Metastatic behavior analyses of tetraspanin TM4SF5-expressing spheres in three-dimensional (3D) cell culture environment

Application of three-dimensional cell culture technology in screening anticancer drugs

The drug development process involves a variety of drug activity evaluations, which can determine drug efficacy, strictly analyze the biological indicators after the drug action, and use these indicators as the preclinical drug evaluation criteria. At present, most of the screening of preclinical anticancer drugs mainly relies on traditional 2D cell culture. However, this traditional technology cannot simulate the tumor microenvironment in vivo, let alone reflect the characteristics of solid tumors in vivo, and has a relatively poor ability to predict drug activity. 3D cell culture is a technology between 2D cell culture and animal experiments, which can better reflect the biological state in vivo and reduce the consumption of animal experiments. 3D cell culture can link the individual study of cells with the study of the whole organism, reproduce in vitro the biological phenotype of cells in vivo more greatly, and thus predict the activity and resistance of anti-tumor drugs more accurately. In this paper, the common techniques of 3D cell culture are discussed, with emphasis on its main advantages and application in the evaluation of anti-tumor resistance, which can provide strategies for the screening of anti-tumor drugs.

STAT3 mediates RCP-induced cancer cell invasion through the NF-κB/Slug/MT1-MMP signaling cascade

Rab coupling protein (RCP) has been known to induce cancer invasion and metastasis, and STAT3 is one of major oncogenic factors. In the present study, we identify the critical role of STAT3 in RCP-induced cancer cell invasion. Immunohistochemical data of ovarian cancer tissues presented that levels of RCP expression are closely correlated with those of phospho-STAT3 (p-STAT3). In addition, ovarian cancer patients with high expression of both RCP and p-STAT3 had significantly lower progress-free and overall survival rates compared to those with low either RCP or p-STAT3 expression. Mechanistically, RCP induced STAT3 phosphorylation in both ovarian and breast cancer cells. Silencing or pharmacological inhibition of STAT3 significantly inhibited RCP-induced cancer cell invasion. In addition, we provide evidence that the β1 integrin/EGFR axis is important for RCP-induced STAT3 phosphorylation. Furthermore, STAT3 activated NF-κB for Slug expression that in turn upregulated MT1-MMP expression for cancer cell invasion. Collectively, our present data demonstrate that STAT3 is located downstream of the β1 integrin/EGFR axis and induces Slug and MT1-MMP expression for cancer cell invasion.

METTL3/IGF2BP1/CD47 contributes to the sublethal heat treatment induced mesenchymal transition in HCC

Microwave ablation is a first-line treatment of small hepatocellular carcinoma (HCC), while incomplete ablation induces recurrence and metastasis. However, its underlying mechanism remains largely unexplored. Here we reported that sublethal heat treatment (46 °C) strongly promoted migration and EMT transition in HCC cells. Mechanistic investigation revealed that compared with 37 °C, HCC cells treated with 46 °C expressed higher level of CD47. Knockdown of CD47 significantly attenuated sublethal heat treatment stimulated migration and EMT transition. In addition, METTL3 which is the key enzyme of m⁶A modification was also induced by 46 °C treatment and triggered CD47 expression in HCC cells. Moreover, CD47 mRNA degradation was further proved to be stabled in the IGF2BP1-dependent manner. Importantly, sublethal heat treatment stimulated CD47 expression and EMT transition were also confirmed in patient-derived organoid. Taken together, our study suggests that METTL3/IGF2BP1/CD47 mediated EMT transition contributes to the incomplete ablation induced metastasis in HCC cells. Moreover, these findings identify the METTL3/IGF2BP1/CD47 axis as a potential therapeutic target for the microwave ablation and shed new lights on the crosstalk between incomplete heat ablation and RNA methylation.