Targeting survivin for therapeutic discovery: past, present, and future promises

Pioneering 4,11-Dioxo-4,11-dihydro-1H-anthra[2,3-d]imidazol-3-ium Compounds as Promising Survivin Inhibitors by Targeting ILF3/NF110 for Cancer Therapy

Survivin is a novel attractive target for cancer therapy; however, it is considered undruggable because it lacks enzymatic activities. Herein, we describe our efforts toward the discovery of a novel series of 4,11-dioxo-4,11-dihydro-1H-anthra[2,3-d]imidazol-3-ium derivatives as survivin inhibitors by targeting ILF3/NF110. Intensive structural modifications led us to identify a lead compound AQIM-I, which remarkably inhibited nonsmall cell lung cancer cells A549 with an IC50 value of 9 nM and solid tumor cell proliferation with more than 700-fold selectivity against human normal cells. Further biological studies revealed that compound AQIM-I significantly inhibited survivin expression and colony formation and induced ROS production, apoptosis, cell cycle arrest, DNA damage, and autophagy. Furthermore, the promoter-luciferase reporter assay showed that AQIM-I attenuated the survivin promoter activity enhanced by the overexpression of ILF3/NF110 in a concentration-dependent manner, and specific binding (KD = 163 nM) of AQIM-I to ILF3/NF110 was detected by surface plasmon resonance.

Small Molecule Inhibitors Targeting the "Undruggable" Survivin: The Past, Present, and Future from a Medicinal Chemist's Perspective

Survivin, a homodimeric protein and a member of the IAP family, plays a vital function in cell survival and cycle progression by interacting with various proteins and complexes. Its expression is upregulated in cancers but not detectable in normal tissues. Thus, it has been regarded and validated as an ideal cancer target. However, survivin is "undruggable" due to its lack of enzymatic activities or active sites for small molecules to bind/inhibit. Academic and industrial laboratories have explored different strategies to overcome this hurdle over the past two decades, with some compounds advanced into clinical testing. These strategies include inhibiting survivin expression, its interaction with binding partners and homodimerization. Here, we provide comprehensive analyses of these strategies and perspective on different small molecule survivin inhibitors to help drug discovery targeting "undruggable" proteins in general and survivin specifically with a true survivin inhibitor that will prevail in the foreseeable future.

Targeting survivin for cancer therapy: Strategies, small molecule inhibitors and vaccine based therapeutics in development

Survivin is a member of the family of inhibitors of apoptosis proteins (IAPs). It is involved in the normal mitotic process and acts as an anti-apoptotic molecule. While terminally differentiated normal tissues lack survivin, several human malignancies have significant protein levels. Resistance to chemotherapy and radiation in tumor cells is associated with survivin expression. Decreased tumor development, apoptosis, and increased sensitivity to chemotherapy and radiation are all effects of downregulating survivin expression or activity. As a prospective cancer treatment, small molecules targeting the transcription and translation of survivin and molecules that can directly bind with the survivin are being explored both in pre-clinical and clinics. Pre-clinical investigations have found and demonstrated the effectiveness of several small-molecule survivin inhibitors. Unfortunately, these inhibitors have also been shown to have off-target effects, which could limit their clinical utility. In addition to small molecules, several survivin peptide vaccines are currently under development. These vaccines are designed to elicit a cytotoxic T-cell response against survivin, which could lead to the destruction of tumor cells expressing survivin. Some survivin-based vaccines are advancing through Phase II clinical studies. Overall, survivin is a promising cancer drug target. However, challenges still need to be addressed before the survivin targeted therapies can be widely used in the clinics.

Toad venom-derived bufadienolides and their therapeutic application in prostate cancers: Current status and future directions

Cancer is the second leading cause of death worldwide. Specially, the high incidence rate and prevalence of drug resistance have rendered prostate cancer (PCa) a great threat to men’s health. Novel modalities with different structures or mechanisms are in urgent need to overcome these two challenges. Traditional Chinese medicine toad venom-derived agents (TVAs) have shown to possess versatile bioactivities in treating certain diseases including PCa. In this work, we attempted to have an overview of bufadienolides, the major bioactive components in TVAs, in the treatment of PCa in the past decade, including their derivatives developed by medicinal chemists to antagonize certain drawbacks of bufadienolides such as innate toxic effect to normal cells. Generally, bufadienolides can effectively induce apoptosis and suppress PCa cells in-vitro and in-vivo, majorly mediated by regulating certain microRNAs/long non-coding RNAs, or by modulating key pro-survival and pro-metastasis players in PCa. Importantly, critical obstacles and challenges using TVAs will be discussed and possible solutions and future perspectives will also be presented in this review. Further in-depth studies are clearly needed to decipher the mechanisms, e.g., targets and pathways, toxic effects and fully reveal their application. The information collected in this work may help evoke more effects in developing bufadienolides as therapeutic agents in PCa.

Survivin Small Molecules Inhibitors: Recent Advances and Challenges

Survivin, as a member of the inhibitor of apoptosis proteins (IAPs) family, acts as a suppressor of apoptosis and plays a central role in cell division. Survivin has been considered as an important cancer drug target because it is highly expressed in many types of human cancers, while it is effectively absent from terminally differentiated normal tissues. Moreover, survivin is involved in tumor cell resistance to chemotherapy and radiation. Preclinically, downregulation of survivin expression or function reduced tumor growth induced apoptosis and sensitized tumor cells to radiation and chemotherapy in different human tumor models. This review highlights the role of survivin in promoting cellular proliferation and inhibiting apoptosis and summarizes the recent advances in and challenges of developing small-molecule survivin inhibitors.

The Prognostic and Therapeutic Implications of the Chemoresistance Gene BIRC5 in Triple-Negative Breast Cancer

Chemoresistance affects TNBC patient treatment responses. Therefore, identifying the chemoresistant gene provides a new approach to understanding chemoresistance in TNBC. BIRC5 was examined in the current study as a tool for predicting the prognosis of TNBC patients and assisting in developing alternative therapies using online database tools. According to the examined studies, BIRC5 was highly expressed in 45 to 90% of TNBC patients. BIRC5 is not only abundantly expressed but also contributes to resistance to chemotherapy, anti-HER2 therapy, and radiotherapy. Patients with increased expression of BIRC5 had a median survival of 31.2 months compared to 85.8 months in low-expression counterparts (HR, 1.73; CI, 1.4−2.13; p = 2.5 × 10−7). The overall survival, disease-free survival, relapse-free survival, distant metastasis-free survival, and the complete pathological response of TNBC patients with high expression of BIRC5 who received any chemotherapy (Taxane, Ixabepilone, FAC, CMF, FEC, Anthracycline) and anti-HER2 therapy (Trastuzumab, Lapatinib) did not differ significantly from those patients receiving any other treatment. Data obtained indicate that the BIRC5 promoter region was substantially methylated, and hypermethylation was associated with higher BIRC5 mRNA expression (p < 0.05). The findings of this study outline the role of BIRC5 in chemotherapy-induced resistance of TNBC, further indicating that BIRC5 may serve as a promising prognostic biomarker that contributes to chemoresistance and could be a possible therapeutic target. Meanwhile, several in vitro studies show that flavonoids were highly effective in inhibiting BIRC5 in genetically diverse TNBC cells. Therefore, flavonoids would be a promising strategy for preventing and treating TNBC patients with the BIRC5 molecule.

