Differentially activated Src kinase in chemo-naïve human primary osteosarcoma cells and effects of a Src kinase inhibitor

Targeting SRC Family Kinases in Mesothelioma: Time to Upgrade

Malignant mesothelioma (MM) is a deadly tumor mainly caused by exposure to asbestos. Unfortunately, no current treatment is able to change significantly the natural history of the disease, which has a poor prognosis in the majority of patients. The non-receptor tyrosine kinase SRC and other SRC family kinase (SFK) members are frequently hyperactivated in many cancer types, including MM. Several works have indeed suggested that SFKs underlie MM cell proliferation, survival, motility, and invasion, overall affecting multiple oncogenic pathways. Consistently, SFK inhibitors effectively counteracted MM cancerous features at the preclinical level. Dasatinib, a multi-kinase inhibitor targeting SFKs, was also assessed in clinical trials either as second-line treatment for patients with unresectable MM or, more recently, as a neoadjuvant agent in patients with resectable MM. Here, we provide an overview of the molecular mechanisms implicating SFKs in MM progression and discuss possible strategies for a more successful clinical application of SFK inhibitors. Our aim is to stimulate discussion and further consideration of these agents in better designed preclinical and clinical studies to make the most of another class of powerful antitumoral drugs, which too often are lost in translation when applied to MM.

The Unfolded Protein Response: Neutron-Induced Therapy Autophagy as a Promising Treatment Option for Osteosarcoma

Radiotherapy using high linear energy transfer (LET) radiation results in effectively killing tumor cells while minimizing dose (biological effective) to normal tissues to block toxicity. It is well known that high LET radiation leads to lower cell survival per absorbed dose than low LET radiation. High-linear energy transfer (LET) neutron treatment induces autophagy in tumor cells, but its precise mechanisms in osteosarcoma are unknown. Here, we investigated this mechanism and the underlying signaling pathways. Autophagy induction was examined in gamma-ray-treated KHOS/NP and MG63 osteosarcoma cells along with exposure to high-LET neutrons. The relationship between radiosensitivity and autophagy was assessed by plotting the cell surviving fractions against autophagy levels. Neutron treatment increased autophagy rates in irradiated KHOS/NP and MG63 cells; neutrons with high-LETs showed more effective inhibition than those with lower LET gamma-rays. To determine whether the unfolded protein response and Akt-mTOR pathways triggered autophagy, phosphorylated eIF2α and JNK levels, and phospho-Akt, phosphor-mTOR, and phospho-p70S6 levels were, respectively, investigated. High-LET neutron exposure inhibited Akt phosphorylation and increased Beclin 1 expression during the unfolded protein response, thereby enhancing autophagy. The therapeutic efficacy of high-LET neutron radiation was also assessed in vivo using an orthotopic mouse model. Neutron-irradiated mice showed reduced tumor growth without toxicity relative to gamma-ray-treated mice. The effect of high-LET neutron exposure on the expression of signaling proteins LC3, p-elF2a, and p-JNK was investigated by immunohistochemistry. Tumors in high-LET-neutron radiation-treated mice showed higher apoptosis rates, and neutron exposure significantly elevated LC3 expression, and increased p-elF2a and p-JNK expression levels. Overall, these results demonstrate that autophagy is important in radiosensitivity, cell survival, and cellular resistance against high-LET neutron radiation. This correlation between cellular radiosensitivity and autophagy may be used to predict radiosensitivity in osteosarcoma.

miR-451a Inhibits the Growth and Invasion of Osteosarcoma via Targeting TRIM66

The importance of microRNAs in regulating osteosarcoma development has been studied in recent years. However, the function of microRNA-451a in osteosarcoma growth is rarely investigated. Here, we explored the expression of microRNA-451a in osteosarcoma cell lines. Bioinformatic software, luciferase activity reporter assay, and Western blot were conducted to determine the association between microRNA-451a and tripartite motif-containing 66. Cell Counting Kit-8 assay and transwell assay were used to explore the regulatory effects of microRNA-451a on osteosarcoma cells. Moreover, we explored whether microRNA-451a modulates osteosarcoma cell biological activity by regulating tripartite motif-containing 66. The expression of microRNA-451a was found to be downregulated in osteosarcoma and negatively regulated the expression of tripartite motif-containing 66. Tripartite motif-containing 66 was further validated as a target of microRNA-451a. MicroRNA-451a inhibits the growth and invasion of osteosarcoma cell lines through targeting tripartite motif-containing 66. The miR-451a targets tripartite motif-containing 66 may provide novel therapeutic targets for the treatment of osteosarcoma.

Synergistic Autophagy Effect of miR-212-3p in Zoledronic Acid-Treated In Vitro and Orthotopic In Vivo Models and in Patient-Derived Osteosarcoma Cells

Osteosarcoma (OS) originates from osteoid bone tissues and is prone to metastasis, resulting in a high mortality rate. Although several treatments are available for OS, an effective cure does not exist for most patients with advanced OS. Zoledronic acid (ZOL) is a third-generation bisphosphonate that inhibits osteoclast-mediated bone resorption and has shown efficacy in treating bone metastases in patients with various types of solid tumors. Here, we sought to clarify the mechanisms through which ZOL inhibits OS cell proliferation. ZOL treatment inhibited OS cell proliferation, viability, and colony formation. Autophagy inhibition by RNA interference against Beclin-1 or ATG5 inhibited ZOL-induced OS cell death. ZOL induced autophagy by repressing the protein kinase B/mammalian target of rapamycin/p70S6 kinase pathway and extracellular signal-regulated kinase signaling-dependent autophagy in OS cell lines and patient-derived OS cells. Microarrays of miRNA showed that ZOL increased the levels of miR-212-3p, which is known to play an important role in autophagy, in OS in vitro and in vivo systems. Collectively, our data provided mechanistic insight into how increased miR-212-3p through ZOL treatment induces autophagy synergistically in OS cells, providing a preclinical rationale for conducting a broad-scale clinical evaluation of ZOL + miR-212-3p in treating OS.

