Long non-coding RNA OR3A4 promotes metastasis of ovarian cancer via inhibiting KLF6

LncRNA OR3A4 Regulated the Growth of Osteosarcoma Cells by Modulating the miR-1207-5p/G6PD Signaling

Background

Increasing evidence has demonstrated the importance of non-coding RNAs including long non-coding RNA (lncRNA) and microRNAs (miRNAs) in the tumorigenesis of osteosarcoma (OS). Abnormal expression of lncRNA olfactory receptor family 3 subfamily A member 4 (OR3A4) was found in multiple human cancers; however, the function of OR3A4 in OS remains largely unknown.

Materials and Methods

The expression level of OR3A4 in OS tissues and cell lines was detected by RT-qPCR. Cell counting kit-8 assay, colony formation and flow cytometry analysis were performed to determine the growth of OS cells. The targets of OR3A4 were predicted using the miRDB database. The binding between OR3A4 and miRNAs was confirmed by dual-luciferase reporter assay.

Results

OR3A4 was overexpressed in OS tissues and correlated with the advanced progression of OS patients. Down-regulation of OR3A4 significantly inhibited the proliferation and colony formation of OS cells. Mechanistically, OR3A4 acted as a sponge of miR-1207-5p. Glucose-6-phosphate dehydrogenase (G6PD) was identified as a target of miR-1207-5p. Knockdown of OR3A4 increased the expression of miR-1207-5p and consequently, suppressed the level of G6PD in OS cells. Due to the essential role of G6PD in the pentose phosphate pathway (PPP), depletion of OR3A4 inhibited NADPH production, glucose consumption and lactate generation. Decreased level of NADPH by depletion of OR3A4 up-regulated the redox state (ROS) content and resulted in endoplasmic reticulum (ER) stress in OS cells. Restoration of G6PD significantly attenuated the cell growth inhibition induced by OR3A4 knockdown.

Conclusion

Our finding suggested the critical role of OR3A4 in the proliferation of OS cells via targeting the miR-1207-5p/G6PD axis.

Long noncoding RNA OR3A4 promotes the proliferation and invasion of osteosarcoma cells by sponging miR-1227-5p

Background

Long noncoding RNAs (lncRNAs) have been identified as key players in promoting tumourigenesis in osteosarcoma. LncRNA OR3A4 (OR3A4) has been reported as an oncogene in a number of tumours. However, the clinical value of OR3A4 in osteosarcoma and the role of OR3A4 in osteosarcoma progression are still unknown.

Methods

The expression levels of OR3A4 in the tumour tissue of osteosarcoma patients and osteosarcoma cell lines were detected by RT-PCR. Kaplan-Meier analysis and log-rank test were performed to evaluate the relationship between the level of OR3A4 expression and the prognosis of osteosarcoma patients. We investigated the association between the tissue expression levels of OR3A4 and different clinicopathological characteristics of osteosarcoma patients by χ² tests. Bioinformatic databases and luciferase reporter assays were used to predict and validate the target microRNA of OR3A4. Finally, the role of OR3A4 in the proliferation and invasion of osteosarcoma cells was tested by MTT and Transwell assays, respectively.

Results

We observed that the expression level of OR3A4 was upregulated in the tumour tissue of osteosarcoma patients (p < 0.001) and osteosarcoma cell lines (p < 0.01) compared with the normal adjacent tissue and a normal human foetal osteoblastic cell line, respectively. The survival curve revealed that patients with high expression levels of OR3A4 had lower overall survival. Increased OR3A4 expression in osteosarcoma patients was associated with distant metastasis (p = 0.02) and advanced clinical stage (p < 0.001). In addition, bioinformatics analysis and luciferase reporter assays verified the complementary binding between OR3A4 and miR-1227-5p. Furthermore, we found that OR3A4 acted as a miR-1227-5p “sponge” to modulate osteosarcoma cell proliferation and invasion via downregulation of miR-1227-5p.

Conclusion

OR3A4 promotes osteosarcoma cell proliferation and invasion by sponging miR-1227-5p, which might be related to the metastasis of osteosarcoma and could be used as a potential prognostic biomarker and therapeutic target in osteosarcoma.