Stellettin B Induces Cell Death in Bladder Cancer Via Activating the Autophagy/DAPK2/Apoptosis Signaling Cascade

Bladder cancer (BC) is one of the most prevalent cancers worldwide. However, the recurrence rate and five-year survival rate have not been significantly improved in advanced BC, and new therapeutic strategies are urgently needed. The anticancer activity of stellettin B (SP-2), a triterpene isolated from the marine sponge Rhabdastrella sp., was evaluated with the MTT assay as well as PI and Annexin V/7-AAD staining. Detailed mechanisms were elucidated through an NGS analysis, protein arrays, and Western blotting. SP-2 suppressed the viability of BC cells without severe toxicity towards normal uroepithelial cells, and it increased apoptosis with the activation of caspase 3/8/9, PARP, and γH2AX. The phosphorylation of FGFR3 and its downstream targets were downregulated by SP-2. Meanwhile, it induced autophagy in BC cells as evidenced by LC3-II formation and p62 downregulation. The inhibition of autophagy using pharmacological inhibitors or through an ATG5-knockout protected RT-112 cells from SP-2-induced cell viability suppression and apoptosis. In addition, the upregulation of DAPK2 mRNA and protein expression also contributed to SP-2-induced cytotoxicity and apoptosis. In RT-112 cells, an FGFR3-TACC3-knockout caused the downregulation of DAPK2, autophagy, and apoptosis. In conclusion, this is the first study demonstrating that SP-2 exhibits potent anti-BC activity by suppressing the FGFR3-TACC3/Akt/mTOR pathway, which further activates a novel autophagy/DAPK2/apoptosis signaling cascade

Stellettin B Induces Cell Death in Bladder Cancer Via Activating the Autophagy/DAPK2/Apoptosis Signaling Cascade

Bladder cancer (BC) is one of the most prevalent cancers worldwide. However, the recurrence rate and five-year survival rate have not been significantly improved in advanced BC, and new therapeutic strategies are urgently needed. The anticancer activity of stellettin B (SP-2), a triterpene isolated from the marine sponge Rhabdastrella sp., was evaluated with the MTT assay as well as PI and Annexin V/7-AAD staining. Detailed mechanisms were elucidated through an NGS analysis, protein arrays, and Western blotting. SP-2 suppressed the viability of BC cells without severe toxicity towards normal uroepithelial cells, and it increased apoptosis with the activation of caspase 3/8/9, PARP, and γH2AX. The phosphorylation of FGFR3 and its downstream targets were downregulated by SP-2. Meanwhile, it induced autophagy in BC cells as evidenced by LC3-II formation and p62 downregulation. The inhibition of autophagy using pharmacological inhibitors or through an ATG5-knockout protected RT-112 cells from SP-2-induced cell viability suppression and apoptosis. In addition, the upregulation of DAPK2 mRNA and protein expression also contributed to SP-2-induced cytotoxicity and apoptosis. In RT-112 cells, an FGFR3-TACC3-knockout caused the downregulation of DAPK2, autophagy, and apoptosis. In conclusion, this is the first study demonstrating that SP-2 exhibits potent anti-BC activity by suppressing the FGFR3-TACC3/Akt/mTOR pathway, which further activates a novel autophagy/DAPK2/apoptosis signaling cascade

Selective depletion of radiolabeled HER2-specific antibody for contrast improvement during PET

The prolonged in vivo persistence of antibodies results in high background and poor contrast during their use as molecular imaging agents for positron emission tomography (PET). We have recently described a class of engineered Fc fusion proteins that selectively deplete antigen-specific antibodies without affecting the levels of antibodies of other specificities. Here, we demonstrate that these Fc fusions (called Seldegs, for selective degradation) can be used to clear circulating, radiolabeled HER2-specific antibody during diagnostic imaging of HER2-positive tumors in mice. The analyses show that Seldegs have considerable promise for the reduction of whole-body exposure to radiolabel and improvement of contrast during PET.</p

Regulation of vascular leak and recovery from ischemic injury by general and VE-cadherin-restricted miRNA antagonists of miR-27

Please see erratum at DOI: 10.1182/blood-2014-09-604066 The errors have been corrected in the online version, which now differs from the print version.Cellular junctions are essential to the normal functioning of the endothelium and control angiogenesis, tissue leak, and inflammation. From a screen of micro RNAs (miRNAs) altered in in vitro angiogenesis, we selected a subset predicted to target junctional molecules. MiR-27a was rapidly downregulated upon stimulation of in vitro angiogenesis, and its level of expression is reduced in neovessels in vivo. The downregulation of miR-27a was essential for angiogenesis because ectopic expression of miR-27a blocked capillary tube formation and angiogenesis. MiR-27a targets the junctional, endothelial-specific cadherin, VE-cadherin. Consistent with this, vascular permeability to vascular endothelial growth factor in mice is reduced by administration of a general miR-27 inhibitor. To determine that VE-cadherin was the dominant target of miR-27a function, we used a novel technology with “Blockmirs,” inhibitors that bind to the miR-27 binding site in VE-cadherin. The Blockmir CD5-2 demonstrated specificity for VE-cadherin and inhibited vascular leak in vitro and in vivo. Furthermore, CD5-2 reduced edema, increased capillary density, and potently enhanced recovery from ischemic limb injury in mice. The Blockmir technology offers a refinement in the use of miRNAs, especially for therapy. Further, targeting of endothelial junctional molecules by miRNAs has clinical potential, especially in diseases associated with vascular leak.Jennifer A. Young, Ka Ka Ting, Jia Li, Thorleif Moller, Louise Dunn, Ying Lu, Joshua Moses, Leonel Prado-Lourenço, Levon M. Khachigian, Martin Ng, Philip A. Gregory, Gregory J. Goodall, Anna Tsykin, Ilana Lichtenstein, Christopher N. Hahn, Nham Tran, Nicholas Shackel, James G. Kench, Geoffrey McCaughan, Mathew A. Vadas, and Jennifer R. Gambl