MicroRNA-638 expression change in osteosarcoma patients via PLD1 and VEGF expression

Molecular mechanism of microRNAs regulating apoptosis in osteosarcoma

Osteosarcoma is a primary malignant bone tumor with no effective treatment. Apoptosis, one of the programmed cell death, is any pathological form of cell death mediated by intracellular processes. Under the pathological state, the de-regulated regulation of apoptosis can disrupt the balance between cell proliferation and death, causing osteosarcoma proliferation and metastasis. As carcinogenic or tumor suppressor factors, microRNAs (miRNAs) regulate apoptosis of osteosarcoma cells by regulating apoptosis-related genes and apoptosis-related signaling pathways, such as mitochondrial apoptosis pathway, death receptor pathway, and endoplasmic reticulum pathway. Meanwhile as these abnormal miRNAs can be stored and transported by exosomes, detecting exosomes can be seen an effective method to diagnose osteosarcoma in the early stage. This review provides the current knowledge of miRNAs and their target genes related to the apoptosis of osteosarcoma, summarizes abnormal expression and regulation of miRNAs and signaling pathways in osteosarcoma and prospects the detection of exosome as a method for early diagnosis of osteosarcoma.

Serum exosomal miR-638 is a prognostic marker of HCC via downregulation of VE-cadherin and ZO-1 of endothelial cells

Hepatocellular carcinoma (HCC) is the second leading cause of cancer‐related death. High recurrence rates after curative resection and the lack of specific biomarkers for intrahepatic metastases are major clinical problems. Recently, exosomal microRNAs (miRNAs) have been reported to have a role in the formation of the pre‐metastatic niche and as promising biomarkers in patients with malignancy. Here we aimed to clarify the molecular mechanisms of intrahepatic metastasis and to identify a novel biomarker miRNA in patients with HCC. A highly intrahepatic metastatic cell line (HuH‐7M) was established by in vivo selection. HuH‐7M showed increased proliferative ability and suppression of apoptosis and anoikis. HuH‐7M and the parental cell (HuH‐7P) showed the similar expression of epithelial‐mesenchymal transition markers and cancer stem cell markers. In vivo, mice treated with exosomes derived from HuH‐7M showed increased tumorigenesis of liver metastases. Exosomes from HuH‐7M downregulated endothelial cell expression of vascular endothelial‐cadherin (VE‐cadherin) and zonula occludens‐1 (ZO‐1) in non‐cancerous regions of liver and increased the permeability of FITC‐dextran through the monolayer of endothelial cells. The miRNAs (miR‐638, miR‐663a, miR‐3648, and miR‐4258) could attenuate endothelial junction integrity by inhibiting VE‐cadherin and ZO‐1 expression. In patients with HCC, higher serum exosomal miR‐638 expression was associated with tumor recurrence. In conclusion, the miRNAs secreted from a highly metastatic cancer cell can promote vascular permeability via downregulation of endothelial expression of VE‐cadherin and ZO‐1. Serum exosomal miR‐638 expression holds potential for serving as a significant and independent prognostic marker in HCC.

Comparison of VEGF-A secretion from tumor cells under cellular stresses in conventional monolayer culture and microfluidic three-dimensional spheroid models