The conservation of IAP-like proteins in fungi, and their potential role in fungal programmed cell death

Programmed cell death (PCD) is a tightly regulated process which is required for survival and proper development of all cellular life. Despite this ubiquity, the precise molecular underpinnings of PCD have been primarily characterized in animals. Attempts to expand our understanding of this process in fungi have proven difficult as core regulators of animal PCD are apparently absent in fungal genomes, with the notable exception of a class of proteins referred to as inhibitors of apoptosis proteins (IAPs). These proteins are characterized by the conservation of a distinct Baculovirus IAP Repeat (BIR) domain and animal IAPs are known to regulate a number of processes, including cellular death, development, organogenesis, immune system maturation, host-pathogen interactions and more. IAP homologs are broadly conserved throughout the fungal kingdom, but our understanding of both their mechanism and role in fungal development/virulence is still unclear. In this review, we provide a broad and comparative overview of IAP function across taxa, with a particular focus on fungal processes regulated by IAPs. Furthermore, their putative modes of action in the absence of canonical interactors will be discussed.

A novel survivin dimerization inhibitor without a labile hydrazone linker induces spontaneous apoptosis and synergizes with docetaxel in prostate cancer cells

Survivin, a member of the inhibitor of apoptosis protein family, exists as a homodimer and is aberrantly upregulated in a wide spectrum of cancers. It was thought to be an ideal target due to its lack of expression in most adult normal tissues and importance in cancer cell survival. However, it has been challenging to target survivin due to its "undruggable" nature. We previously attempted to target its dimerization domain with a hypothesis that inhibiting survivin dimerization would promote its degradation in proteasome, which led to identification of a lead small-molecule inhibitor, LQZ-7F. LQZ-7F consists of a flat tetracyclic aromatic core with labile hydrazone linking a 1,2,5-oxadiazole moiety. In this study, we tested the hypothesis that LQZ-7F could be developed as a prodrug because the labile hydrazone linker could be hydrolyzed, releasing the tetracyclic aromatic core. To this end, we synthesized the tetracyclic aromatic core (LQZ-7F1) using reported procedure and tested LQZ-7F1 for its biological activities. Here we show that LQZ-7F1 has a significantly improved potency with submicromolar IC_50's and induces spontaneous apoptosis in prostate cancer cells. It also more effectively inhibits survivin dimerization and induces survivin degradation in a proteasome-dependent manner than LQZ-7F. We also show that the combination of LQZ-7F1 and docetaxel have strong synergism in inhibiting prostate cancer cell survival. Together, we conclude that the hydrazone linker with the oxadiazole tail is dispensable for survivin inhibition and the survivin dimerization inhibitor, LQZ-7F, may be developed as a prodrug for prostate cancer treatment and to overcome docetaxel resistance.

A Mini-Review of Flavone Isomers Apigenin and Genistein in Prostate Cancer Treatment

The initial responses to standard chemotherapies among prostate cancer (PCa) patients are usually significant, while most of them will finally develop drug resistance, rendering them with limited therapies. To discover new regimens for the treatment of PCa including resistant PCa, natural products, the richest source of bioactive compounds, can serve as a library for screening and identifying promising candidates, and flavones such as apigenin and genistein have been used in lab and clinical trials for treating PCa over decades. In this mini-review, we take a look into the progress of apigenin and genistein, which are isomers, in treating PCa in the past decade. While possessing very similar structure, these two isomers can both target the same signaling pathways; they also are found to work differently in PCa cells. Given that more combinations are being developed and tested, genistein appears to be the more promising option to be approved. The anticancer efficacies of these two flavones can be confirmed by in-vitro and in-vivo studies, and their applications remain to be validated in clinical trials. Information gained in this work may provide important information for new drug development and the potential application of apigenin and genistein in treating PCa.

Local Anesthetic Ropivacaine Exhibits Therapeutic Effects in Cancers

Despite the significant progress in cancer treatment, new anticancer therapeutics drugs with new structures and/or mechanisms are still in urgent need to tackle many key challenges. Drug repurposing is a feasible strategy in discovering new drugs among the approved drugs by defining new indications. Recently, ropivacaine, a local anesthetic that has been applied in clinical practice for several decades, has been found to possess inhibitory activity and sensitizing effects when combined with conventional chemotherapeutics toward cancer cells. While its full applications and the exact targets remain to be revealed, it has been indicated that its anticancer potency was mediated by multiple mechanisms, such as modulating sodium channel, inducing mitochondria-associated apoptosis, cell cycle arrest, inhibiting autophagy, and/or regulating other key players in cancer cells, which can be termed as multi-targets/functions that require more in-depth studies. In this review, we attempted to summarize the research past decade of using ropivacaine in suppressing cancer growth and sensitizing anticancer drugs both in-vitro and in-vivo, and tried to interpret the underlying action modes. The information gained in these findings may inspire multidisciplinary efforts to develop/discover more novel anticancer agents via drug repurposing.

Multistage targeting and dual inhibiting strategies based on bioengineered tumor matrix microenvironment‐mediated protein nanocages for enhancing cancer biotherapy

Regulation of the apoptotic pathway plays a critical role in inducing tumor cell death and circumventing drug resistance. Survivin protein is the strongest inhibitor of apoptosis found so far. It is highly expressed in several cancers and is a promising target for cancer therapy. However, clinical applications are limited by incomplete inhibition of survivin expression. Here, we present a novel strategy that extended the release of YM155 (an effective survivin inhibitor that works by inhibiting the activity of survivin promoter) and TATm‐survivin (T34A) (TmSm) protein (survivin protein mutant with penetrating peptide, a potential anticancer protein therapeutic) via tumor matrix microenvironment‐mediated ferritin heavy chain nanocages (FTH1 NCs), enabling significant inhibition of survivin activity at both transcript and protein levels. FTS (FTH1‐matrix metalloproteinase‐2‐TmSm)/YM155 NC synthesis was easily scaled up, and these NCs could sequentially release TmSm protein through matrix metalloproteinase‐2 and promote YM155 to enter the nucleus via transferrin receptor 1 (TfR1) binding, which increased the cytotoxicity and apoptosis of Capan‐2 and A549 cells compared to that with individual drugs. Moreover, FTS/YM155 NCs enhanced drug accumulation at tumor sites and had a higher tumor inhibition rate (88.86%) than the compounds alone in A549 tumor‐bearing mice. In addition, FTS/YM155 NCs exerted significant survivin downregulation (4.43‐fold) and caspase‐3 upregulation (4.31‐fold) and showed better therapeutic outcomes without inducing organ injury, which highlights their promising future clinical application in precision therapy. This tumor microenvironment‐responsive platform could be harnessed to develop an effective therapy via multilevel inhibition of cancer targets.

Targeting abundant survivin expression in liposarcoma: subtype dependent therapy responses to YM155 treatment

Purpose

Liposarcoma (LPS) represent the largest group of malignant soft tissue tumours comprising a heterogeneous group of subtypes in which the degrees of chemoresistance and radiosensitivity strongly vary. Consequently, it is of utmost interest to establish novel therapeutic regimens based on molecular targets.

Methods

Immunohistochemical staining of survivin was performed in tissue microarrays comprising 49 primary LPS specimens. LPS cell lines were treated with survivin antagonist YM155 and doxorubicin or etoposide alone as well as in combination. Changes in cell viability were investigated and the synergistic effect of a combined therapy analysed.

Results

Immunohistochemistry revealed an abundant expression of survivin in LPS that significantly concurred with less-differentiated tumour subtypes and grading. In vitro, we demonstrated the impact of the survivin inhibitor YM155 on dedifferentiated LPS (DDLPS) and, even more imposing, pleomorphic LPS (PLS) tumour cell viability with a strong induction of apoptosis. A combined treatment of doxorubicin or etoposide with YM155 augmented the cytotoxic effects on DDLPS and PLS cells.

