Effect of DEC1 on the proliferation, adhesion, invasion and epithelial-mesenchymal transition of osteosarcoma cells

Cisplatin increases carboxylesterases through increasing PXR mediated by the decrease of DEC1

cis-Diamminedichloroplatinum (CDDP) is widely used for the treatment of various solid cancers. Here we reported that CDDP increased the expression and enzymatic activities of carboxylesterase 1 (CES1) and carboxylesterase 2 (CES2), along with the upregulation of pregnane X receptor (PXR) and the downregulation of differentiated embryonic chondrocyte-expressed gene 1 (DEC1) in human hepatoma cells, primary mouse hepatocytes, mouse liver and intestine. The overexpression or knockdown of PXR alone upregulated or downregulated the CES1 and CES2 expression, respectively. The increases in CES1 and CES2 expression levels induced by CDDP abolished or enhanced by PXR knockdown or overexpression, implying that CDDP induces carboxylesterases through the activation of PXR. Likewise, the overexpression or knockdown of DEC1 alone significantly decreased or increased PXR and its targets. Moreover, the increases of PXR and its targets induced by CDDP were abolished or alleviated by the overexpression or knockdown of DEC1. The overexpression or knockdown of DEC1 affected the response of PXR to CDDP, but not vice versa, suggesting that CDDP increases carboxylesterases by upregulating PXR mediated by the decrease of DEC1. In addition, CDDP did not increase DEC1 mRNA degradation but suppressed DEC1 promoter reporter activity, indicating that it suppresses DEC1 transcriptionally. The combined use of CDDP and irinotecan had a synergistic effect on two cell lines, especially when CDDP was used first.

Expression of E-cadherin and N-cadherin in Epithelial-to-Mesenchymal Transition of Osteosarcoma: A Systematic Review

Osteosarcoma (OS) is a debilitating cancer of the bone that commonly afflicts the young and old. This may be de novo or associated with tumorigenic syndromes. However, many molecular mechanisms are still being uncovered and may offer greater avenues for screening and therapy. Cadherins, including E-cadherin and N-cadherin/vimentin, are involved in epithelial-to-mesenchymal transmission (EMT), which is key for tumor invasion. A study reviewing the relationship between OS and cadherins might elucidate a potential target for therapy and screening. A robust literature review was conducted by searching PubMed with the keywords "osteosarcoma", "cadherin", "e-cadherin" and "n-cadherin". Of a preliminary 266 papers, 25 were included in the final review. Review articles and those without primary data were excluded. Loss of E-cadherin is noted in metastatic cell lines of osteosarcoma. Overexpression of E-cadherin or knockout of N-cadherin/vimentin results in loss of metastatic potential. There are several methods of gene knockout, including CRISPR-Cas9 gene editing, viral vector insertion with micro RNA complementary to long noncoding RNA within gene segments, or proteomic editing. Screening for EMT and genetic treatment of EMT is a possible avenue for the treatment of refractory osteosarcoma. Several studies were conducted ex vivo. Further testing involving in vitro therapy is necessary to validate these methods. Limitations of this study involve a lack of in vivo trials to validate methods.

Circular RNA_0078767 upregulates Kruppel-like factor 9 expression by targeting microRNA-889, thereby inhibiting the progression of osteosarcoma

Among kids and juveniles, osteosarcoma (OS) is a common bone malignancy. Circular RNAs (circs, circRNAs) play important roles in multiple malignancies including OS, yet circ_0078767ʹs biological functions in OS are far from well elucidated. This study is targeted at understanding circ_0078767ʹs biological functions in OS and its molecular mechanisms. This study confirmed that circ_0078767 expression was reduced in OS cell lines and tissues. Circ_0078767 overexpression remarkably inhibited OS cell growth, migration, invasion, epithelial-mesenchymal transition (EMT), and promoted apoptosis, whereas circ_0078767 knockdown resulted in the opposite effects. MicroRNA-889 (miR-889) was targeted and regulated by circ_0078767, and miR-889 could negatively modulate Kruppel-like factor 9 (KLF9) expression. Besides, circ_0078767 positively regulated KLF9 expression in OS cells via repressing miR-889. In conclusion, circ_0078767 enhances KLF9 expression by targeting miR-889 to inhibit OS progression.