Apatinib, an inhibitor of vascular endothelial growth factor receptor-2, has been shown to promote anti-cancer action across a wide range of malignancies, including gastric, lung, and breast cancers. Our previous study showed that apatinib increases apoptosis in anaplastic thyroid carcinoma (ATC), but the direct functional mechanism of tumor lethality mediated by apatinib is still unknown. In this study, we demonstrated that apatinib induced both autophagy and apoptosis in human ATC cells through downregulation of p-AKT and p-mTOR signals via the AKT/mTOR pathway. Moreover, inhibition of apatinib-induced autophagy increased apatinib-induced apoptosis in ATC cells, and additional tumor suppression was critically produced by the combination of apatinib and the autophagy inhibitor chloroquine in vivo and in vitro. These findings showed that both autophagy and AKT/mTOR signals were engaged in ATC cell death evoked by apatinib. ATC patients might benefit from the new anti-cancer drug, and molecular targeted treatment in combination with autophagy inhibitors shows promise as a treatment improvement.

Acquired resistance to tyrosine kinase inhibitors (TKIs) is the major obstacle to improve clinical efficacy in cancer patients. The epithelial-stromal interaction in tumor microenvironment influences cancer drug response to TKIs. Anlotinib is a novel oral multi-targeted TKI, and has recently been proven to be effective and safe for several tumors. However, if and how the epithelial-stromal interaction in tumor microenvironment affects anlotinib response in gastric cancer (GC) is not known. In this study, we found that anlotinib inhibited GC cells growth by inducing GC cells apoptosis and G2/M phase arrest in a dose- and time-dependent manner. Reactive oxygen species (ROS) mediated anlotinib-induced apoptosis in GC cells, while cancer-associated fibroblasts (CAFs) significantly suppressed anlotinib-induced apoptosis and ROS in GC cells. Increased BDNF that was derived from CAFs activated TrkB-Nrf2 signaling in GC cells, and reduced GC cells response to anlotinib. We identified secreted lactate from GC cells as the key molecule instructing CAFs to produce BDNF in a NF-κB-dependent manner. Additionally, functional targeting BDNF-TrkB pathway with neutralizing antibodies against BDNF and TrkB increased the sensitivity of GC cells towards anlotinib in human patient-derived organoid (PDO) model. Taken together, these results characterize a critical role of the epithelial-stroma interaction mediated by the lactate/BDNF/TrkB signaling in GC anlotinib resistance, and provide a novel option to overcome drug resistance.

Apatinib, a novel tyrosine kinase inhibitor (TKI), has been confirmed for its efficacy and safety in the treatment of advanced gastric carcinoma and some other solid tumors. However, the direct functional mechanisms of tumor lethality mediated by apatinib have not yet been fully characterized, and the precise mechanisms of drug resistance are largely unknown. Here, in this study, we demonstrated that apatinib could induce both apoptosis and autophagy in human colorectal cancer (CRC) via a mechanism that involved endoplasmic reticulum (ER) stress. Moreover, activation of the IRE1α pathway from apatinib-induced ER stress is responsible for the induction of autophagy; however, blocking autophagy could enhance the apoptosis in apatinib-treated human CRC cell lines. Furthermore, the combination of apatinib with autophagy inhibitor chloroquine (CQ) tends to have the most significant anti-tumor effect of CRC both in vitro and in vivo. Overall, our data show that because apatinib treatment could induce ER stress-related apoptosis and protective autophagy in human CRC cell lines, targeting autophagy is a promising therapeutic strategy to relieve apatinib drug resistance in CRC.