Conclusion

These findings support the significant role of survivin in the oncogenesis and progression of LPS subtypes providing a rationale to target survivin in eligible in-vivo models and to pioneer clinical applications of survivin-specific substances unfolding their therapeutic potential in LPS patients prospectively.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-021-03871-5.

miR-874-3p mitigates cisplatin resistance through modulating NF-κB/inhibitor of apoptosis protein signaling pathway in epithelial ovarian cancer cells

The resistance to cisplatin, the most common platinum chemotherapy drug, may confine the efficacy of treatment in epithelial ovarian cancer patients. Aberrant expression of inhibitor of apoptosis proteins set the stage for resistance to cisplatin in EOC; besides, chemosensitivity in EOC can be chalked up to dysregulation of specific miRNAs. Herein, we investigated whether there is a potential correlation between miR-874-3p and the X-chromosome-linked inhibitor of apoptosis, a member of the IAP protein family in cisplatin-resistant EOC cells. The lower expression of miR-874-3p was found in SKOV3-DDP cells; it was also in association with cisplatin-resistance in EOC cells. XIAP was found to contribute to developing platinum resistance and is an authentic target for miR-874-3p in SKOV3-DDP cells. Consistently, restoration of miR-874-3p expression reversed cisplatin resistance in such cells by modulating XIAP and NF-κB/Survivin signaling pathway. Besides, siRNA knock down of XIAP in SKOV3-DDP cells had an anti-migratory effect like those with miR-874 overexpression. Importantly, the enforced expression of XIAP rescued SKOV3-DDP cells from the cytotoxic effects of miR-874-3p. Finally, miR-874-3p sensitized EOC cells to cisplatin-induced apoptosis, at least in part, through targeting XIAP. The cytotoxic effects of miR-874-3p can be attributed to the targeting XIAP in cisplatin-resistant EOC cells. We believe that the combination of cisplatin with miR-874-3p may make a potential strategy to reverse cisplatin resistance.

Newly designed compounds from scaffolds of known actives as inhibitors of survivin: computational analysis from the perspective of fragment-based drug design

Survivin is an apoptosis suppressing protein linked to different forms of cancer. As it stands, there are no approved drugs for the inhibition of survivin in cancer cells despite a number of promising compounds in clinical trials. This study designed a new set of compounds from fragments of active survivin inhibitors to potentiate their binding with survivin at BIR domain. Three hundred and five (305) fragments made from eight potent inhibitors of survivin were reconstructed to form a new set of compounds. The compounds were optimized using R group enumeration and bioisostere replacement after extensive docking analysis. The optimised compounds were filtered by a validated pharmacophore model to reveal how well they are aligned to the pharmacophore sites. Molecular docking of the well aligned compounds revealed the top-scoring compounds; and these compounds were compared with the eight inhibitors used as template for fragment-based design on the basis of binding affinity (rigid and flexible docking), predicted pIC50 and intermolecular interactions. The electronic behaviours (global descriptors, HOMO/LUMO, molecular electrostatic potential and Fukui functions) of newly designed compounds were calculated to investigate their reactivity and atomic sites prone to neutrophilic/electrophilic attack. The nine newly designed compounds had better rigid and flexible docking scores, free energy of binding and intermolecular interactions with survivin at BIR domain than the eight active inhibitors. Based on frontier molecular orbitals, OPE-3 was found to be the most reactive and less stable compound (0.13194 eV), followed by OPE-4 and OPE-9. The global descriptive parameters showed that OPE-3 had highest softness value (7.5245 eV) while OPE-8 recorded the maximum hardness value (0.08486 eV). The well-validated QSAR model also showed that OPE-3, OPE-7 and OPE-8 had the most significant bioactivity of all the inhibitors. This study thus provides new insight into the design of compounds capable of modulating the activity of survivin.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40203-021-00108-8.

Emerging Importance of Survivin in Stem Cells and Cancer: the Development of New Cancer Therapeutics

Survivin is one of the rare proteins that is differentially expressed in normal and cancer cells and is directly or indirectly involved in numerous pathways required for tumor maintenance. It is expressed in almost all cancers and its expression has been detected at early stages of cancer. These traits make survivin an exceptionally attractive target for cancer therapeutics. Even with these promising features to be an oncotherapeutic target, there has been limited success in the clinical trials targeting survivin. Only recently it has emerged that survivin was not being specifically targeted which could have resulted in the negative clinical outcome. Also, focus of research has now shifted from survivin expression in the overall heterogeneous tumor cell populations to survivin expression in cancer stem cells as these cells have proved to be the major drivers of tumors. Therefore, in this review we have analyzed the expression of survivin in normal and cancer cells with a particular focus on its expression in cancer stem cell compartment. We have discussed the major signaling pathways involved in regulation of survivin. We have explored the current development status of various types of interventions for inhibition of survivin. Furthermore, we have discussed the challenges involving the development of potent and specific survivin inhibitors for cancer therapeutics. Finally we have given insights for some of the promising future anticancer treatments.

hnRNPA2B1 regulates the alternative splicing of BIRC5 to promote gastric cancer progression

Background

Systematic profiling studies have implicated regulators of pre-mRNA splicing as important disease determinants in gastric cancer (GC), but the underlying mechanisms have remained elusive. Here we focused on hnRNPA2B1 splicing factor-dependent mechanisms governing GC development.

Methods

The expression of hnRNPA2B1 was analyzed among the Cancer Genome Atlas (TCGA) datasets of GC and validated at mRNA level. The function of hnRNPA2B1 in GC cells was analyzed and its downstream gene was identified using RNA immunoprecipitation. Further, effect of hnRNPA2B1 on BIRC5 alternative splicing was investigated.

Results

We show that overexpression of hnRNPA2B1 in GC is correlated with poor survival, and hnRNPA2B1 is required for maintaining GC malignant phenotype by promoting cell proliferation, inhibiting cell apoptosis and increasing cell metastasis. Mechanistically, hnRNPA2B1 co-expressed with several core spliceosome components and controls alternative splicing of anti-apoptotic factor BIRC5. BIRC5 isoform 202 (BIRC5-202) played the oncogenic function in GC cells, and overexpression of the BIRC5-202 transcript partly rescued the decrease in cisplatin resistance induced by downregulation of hnRNPA2B1.

Conclusions

We demonstrate that hnRNPA2B1 regulates BIRC5 splicing and might act as a therapeutic target of chemo-resistant GC cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01968-y.

Arsenic trioxide-induced cell apoptosis and cell cycle arrest are potentiated by 1,25-dihydroxyvitamin D3 in human leukemia K562 cells

The interaction between 1,25-dihydroxyvitamin [1,25(OH)2D3] and vitamin D receptor (VDR) plays a critical role in regulating cell proliferation and programmed cell death. The present study aimed to investigate the effects of 1,25(OH)2D3 in combination with arsenic trioxide (As₂O₃) on the proliferation and cell cycle of a K562 leukemia cell line. K562 cells were treated with 100 nM 1,25(OH)2D3, 2.5 µM As₂O₃, and 100 nM 1,25(OH)2D3 combined with 2.5 µM As₂O₃. Cell proliferation was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt/phenazine ethosulfate method. Cell cycle progression and apoptosis were detected by flow cytometry. The expression levels of genes associated with the cell cycle and apoptosis were analyzed by reverse transcription-quantitative PCR and western blotting analyses. The present findings indicated that combined treatment of 1,25(OH)2D3 and As₂O₃ led to a significant increase in cytotoxicity, apoptotic cell death and G₁ cell cycle arrest when compared to those treated with 1,25(OH)2D3 or As₂O₃ alone. The downregulation of the Bax/Bcl-2 ratio and decreased survivin expression may be involved in combined treatment-mediated apoptosis. G₀/G₁ cell cycle arrest induced by combined treatment was associated with the activation of p21 and p27. In addition, the increased expression of VDR was found to participate in the anticancer effect of combination treatment. The data suggested that the combination of 1, 25-(OH)₂D₃ and As₂O₃ had clear synergistic effects on the inhibition of K562 cell proliferation, which could provide a novel therapeutic approach for the treatment of acute myeloid leukemia.

