MicroRNA-761 targets FGFR1 to suppress the malignancy of osteosarcoma by deactivating PI3K/Akt pathway

MicroRNAs and osteosarcoma: Potential targets for inhibiting metastasis and increasing chemosensitivity

Osteosarcoma (OS) is the third most common cancer in young adults after lymphoma and brain cancer. Metastasis, like other cellular events, is dependent on signaling pathways; a series of changes in some proteins and signaling pathways pave the way for OS cells to invade and migrate. Ezrin, TGF-β, Notch, RUNX2, matrix metalloproteinases (MMPs), Wnt/β-catenin, and phosphoinositide 3-kinase (PI3K)/AKT are among the most important of these proteins and signaling pathways. Despite the improvements in treating OS, the overall survival of patients suffering from the metastatic disease has not experienced any significant change after surgical treatments and chemotherapy and 5-years overall survival in patients with metastatic OS is about 20%. Studies have shown that overexpression or inhibition of some microRNAs (miRNAs) has significant effects in limiting the invasion and migration of OS cells. The results of these studies highlight the potential of the clinical application of some miRNA mimics and miRNA inhibitors (antagomiRs) to inhibit OS metastasis in the future. In addition, some studies have shown that miRNAs are associated with the most important drug resistance mechanisms in OS, and some miRNAs are highly effective targets to increase chemosensitivity. The results of these studies suggest that miRNA mimics and antagomiRs may be helpful to increase the efficacy of conventional chemotherapy drugs in the treatment of metastatic OS. In this article, we discussed the role of various signaling pathways and the involved miRNAs in the metastasis of OS, attempting to provide a comprehensive review of the literature on OS metastasis and chemosensitivity.

miR-29a-3p mitigates the development of osteosarcoma through modulating IGF1 mediated PI3k/Akt/FOXO3 pathway by activating autophagy

Osteosarcoma (OS), occurring in mesenchymal tissues and with a high degree of malignancy, is most common in children and adolescents. At present, we intend to figure out the expression and functions of miR-29a-3p in OS development. Reverse transcription-polymerase chain reaction (RT-PCR) was adopted to monitor the expression of miR-29a-3p and IGF1 in OS tissues and adjacent non-tumor tissues. Then, the 3- (4,5)-dimethylthiahiazo (-z-y1)-3,5-di- phenytetrazoliumromide (MTT) assay, colony formation experiment, western blot and Transwell assay were conducted to validate OS cell proliferation, colony formation ability, apoptosis, migration and invasion. Next, the association between miR-29a-3p and IGF1 was corroborated by the dual-luciferase reporter assay and the Pearson correlation analysis. Finally, WB was implemented to test the levels of autophagy-related proteins LC3-I/LC3-II, Beclin-1, p62, and the IGF-1R/PI3k/Akt/FOXO3 axis in OS cells. As a result, miR-29a-3p was down-regulated in OS tissues (versus adjacent non-tumor tissues) and OS cell lines. Overexpressing miR-29a-3p aggravated apoptosis, dampened cell proliferation, colony formation, migration and invasion, and promoted autophagy of OS cells. IGF1 was identified as a target of miR-29a-3p. IGF1 induced oncogenic effects in OS by activating IGF-1R/ PI3k/Akt pathway, and it dampened the tumor-suppressive effect of miR-29a-3p on OS. Taken together, miR-29a-3p repressed the OS evolvement through inducing autophagy and inhibiting IGF1 mediated PI3k/Akt/FOXO3 pathway.

Long noncoding RNA ADIRF antisense RNA 1 upregulates insulin receptor substrate 1 to decrease the aggressiveness of osteosarcoma by sponging microRNA-761

An increasing number of studies have supported the critical regulatory actions of long noncoding RNAs (lncRNAs) in osteosarcoma (OS). However, the detailed roles of adipogenesis regulatory factor-antisense RNA 1 (ADIRF-AS1) in OS have not been comprehensively described. Hence, we first detected ADIRF-AS1 expression in OS and evaluated its clinical significance. Functional experiments were then performed to determine the modulatory role of ADIRF-AS1 in OS progression. ADIRF-AS1 was found to be overexpressed in OS, and the overall survival of patients with OS who had high ADIRF-AS1 levels was shorter than that of those with low levels. ADIRF-AS1 knockdown led to restricted proliferation, migration, and invasiveness of OS cells and increased apoptosis. Additionally, ADIRF-AS1 downregulation impeded tumor growth in vivo. Mechanistically, ADIRF-AS1 acted as a competitive endogenous RNA for microRNA-761 (miR-761) that siphoned miR-761 away from its target, namely insulin receptor substrate 1 (IRS1), leading to IRS1 overexpression. Rescue experiments showed that low levels of miR-761 or restoration of IRS1 could neutralize the effects of ADIRF-AS1 ablation in OS cells. In summary, ADIRF-AS1 exacerbates the oncogenicity of the OS cells by targeting the miR-761/IRS1 axis. Our findings may aid in the advancement of lncRNA-directed therapeutics for OS.