In our previous study, ETV5 mediated-angiogenesis was demonstrated to be dependent upon the PDGF-BB/PDGFR-β/Src/STAT3/VEGFA pathway in colorectal cancer (CRC). However, the ability of ETV5 to affect the efficacy of anti-angiogenic therapy in CRC requires further investigation. Gene set enrichment analysis (GSEA) and a series of experiments were performed to identify the critical candidate gene involved in Bevacizumab resistance. Furthermore, the ability of treatment targeting the candidate gene to enhance Bevacizumab sensitivity in vitro and in vivo was investigated. Our results revealed that ETV5 directly bound to the VEGFA promoter to promote translation of VEGFA. However, according to in vitro and in vivo experiments, ETV5 unexpectedly accelerated antiVEGF therapy (Bevacizumab) resistance. GSEA and additional assays confirmed that ETV5 could promote angiogenesis by inducing the secretion of another tumor angiogenesis factor (CCL2) in CRC cells to facilitate Bevacizumab resistance. Mechanistically, ETV5 upregulated CCL2 by activating STAT3 to facilitate binding with the CCL2 promoter. ETV5 induced-VEGFA translation and CCL2 secretion were mutually independent mechanisms, that induced angiogenesis by activating the PI3K/AKT and p38/MAPK signaling pathways in human umbilical vein endothelial cells (HUVECs). In CRC tissues, ETV5 protein levels were positively associated with CD31, CCL2, and VEGFA protein expression. CRC patients possessing high expression of ETV5/VEGFA or ETV5/CCL2 exhibited a poorer prognosis compared to that of other patients. Combined antiCCL2 and antiVEGFA (Bevacizumab) treatment could inhibit tumor angiogenesis and growth more effectively than single treatments in CRCs with high expression of ETV5 (ETV5⁺ CRCs). In conclusion, our results not only revealed ETV5 as a novel biomarker for anti-angiogenic therapy, but also indicated a potential combined therapy strategy that involved in targeting of both CCL2 and VEGFA in ETV5⁺ CRC.

Studies indicate that the chemokine receptor is responsible for poor prognosis of hepatocellular carcinoma (HCC) patients. In this study, we initially demonstrated that CCR4 is overexpressed in HCC specimens, and its elevation in HCC tissues positively correlates with tumor capsule breakthrough and vascular invasion. Although overexpression of CCR4 failed to influent proliferation of HCC cells in vitro apparently, the prominent acceleration on HCC tumor growth in vivo was remarkable. The underlying mechanism may be involved in neovascularization. Interestingly, different from effect on proliferation, CCR4 overexpression could trigger HCC metastasis both in vitro and in vivo also induced HCC cell epithelial-mesenchymal transition (EMT) as well. Then we identified matrix metalloproteinase 2 (MMP2) as a direct target of CCR4 which plays an important role in CCR4-mediated HCC cell invasion, which was up-regulated by ERK/AKT signaling. Positive correlation between CCR4 and MMP2 expression was also observed in HCC tissues. In conclusion, our study suggested that chemokine receptor CCR4 promotes HCC malignancy and facilitated HCC cell metastases via ERK/AKT/MMP2 pathway. These findings suggest that CCR4 may be a potential new diagnostic and prognostic marker in HCC, and targeting CCR4 may be a potential therapeutic option for blocking HCC metastasis.

Background/Aims: Anaplastic thyroid carcinoma (ATC) is one of the most lethal human malignancies, and there is no efficient method to slow its process. Apatinib, a novel tyrosine kinase inhibitor (TKI), has been confirmed for its efficacy and safety in the treatment of advanced gastric carcinoma patients. However, the effects of Apatinib in ATC are still unknown. Methods: In this study, we explored the effects and mechanisms of Apatinib on tumor growth and angiogenesis in vitro and in vitro in ATC cells. Angiogenesis antibodies array was utilized to detect the expression of angiogenesis-related genes after Apatinib treatment in ATC cells. In addition, we used Akt activator, Akt inhibitor and GSK3β inhibitor to further study the mechanism for how Apatinib suppressed angiogenesis. Results: Apatinib treatment could suppress the growth of ATC cells in a dose- and time-dependent manner via inducing apoptosis and blocking cell cycle progression at G0/G1 phase. Moreover, Apatinib treatment decreased the expression of angiogenin (ANG) and inhibited angiogenesis of ATC cells in vitro and in vitro. We further confirmed that recombinant human ANG (rhANG) significantly abrogated Apatinib-mediated anti-angiogenic ability in ATC cells. Additionally, Apatinib treatment decreased the level of p-Akt and p-GSK3β. Moreover, the Apatinib-mediated decrease of ANG and anti-angiogenic ability were partly reversed when an Akt activator, SC79, was administered. Furthermore, the anti-angiogenic ability of Apatinib can be enhanced in the presence of Akt inhibitor, and the inhibition of GSK3β attenuated the anti-angiogenic ability of Apatinib. Conclusion: Our results demonstrated that Apatinib treatment inhibited tumor growth, and Apatinib-induced suppression of Akt/GSK3β/ANG signaling pathway may play an important role in the inhibition of angiogenesis in ATC, supporting a potential therapeutic approach for using Apatinib in the treatment of ATC.