Discovering and Characterizing of Survivin Dominant Negative Mutants With Stronger Pro-apoptotic Activity on Cancer Cells and CSCs

Survivin as a member of the inhibitor of apoptosis proteins (IAPs) family is undetectable in normal cells, but highly expressed in cancer cells and cancer stem cells (CSCs) which makes it an attractive target in cancer therapy. Survivin dominant negative mutants have been reported as competitive inhibitors of endogenous survivin protein in cancer cells. However, there is a lack of systematic comparative studies on which mutants have stronger effect on promoting apoptosis in cancer cells, which will hinder the development of novel anti-cancer drugs. Here, based on the previous study of survivin and its analysis of the relationship between structure and function, we designed and constructed a series of different amino acid mutants from survivin (TmSm34, TmSm48, TmSm84, TmSm34/48, TmSm34/84, and TmSm34/48/84) fused cell-permeable peptide TATm at the N-terminus, and a dominant negative mutant TmSm34/84 with stronger pro-apoptotic activity was selected and evaluated systematically in vitro. The double-site mutant of survivin (TmSm34/84) showed more robust pro-apoptotic activity against A549 cells than others, and could reverse the resistance of A549 CSCs to adriamycin (ADM) (reversal index up to 7.01) by decreasing the expression levels of survivin, P-gp, and Bcl-2 while increasing cleaved caspase-3 in CSCs. This study indicated the selected survivin dominant negative mutant TmSm34/84 is promising to be an excellent candidate for recombinant anti-cancer protein by promoting apoptosis of cancer cells and their stem cells and sensitizing chemotherapeutic drugs.

Synthesis and biological evaluation of naphthoquinone phenacylimidazolium derivatives

In order to expand structural diversity and improve antitumor efficiency, forty new naphthoquinone phenacylimidazolium derivatives were designed, synthesized and evaluated. Good synthetic yields were obtained under mild conditions using easily available starting materials. Cytotoxicity of these compounds was evaluated in vitro against a panel of human tumor cell lines: human breast carcinoma cell lines (MCF-7), human cervical carcinoma cell lines (HeLa), and human lung carcinoma cell lines (A549). Among them, the optimal compound 7m showed splendid antiproliferative activity with low to 50 nM IC₅₀ values against MCF-7 and excellent selectivity of 256-fold compared with the normal cell lines L929. Compound 7m induced apoptosis in a dose-dependent manner. Further mechanism experiments showed that compound 7m dramatically inhibited the expression of survivin and activated the pro-apoptotic protein caspase-3. Our results indicated that the structural modification on the 1,3-substituents of naphthoquinone imidazoliums without 2-substituent is also promising to obtain new antitumor compounds.

Combination Therapy of Breast Cancer by Codelivery of Doxorubicin and Survivin siRNA Using Polyethylenimine Modified Silk Fibroin Nanoparticles

Here, polyethylenimine (PEI) modified silk fibroin nanoparticles (SFNPs) were prepared for codelivery of doxorubicin (DOX) and survivin siRNA. The prepared NPs were characterized in terms of stability and structural, functional, and physicochemical properties. Moreover, the ability of the conjugate to escape from the endosome and cellular uptake were assessed. Afterward, the in vivo therapeutic efficacy was analyzed in the mice model. The siRNA loaded PEI-SFNPs showed acceptable size, zeta potential, and stability in serum. It also effectively induced apoptosis in the 4T1 mouse mammary tumor cell line. Cellular uptake and endosomal escape analyses confirmed that PEI-SFNPs containing siRNA could escape from the endosome and accumulate in the cytoplasm of 4T1 cells. Real time-PCR indicated the significant decrease in the expression of survivin mRNA in the 4T1 cell line 48 h postincubation with siRNA loaded PEI-SFNPs. In vivo biodistribution of PEI-SFNPs confirmed higher accumulation of SFNPs in the tumor site compared with other organs. The codelivery systems remarkably reduced the growth rate of breast tumor in the mice model without any obvious weight lost. Histopathological and tunnel staining exhibited more apoptotic tumor cells in the group containing both DOX and survivin siRNA. Tumorigenic breast tissue resected from the animals after treatment with siRNA also exhibited significant suppression of survivin gene. In conclusion, the prepared drug delivery system had an acceptable potential in tumor removal, apoptosis induction in cancer cells, and therapeutic efficacy. Thus, it would be a good candidate for breast cancer therapy.

Knockdown of eIF3a attenuated cell growth in K1 human thyroid cancer cells

BACKGROUND

In ribosome establishment and the initiation of translation, eukaryotic translation initiation factor (eIF) 3a is a pivotal functional subunit of the eIF3 complex. In various cancer types, abnormal eIF3a expression plays an important role in tumorigenesis.

OBJECTIVE

We aimed to explore the role of eIF3a in human thyroid cancer (TC).

MATERIAL AND METHODS

The expression of eIF3a was determined in TC tissues by qRT-PCR and immunohistochemistry (IHC) assay, respectively. In addition, the expression of eIF3a in K1 and BCPAP cells were detected by qRT-PCR. Cell proliferation, cell cycle, and cell apoptosis were assessed after eIF3a knockdown in K1 in cell line.

RESULTS

The expression of eIF3a mRNA was high in TC tissues and cancer cell lines. Moreover, eIF3a expression in TC tissues indicated that high eIF3a level was associated with tumor grade. In addition, eIF3a knockdown resulted in a significantly decrease in cell proliferation and increased the apoptosis of K1 cells. Cell cycle was arrested in both the S and G2/M phase. The levels of phosphorylated ERK1/2 and surviving were decreased after eIF3a knockdown.

CONCLUSION

Our study suggested that eIF3a contributed to TC cell proliferation. It may be a promising target for gene therapy in human thyroid cancer.

A two-step resin based approach to reveal survivin-selective fluorescent probes

The identification of modulators for proteins without assayable biochemical activity remains a challenge in chemical biology. The presented approach adapts a high-throughput fluorescence binding assay and functional chromatography, two protein-resin technologies, enabling the discovery and isolation of fluorescent natural product probes that target proteins independently of biochemical function. The resulting probes also suggest targetable pockets for lead discovery. Using human survivin as a model, we demonstrate this method with the discovery of members of the prodiginine family as fluorescent probes to the cancer target survivin.

Codelivery of survivin inhibitor and chemotherapeutics by tumor-derived microparticles to reverse multidrug resistance in osteosarcoma

Reportedly, the elevated expression of survivin has been observed in several tumor types, strictly involved in tumor development. In the present study, we detected elevated survivin expression in tumor tissues derived from patients with chemoresistant osteosarcoma when compared with those from chemosensitive patients. Importantly, knockdown of survivin in osteosarcoma cells significantly suppressed cell proliferation and chemoresistance both in vitro and in vivo. Simultaneously, chemotherapy mediates the upregulation of survivin in osteosarcoma cells through a survivin-based selective killing effect, resulting in the development of multidrug resistance. The utilization of tumor-derived microparticles to coencapsulate the survivin inhibitor YM155 and chemotherapeutic agents could effectively reverse multidrug resistance, leading to improved anticancer effects, as well as reduced systemic toxicity. In summary, the expression of survivin contributes to resistance toward osteosarcoma drugs, whereas employing survivin inhibiting combination therapy, based on a microparticle codelivery system, could efficiently reverse resistance and avoid potential systemic toxicity.

