Delivery of a survivin promoter-driven antisense survivin-expressing plasmid DNA as a cancer therapeutic: a proof-of-concept study

Apoptotic proteins with non-apoptotic activity: expression and function in cancer

Apoptosis is a process of programmed cell death in which a cell commits suicide while maintaining the integrity and architecture of the tissue as a whole. Apoptosis involves activation of one of two major pathways: the extrinsic pathway, where extracellular pro-apoptotic signals, transduced through plasma membrane death receptors, activate a caspase cascade leading to apoptosis. The second, the intrinsic apoptotic pathway, where damaged DNA, oxidative stress, or chemicals, induce the release of pro-apoptotic proteins from the mitochondria, leading to the activation of caspase-dependent and independent apoptosis. However, it has recently become apparent that proteins involved in apoptosis also exhibit non-cell death-related physiological functions that are related to the cell cycle, differentiation, metabolism, inflammation or immunity. Such non-conventional activities were predominantly reported in non-cancer cells although, recently, such a dual function for pro-apoptotic proteins has also been reported in cancers where they are overexpressed. Interestingly, some apoptotic proteins translocate to the nucleus in order to perform a non-apoptotic function. In this review, we summarize the unconventional roles of the apoptotic proteins from a functional perspective, while focusing on two mitochondrial proteins: VDAC1 and SMAC/Diablo. Despite having pro-apoptotic functions, these proteins are overexpressed in cancers and this apparent paradox and the associated pathophysiological implications will be discussed. We will also present possible mechanisms underlying the switch from apoptotic to non-apoptotic activities although a deeper investigation into the process awaits further study.

Biodegradable mesoporous manganese carbonate nanocomposites for LED light-driven cancer therapy via enhancing photodynamic therapy and attenuating survivin expression

Triple-negative breast cancer (TNBC) is one of the most daunting diseases, low toxicity and efficient approaches are in urgent demand. Herein, we developed degradable mesoporous manganese carbonate nanocubes (MnCO₃ NCs), incorporated with survivin shRNA-expressing plasmid DNA (iSur-pDNA) and riboflavin (Rf), namely MRp NCs, for synergistic TNBC therapy. The MnCO₃, itself, could generate O₂ and CO₂ under H₂O₂ and thus relieve the hypoxia and acidic tumor microenvironment (TME). Furthermore, the MnCO₃ NCs exhibited high Rf loading capacity and iSur-pDNA delivery ability after polyethyleneimine modification. Specifically, MRp NCs decompose in TME, meanwhile they deprived the endogenous expression of survivin gene and significantly amplified the generation of reactive oxygen species after exposure to LED light, resulting in serious tumor destruction. The multifunctional MRp NCs with LED light-driven characters are able to provide a high efficiency, low toxicity and promising strategy for TNBC therapy.

Anti-apoptotic proteins in the autophagic world: an update on functions of XIAP, Survivin, and BRUCE

X-linked inhibitor of apoptosis protein (XIAP), survivin, and BRUCE are members of the inhibitor-of-apoptosis protein (IAP) family known for their inhibitory effects on caspase activity and dysregulation of these molecules has widely been shown to cause embryonic defects and to promote tumorigenesis in human. Besides the anti-apoptotic functions, recent discoveries have revealed that XIAP, survivin, and BRUCE also exhibit regulatory functions for autophagy in cells. As the role of autophagy in human diseases has already been discussed extensively in different reviews; in this review, we will discuss the emerging autophagic role of XIAP, survivin, and BRUCE in cancer cells. We also provide an update on the anti-apoptotic functions and the roles in maintaining DNA integrity of these molecules. Second mitochondria-derived activator of caspases (Smac) is a pro-apoptotic protein and IAPs are the molecular targets of various Smac mimetics currently under clinical trials. Better understanding on the functions of XIAP, survivin, and BRUCE can enable us to predict possible side effects of these drugs and to design a more “patient-specific” clinical trial for Smac mimetics in the future.

BIRC5/Survivin is a novel ATG12-ATG5 conjugate interactor and an autophagy-induced DNA damage suppressor in human cancer and mouse embryonic fibroblast cells

BIRC5/Survivin is known as a dual cellular functions protein that directly regulates both apoptosis and mitosis in embryonic cells during embryogenesis and in cancer cells during tumorigenesis and tumor metastasis. However, BIRC5 has seldom been demonstrated as a direct macroautophagy/autophagy regulator in cells. ATG7 expression and ATG12-ATG5-ATG16L1 complex formation are crucial for the phagophore elongation during autophagy in mammalian cells. In this study, we observed that the protein expression levels of BIRC5 and ATG7 were inversely correlated, whereas the expression levels of BIRC5 and SQSTM1/p62 were positively correlated in normal breast tissues and tumor tissues. Mechanistically, we found that BIRC5 negatively modulates the protein stability of ATG7 and physically binds to the ATG12-ATG5 conjugate, preventing the formation of the ATG12-ATG5-ATG16L1 protein complex in human cancer (MDA-MB-231, MCF7, and A549) and mouse embryonic fibroblast (MEF) cells. We also observed a concurrent physical dissociation between BIRC5 and ATG12-ATG5 (but not CASP3/caspase-3) and upregulation of autophagy in MDA-MB-231 and A549 cells under serum-deprived conditions. Importantly, despite the fact that upregulation of autophagy is widely thought to promote DNA repair in cells under genotoxic stress, we found that BIRC5 maintains DNA integrity through autophagy negative-modulations in both human cancer and MEF cells under non-stressed conditions. In conclusion, our study reveals a novel role of BIRC5 in cancer cells as a direct regulator of autophagy. BIRC5 may act as a "bridging molecule", which regulates the interplay between mitosis, apoptosis, and autophagy in embryonic and cancer cells.