HER4 Promotes Osteosarcoma Progression and Predicts Poor Prognosis through the PTEN-PI3K/AKT Pathway

Studies have reported a relationship between human epidermal growth factor receptor 4 (HER4), a ubiquitously expressed and unique member of the ErbB family, and clinicopathological features of osteosarcoma. However, further investigation is warranted. HER4 expression was analyzed by quantitative reverse transcription-polymerase chain reaction, western blotting, and immunohistochemistry. The relationship between HER4 expression and the prognosis of patients with osteosarcoma was determined by constructing a Kaplan-Meier curve. Cell viability and proliferation were investigated by MTT and colony formation assays. The mechanism underlying HER4-modulated proliferation and invasion/migration of osteosarcoma cells was determined by short hairpin RNA (shRNA) interference, colony formation, migration, invasion, and western blotting experiments. Spheroid formation assay and CD133+ cell populations were used to examine HER4-induced stem-like traits.

The present findings revealed that HER4 was overexpressed in both osteosarcoma cells and tissues. Moreover, this overexpression was associated with high Enneking stage, metastasis, and recurrence. Sh-HER4 showed obviously suppressed cell viability, colony formation, and invasion/migration. In addition, knockdown of HER4 markedly attenuated the spheroid size and proportion of CD133-positive cells, as well as the expression of stemness markers. Sh-HER4 also reduced the tumor size, downregulated the expression of phosphorylated-PI3K (p-PI3K) and p-AKT, and increased that of p-phosphatase and tensin homolog (p-PTEN) in mouse tissue. From a mechanistic perspective, HER4 knockdown activated p-PTEN and suppressed p-PI3K and p-AKT expression. HER4 promoted osteosarcoma progression through inactivation of the PTEN-PI3K/AKT pathway.

Taken together, the results indicate that HER4 represents a novel target in osteosarcoma progression and stemness modulation, and may be of value for the development of treatments against osteosarcoma.

CircIL4R activates the PI3K/AKT signaling pathway via the miR-761/TRIM29/PHLPP1 axis and promotes proliferation and metastasis in colorectal cancer

BACKGROUND

Accumulating studies have revealed that aberrant expression of circular RNAs (circRNAs) is widely involved in the tumorigenesis and progression of malignant cancers, including colorectal cancer (CRC). Nevertheless, the clinical significance, levels, features, biological function, and molecular mechanisms of novel circRNAs in CRC remain largely unexplored.

METHODS

CRC-related circRNAs were identified through bioinformatics analysis and verified in clinical specimens by qRT-PCR and in situ hybridization (ISH). Then, in vitro and in vivo experiments were performed to determine the clinical significance of, functional roles of, and clinical characteristics associated with circIL4R in CRC specimens and cells. Mechanistically, RNA pull-down, fluorescence in situ hybridization (FISH), luciferase reporter, and ubiquitination assays were performed to confirm the underlying mechanism of circIL4R.

RESULTS

CircIL4R was upregulated in CRC cell lines and in sera and tissues from CRC patients and was positively correlated with advanced clinicopathological features and poor prognosis. Functional experiments demonstrated that circIL4R promotes CRC cell proliferation, migration, and invasion via the PI3K/AKT signaling pathway. Mechanistically, circIL4R was regulated by TFAP2C and competitively interacted with miR-761 to enhance the expression of TRIM29, thereby targeting PHLPP1 for ubiquitin-mediated degradation to activate the PI3K/AKT signaling pathway and consequently facilitate CRC progression.

CONCLUSIONS

Our findings demonstrate that upregulation of circIL4R plays an oncogenic role in CRC progression and may serve as a promising diagnostic and prognostic biomarker for CRC detection and as a potential therapeutic target for CRC treatment.

Long non-coding RNA HOTAIR/microRNA-761 sponge regulates PPME1 and further influences cell biological functions in thyroid carcinoma

BACKGROUND

Most well-differentiated thyroid carcinomas display good therapeutic outcomes, but there are still some patients who are not sensitive to the general treatments lose their treatment opportunities. Thus, it is important to understand the molecular mechanisms that cause thyroid carcinoma, so as to find effective diagnostic and therapeutic targets.

AIM OF THE STUDY

To explore the role of homeobox transcript antisense RNA (HOTAIR) in thyroid carcinoma through protein phosphatase methylesterase 1 (PPME1) by sponging microRNA 761 (miR-761).

METHODS

The regulation network amongst HOTAIR, miR-761 and PPME1 was predicted by online sources. RT-PCR was conducted to evaluate the expression of HOTAIR and miR-761 in tumor tissues. Clinical data was collected and analyzed by Chi-square test. Cell apoptosis and proliferation was evaluated using three types of cancer cells (HTh-7, CAL-62, BCPAP) after treated with si-HOTAIR and miR-761inhibitor. The binding site among HOTAIR, miR-761 and PPME1 was verified by dual luciferase reporter assay. PPME1 expression was measured after HOTAIR and miR-761 were suppressed by western blot. Survival time was measured in nude mice using log-rank test.