Verteporfin inhibits cell proliferation and induces apoptosis in different subtypes of breast cancer cell lines without light activation

Background

Breast cancer (BC) can be divided into five subtypes: Lumina1A, Lumina1B, HER-2 overexpression, Basal-like and Normal breast-like subtype, based on the differently expressed genes in breast cancer tissue. The Hippo signaling pathway plays an indispensable role in BC. The YAP gene is a terminal effector of Hippo pathway, and hyperactivation of YAP mediates tumorigenesis. As an inhibitor of YAP, non-photoactivated verteporfin (VP) can inhibit YAP-mediated tumor proliferation and angiogenesis by eliminating its interaction with TEAD. This study aimed to determine the effect and molecular mechanisms of VP-mediated inhibition of YAP in different subtypes of BC.

Methods

Luminal A, Luminal B and Basal-like BC cells were cultivated in vitro to study effects of VP on proliferation and apoptosis of these three molecular BC subtypes.

Results

Our experimental results showed that VP inhibited cell proliferation, YAP-TEAD interaction and expression of its downstream targets. VP also induced tumor cell apoptosis, and promoted the cleavage of Caspase-9 and PARP in the cells of various molecular subtypes of BC.

Conclusion

These findings provide a basis for the use of VP as a potential anti-tumor therapeutic for BC by targeting the Hippo pathway effector YAP.

Caffeic acid phenethyl ester induces apoptosis in colorectal cancer cells via inhibition of survivin

Colorectal cancer is one of the most common types of cancer. Drug resistance and drug-induced damage of healthy tissues are major obstacles in cancer treatment. Therefore, to develop efficient anticancer therapy, it is necessary to find compounds that affect tumor cells, but do not exhibit toxicity to healthy cells. Caffeic acid phenethyl ester (CAPE) has been demonstrated to have anticancer properties in many types of cancer. In this study, the cytotoxic and apoptotic effects of CAPE on the RKO colorectal cancer cell line and CCD 841-CoN normal colorectal cell line was investigated. In addition, changes in the survivin expression were determined. According to the results, CAPE decreased cell viability in the RKO cell line in a dose-dependent manner. Likewise, CAPE induced apoptotic cell death in approximately 40% of the RKO cells. Furthermore, CAPE treatment increased the Serine 15 (Ser15) and Serine 46 (Ser46) phosphorylation of p53, while decreased the survivin expression. The results suggested that CAPE induced apoptosis by regulating p53 phosphorylation, leading to inhibition of the survivin expression. In accordance with the results, it is suggested that CAPE might be evaluated as an alternative drug in cancer therapy and further investigation is needed within this scope.

Novel Polymeric Hybrid Nanocarrier for Curcumin and Survivin shRNA Co-delivery Augments Tumor Penetration and Promotes Synergistic Tumor Suppression

A major barrier for co-delivery of gene medicine with small molecular chemotherapeutic drugs in solid tumors is the inadequate tumor penetration and transfection. In this study, a novel polymeric nanocarrier with integrated properties of tumor penetration, nuclear targeting, and pH-responsive features was designed, and further used to achieve the synergistic anti-tumor effect of curcumin (CUR) and survivin shRNA (pSUR). The polymeric hybrid nanocarrier was constructed from the FDA-approved polymer PLGA and a novel conjugated triblock polymer W5R4K-PEG_2K-PHIS (WPH). CUR and pSUR were simultaneously encapsulated in the dual-drug-loaded nanoparticles (CUR/pSUR-NPs) by a modified double-emulsion solvent evaporation (W/O/W) method. The obtained nanoparticles exhibited better pharmaceutical properties with a uniform spherical morphology and sustained release manners of CUR and pSUR. Excellent features including preferable cellular uptake, efficient endosomal escape, enhanced tumor penetration, and elevated transfection efficiency were further proven. Additionally, a markedly enhanced anti-tumor efficacy for CUR/shRNA-NPs was achieved on SKOV-3 and Hela cells. The synergistic anti-tumor effect involved the inhibition of tumor cell proliferation, induction of cell apoptosis, and the activation of caspase-3 pathways. This work sets up an innovative co-delivery nanosystem to suppress tumor growth, contributing to the development of a comprehensive nanoparticulate strategy for future clinical applications.

Trace of survivin in cancer

Survivin is one of the most cancer-specific proteins overexpressed in almost all malignancies, but is nearly undetectable in most normal tissues in adults. Functionally, as a member of the inhibitor of apoptosis family, survivin has been shown to inhibit apoptosis and increase proliferation. The antiapoptotic function of survivin seems to be related to its ability to inhibit caspases directly or indirectly. Furthermore, the role of survivin in cell cycle division control is related to its role in the chromosomal passenger complex. Consistent with its determining role in these processes, survivin plays a crucial role in cancer progression and cancer cell resistance to anticancer drugs and ionizing radiation. On the basis of these findings, recently survivin has been investigated intensively as an ideal tumor biomarker. Thus, multiple molecular approaches such as use of the RNA interfering technique, antisense oligonucleotides, ribozyme, and small molecule inhibitors have been used to downregulate survivin regulation and inhibit its biological function consequently. In this review, all these approaches are explained and other compounds that induced apoptosis in different cell lines through survivin inhibition are also reported.

Synthesis and Identification of a Novel Lead Targeting Survivin Dimerization for Proteasome-Dependent Degradation

Survivin, a homodimeric member of the Inhibitor of Apoptosis Protein (IAP) family, is required for cancer cell survival and overexpressed in almost all solid tumors. However, targeting survivin has been challenging due to its "undruggable" nature. Recently, we used a novel approach to target the dimerization interface and identified inhibitors of two scaffolds that can directly bind to and inhibit survivin dimerization. One of the scaffolds, represented by the compound LQZ-7, contains an undesirable labile hydrazone linker and a potentially nonfunctional furazanopyrazine ring that we attempted to eliminate in this study. We found one compound, 7I, that is more active than the parent compound, LQZ-7, and when given orally effectively inhibits xenograft tumor growth and induces survivin loss in tumors. These findings indicate that 7I with a stable linker and a quinoxaline ring can be used as a lead for further optimization of this novel class of survivin inhibitors.

Glycyrrhizic Acid Inhibits Proliferation of Gastric Cancer Cells by Inducing Cell Cycle Arrest and Apoptosis

Purpose

Glycyrrhizic acid (GA) is the main active ingredient extracted from Chinese herb licorice root, and it shows anti-tumor effects in many cancer types, while its role in gastric cancer (GC) is still unknown. In this study, we evaluated the effects of GA on GC cells and explored the underlying mechanisms.

Methods

The anti-proliferation effect of GA on GC cells was assessed by CCK-8, colony formation, and EdU assay. The effects of GA on cell cycle and apoptosis were detected by flow cytometer. Western blotting was performed to explore the underlying mechanisms.

Results

Our results showed that GA had a time- and dose-dependent inhibitory effect on proliferation of GC cells. Flow cytometer analysis demonstrated that GA would lead to G1/S-phase arrest and apoptosis. GA treatment down-regulated the levels of G1 phase-related proteins, including cyclin D1, D2, D3, E1, and E2. In terms of apoptosis, GA treatment up-regulated the levels of Bax, cleaved PARP, and pro-caspase-3, -8, -9, but did not influence their cleavage patterns. The expression of Bcl-2, survivin and p65 was attenuated after treatment. Besides, GA would down-regulate the phosphorylation of PI3K/AKT pathway.

Conclusion

This study focused on inhibitory effect of GA on GC cells by inducing cell cycle arrest and apoptosis. Several important cyclins- and apoptosis-related proteins were involved in the regulation of GA to GC cells, and phosphorylated PI3K and AKT were attenuated. The results of this study indicated that GA is a potential and promising anti-cancer drug for GC.

