers. Furthermore, TSSC3 downregulation elicited a signaling cascade that included increased levels of Wnt3a and LRP5, inactivation of GSK-3β, accumulation of nuclear β-catenin and Snail, the augmented binding of β-catenin to TCF-4, and accordingly increased the expression of Wnt target genes (CD44, MMP7). The gene knockdown of these signaling proteins could inhibit TSSC3 downregulation-promoted EMT, migration, and invasion in osteosarcoma. Finally, TSSC3 overexpression obviously inhibited cell migration, invasion, and repressed mesenchymal phenotypes, reducing lung metastasis through GSK-3β activation. Collectively, TSSC3 downregulation promotes the EMT of osteosarcoma cells by regulating EMT markers via a signal transduction pathway that involves Snail, Wnt-β-catenin/TCF, and GSK-3β.

CD151 knockdown inhibits osteosarcoma metastasis through the GSK-3β/β-catenin/MMP9 pathway

Osteosarcoma (OS) is a primary bone malignancy with a high early metastatic propensity. It is crucial to find specific protein targets to develop therapeutic strategies against this lethal disease. Tetraspanin CD151 is involved in facilitating tumor metastasis. However, the role and molecular mechanism of CD151 in promoting OS metastasis remain enigmatic. In the present study, we used small interfering RNA (siRNA) to inhibit CD151 expression in highly metastatic OS cells and the results demonstrated that CD151 knockdown inhibited their migration, invasion and metastasis. We further investigated the molecular mechanism of CD151 by inhibiting genes known to be involved in metastasis in OS cells and found that CD151 modulated matrix metalloproteinase 9 (MMP9) expression through the glycogen synthase kinase 3 (GSK-3β)/β-catenin signaling pathway. We conclude that CD151 knockdown inhibits the expression of MMP9 through the GSK-3β/β‑catenin pathway and also inhibits OS migration and invasion in vitro and metastasis in vivo in highly metastatic OS. This suggests that CD151 may be a useful antimetastatic target for OS.

Antibiotic monensin synergizes with EGFR inhibitors and oxaliplatin to suppress the proliferation of human ovarian cancer cells

Ovarian cancer is the most lethal gynecologic malignancy with an overall cure rate of merely 30%. Most patients experience recurrence within 12–24 months of cure and die of progressively chemotherapy-resistant disease. Thus, more effective anti-ovarian cancer therapies are needed. Here, we investigate the possibility of repurposing antibiotic monensin as an anti-ovarian cancer agent. We demonstrate that monensin effectively inhibits cell proliferation, migration and cell cycle progression, and induces apoptosis of human ovarian cancer cells. Monensin suppresses multiple cancer-related pathways including Elk1/SRF, AP1, NFκB and STAT, and reduces EGFR expression in ovarian cancer cells. Monensin acts synergistically with EGFR inhibitors and oxaliplatin to inhibit cell proliferation and induce apoptosis of ovarian cancer cells. Xenograft studies confirm that monensin effectively inhibits tumor growth by suppressing cell proliferation through targeting EGFR signaling. Our results suggest monensin may be repurposed as an anti-ovarian cancer agent although further preclinical and clinical studies are needed.

Inhibition of oleandrin on the proliferation show and invasion of osteosarcoma cells in vitro by suppressing Wnt/β-catenin signaling pathway

Background

Osteosarcoma (OS) is a high-grade bone sarcoma with early metastasis potential, and the clinical chemotherapy drugs that are currently used for its treatment have some limitations. Recently, several studies have reported the selective antitumor effect of oleandrin on various tumor cells. In this study, we aimed to evaluate the effects and underlying mechanisms of oleandrin on OS cells.

Methods

The effect of oleandrin on the proliferation, morphology, and apoptosis of U2OS and SaOS-2 cells were analyzed in vitro. The activity of the Wnt/β-catenin signaling pathway was determined using a dual luciferase assay. Semi-quantitative RT-PCR and western blot assays were performed to evaluate the mRNA and total protein expression of the downstream target genes. Changes of β-catenin in intracellular localization were also explored using a western blot after separating the nucleus and cytoplasm proteins. The MMP-2 and MMP-9 enzymatic activities were determined using gelatin zymography.

Results

Oleandrin significantly inhibited the proliferation and invasion of OS cells in vitro, and induced their apoptosis. After treatment with oleandrin, the TOP/FOP flash ratio in OS cells was noticeably decreased, which indicated that the Wnt/β-catenin signaling pathway was repressed. The expression of related Wnt target genes and total β-catenin was downregulated, and a reduced nuclear β-catenin level by oleandrin was observed as well. In addition, oleandrin suppressed the activities of MMP-2 and MMP-9.

Conclusions

Oleandrin, in vitro, exerted a strong antitumor effect on human OS cells by suppressing the Wnt/β-catenin signaling pathway, which interfered with the proliferation and invasion of OS cells, as well as induced cells apoptosis. Moreover, the expression and activities of MMP-2 and MMP-9 were downregulated by oleandrin, which contributed to the cells’ lower invasiveness.