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.

Survivin suppression heightens BZML-induced mitotic catastrophe to overcome multidrug resistance by removing therapy-induced senescent A549/Taxol cells.

Mitotic catastrophe (MC) is a newly identified type of anticancer mechanism for multidrug resistance (MDR) prevention. However, the long cellular death process resulting from MC is not beneficial for anticancer treatment. BZML is a novel colchicine-binding site inhibitor which can overcome MDR by inducing MC; however, BZML-induced MC cells underwent a long cellular death process. Thus, to improve anticancer therapies based on drug-induced MC, BZML-induced MC was served as a model to further study the underlying molecular mechanisms in the process of MC. Here, BZML could induce p53-dependent senescence in A549/Taxol cells, a MDR cell line. This senescence was a secondary effect of MC in overcoming MDR. During MC, BZML-induced destruction of protein-degradation system contributed not only to an increase of p53 protein but also to the accumulation of survivin in nucleus of A549/Taxol cells. Importantly, the nuclear accumulation of survivin was not the inducer but the result of BZML-induced MC, and it promoted the survival of senescent cells. Moreover, it provided additional vulnerability and critical opportunities for sequentially applied therapies. Further, targeting survivin with YM155 accelerated the death of MC cells by timely eliminating therapy-induced senescent cells and strengthening the efficiency of BZML in overcoming MDR in A549/Taxol cells. Collectively, nuclear accumulation of survivin delayed cellular death during MC by promoting the survival of BZML-induced senescent A549/Taxol cells. Moreover, "one-two punch" approach to cancer treatment based on combination therapy with YM155 for survivin suppression might be a new strategy for potentiating MC to overcome MDR.

Survivin expression is essential for early activation of hepatic stellate cells and fibrosis progression in chronic liver injury.

AIM: Hepatic fibrosis in injured liver is characterized by the activation of hepatic stellate cells (HSCs) from their quiescent state. Survivin (BIRC5) is one of the key genes that are upregulated during activation of HSCs but their role in HSC activation and fibrosis progression is unknown. Here, we have investigated the role of survivin protein in early fibrogenic activation of HSCs and fibrosis progression in chronic liver injury. MATERIALS & METHODS: Primary quiescent HSCs were isolated from healthy mice liver through perfusion and cultured for fibrogenic activation. Survivin expression was suppressed by its pharmacological suppressant, YM155. We developed chronic liver injury induced fibrotic mice model through administrating repeated dose of CCl4 for 2 weeks and 4 weeks. Mice were pre-treated with YM155 a week before CCl4 administration till 2nd week of dosing and then discontinued. Hepatic parameters were characterized and underlying mechanisms were investigated. KEY FINDINGS: Survivin expression gradually increased along with the expression of αSMA, collagen I activation maker in HSCs during their activation from quiescent state. Survivin suppression through YM155 downregulated αSMA, collagen I. Pre-treatment of YM155 in mice ceased the early activation of HSCs and onset of fibrosis in injured liver. However, discontinuation of YM155 initiated the activation of HSCs and fibrosis progression that shows survivin expression in HSCs is essential for their early activation and onset of liver fibrosis. SIGNIFICANCE: Survivin expression induces with activation of HSCs and drives onset of liver fibrosis in injured liver. Targeting survivin protein in activated HSCs could be a potential anti-fibrotic therapeutic approach in chronic liver injury.

A novel EGFR inhibitor suppresses survivin expression and tumor growth in human gefitinib-resistant EGFR-wild type and -T790M non-small cell lung cancer.