RESULTS

HOTAIR was expressed to a significantly greater extent than miR-761 in thyroid tumor tissues (P < .001). miR-761 and PPME1 were negatively correlated (coef = -1.91, P < .001). HOTAIR competitively binds to miR-761 and miR-761 directly targets PPME1. HOTAIR was highly correlated with TNM (χ 2 = 5.797, P = .016), tumor size (χ 2 = 7.955, P = .005) and lymphatic metastasis (χ 2 = 6.0, P = .014). HOTAIR promoted cell proliferation and inhibited cell apoptosis, whereas miR-761 did not. HOTAIR elevated and miR-761 suppressed PPME1 expression. HOTAIR expression appears to affect the survival time in vivo.

CONCLUSION

HOTAIR regulated thyroid cancer cells by binding to miR-761 through PPME1.

Transcription factor activation and protein phosphorylation patterns are distinct for CD28 and ICAM-1 co-stimulatory molecules

We examined signaling differences between two co-stimulatory molecules, CD28 and ICAM-1 by analyzing transcription factors and proteins that are activated downstream of these co-stimulations. We observed that FAST-1, a crucial protein in the TGFβ signaling pathway, was activated by only ICAM-1 co-stimulation, and not by CD28. We also observed that receptor tyrosine kinases Csk, Dtk, FGFR1 and ROR2 were phosphorylated upon CD28 co-stimulation and IGF-1R, HGFR, MuSK and EphA8 were phosphorylated upon ICAM-1 co-stimulation. Together, these findings suggest that these two co-stimulators induce the activation of different sets of proteins, suggesting that each co-stimulatory molecule has its unique signaling profile.

MicroRNA-761 suppresses tumor progression in osteosarcoma via negatively regulating ALDH1B1

AIMS

Our previous study has demonstrated that high expression of ALDH1B1 promoted osteosarcoma tumor progression and was correlated with unfavorable prognosis in osteosarcoma patients. In the current study, we investigated the underlying mechanism and regulation of ALDH1B1 in osteosarcoma.

MATERIALS AND METHODS

qRT-PCR assay was applied to detect miR-761 expression. CCK-8, colony formation and EdU assays were conducted to explore the functional role of miR-761/ALDH1B1 axis in osteosarcoma. Bioinformatics analysis and luciferase reporter assay was utilized to assess the regulation between miR-761 and ALDH1B1. Mechanism experiments were implemented to investigate the underlying molecular mechanism of miR-761/ALDH1B1 axis.

KEY FINDINGS

ALDH1B1 was negatively regulated by microRNA-761 (miR-761). Functionally, miR-761 suppressed cell growth, migration, and invasion in osteosarcoma via targeting ALDH1B1 in vitro. Xenograft tumor model demonstrated that miR-761 inhibited osteosarcoma tumor development in vivo through regulating ALDH1B1. Consistently, we showed that miR-761 expression was decreased in osteosarcoma patients and low expression of miR-761 was correlated with worse prognosis in osteosarcoma patients. Mechanistically, we revealed that high expression of ALDH1B1 was significantly associated with enhanced TGF-β signaling, epithelial-mesenchymal transition (EMT), and cell adhesion. Furthermore, miR-761 regulated TGF-β and EMT/cell adhesion in osteosarcoma via targeting ALDH1B1.

SIGNIFICANCE

Taken together, our findings suggest that the oncogenic ALDH1B1 is regulated by miR-761 during osteosarcoma development and progression, which might provide a novel prognostic biomarker and therapeutic strategy for osteosarcoma treatment.

Proanthocyanidin B2 inhibits proliferation and induces apoptosis of osteosarcoma cells by suppressing the PI3K/AKT pathway

Osteosarcoma (OS) is the most common primary malignant bone tumour in children and adolescents. The long‐term survival rate of OS patients is stubbornly low mainly due to the chemotherapy resistance. We therefore aimed to investigate the antitumoral effects and underlying mechanisms of proanthocyanidin B2 (PB2) on OS cells in the current study. The effect of PB2 on the proliferation and apoptosis of OS cell lines was assessed by CCK‐8, colony formation, and flow cytometry assays. The target gene and protein expression levels were measured by qRT‐PCR and Western blotting. A xenograft mouse model was established to assess the effects of PB2 on OS proliferation and apoptosis in vivo. Results from in vitro experiments showed that PB2 inhibited the proliferation and induced apoptosis of OS cells, and also increased the expression levels of apoptosis‐related proteins. Moreover, PB2 induced OS cell apoptosis through suppressing the PI3K/AKT signalling pathway. The in vivo experiments further confirmed that PB2 could inhibit OS tumour growth and induce its apoptosis. Taken together, these results suggested that PB2 inhibited the proliferation and induced apoptosis of OS cells through the suppression of the PI3K/AKT signalling pathway.