Differential expression pattern of Twist1 in mouse preimplantation embryos suggests its multiple roles during early development

Targeting methyltransferase PRMT5 retards the carcinogenesis and metastasis of HNSCC via epigenetically inhibiting Twist1 transcription

Protein arginine methyltransferase 5 (PRMT5) is an important type II arginine methyltransferase that can play roles in cancers in a highly tissue-specific manner, but its role in the carcinogenesis and metastasis of head and neck squamous cell carcinoma (HNSCC) remains unclear. Here, we detected PRMT5 expression in HNSCC tissues and performed series of in vivo and in vitro assays to investigate the function and mechanism of PRMT5 in HNSCC. We found that PRMT5 was overexpressed in dysplastic and cancer tissues, and associated with lymph node metastasis and worse patient survival. PRMT5 knockdown repressed the malignant phenotype of HNSCC cells in vitro and in vivo. PRMT5 specific inhibitor blocked the formation of precancerous lesion and HNSCC in 4NQO-induced tongue carcinogenesis model, prevented lymph node metastasis in tongue orthotopic xenograft model and inhibited cancer development in subcutaneous xenograft model and Patient-Derived tumor Xenograft (PDX) model. Mechanistically, PRMT5-catalyzed H3R2me2s promotes the enrichment of H3K4me3 in the Twist1 promoter region by recruiting WDR5, and subsequently activates the transcription of Twist1. The rescue experiments indicated that overexpressed Twist1 abrogated the inhibition of cell invasion induced by PRMT5 inhibitor. In summary, this study elucidates that PRMT5 inhibition could reduce H3K4me3-mediated Twist1 transcription and retard the carcinogenesis and metastasis of HNSCC.

Downregulation of miR-22 Contributes to Epithelial-Mesenchymal Transition in Osteosarcoma by Targeting Twist1

The epithelial-mesenchymal transition (EMT) is a vital step in osteosarcoma (OS) progression toward metastasis, but the specific molecular events governing this process are incompletely characterized, with miRNAs having increasingly been found to regulate the EMT. In this study, We assessed levels of miR-22 and its target, Twist1, via real-time PCR (qRT-PCR). We further used functional proliferation assays, measures of cell morphology, and western blotting to assess the functional relevance of miR-22 in OS and confirmed Twist1 as a miR-22 target via luciferase reporter assay. We observed a significant decrease in miR-22 levels in OS tumor samples relative to normal tissue, with such downregulating being significantly associated with tumor histological grade. When overexpressed, miR-22 impaired OS cell proliferation and EMT progression. We found Twist1 to be a direct miR-22 target, with levels of miR-22 and Twist1 mRNA being inversely correlated in patient samples. When overexpressed, miR-22 suppressed Twist1 translation and thereby attenuated the EMT in OS cells. These results clearly demonstrate that miR-22 can regulate the EMT in OS cells via targeting Twist1, thus highlighting a potentially novel pathway that can be therapeutically targeted in order to treat OS.

Role of epithelial–mesenchymal transition regulated by twist basic helix-loop-helix transcription factor 2 (Twist2) in embryo implantation in mice

In a previous study we found the expression of epithelial–mesenchymal transition (EMT) biomarkers, including E-cadherin and N-cadherin, was significantly altered in uterine endometrium during embryo implantation via regulation by microRNA (miRNA)-429 and protocadherin-8 (Pcdh8). As a natural continuation of the previous study, the aim of the present study was to explore the role of EMT during embryo implantation and the potential activity of twist basic helix-loop-helix transcription factor 2 (Twist2) in regulating embryo implantation. A pregnancy model was established by naturally mating adult female ICR mice with fertile males. A pseudopregnancy model was established by mating fertile female ICR mice with vasectomised males. An invitro model of embryo implantation was established by the coculture of Ishikawa and JAR spheroids. Endometrial tissue during the peri-implantation period was collected, as were Ishikawa cells, JAR cells and cocultured cells. The expression of EMT markers (E-cadherin, N-cadherin, vimentin and cytokeratin) and Twist2 was detected invivo and invitro using the western blot analysis during embryo implantation. The expression of N-cadherin and vimentin (mesenchymal markers) was upregulated in the invitro implantation model, with downregulation of E-cadherin and cytokeratin (epithelial markers) expression. The expression of N-cadherin, vimentin and Twist2 increased significantly at the implantation sites at the time of implantation (Day 5), whereas the expression of E-cadherin and cytokeratin decreased. Location of Twist2 during embryo implantation was detected by immunohistochemistry (IHC), which revealed that it was extensively expressed in endometrial glandular epithelium and luminal epithelium at implantation sites on Day 5. The effect of the expression of Twist2 on embryo implantation was evaluated by suppressing Twist2 using Twist2-short interference (si) RNA in invivo and invitro models. The numbers of implanted embryos and the implantation rate were compared invivo and invitro. Western blot analysis showed that suppression of Twist2 led to upregulation of E-cadherin and cytokeratin, accompanied by downregulation of N-cadherin and vimentin (P<0.05). The number of implanted embryos after Twist2-siRNA interference was lower than in normal pregnancy (mean (±s.d.) 2.4±0.5 vs 6.8±1.3 respectively; P<0.05). These findings suggest the involvement of EMT in embryo implantation. The suppression of Twist2 could suppress embryo implantation by regulating EMT.