Vascular endothelial growth factor (VEGF) is a major cytokine in tumor biology affecting tumor survival, aggressiveness and pro-angiogenetic activities. In addition, cellular stresses often result in aggressive pro-angiogenetic behavior in tumors. For in vitro study, conventional monolayer cell culture has been broadly exploited; however, it often provides limited information due to its different microenvironment from that in vivo. Recently, three-dimensional (3D) cell spheroid culture provides in vivo-like microenvironments to study tumor biology and their survival mechanisms with better predictive power. In this work, vascular endothelial growth factor of type A (VEGF-A) secretion from osteosarcoma (MG-63) cells cultured using monolayer and 3D spheroid models under two stress conditions: nutrient deficiency (reduced serum culture) and hypoxia-inducible factor (HIF) inhibition (HIF inhibitor, YC-1) are characterized and systematically compared. In order to obtain ample sample size for consistent characterization of cellular responses from cancer spheroids under the stresses and compare the responses to those from the conventional monolayer model, a microfluidic spheroid formation and culture device is utilized in the experiments. In the analysis, cell viability is estimated from captured images, and quantification of VEGF-A secreted from the cells is achieved using enzyme-linked immunosorbent assay (ELISA). The experimental results show that the viabilities decrease when the cells face higher stress levels in both monolayer and 3D spheroid culture models; however, the VEGF-A secretion profiles between the cell culture models are different. The VEGF-A secretion decreases when the cells face higher stress conditions in the monolayer cell culture. In contrast, for the 3D spheroid culture, the VEGF-A concentration decreases for low stress levels but increases while the stress level is high. The VEGF-A regulation in the 3D models mimics in vivo cases of tumor survival and can provide insightful information to investigate tumor angiogenesis in vitro. The approach developed in this paper provides an efficient method to quantitatively and statistically study tumor growth kinetics and stress responses from highly uniform samples and it can also be applied to compare the underlying biomolecular mechanisms in monolayer and 3D spheroid culture models to elucidate the effects of microenvironments on cellular response in cancer research.

TRIP6 regulates the proliferation, migration, invasion and apoptosis of osteosarcoma cells by activating the NF-κB signaling pathway

Thyroid hormone receptor-interacting protein 6 (TRIP6), a member of the zyxin family of Lin-Isl-Mec (LIM) proteins, is an adaptor protein primarily expressed in epithelial cells. TRIP6 can regulate a variety of cellular responses, such as actin cytoskeletal reorganization and cell adhesion. However, to the best of our knowledge, the role of TRIP6 in osteosarcoma (Os) has not been previously reported. Therefore, the present study investigated the role of TRIP6 in the occurrence and development of Os, and the potential of utilizing TRIP6 as a therapeutic target in Os. The present results suggested that the expression levels of TRIP6 were significantly increased in Os cells and clinical tissue specimens compared with normal osteoblasts and adjacent non-tumor tissue. Moreover, the present results suggested that overexpressing TRIP6 significantly increased proliferation, migration and invasion, while inhibiting apoptosis in Os cells. However, silencing TRIP6 decreased proliferation, migration and invasion, while activating apoptosis in Os cells. The present results suggested that overexpression of TRIP6 increased NF-κB activation by decreasing the protein expression levels of inhibitor of κBα, and increasing total and phosphorylated P65 levels. The present results indicated that TRIP6 silencing decreased NF-κB activation. Collectively, the present results suggested that TRIP6 may play a role in promoting Os cell proliferation, migration and invasion, while inhibiting cell apoptosis. Furthermore, TRIP6 may be utilized as a novel prognostic biomarker and therapeutic target in Os.

Downregulation of miR-1826 Indicates a Poor Prognosis for Osteosarcoma Patients and Regulates Tumor Cell Proliferation, Migration, and Invasion

Background

Osteosarcoma (OS) is the most frequent bone tumor with high metastasis. This study is aimed at assessing the expression and prognostic significance of microRNA-1826 (miR-1826) in OS patients, as well as its biological function in tumor progression.

Methods

Quantitative Real-Time PCR was employed to measure the expression of miR-1826 in OS tissues and cell lines. Kaplan-Meier survival analysis and Cox regression model were used to evaluate the prognostic value of miR-1826. CCK-8 and Transwell assay were conducted to investigate the effect of miR-1826 on OS cell proliferation, migration, and invasion.

Results

miR-1826 expression was downregulated in OS tissues and cell lines and associated with OS patients' clinical stage and distant metastasis. Low levels of miR-1826 were related with shorter survival time and determined as an independent prognostic indicator for the overall survival of OS patients. The overexpression of miR-1826 in OS cells led to inhibited cell proliferation, migration, and invasion.

Conclusion

The decreased expression of miR-1826 predicts a poor prognosis in OS patients, and its overexpression inhibits OS cell proliferation, migration, and invasion. This newly identified miR-1826 provides a novel sight into the pathogenesis of OS and offers a candidate prognostic biomarker and therapeutic target for OS treatment.