Dihydrotanshinone I inhibits the growth of osteosarcoma through the Wnt/β-catenin signaling pathway

Background: Osteosarcoma is a common malignant tumor, with relatively lower survival rates in adolescents. Dihydrotanshinone I (DHI) was extracted from the traditional Chinese medicine Salvia miltiorrhiza and was shown to inhibit several types of cancer. Purpose: To explore the effect of DHI on the proliferation, migration, invasion, and apoptosis of osteosarcoma cells, as well as the possible molecular mechanism. Methods: The effect of DHI on the proliferation of osteosarcoma was detected by crystal violet assay, MTT assay, colony formation assay. The effects of DHI on the migration and invasion of osteosarcoma were detected by wound healing assays, cell migration and invasion assays. The effect of DHI on apoptosis of osteosarcoma was detected by cell apoptosis assay and Hoechst apoptosis staining. The protein expression levels were detected by Western blotting assay. The activity of Wnt/β-Catenin signaling pathway was detected by luciferase reporter assay and Western blot. The inhibitory effect of DHI on osteosarcoma in vivo was analyzed by an orthotopic OS tumor animal model and immunohistochemistry. Result: DHI may inhibit the proliferation, decrease the migration, reduce the invasion, and promote the apoptosis of osteosarcoma cells. In vivo mouse model, DHI can inhibit the formation of osteosarcoma. In terms of mechanism, DHI may inhibit both the transcriptional activity and the total protein level of β-catenin. Conclusion: DHI may inhibit the proliferation, migration, and invasion as well as induce the apoptosis of osteosarcoma cells, possibly through suppressing the Wnt/β-catenin signaling pathway.

Pro-Apoptotic Activity of French Polynesian Padina pavonica Extract on Human Osteosarcoma Cells

Recently, seaweeds and their extracts have attracted great interest in the pharmaceutical industry as a source of bioactive compounds. Studies have demonstrated the cytotoxic activity of macroalgae towards different types of cancer cell models, and their consumption has been suggested as a chemo-preventive agent against several cancers such as breast, cervix and colon cancers. Reports relevant to the chemical properties of brown algae Padina sp. are limited and those accompanied to a comprehensive evaluation of the biological activity on osteosarcoma (OS) are non existent. In this report, we explored the chemical composition of French Polynesian Padina pavonica extract (EPP) by spectrophotometric assays (total phenolic, flavonoid and tannin content, and antioxidant activity) and by gas chromatography-mass spectrometry (GC-MS) analysis, and provided EPP lipid and sterols profiles. Several compounds with relevant biological activity were also identified that suggest interesting pharmacological and health-protecting effects for EPP. Moreover, we demonstrated that EPP presents good anti-proliferative and pro-apoptotic activities against two OS cell lines, SaOS-2 and MNNG, with different cancer-related phenotypes. Finally, our data suggest that EPP might target different properties associated with cancer development and aggressiveness.

Identification of key genes in non‑alcoholic fatty liver disease progression based on bioinformatics analysis

Due to economic development and lifestyle changes, the incidence of non-alcoholic fatty liver disease (NAFLD) has gradually increased in recent years. However, the pathogenesis of NAFLD is not yet fully understood. To identify candidate genes that contribute to the development and progression of NAFLD, two microarray datasets were downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) were identified and functional enrichment analyses were performed. A protein-protein interaction network was constructed and modules were extracted using the Search Tool for the Retrieval of Interacting Genes and Cytoscape. The enriched functions and pathways of the DEGs included ‘cellular macromolecule biosynthetic process’, ‘cellular response to chemical stimulus’, ‘extracellular matrix organization’, ‘metabolic pathways’, ‘insulin resistance’ and ‘forkhead box protein O1 signaling pathway’. The DEGs, including type-1 angiotensin II receptor, formin-binding protein 1-like, RNA-binding protein with serine-rich domain 1, Ras-related C3 botulinum toxin substrate 1 and polyubiquitin-C, were identified using multiple bioinformatics methods and validated in vitro with reverse transcription-quantitative polymerase chain reaction analysis. In conclusion, five hub genes were identified in the present study, and they may aid in understanding of the molecular mechanisms underlying the development and progression of NAFLD.

Novel smoothened antagonists as anti-neoplastic agents for the treatment of osteosarcoma

Osteosarcoma (OS) is an ultra-rare highly malignant tumor of the skeletal system affecting mainly children and young adults and it is characterized by an extremely aggressive clinical course. OS patients are currently treated with chemotherapy and complete surgical resection of cancer tissue. However, resistance to chemotherapy and the recurrence of disease, as pulmonary metastasis, remain the two greatest challenges in the management, and treatment of this tumor. For these reasons, it is of primary interest to find alternative therapeutic strategies for OS. Dysregulated Hedgehog signalling is involved in the development of various types of cancers including OS. It has also been implicated in tumor/stromal interaction and cancer stem cell biology, and therefore presents a novel therapeutic strategy for cancer treatment. In our work, we tested the activity of five potent Smoothened (SMO) inhibitors, four acylguanidine and one acylthiourea derivatives, against an OS cell line. We found that almost all our compounds were able to inhibit OS cells proliferation and to reduce Gli1 protein levels. Our results also indicated that SMO inhibition in OS cells by such compounds, induces apoptosis with a nanomolar potency. These findings suggest that inactivation of SMO may be a useful approach to the treatment of patients with OS.