[Twist regulates proliferation, migration and invasion of osteosarcoma cells in vitro]

OBJECTIVE

To investigate the role of Twist in regulating the proliferation, migration, and invasion of osteosarcoma cells with different levels of malignancy.

METHODS

The baseline expressions of Twist in 3 different osteosarcoma cell lines (143B, MG63 and TE85) were detected using real-time PCR and Western blotting. The cells were infected with the recombinant adenoviruses Ad-Twist or Ad-siTwist for Twist overexpression or knockdown, respectively, and the cell growth curves were drawn to assess the cell proliferation. The migration abilities and invasiveness of the cells were evaluated using wound healing assay and Transwell assay. Luc-labeled 143B cells infected with Ad-Twist or Ad-siTwist were intrathecally injected to establish nude mouse models bearing osteosarcoma xenografts, in which the tumor formation was monitored using living body imaging technique.

RESULTS

The baseline expressions of Twist in the 3 osteosarcoma cells were significantly higher than that in C3H10 cells (P<0.05). Twist expression was the highest in 143B cells followed by MG63 cells, and was the lowest in TE85 cells, indicating its positive correlation with the level of malignancy of the osteosarcoma cells. Ad-Twist or Ad-siTwist infection efficiently enhanced or lowered Twist expressions at both mRNA and protein levels in osteosarcoma cells (P<0.05). Twist overexpression resulted in enhanced proliferation, migration and invasion abilities of osteosarcoma cells, and Twist knockdown obviously inhibited the cell proliferation, migration and invasion. In nude mice, 143B cells with Twist overexpression showed accelerated tumor formation compared with the control cells, while Twist knockdown significantly inhibited the tumor formation ability of the cells.

CONCLUSION

Twist overexpression can promote the proliferation, migration, invasion and tumorigenicity of osteosarcoma cells.

MicroRNA-610 suppresses osteosarcoma oncogenicity via targeting TWIST1 expression

Osteosarcoma is the most frequent primary bone tumor affects adolescents and young adults. Recently, microRNAs (miRNAs) are short, non-coding and endogenous RNAs that played as important roles in the initiation and progression of tumors. In this study, we try to explore the biological function and expression of miR-610 in the osteosarcoma. We showed that miR-610 expression was downregulated in the osteosarcoma tissues and cell lines. Elevated expression of miR-610 suppressed the osteosarcoma cell proliferation, cell cycle, invasion and EMT program. Moreover, overexpression of miR-610 increased sensitivity of MG-63 and U2OS cells to cisplatin. Twist1 was identified as a direct target gene of miR-610 in the osteosarcoma cell. Furthermore, we demonstrated that Twist1 was upregulated in the osteosarcoma tissues and cell lines. The expression of Twist1 was negatively associated with the expression of miR-610 expression in the osteosarcoma tissues. Ectopic expression of Twist1 inhibited the sensitivity of miR-610-overexpressing MG-63 cells to cisplatin. We also showed that overexpression of Twist1 increased the proliferation and invasion of miR-610-overexpressing MG-63 cells. These data indicated that ectopic expression of miR-610 suppressed the osteosarcoma cell proliferation, cell cylce, invasion and increased the sensitivity of osteosarcoma cells to cisplatin through targeting the Twist1 expression.