Discovery of inner centromere protein-derived small peptides for cancer imaging and treatment targeting survivin

Survivin belongs to the inhibitor of apoptosis protein family, which is consistently overexpressed in most cancer cells but rarely expressed in normal adult tissues. Therefore, the detection and inhibition of survivin are regarded as attractive strategies for cancer‐specific treatment. In this study, we designed and synthesized 7‐19 residues of inner centromere protein (INCENP)‐derived small peptides (INC peptides) as novel survivin‐targeting agents. The INC peptides showed binding affinity for the human survivin protein (K_d = 91.4‐255 nmol L⁻¹); INC_16‐22, which contains residues 16‐22 of INCENP, showed the highest affinity (91.4 nmol L⁻¹). Confocal fluorescence imaging showed consistent colocalization of FITC‐INC_16‐22 and survivin in cell lines. Nona‐arginine‐linked INC_16‐22 (r9‐INC_16‐22) rendered INC_16‐22 cells penetrable and strongly inhibited cell growth of MIA PaCa‐2 cells (52% inhibition at 1.0 µmol L⁻¹) and MDA‐MB‐231 cells (60% inhibition at 10 µmol L⁻¹) as determined by MTT assays. The exposure of MIA PaCa‐2 cells to 40 µmol L⁻¹ r9‐INC_16‐22 apparently reduced the intracellular protein expression levels of survivin. However, cleaved caspase‐3 was significantly increased in cells treated with r9‐INC_16‐22, even at 10 µmol L⁻¹, compared to untreated cells. Flow cytometry revealed that r9‐INC_16‐22 strongly induced apoptosis in MIA PaCa‐2 cells. These results indicate that the cytotoxic effects of r9‐INC_16‐22 could be mediated mainly through the disruption of survivin‐dependent antiapoptotic functions and partly because of the direct degradation of the survivin protein. Our findings suggest that INC peptides can act as useful scaffolds for novel cancer imaging and anticancer agents.

miR-3622b-5p regulates cisplatin resistance of human gastric cancer cell line by targeting BIRC5

Many evidences showed that drug resistance of gastric cancer cells could be regulated by the abnormal expression of microRNAs (miRNAs), a post-transcriptional regulator of gene expression. Thus, we investigated the role of miR-3622b-5p in the development of cisplatin (DDP) resistance in human gastric cancer cell lines. A set of biochemical assays were used to elucidate the mechanism by which miR-3622b-5p regulates drug resistance in cancer cells. The expression of miR-3622b-5p was measured by quantitative real-time PCR and showed that miR-3622b-5p was significantly downregulated in the plasma of patients with acquired drug resistance to platinum-based chemotherapy for gastric cancer. miR-3622b-5p was also found significantly downregulated in DDP-resistant gastric cancer cell line SGC7901/DDP, compared with the parental SGC7901 cells. An in vitro drug sensitivity assay showed that overexpression of miR-3622b-5p sensitized SGC7901/DDP cells to DDP. The luciferase activity of reporters constructed by BIRC5 3′-untranslated regions in SGC7901/DDP cells suggested that BIRC5 was target gene of miR-3622b-5p. Ecpotic miR-3622b-5p expression in SGC7901/DDP cells significantly repressed the expression of the BIRC5 and sensitized the cells to DDP-induced apoptosis. By contrast, treatment with miR-3622b-5p inhibitor increased the protein expression of BIRC5 and led to a lower proportion of apoptotic cells in the SGC7901 cells. In conclusion, our findings suggest that miR-3622b-5p regulates DDP resistance of human gastric cancer cells at least in part by repressing the expression of BIRC5. Altering miR-3622b-5p expression may be a potential therapeutic strategy for the treatment of chemoresistance in gastric cancer in the future.

Dominant-negative ATF5 rapidly depletes survivin in tumor cells

Survivin (BIRC5, product of the BIRC5 gene) is highly expressed in many tumor types and has been widely identified as a potential target for cancer therapy. However, effective anti-survivin drugs remain to be developed. Here we report that both vector-delivered and cell-penetrating dominant-negative (dn) forms of the transcription factor ATF5 that promote selective death of cancer cells in vitro and in vivo cause survivin depletion in tumor cell lines of varying origins. dn-ATF5 decreases levels of both survivin mRNA and protein. The depletion of survivin protein appears to be driven at least in part by enhanced proteasomal turnover and depletion of the deubiquitinase USP9X. Survivin loss is rapid and precedes the onset of cell death triggered by dn-ATF5. Although survivin downregulation is sufficient to drive tumor cell death, survivin over-expression does not rescue cancer cells from dn-ATF5-promoted apoptosis. This indicates that dn-ATF5 kills malignant cells by multiple mechanisms that include, but are not limited to, survivin depletion. Cell-penetrating forms of dn-ATF5 are currently being developed for potential therapeutic use and the present findings suggest that they may pose an advantage over treatments that target only survivin.

Exposure time versus cytotoxicity for anticancer agents

PURPOSE

Time is a critical factor in drug action. The duration of inhibition of the target or residence time of the drug molecule on the target often guides drug scheduling.

METHODS

The effects of time on the concentration-dependent cytotoxicity of approved and investigational agents [300 compounds] were examined in the NCI60 cell line panel in 2D at 2, 3, 7 and in 3D 11 days.

RESULTS

There was a moderate positive linear relationship between data from the 2-day NCI60 screen and the 3-, 7- and 11-day and a strong positive linear relationship between 3-, 7- and 11-day luminescence screen IC50s by Pearson correlation analysis. Cell growth inhibition by agents selective for a specific cell cycle phase plateaued when susceptible cells were growth inhibited or killed. As time increased the depth of cell growth inhibition increased without change in the IC50. DNA interactive agents had decreasing IC50s with increasing exposure time. Epigenetic agents required longer exposure times; several were only cytotoxic after 11 days' exposure. For HDAC inhibitors, time had little or no effect on concentration response. There were potency differences amongst the three BET bromodomain inhibitors tested, and an exposure duration effect. The PARP inhibitors, rucaparib, niraparib, and veliparib reached IC50s < 10 μM in some cell lines after 11 days.

CONCLUSIONS

The results suggest that variations in compound exposure time may reflect either mechanism of action or compound chemical half-life. The activity of slow-acting compounds may optimally be assessed in spheroid models that can be monitored over prolonged incubation times.

Radiosensitizing effects of Cyclocarya paliurus polysaccharide on hypoxic A549 and H520 human non-small cell lung carcinoma cells

Cyclocarya paliurus (CP) polysaccharide (CPP) is a chemical component contained in CP, which has been reported to possess significant hypoglycemic activity. The present study aimed to investigate the radiosensitizing effect and underlying mechanisms of CPP on hypoxic A549 and H520 human non-small cell lung carcinoma cells. Cell viability, apoptosis and proliferation were determined using Cell Counting kit-8 assay, flow cytometry and colony formation assay, respectively. mRNA and protein expression levels were determined by reverse transcription-quantitative PCR and western blot analysis, respectively. The results suggested that CPP markedly inhibited the viability of hypoxic A549 and H520 cells. In response to combined treatment with CPP and radiation, hypoxic A549 and H520 cells exhibited enhanced apoptosis; in addition, cell proliferation was suppressed and the expression levels of hypoxia-inducible factor-1α, survivin and cleaved caspase-3 were modified. Furthermore, CPP in combination with radiation affected the mammalian target of rapamycin (mTOR)/Akt/phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) pathway. These findings indicated that CPP may enhance the radiosensitivity of hypoxic A549 and H520 cells; this effect may be associated with inhibition of the mTOR/Akt/PI3K pathway. The potential radiosensitizing effects of CPP on hypoxic A549 and H520 cells suggested that CPP may be an effective target for treatment of non-small cell lung carcinoma.