Tyrosine kinase inhibitors of epidermal growth factor receptor (EGFR-TKIs) are currently used therapy for non-small cell lung cancer (NSCLC) patients; however, drug resistance during cancer treatment is a critical problem. Survivin is an anti-apoptosis protein, which promotes cell proliferation and tumor growth that highly expressed in various human cancers. Here, we show a novel synthetic compound derived from gefitinib, do-decyl-4-(4-(3-(4-(3-chloro-4-fluorophenylamino)-7-methoxyquinazolin-6-yloxy)propyl) piper-azin-1-yl)-4-oxobutanoate, which is named as SP101 that inhibits survivin expression and tumor growth in both the EGFR-wild type and -T790M of NSCLC. SP101 blocked EGFR kinase activity and induced apoptosis in the A549 (EGFR-wild type) and H1975 (EGFR-T790M) lung cancer cells. SP101 reduced survivin proteins and increased active caspase 3 for inducing apoptosis. Ectopic expression of survivin by a survivin-expressed vector attenuated the SP101-induced cell death in lung cancer cells. Moreover, SP101 inhibited the gefitinib-resistant tumor growth in the xenograft human H1975 lung tumors of nude mice. SP101 substantially reduced survivin proteins but conversely elicited active caspase 3 proteins in tumor tissues. Besides, SP101 exerted anticancer abilities in the gefitinib resistant cancer cells separated from pleural effusion of a clinical lung cancer patient. Consistently, SP101 decreased the survivin proteins and the patient-derived xenografted lung tumor growth in nude mice. Anti-tumor ability of SP101 was also confirmed in the murine lung cancer model harboring EGFR T790M-L858R. Together, SP101 is a new EGFR inhibitor with inhibiting survivin that can be developed for treating EGFR wild-type and EGFR-mutational gefitinib-resistance in human lung cancers.

Induction of apoptosis, cytotoxicity and radiosensitization by novel 3,4-dihydroquinazolinone derivatives.

Twenty new quinazolinone derivatives bearing a piperonyl moiety were designed and synthesized. The structures of the target compounds were in agreement with the microanalytical and spectral data. Compounds 4-10, 13, 14 and 17-27 were screened for their cytotoxic activity against HepG-2 and MCF-7 cancer cell lines. The target compounds showed IC50 in the range of 2.46-36.85 µM and 3.87-88.93 µM for HepG-2 and MCF-7, respectively. The promising compounds 7, 19, 26 and 27 were selected to measure their EGFR inhibitory activity. The IC50 values of the promising compounds were in the range of 146.9-1032.7 nM for EGFR in reference to Erlotinib (IC50 = 96.6 nM). In further studies on compounds 7, 19, 26 and 27 using HepG-2 cell line, there was significant overexpression of p21 and downregulation of two members of IAPs protein family; Survivin and XIAP, relative to their controls. Annexin V-FITC and caspase-3 analyses have established a significant increase in early apoptosis. Moreover, the four selected compounds have impaired cell proliferation by cell cycle arrest at the G2/M phase compared to their respective control. Considering radiotherapy as the primary treatment for many types of solid tumors, the radiosensitizing abilities of compounds 7, 19, 26 and 27 were measured against HepG-2 and MCF-7 cell lines combined with a single dose of 8 Gy gamma radiation. Measurement of the IC50 of the promising compounds after irradiation revealed their ability to sensitize the cells to the lethal effect of gamma irradiation (IC50 = 1.56-4.32 µM and 3.06-5.93 µM for HepG-2 and MCF-7 cells, respectively). Molecular docking was performed to gain insights into the ligand-binding interactions of 7, 19, 26 and 27 inside the EGFR binding sites and revealed their essential interactions, explaining their good activity towards EGFR.

Synthesis and biological evaluation of selective survivin inhibitors derived from the MX-106 hydroxyquinoline scaffold.

The survivin (BIRC5) expression is very low in normal differentiated adult tissues, but it is one of the most widely upregulated genes in tumor cells. The overexpression of survivin in many cancer types has been positively correlated with resistance to chemotherapy, tumor metastasis, and poor patient survival. Survivin is considered to be a cancer specific biomarker and serves as a potential cancer drug target. In this report, we describe the design and syntheses of a series of novel selective survivin inhibitors based on the hydroxyquinoline scaffold from our previously reported lead compound MX-106. The best compound identified in this study is compound 12b. In vitro, 12b inhibited cancer cell proliferation with an average IC50 value of 1.4 µM, using a panel of melanoma, breast, and ovarian cancer cell lines. The metabolic stability of 12b improved over MX-106 by 1.7-fold (88 vs 51 min in human microsomes). Western blot analyses demonstrated that treatments with 12b selectively decreased survivin protein levels, but negligibly affected other closely related members in the IAP family proteins, and strongly induced cancer cell apoptosis. In vivo, compound 12b effectively inhibited melanoma tumor growth when tested using a human A375 melanoma xenograft model. Further evaluation using an aggressive, orthotopic ovarian cancer mouse model showed that 12b was highly efficacious in suppressing both primary tumor growth in ovaries and tumor metastasis to multiple peritoneal organs. Collectively, results in this study strongly suggest that the hydroxyquinoline scaffold, represented by 12b and our earlier lead compound MX-106, has abilities to selectively target survivin and is promising for further preclinical development.

