Forecast of actin-binding proteins as the oncotarget in osteosarcoma - a review of mechanism, diagnosis and therapy

How does plasticity of migration help tumor cells to avoid treatment: Cytoskeletal regulators and potential markers

Tumor shrinkage as a result of antitumor therapy is not the only and sufficient indicator of treatment success. Cancer progression leads to dissemination of tumor cells and formation of metastases - secondary tumor lesions in distant organs. Metastasis is associated with acquisition of mobile phenotype by tumor cells as a result of epithelial-to-mesenchymal transition and further cell migration based on cytoskeleton reorganization. The main mechanisms of individual cell migration are either mesenchymal, which depends on the activity of small GTPase Rac, actin polymerization, formation of adhesions with extracellular matrix and activity of proteolytic enzymes or amoeboid, which is based on the increase in intracellular pressure caused by the enhancement of actin cortex contractility regulated by Rho-ROCK-MLCKII pathway, and does not depend on the formation of adhesive structures with the matrix, nor on the activity of proteases. The ability of tumor cells to switch from one motility mode to another depending on cell context and environmental conditions, termed migratory plasticity, contributes to the efficiency of dissemination and often allows the cells to avoid the applied treatment. The search for new therapeutic targets among cytoskeletal proteins offers an opportunity to directly influence cell migration. For successful treatment it is important to assess the likelihood of migratory plasticity in a particular tumor. Therefore, the search for specific markers that can indicate a high probability of migratory plasticity is very important.

Actin-Associated Proteins and Small Molecules Targeting the Actin Cytoskeleton

Actin-associated proteins (AAPs) act on monomeric globular actin (G-actin) and polymerized filamentous actin (F-actin) to regulate their dynamics and architectures which ultimately control cell movement, shape change, division; organelle localization and trafficking. Actin-binding proteins (ABPs) are a subset of AAPs. Since actin was discovered as a myosin-activating protein (hence named actin) in 1942, the protein has also been found to be expressed in non-muscle cells, and numerous AAPs continue to be discovered. This review article lists all of the AAPs discovered so far while also allowing readers to sort the list based on the names, sizes, functions, related human diseases, and the dates of discovery. The list also contains links to the UniProt and Protein Atlas databases for accessing further, related details such as protein structures, associated proteins, subcellular localization, the expression levels in cells and tissues, mutations, and pathology. Because the actin cytoskeleton is involved in many pathological processes such as tumorigenesis, invasion, and developmental diseases, small molecules that target actin and AAPs which hold potential to treat these diseases are also listed.

The inhibitory effect of CTAB on human osteosarcoma through the PI3K/AKT signaling pathway

Osteosarcoma (OS) metastasis and recurrence and multidrug resistance are three major obstacles in the clinic. New highly effective and low toxicity drugs for osteosarcoma are needed. The antitumoral efficacy of cetrimonium bromide (CTAB), a quaternary ammonium compound, is gradually being investigated. The aim of the present study was to investigate the effects of CTAB on OS cells and the underlying mechanisms. CTAB inhibited the proliferation of osteosarcoma cells in a concentration‑ and time‑dependent manner, resulting in cell cycle arrest in G1 phase. CTAB also suppressed the migration and invasion of HOS and MG63 cells at a low concentration without inhibiting the growth of human osteoblasts. Moreover, CTAB promoted caspase‑mediated apoptosis of osteosarcoma cells through the PI3K/AKT cascade, and this effect was accompanied by obvious mitochondrial toxicity. In vivo, CTAB inhibited OS proliferation without inducing organ toxicity. In conclusion, this study reveals that CTAB has an inhibitory effect on OS by suppressing proliferation and metastasis and inducing apoptosis through the PI3K/AKT signaling pathway and identifies CTAB as a potential therapeutic drug.

A Bibliometric Analysis and Visualization of Current Research Trends in Chinese Medicine for Osteosarcoma

BACKGROUND

To illustrate the research framework, overall knowledge structure, and development trends of Chinese medicine (CM) treatment for osteosarcoma (OS) by using a bibliometric analysis and newly developed visualization tools.

METHODS

Research datasets were acquired from the Web of Science (WOS) database from January 1, 1980 to September 30, 2019. VOS viewer and Citespace software was used to analyze the data and generate visualization knowledge maps. Annual trends of publications, distribution of institutes, distribution of journals, citation and H-index status, co-authorship status, research hotspots and co-citation status were analyzed.

RESULTS

A total of 223 publications in the WOS database met the requirement. The number of published articles showed a rise but the citation frequency and the H-index of China were relatively low. The cooperation between the countries, institutes and authors were relatively weak. Most publications were basic researches. Most of the previous researches focused on basic mechanisms of CM in treating OS, and therapy and improvement of dosage form may become a frontier in this research field.

CONCLUSIONS

Compared with other fields, the field of CM treatment for osteosarcome is still in infancy. The distribution of researches is imbalanced and cooperation between countries, institutions and authors remains to be strengthened. Furthermore, basic research occupies an absolute dominant position, and the exploration of the molecular mechanism of CM in preventing and treating OS may become a key point in the future.

CCN2 promotes drug resistance in osteosarcoma by enhancing ABCG2 expression

In recent years, osteosarcoma survival rates have failed to improve significantly with conventional treatment modalities because of the development of chemotherapeutic resistance. The human breast cancer resistance protein/ATP binding cassette subfamily G member 2 (BCRP/ABCG2), a member of the ATP-binding cassette family, uses ATP hydrolysis to expel xenobiotics and chemotherapeutics from cells. CCN family member 2 (CCN2) is a secreted protein that modulates the biological function of cancer cells, enhanced ABCG2 protein expression and activation in this study via the α6β1 integrin receptor and increased osteosarcoma cell viability. CCN2 treatment downregulated miR-519d expression, which promoted ABCG2 expression. In a mouse xenograft model, knockdown of CCN2 expression increased the therapeutic effect of doxorubicin, which was reversed by ABCG2 overexpression. Our data show that CCN2 increases ABCG2 expression and promotes drug resistance through the α6β1 integrin receptor, whereas CCN2 downregulates miR-519d. CCN2 inhibition may represent a new therapeutic concept in osteosarcoma.