An Inhibitor of the Interaction of Survivin with Smac in Mitochondria Promotes Apoptosis

Herein we report the first small molecule that disrupts the survivin-Smac interaction taking place in mitochondria. The inhibitor, PZ-6-QN, was identified by initially screening a phenothiazine library using a fluorescence anisotropy assay and then conducting a structure-activity relationship study. Mutagenesis and molecular docking studies suggest that PZ-6-QN binds to survivin similarly to the known Smac peptide, AVPI. The results of the effort also show that PZ-6-QN exhibits good anticancer activity against various cancer cells. Moreover, cell-based mechanistic studies provide evidence for the proposal that PZ-6-QN enters mitochondria to inhibit the survivin-Smac interaction and promotes release of Smac and cytochrome c from mitochondria into the cytosol, a process that induces apoptosis in cancer cells. Overall, the present study suggests that PZ-6-QN can serve as a novel chemical probe for study of processes associated with the mitochondrial survivin-Smac interaction and it will aid the discovery of novel anticancer agents.

Downregulation of survivin by adenovirus-mediated shRNA promotes apoptosis in skin cancer cells

Background

Survivin, a member of the inhibitor of apoptosis protein family, is highly expressed in many cancers and has important roles in inhibiting apoptosis by blocking caspase activation. However, its antitumor effects remain largely unknown. Here we explore the function of survivin in skin cancer.

Methods

We used qPCR and Western blot to examine survivin expression in skin cancer patients and cell line. We generated several survivin shRNA constructs and tested the effects of survivin shRNA on cancer cell viability using MTT assay, flow cytometry, and TUNEL assay.

Results

We found that survivin was upregulated in both skin cancer patients and skin cancer cell line A431. Knockdown survivin via shRNA inhibited cancer cell proliferation and promoted apoptosis in both A431 cell and in vivo xenograft tumor mouse model. The antitumor effect is comparable to resveratrol, a drug known to inhibit cancer progression. Moreover, we showed that inhibition of survivin was able to increase the expression of cleaved caspase 7/caspase 9 and activate the ataxia-telangiectasia mutated-NF-κB pathway in A431 cells.

Conclusion

Survivin-shRNA possesses antitumor abilities in vitro and in vivo by inhibiting the proliferation and promoting apoptosis of A431 cells. It may serve as a potential anticancer target for skin cancer therapy in the future.

MS-275 potentiates the effect of YM-155 in lung adenocarcinoma via survivin downregulation induced by miR-138 and miR-195

Background

YM‐155 has been proven to be an efficient antitumor suppressor in non‐small cell lung cancer (NSCLC) cells. However, the suppressive effect of YM‐155 on the expression of survivin is not sufficient and has a short half‐life. MS‐275, a histone deacetylase inhibitor, has significant antitumor capacity with a relatively long half‐life. Our study explored whether MS‐275 could enhance the inhibitory effect of YM‐155 on LUAD proliferation.

Methods

To investigate the synergistic effect of MS‐275 and YM‐155, we employed methyl thiazolyl tetrazolium and colony formation assays to access the inhibition effect of MS‐275, YM‐155, or a combination in A549 and HCC827 cell lines. We then detected the effect of MS‐275 and YM‐155 on the expression of survivin and pro‐apoptotic proteins by Western blot and miR‐138 or miR‐195 expression by quantitative PCR. We also analyzed the methylation level of microRNAs (miRNAs) using methylation‐sensitive quantitative PCR. Finally, we investigated the interaction between miRNAs and survivin by luciferase reporter assay.

Results

MS‐275 facilitated an inhibitory effect of YM‐155 on lung adenocarcinoma cell proliferation. MS‐275 can upregulate the level of acetylated H3, promote the degradation of DNA methyltransferases, and inhibit the methylation of miR‐138 and miR‐195 genes to elevate the expression of miR‐138 and miR‐195. Moreover, miR‐138 and miR‐195 showed a synergistic effect with YM‐155 by directly binding to the 3 untranslated region of survivin to attenuate its expression.

Conclusion

For the first time, we report the synergistic effective of MS‐275 and YM‐155 and suggest a new direction for the future application of YM‐155.

Targeted Co-Delivery of siRNA and Methotrexate for Tumor Therapy via Mixed Micelles

A combination of chemotherapeutic drugs and siRNA is emerging as a new modality for cancer therapy. A safe and effective carrier platform is needed for combination drug delivery. Here, a functionalized mixed micelle-based delivery system was developed for targeted co-delivery of methotrexate (MTX) and survivin siRNA. Linolenic acid (LA) was separately conjugated to branched polyethlenimine (b-PEI) and methoxy-polyethyleneglycol (mPEG). MTX was then conjugated to LA-modified b-PEI (MTX-bPEI-LA) to form a functionalized polymer-drug conjugate. Functionalized mixed micelles (M-MTX) were obtained by the self-assembly of MTX-bPEI-LA and LA-modified mPEG (mPEG-LA). M-MTX had a narrow particle size distribution and could successfully condense siRNA at an N/P ratio of 16/1. M-MTX/siRNA was selectively taken up by HeLa cells overexpressing the folate receptor (FR) and facilitated the release of the siRNA into the cytoplasm. In vitro, M-MTX/siRNA produced a synergy between MTX and survivin siRNA and markedly suppressed survivin protein expression. In tumor-bearing mice, M-MTX/Cy5-siRNA showed an elevated tumor uptake. In addition, M-MTX/siRNA inhibited tumor growth. Immunohistochemistry and a western blot analysis showed a significant target gene downregulation. In conclusion, M-MTX/siRNA was highly effective as a delivery system and may serve as a model for the targeted co-delivery of therapeutic agents.

One step ahead: miRNA-34 in colon cancer-future diagnostic and therapeutic tool?

The discovery that microRNAs (miRNAs) - short, non-coding RNA molecules which regulate gene expression - are implicated in many types of cancer has revolutionised cancer research, giving hope for a new perspective in diagnostics and treatment. Dysregulation of miRNAs occurs in various malignancies, including colorectal cancer (CRC). CRC is one of the leading causes of cancer-related death and in most countries its incidence is still rising. Among several miRNAs which have been linked to CRC, miR-34 has attracted particular attention. This miRNA is involved in the regulation of cell cycle and apoptosis through multiple signaling pathways such as p53, Ra and Wnt signaling. Understanding its role in CRC may facilitate its future use as a diagnostic tool and therapeutic target.

The Lipid Side of Bone Marrow Adipocytes: How Tumor Cells Adapt and Survive in Bone

PURPOSE OF REVIEW

Bone marrow adipocytes have emerged in recent years as key contributors to metastatic progression in bone. In this review, we focus specifically on their role as the suppliers of lipids and discuss pro-survival pathways that are closely linked to lipid metabolism, affected by the adipocyte-tumor cell interactions, and likely impacting the ability of the tumor cell to thrive in bone marrow space and evade therapy.

RECENT FINDINGS

The combined in silico, pre-clinical, and clinical evidence shows that in adipocyte-rich tissues such as bone marrow, tumor cells rely on exogenous lipids for regulation of cellular energetics and adaptation to harsh metabolic conditions of the metastatic niche. Adipocyte-supplied lipids have a potential to alter the cell's metabolic decisions by regulating glycolysis and respiration, fatty acid oxidation, lipid desaturation, and PPAR signaling. The downstream effects of lipid signaling on mitochondrial homeostasis ultimately control life vs. death decisions, providing a mechanism for gaining survival advantage and reduced sensitivity to treatment. There is a need for future research directed towards identifying the key metabolic and signaling pathways that regulate tumor dependence on exogenous lipids and consequently drive the pro-survival behavior in the bone marrow niche.

