Tankyrase1 antisense oligodeoxynucleotides suppress the proliferation, migration and invasion through Hippo/YAP pathway in human osteosarcoma cells

Regulation of the Epithelial to Mesenchymal Transition in Osteosarcoma

The epithelial to mesenchymal transition (EMT) is a cellular process that has been linked to the promotion of aggressive cellular features in many cancer types. It is characterized by the loss of the epithelial cell phenotype and a shift to a more mesenchymal phenotype and is accompanied by an associated change in cell markers. EMT is highly complex and regulated via multiple signaling pathways. While the importance of EMT is classically described for carcinomas-cancers of epithelial origin-it has also been clearly demonstrated in non-epithelial cancers, including osteosarcoma (OS), a primary bone cancer predominantly affecting children and young adults. Recent studies examining EMT in OS have highlighted regulatory roles for multiple proteins, non-coding nucleic acids, and components of the tumor micro-environment. This review serves to summarize these experimental findings, identify key families of regulatory molecules, and identify potential therapeutic targets specific to the EMT process in OS.

Genetic Alterations and Deregulation of Hippo Pathway as a Pathogenetic Mechanism in Bone and Soft Tissue Sarcoma

The Hippo pathway is an evolutionarily conserved modulator of developmental biology with a key role in tissue and organ size regulation under homeostatic conditions. Like other signaling pathways with a significant role in embryonic development, the deregulation of Hippo signaling contributes to oncogenesis. Central to the Hippo pathway is a conserved cascade of adaptor proteins and inhibitory kinases that converge and regulate the activity of the oncoproteins YAP and TAZ, the final transducers of the pathway. Elevated levels and aberrant activation of YAP and TAZ have been described in many cancers. Though most of the studies describe their pervasive activation in epithelial neoplasms, there is increasing evidence pointing out its relevance in mesenchymal malignancies as well. Interestingly, somatic or germline mutations in genes of the Hippo pathway are scarce compared to other signaling pathways that are frequently disrupted in cancer. However, in the case of sarcomas, several examples of genetic alteration of Hippo members, including gene fusions, have been described during the last few years. Here, we review the current knowledge of Hippo pathway implication in sarcoma, describing mechanistic hints recently reported in specific histological entities and how these alterations represent an opportunity for targeted therapy in this heterogeneous group of neoplasm.

Long non-coding RNA ZMIZ1-AS1 promotes osteosarcoma progression by stabilization of ZMIZ1

BACKGROUND

Osteosarcomas (OS) are frequent primary sarcomas of the bone in children and adolescents. The long non-coding RNAs (lncRNAs) can affect the progression of many cancers by their sense transcripts. The present study was designed to probe the role of ZMIZ1-AS1 and the downstream pathway in OS progression.

METHODS

Cell proliferation, invasion, and migration were detected by colony formation, transwell, and wound healing assays. The binding of SOX2 or MYC protein with ZMIZ1-AS1 promoter was explored by ChIP assay and dual-luciferase reporter assay. Interaction between PTBP1 protein and ZMIZ1-AS1 (or ZMIZ1 mRNA) was detected by RIP assay.

RESULTS

SOX2 and MYC are the downstream effectors of the Hippo pathway and transcriptionally activated ZMIZ1-AS1. Compared to the controls, OS tissues and cells contained higher ZMIZ1-AS1 expression. Silencing of ZMIZ1-AS1 repressed OS cell viability, proliferation, migration, and invasion. Our findings further showed that ZMIZ1-AS1 recruits RNA-binding protein PTBP1 to stabilize ZMIZ1 mRNA. PTBP1 or ZMIZ1 overexpression rescues the suppressive effects of silenced ZMIZ1-AS1 on OS cellular processes. Importantly, ZMIZ1-AS1 promotes OS growth in vivo by stabilization of ZMIZ1.

CONCLUSIONS

Long non-coding RNA ZMIZ1-AS1 promotes OS progression by stabilization of ZMIZ1. The Hippo pathway is inactivated in osteosarcoma. Transcriptional factors SOX2 and MYC downstream the Hippo pathway induce the upregulation of ZMIZ1-AS1 in osteosarcoma. ZMIZ1-AS1 recruits RNA binding protein PTBP1 that stabilizes ZMIZ1, the sense transcript of ZMIZ1-AS1. ZMIZ1-AS1 promotes osteosarcoma cell viability, proliferation, migration, and invasion by ZMIZ1 in a PTBP1 dependent manner.