Inhibition of Sp1-mediated survivin and MCL1 expression cooperates with SLC35F2 and myeloperoxidase to modulate YM155 cytotoxicity to human leukemia cells.

Although YM155 is reported to suppress survivin (also known as BIRC5) expression in cancer cells, its cytotoxic mechanism in human acute myeloid leukemia (AML) cells has not been clearly resolved. In this study, we analyzed the mechanistic pathways that modulate the sensitivity of human AML U937 and HL-60 cells to YM155. YM155 induced apoptosis in AML cells, which was characterized by p38 MAPK phosphorylation and downregulation of survivin and MCL1 expression. Phosphorylated p38 MAPK causes autophagy-mediated Sp1 degradation, thereby inhibiting the transcription of survivin and MCL1. The reduction of survivin and MCL1 levels further facilitated Sp1 protein degradation through autophagy. The restoration of Sp1, survivin, or MCL1 expression protected U937 and HL-60 cells from YM155-mediated cytotoxicity. U937 and HL-60 cells were continuously exposed to hydroquinone (HQ) to generate U937/HQ and HL-60/HQ cells, which showed increased SLC35F2 expression. The increase in SLC35F2 expression led to an increase in the sensitivity of U937/HQ cells to YM155-mediated cytotoxicity, whereas no such effect was observed in HL-60/HQ cells. Of note, myeloperoxidase (MPO) activity in HL-60 and HL-60/HQ cells enhanced YM155 cytotoxicity in these cells, and the enforced expression of MPO also increased the sensitivity of U937 cells to YM155. Taken together, we conclude that p38 MAPK-modulated autophagy inhibits Sp1-mediated survivin and MCL1 expression, which, in turn, leads to the death of U937 and HL-60 cells following YM155 treatment. In addition, our data indicate that SLC35F2 increases the sensitivity of U937 cells to YM155-mediated cytotoxicity, whereas MPO enhances YM155 cytotoxicity in U937 and HL-60 cells.

Discovery of Survivin Inhibitors Part 1: Screening the Harbor Branch Pure Compound Library.

Survivin is a 16.5 KDa protein whose functions include promoting cellular mitosis, angiogenesis, and senescence as well as inhibiting apoptosis. Higher survivin expression is found in cancer tissues than normal tissues, and this expression correlates with disease progression and aggressiveness. Survivin has been validated as a clinical target for cancer. Small molecules are important antagonists of survivin levels in cancer cells. A structurally diverse library of genetically encoded small molecules (natural products) derived from marine plants, invertebrates, and microbes was screened for their ability to reduce expression levels of survivin in the DLD-1 colon adenocarcinoma and the A549 nonsmall cell lung carcinoma cell lines. This led to the identification of this novel activity for the known compounds eryloside E, ilicicolin H, tanzawaic acid A, and p-hydroxyphenopyrrozin. Both eryloside E and ilicicolin H showed the ability to reduce survivin expression in the low micromolar range against both cell lines.

Alantolactone induces apoptosis in THP-1 cells through STAT3, survivin inhibition, and intrinsic apoptosis pathway.

Cancer is the second foremost cause of mortality in the world, and THP-1 cells play an important role in cancer progression. Alantolactone (ALT), a sesquiterpene lactone compound derived from Inula helenium, has a number of biological activities including antibacterial, antifungal, and anticancer. The current study was conducted to investigate the effects of ALT on THP-1 cells and its underlying molecular mechanisms. THP-1 cells were cultured and treated with ALT (20, 40 µM) for 12 hr, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, cell morphology, live/dead, and apoptosis assays were performed. The gene expressions at the protein level were checked through Western blot. Results show that ALT decreased cell viability and increased cell death and apoptosis. We found that ALT inhibited STAT3 and survivin expression. Furthermore, ALT induced mitochondrial-dependent apoptosis through a decrease in B-cell lymphoma-2 (Bcl-2) and Bcl-xL and increase in Bax expression, resulting in the release of cytochrome c (Cyt-c) from mitochondria. Cyt-c release from mitochondria further increased cleaved (cl) caspase-3 and cl-PARP expression and led the cells to apoptosis. Therefore, ALT might be a good therapy for the progression due to THP-1 cells.