Effects of Sepantronium Bromide (YM-155) on the Whole Transcriptome of MDA-MB-231 Cells: Highlight on Impaired ATR/ATM Fanconi Anemia DNA Damage Response

Sepantronium bromide (YM-155) is believed to elicit apoptosis and mitotic arrest in tumor cells by reducing (BIRC5, survivin) mRNA. In this study, we monitored changes in survivin mRNA and protein after treating MDA-MB-231 cells with YM-155 concurrent with evaluation of whole transcriptomic (WT) mRNA and long intergenic non-coding RNA at 2 time points: 8 h sub-lethal (83 ng/mL) and 20 h at the LC50 (14.6 ng/mL). The data show a tight association between cell death and the precipitating loss of survivin protein and mRNA (-2.67 fold-change (FC), p<0.001) at 20 h, questioning if the decline in survivin is attributed to cell death or drug impact. The meager loss of survivin mRNA was overshadowed by enormous differential change to the WT in both magnitude and significance for over 2000 differentially up/down-regulated transcripts: (+22 FC to -12 FC, p<0.001). The data show YM-155 to up-regulate transcripts in control of circadian rhythm (NOCT, PER, BHLHe40, NFIL3), tumor suppression (SIK1, FOSB), histone methylation (KDM6B) and negative feedback of NF-kappa B signaling (TNFAIP3). Down-regulated transcripts by YM-155 include glucuronidase (GUSBP3), numerous micro-RNAs, DNA damage repair elements (CENPI, POLQ, RAD54B) and the most affected system was the ataxia-telangiectasia mutated (ATM)/Fanconi anemia E3 monoubiquitin ligase core complexes (FANC transcripts - A/B/E/F/G/M), FANC2, FANCI, BRCA1, BRCA2, RAD51, PALB2 gene and ATR (ATM- and Rad3-Related) pathway. In conclusion, these findings suggest that a primary target of YM-155 is the loss of replicative DNA repair systems.

Inhibition of survivin enhances radiosensitivity of esophageal cancer cells by switching radiation-induced senescence to apoptosis

Purpose

Strategies to increase radiosensitivity are urgently needed. Combining radiosensitizing reagents with radiotherapy could improve the outcome of cancer treatment. Some preclinical studies showed that sepantronium bromide (YM155) could sensitize cancer cells to radiation by inhibiting the survivin protein. In this study, we try to investigate the function of YM155 on radiosensitivity of esophageal squamous cell carcinoma (ESCC) cells.

Materials and methods

ESCC cell lines were treated with radiation and YM155, and the radiation efficacy was evaluated by cell counting kit-8 assay and clonogenic survival assay. Cell senescence was measured by senescence-associated β-galactosidase staining. Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay, fluorescein isothiocyanate-labeled Annexin V/propidium iodide assay, and poly ADP-ribose polymerase cleavage were used to detect apoptosis. KYSE150 xenografts model was used to test the efficacy of radiation combined with YM155.

Results

YM155 could inhibit the upregulation of survivin induced by radiation in all ESCC cell lines, but the efficacy of radiosensitization varied in different cell lines. Radiation-induced senescence in KYSE150 and KYSE410 cells, and the combination with YM155 inhibited senescence and promoted apoptosis of ESCC cells, thereby enhancing radiosensitivity. Combination with YM155 and radiation delayed the growth of KYSE150 xenografts in nude mice by switching radiation-induced senescence to apoptosis. When p21 was inhibited in KYSE150 cells, radiation did not induce senescence, and the radiosensitization of YM155 was also attenuated. In KYSE510 and KYSE180 cells, radiation did not induce senescence, and YM155 could not enhance the radiosensitivity.

Conclusion

Our results suggest a new mechanism that YM155 might sensitize ESCC cells to radiation by switching radiation-induced senescence to apoptosis. The major determinant of radiosensitization by YM155 might be the induction of senescence by radiation.

Clinically relevant inflammatory breast cancer patient-derived xenograft-derived ex vivo model for evaluation of tumor-specific therapies

Inflammatory breast cancer (IBC) is a rare and aggressive presentation of invasive breast cancer with a 62% to 68% 5-year survival rate. It is the most lethal form of breast cancer, and early recognition and treatment is important for patient survival. Like non-inflammatory breast cancer, IBC comprises multiple subtypes, with the triple-negative subtype being overrepresented. Although the current multimodality treatment regime of anthracycline- and taxane-based neoadjuvant therapy, surgery, and radiotherapy has improved the outcome of patients with triple-negative IBC, overall survival continues to be worse than in patients with non-inflammatory locally advanced breast cancer. Translation of new therapies into the clinics to successfully treat IBC has been poor, in part because of the lack of in vitro preclinical models that can accurately predict the response of the original tumor to therapy. We report the generation of a preclinical IBC patient-derived xenograft (PDX)-derived ex vivo (PDXEx) model and show that it closely replicates the tissue architecture of the original PDX tumor harvested from mice. The gene expression profile of our IBC PDXEx model had a high degree of correlation to that of the original tumor. This suggests that the process of generating the PDXEx model did not significantly alter the molecular signature of the original tumor. We demonstrate a high degree of similarity in drug response profile between a PDX mouse model and our PDXEx model generated from the same original PDX tumor tissue and treated with the same panel of drugs, indicating that our PDXEx model had high predictive value in identifying effective tumor-specific therapies. Finally, we used our PDXEx model as a platform for a robotic-based high-throughput drug screen of a 386-drug anti-cancer compound library. The top candidates identified from this drug screen all demonstrated greater therapeutic efficacy than the standard-of-care drugs used in the clinic to treat triple-negative IBC, doxorubicin and paclitaxel. Our PDXEx model is simple, and we are confident that it can be incorporated into a PDX mouse system for use as a first-pass screening platform. This will permit the identification of effective tumor-specific therapies with high predictive value in a resource-, time-, and cost-efficient manner.

Survivin Inhibitors Mitigate Chemotherapeutic Resistance in Breast Cancer Cells by Suppressing Genotoxic Nuclear Factor-κB Activation

Therapeutic resistance developed after chemotherapy and aggressive metastasis are the major causes of cancer-related death in patients with triple-negative breast cancer (TNBC). Survivin is the smallest member of the inhibitor-of-apoptosis proteins (IAPs) family, which plays critical roles in cell division and cell survival. High expression levels of survivin have been associated with therapeutic resistance in various cancers. We recently developed a novel small-molecule survivin inhibitor mimicking the IAP-binding motif of second mitochondria-derived activator of caspase, which showed high potency in promoting survivin degradation. Here, we show that survivin inhibitor MX106/MX107 suppresses TNBC cell proliferation. Moreover, MX106/MX107 synergized with chemotherapeutic drugs or radiation and significantly enhanced tumoricidal efficacy of genotoxic treatments. Mechanistically, MX106/MX107 induced degradation of XIAP and/or cIAP1, which inhibited nuclear factor κB (NF-κB) activation by genotoxic agents. Treatment with MX106/MX107 alone did not activate alternative NF-κB signaling in breast cancer cells, which is likely attributable to their selective potency in degrading survivin in these cells. In addition, survivin degradation by MX106/MX107 dramatically increased abnormal mitotic spindle formation and cell division failure, which led to cell cycle arrest in breast cancer cells. Overall, our study suggests that combination treatment of TNBC using survivin inhibitors MX106/MX107 with cytotoxic chemotherapeutic drugs can achieve significantly improved therapeutic efficacy, which depends on MX106/MX107-mediated inhibition of genotoxic NF-κB activation.