ABBREVIATIONS

ACTA1: actin; ATG: autophagy related; BIRC: baculoviral inhibitor of apoptosis repeat-containing; BAF: bafilomycin A₁; CQ: chloroquine; CASP3: caspase 3; HSPB1/Hsp27: heat shock protein family B (small) member 1/heat shock protein 27; IAPs: inhibitors of apoptosis proteins; IP: immunoprecipitation; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; PLA: proximity ligation assay; SQSTM1/p62: sequestosome 1; siRNA: small interfering RNA.

Improved radioiodine-131 imaging of prostatic carcinoma using the sodium iodide symporter gene under control of the survivin promoter

Improvement of radioiodine accumulation in non-thyroidal tumors by transfecting the sodium iodide symporter (NIS) gene has been successfully investigated in many studies. However, regarding the uncertain iodine influx and efflux efficiencies in different cells, the optimal imaging time by radioiodine following NIS gene transport remains unclear. This study aimed to investigate the serial expression of NIS under control of survivin promoter in prostate cancer PC-3 cells and xenografts by adenoviral vector (Ad-Sur-NIS), and determine the optimal imaging time for radioiodine application. In vitro, the 125I accumulation in Ad-Sur-NIS-infected PC-3 cells was 44 times higher than that in control cells (P<0.05). Moreover, the expression efficiency of NIS reached a peak at 48 h post transfection, at which a 1.9-fold or 1.4-fold increase of 125I accumulation was found compared with 24 h or 72 h. In the clonogenic assay, the cell inhibition rates induced by 131I were 93.4 ± 11.2% in Ad-Sur-NIS and 71.8 ± 10.1% in Ad-NIS infected cells, both of which were significantly higher than that in Ad-Sur-GFP infected cells (10.9 ± 1.9%, P<0.05). In in vivo studies, the 131I uptake of tumor-to-muscle ratios were more prominent on day 2 (15.23 ± 4.55) and day-9 (9.78 ± 2.34) compared to the day 16 (1.29 ± 0.49), which showed a gradual reduction (P<0.05). Therefore, the Ad-Sur-NIS transfection allowed PC-3 tumor imaging by iodine-131 with an optimal time no later than 9 days post-transfection.

Topical Ophthalmic Formulation of Trichostatin A and SurR9-C84A for Quick Recovery Post-alkali Burn of Corneal Haze

Alkali burn injury is a true ocular emergency of the conjunctiva and cornea that requires immediate precision. Lack of an immediate therapy can lead to a substantial damage in the ocular surface and anterior segment further causing visual impairment and disfigurement. We explored the regenerative capability of dominant negative survivin protein (SurR9-C84A) and histone deacetylase inhibitor trichostatin-A (TSA) in vivo, in a rat alkali burn model. A topical insult in rat eyes with NaOH led to degradation of the conjunctival and corneal epithelium. The integrity of the conjunctival and corneal tissue was increased by TSA and SurR9-C84A by improving the clathrin and claudin expressions. Wound healing was initiated by an increase in TGF-beta-1 and, increased endogenous survivin which inhibited apoptosis post-TSA and SurR9-C84A treatments. Protein expressions of fibronectin and alpha-integrin 5 were found to increase promoting corneal integrity. The cytokine analysis confirmed increased expressions of IL-1beta, IL-6, IL-12, IL-13, IFN-gamma, TNF-alpha, GMCSF, Rantes, and MMP-2 in injured cornea, which were found to be significantly downregulated by the combined treatment of SurR9-C84A and TSA. The ocular and systemic pharmacokinetic (PK) parameters were measured post-topical ocular administration of TSA and SurR9-C84A. The SurR9-C84A and TSA sustained relatively longer in the cornea, conjunctiva, and aqueous humor than in the tear fluid and plasma. Our results confirmed that a combination of TSA with SurR9-C8A worked in synergy and showed a promising healing and anti-inflammatory effect in a very short time against alkali burn. Therefore, a combination of TSA and SurR9-C84A can fulfill the need for an immediate response to wound healing in alkali burnt cornea. We also synthesized ultra-small chitosan nanoparticles (USC-NPs) targeted with alpha-SMA antibodies that can be used for delivery of TSA and SurR9-C84A specifically to the ocular burn site.