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.

Commitment toward cell death by activation of autophagy with survivin inhibitor YM155 in two canine squamous cell carcinoma cell lines with high expression of survivin.

Canine squamous cell carcinoma (SCC) is difficult to treat if local therapy is not feasible. Recently, survivin inhibitor YM155 was shown to have growth inhibitory activity on high-survivin-expressing canine SCC cell lines HAPPY and SQ4. Here, the mechanisms underlying the effect of YM155 on these cell lines were investigated. YM155 induced cleavage of poly(ADP-ribose) polymerase (PARP) in HAPPY, but not in SQ4 cells. Analyzing two autophagy markers, the level of microtubule-associated protein 1 light chain 3 (LC3)-II and the LC3-II/LC3-I ratio, indicated that YM155 activates autophagy in both cell lines, and this activation occurs prior to PARP cleavage in HAPPY cells. Moreover, inhibition of autophagic flux by chloroquine almost completely prevented the toxic effect of YM155 in both cell lines. Although there are differences in their eventual cell death type, both cell lines may be committed to cell death by activation of autophagy with YM155. Activation of autophagy is likely to be a key mechanism in the growth-inhibitory effects of YM155 in these lines. These data provide new insights into the cytotoxic mechanism of YM155 in canine SCC cells.

Typhonium flagelliforme extract induce apoptosis in breast cancer stem cells by suppressing survivin.

CONTEXT: Breast cancer stem cells (bCSCs) are a small population of cancer-initiating cells within breast cancer, characterized as CD44+ CD24-/low. bCSCs develop apoptosis resistance by expressing survivin and suppressing caspase-9 and caspase-3 expression. Typhonium flagelliforme tuber extract (TFTe) can induce apoptosis in several types of cancer cells; however, the effects of TFTe to induce the bCSCs remain unclear. AIMS: This study aimed to investigate the effects of TFTe on apoptosis induction in bCSCs through the suppression of survivin and the exhibition of caspase-9 and caspase-3. SETTINGS AND DESIGN: This study employed a posttest only, control group design. SUBJECTS AND METHODS: To analyze the apoptotic index, TFTe, at concentrations of 25 (Tf1d), 50.89 (Tf2d), and 100 µg/mL (Tf3d) were used to treat bCSCs for 24 h, in a humidified incubator containing 5% CO2, at 37°C. The control group was exposed to dimethyl sulfoxide. Apoptosis was measured by propidium iodide and acridine orange double-staining, and the expression levels of survivin, caspase-9, and caspase-3 were assessed by immunocytochemistry. STATISTICAL ANALYSIS USED: Differences were analyzed by the independent Student's t-test, to compare two groups, and the Kruskal-Wallis test, to compare more than two groups. P < 0.05 was considered statistically significant. RESULTS: TFTe inhibited bCSC proliferation, with an IC50 value of 50.89 µg/mL, and significantly induced apoptosis in bCSCs (P < 0.001). TFTe also significantly decreased the expression levels of survivin in bCSCs (P < 0.001) and increased the expression levels of caspase-9 and caspase-3 (P < 0.001). CONCLUSIONS: TFTe can induce apoptosis in bCSCs by decreasing survivin expression levels and increasing the levels of caspase-9 and caspase-3.

Suppression of Rotenone-Treated Human Breast Cancer Stem Cell Survival Using Survivin Inhibitor YM155 is Associated to Oxidative Stress Modulation.

