Anti-angiogenesis is currently considered as one of the major antitumor strategies for its protective effects against tumor emergency and later progression. The anti-diabetic drug metformin has been demonstrated to significantly inhibit tumor angiogenesis based on recent studies. However, the mechanism underlying this anti-angiogenic effect still remains an enigma. In this study, we investigated metformin-induced inhibitory effect on tumor angiogenesis in vitro and in vivo. Metformin pretreatment significantly suppressed tumor paracrine signaling-induced angiogenic promotion even in the presence of heregulin (HRG)-β1 (a co-activator of HER2) pretreatment of HER2+ tumor cells. Similar to that of AG825, a specific inhibitor of HER2 phosphorylation, metformin treatment decreased both total and phosphorylation (Tyr 1221/1222) levels of HER2 protein and significantly reduced microvessel density and the amount of Fitc-conjugated Dextran leaking outside the vessel. Furthermore, our results of VEGF-neutralizing and -rescuing tests showed that metformin markedly abrogated HER2 signaling-induced tumor angiogenesis by inhibiting VEGF secretion. Inhibition of HIF-1α signaling by using RNAi or YC-1, a specific inhibitor of HIF-1α synthesis, both completely diminished mRNA level of VEGF and greatly inhibited endothelial cell proliferation promoted by HER2+ tumor cell-conditioned medium in both the absence and presence of HRG-β1 pretreatment. Importantly, metformin treatment decreased the number of HIF-1α nucleus positive cells in 4T1 tumors, accompanied by decreased microvessel density. Our data thus provides novel insight into the mechanism underlying the metformin-induced inhibition of tumor angiogenesis and indicates possibilities of HIF-1α-VEGF signaling axis in mediating HER2-induced tumor angiogenesis.

DEP domain containing 1 (DEPDC1) is a newly identified cancer-related and cell cycle related gene and has been demonstrated as a novel therapeutic target for bladder cancer. However, the functional involvement and therapeutic potential of DEPDC1 in nasopharyngeal carcinoma (NPC) remains unclear. Our results showed that DEPDC1 was overexpressed at both mRNA and protein levels in NPC tissues compared with normal or non-tumor tissues. The siRNA-mediated DEPDC1 depletion resulted in significant inhibition of proliferation and delay in cell cycle progression in both NPC cell lines, CNE-1 and HNE-1. Detailed analysis with indirect immunofluorescence assays revealed that DEPDC1 depletion caused significant mitotic arrest accompanied with mitotic defects such as multipolar spindles and multiple nuclei followed by apoptotic cell death. Notably, DEPDC1 depletion also reduces migration and invasion ability in both cell lines. Consistent with its regulatory role in NF-κB pathway, knockdown of DEPDC1 caused significant upregulation of A20 and downregulation of mutiple NF-κB downstream target genes implicated in proliferation and tumorigenesis (c-Myc, BCL2, CCND1, CCNB1 and CCNB2), and metastasis (MMP2, MMP9, ICAM1, vimentin, Twist1). Moreover, in vivo study demonstrated that DEPDC1 knockdown also caused significant inhibition of tumor growth in the NPC xenograft nude mouse model. Taken together, our present study demonstrated that DEPDC1 is essentially required for the accelerated cell cycle progression and motility in NPC cells, and strongly suggested that DEPDC1 may serve as a novel therapeutic target in NPC.

Background Triple Negative Breast cancer (TNBC) is incurable cancer with higher rates of relapse and shorter overall survival compared with other subtypes of breast cancer. Cellular retinoic acid binding protein 2 (CRABP2) belongs to fatty acid binding protein (FABP) family which binds with all-trans retinoic acid (RA). Previous studies from the database have reported the patients with high expression of CRABP2 showed different prognosis in ER + and ER − breast cancer. However, its biological role and exact mechanism in breast cancer remain unknown. This aim of this study was to explore how CRABP2 regulated invasion and metastasis based on the estrogen receptor-α (herein called ER) status in breast cancer. Methods Immunohistochemical staining method was used to analyze the expression of CRABP2 in human breast cancer tissues. Lentivirus vector-based shRNA technique was used to test the functional relevance of CRABP2 knockdown in breast tumors. Tail vein injection model was used to examine the lung metastasis. Co-immunoprecipitation, Western blotting, immunofluorescence, and quantitative reverse transcription polymerase chain reaction (RT-qPCR) were conducted to investigate the underlying mechanism that influenced the ER to the regulation of CRABP2 to Lats1. Results We observed that knockdown of CRABP2 promotes EMT, invasion and metastasis of ER + breast cancer cells in vitro and in vivo, whereas overexpression of CRABP2 yields the reverse results. In ER + mammary cancer cells, the interaction of CRABP2 and Lats1 suppress the ubiquitination of Lats1 to activate Hippo pathway to inhibit the invasion and metastasis of ER + mammary cancer. However, in ER − mammary cancer cells, the interaction of CRABP2 and Lats1 promote the ubiquitination of Lats1 to inactivate Hippo pathway to promote the invasion and metastasis of ER − mammary cancer. Conclusions Our findings indicate that CRABP2 can suppress invasion and metastasis of ER + breast cancer and promote invasion and metastasis of ER − breast cancer by regulating the stability of Lats1 in vitro and in vivo, and it provides new ideas for breast cancer therapy. Electronic supplementary material The online version of this article (10.1186/s13046-019-1345-2) contains supplementary material, which is available to authorized users.

Translation has important roles in almost all physiological and pathological processes, and translation initiation factors are particularly relevant to the translation initiation step, which is the most important step in translation regulation. Translation initiation factor 3b (eIF3b), a key subunit of the largest translation initiation factor 3 (eIF3), is widely considered a scaffold protein that acts to ensure the accuracy of translation initiation. A series of recent finds has revealed that eIF3 is closely related to oncogenesis. However, the concrete mechanism by which eIF3b is involve in carcinogenesis remains elusive. Here, we summarize a series of research findings regarding the relationship between eIF3b, translation and cancer.

Acquired tamoxifen-resistance is an important cause of death in patients with hormone-dependent breast tumors. Therefore, understanding the molecular mechanisms underlying the development of tamoxifen-resistance is critical for successful endocrine therapy. This study aimed to define the role of WW domain-containing oxidoreductase (WWOX) in acquired tamoxifen-resistance. Our results show that low WWOX expression was significantly related to tamoxifen-resistance. Moreover, WWOX-knockdown increased resistance to tamoxifen, while WWOX overexpression decreased the resistance. Furthermore, WWOX silencing decreased Yes-associated protein (YAP) phosphorylation and increased YAP nuclear translocation. Finally, YAP silencing decreased tamoxifen-resistance in WWOX-knockdown cells. Our findings demonstrate that WWOX downregulation can lead to the development of tamoxifen-resistance by inactivating Hippo signaling. Thus, WWOX might be a valuable target and prognostic marker for tamoxifen-resistance. Impact statement Understanding the molecular pathways leading to the development of tamoxifen-resistance is an important research focus as acquired tamoxifen-resistance is the main cause of death in patients with benign primary prognosis. Although WW domain-containing oxidoreductase (WWOX) has been related to breast tumorigenesis, its role in acquired tamoxifen-resistance has not yet been demonstrated. Our findings show that WWOX might be a valuable therapeutic target and prognostic marker for tamoxifen-resistance.