Conservation of Epithelial-to-Mesenchymal Transition Process in Neural Crest Cells and Metastatic Cancer

Epithelial to mesenchymal transition (EMT) is a highly conserved cellular process in several species, from worms to humans. EMT plays a fundamental role in early embryogenesis, wound healing, and cancer metastasis. For neural crest cell (NCC) development, EMT typically results in forming a migratory and potent cell population that generates a wide variety of cell and tissue, including cartilage, bone, connective tissue, endocrine cells, neurons, and glia amongst many others. The degree of conservation between the signaling pathways that regulate EMT during development and metastatic cancer (MC) has not been fully established, despite ample studies. This systematic review and meta-analysis dissects the major signaling pathways involved in EMT of NCC development and MC to unravel the similarities and differences. While the FGF, TGFβ/BMP, SHH, and NOTCH pathways have been rigorously investigated in both systems, the EGF, IGF, HIPPO, Factor Receptor Superfamily, and their intracellular signaling cascades need to be the focus of future NCC studies. In general, meta-analyses of the associated signaling pathways show a significant number of overlapping genes (particularly ligands, transcription regulators, and targeted cadherins) involved in each signaling pathway of both systems without stratification by body segments and cancer type. Lack of stratification makes it difficult to meaningfully evaluate the intracellular downstream effectors of each signaling pathway. Finally, pediatric neuroblastoma and melanoma are NCC-derived malignancies, which emphasize the importance of uncovering the EMT events that convert NCC into treatment-resistant malignant cells.

Long non‑coding RNA FOXD2‑AS1 regulates the tumorigenesis and progression of breast cancer via the S100 calcium binding protein A1/Hippo signaling pathway

Breast cancer is one of the most prevalent cancer types and is accompanied by a high incidence and mortality rate, severely threatening women's health globally. Long non‑coding RNA forkhead box D2 adjacent apposite strand RNA 1 (lncRNA FOXD2‑AS1) has been identified to function as an oncogene in human cancers; however, it has rarely been investigated in breast cancer. The aim of the present study was to investigate the role of FOXD2‑AS1 in breast cancer, and to clarify the underlying mechanisms. The expression of FOXD2‑AS1 in breast cancer cell lines was first quantified by reverse transcription‑quantitative PCR, and the biological function of FOXD2‑AS1 was then determined. Cellular proliferative ability was determined by Cell Counting kit‑8 assay, and wound healing and Transwell assays were conducted to assess the cell migratory and invasive ability. Corresponding protein expression levels were determined by western blot analysis. In addition, experimental animal models were established by the subcutaneous injection of MDA‑MB‑468 cells into the right axillary lymph nodes of BALB/c nude mice, and the effects of FOXD2‑AS1 on tumor growth were observed. The results indicated that FOXD2‑AS1 expression was upregulated in breast cancer cell lines, and that FOXD2‑AS1 downregulation significantly inhibited the proliferation, migration and invasiveness of MCF‑7 and MDA‑MB‑468 cells. S100 calcium binding protein A1 (S100A1) was also upregulated in breast cancer cell lines and was positively regulated by FOXD2‑AS1. Furthermore, the inhibition of S100A1 and the overexpression of the serine/threonine‑protein kinase, large tumor suppressor homolog 1 (LATS1), inhibited the FOXD2‑AS1‑induced cellular proliferation, migration and invasiveness in breast cancer. Experimental mouse models revealed that FOXD2‑AS1 downregulation significantly inhibited tumor growth, and that the levels of phosphorylated (p‑)YAP and p‑LATS1 were upregulated by FOXD2‑AS1 knockdown, indicating that the inhibition of FOXD2‑AS1 activated Hippo/yes‑associated protein signaling. On the whole, the findings of the present study suggest that the FOXD2‑AS1/S100A1/Hippo axis is involved in the tumorigenesis and progression of breast cancer. In the future, these may contribution to the identification of more effective breast cancer treatments.

The Hippo in the room: Targeting the Hippo signalling pathway for osteosarcoma therapies

Osteosarcoma (OS) is a primary malignant bone tumour which usually occurs in children and adolescents. OS is primarily a result of chromosomal aberrations, a combination of acquired genetic changes and, hereditary, resulting in the dysregulation of cellular functions. The Hippo signalling pathway regulates cell and tissue growth by modulating cell proliferation, differentiation, and migration in developing organs. Mammalian STE20-like 1/2 (MST1/2) protein kinases are activated by neurofibromatosis type 2, Ras association domain family member 2, kidney and brain protein, or other factors. Interactions between MST1/2 and salvador family WW domain-containing protein 1 activate large tumour suppressor kinase 1/2 proteins, which in turn phosphorylate the downstream Yes-associated protein 1/transcriptional coactivator with PDZ-binding motif (YAP/TAZ). Moreover, dysregulation of this pathway can lead to aberrant cell growth, resulting in tumorigenesis. Interestingly, small molecules targeting the Hippo signalling pathways, through affecting YAP/TAZ cellular localisation and their interaction with members of the TEA/ATTS domain family of transcriptional enhancers are being developed and hold promise for the treatment of OS. This review discusses the existing knowledge about the involvement of the Hippo signalling cascade in OS and highlights several small molecule inhibitors as potential novel therapeutics.