BACKGROUND: Despite recent progress in molecular-targeted therapies, breast cancer remains the primary leading cause of cancer related death among women worldwide. Breast cancer stem cells (BCSCs) are believed to be responsible for therapy resistance and cancer recurrence. We recently demonstrated that human BCSCs (CD24-/CD44+) could survive better than their counterpart non-BCSCs (CD24-/CD44-) when treated with rotenone, possibly due to lower levels of reactive oxygen species (ROS) production, high expression of antioxidant manganese superoxide dismutase (MnSOD), and anti-apoptotic survivin. The aim of this study was to verify the role of survivin on human BCSCs survival under oxidative stress modulation by suppressing its expression using YM155, a survivin inhibitor. METHODS: Human BCSCs (ALDH+ cells) were treated with YM155 for 24 h prior to treatment with rotenone for a further 6 h. We determined intracellular superoxide levels were determined using dihydroethidium assay, survivin and MnSOD expression using qRT-PCR, survivin protein level using ELISA, as well as cell viability using trypan blue exclusion and acridine orange/ethidium bromide apoptosis assay. RESULTS: Suppression of survivin expression using YM155 could reduce the survival of rotenone-treated BCSCs, which may be associated with oxidative stress modulation, as shown by increased ROS levels and decreased MnSOD expression. We confirm that survivin is responsible for maintaining BCSCs survival under oxidative stress modulation. Furthermore, YM155 could modulate oxidative stress in BCSCs by reducing MnSOD expression and increasing ROS levels. CONCLUSION: YM155 treatment could be used to overcome BCSCs resistance to oxidative stress-based anticancer therapies.

Survivin modulation in the antimelanoma activity of prodiginines.

Melanoma is a type of skin cancer with an elevated incidence of metastasis and chemoresistance. Such features hamper treatment success of these neoplasms, demanding the search for new therapeutic options. Using a two-step resin-based approach, we recently demonstrated that cytotoxic prodiginines bind to the inhibitor of apoptosis protein, survivin. Herein, we explore the role of survivin in melanoma and whether its modulation is related to the antimelanoma properties of three cytotoxic prodiginines (prodigiosin, cyclononylprodigiosin, and nonylprodigiosin) isolated from marine bacteria. In melanoma patients and cell lines, survivin is overexpressed, and higher levels negatively impact survival. All three prodiginines caused a decrease in cell growth with reduced cytotoxicity after 24 h compared to 72 h treatment, suggesting that low concentrations promote cytostatic effects in SK-Mel-19 (BRAF mutant) and SK-Mel-28 (BRAF mutant), but not in SK-Mel-147 (NRAS mutant). An increase in G1 population was observed after 24 h treatment with prodigiosin and cyclononylprodigiosin in SK-Mel-19. Further studies indicate that prodigiosin induced apoptosis and DNA damage, as detected by increased caspase-3 cleavage and histone H2AX phosphorylation, further arguing for the downregulation of survivin. Computer simulations suggest that prodigiosin and cyclononylprodigiosin bind to the BIR domain of survivin. Moreover, knockdown of survivin increased long-term toxicity of prodigiosin, as observed by reduced clonogenic capacity, but did not alter short-term cytotoxicity. In summary, prodiginine treatment provoked cytostatic rather than cytotoxic effects, cell cycle arrest at G0/G1 phase, induction of apoptosis and DNA damage, downregulation of survivin, and decreased clonogenic capacity in survivin knockdown cells.

Repurposing metformin, simvastatin and digoxin as a combination for targeted therapy for pancreatic ductal adenocarcinoma.

Patients with pancreatic adenocarcinoma (PDAC) have a 5-year survival rate of 8%, the lowest of any cancer in the United States. Traditional chemotherapeutic regimens, such as gemcitabine- and fluorouracil-based regimens, often only prolong survival by months. Effective precision targeted therapy is therefore urgently needed to substantially improve survival. In an effort to expedite approval and delivery of targeted therapy to patients, we utilized a platform to develop a novel combination of FDA approved drugs that would target pancreaticoduodenal homeobox1 (PDX1) and baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5) utilizing super-promoters of the target genes to interrogate an FDA approved drug library. We identified and selected metformin, simvastatin and digoxin (C3) as a novel combination of FDA approved drugs, which were shown to effectively target PDX1 and BIRC5 in human PDAC tumors in mice with no toxicity.

Phase I safety and pharmacokinetic study of YM155, a potent selective survivin inhibitor, in combination with erlotinib in patients with EGFR TKI refractory advanced non-small cell lung cancer.

PURPOSE: This phase I study was conducted to evaluate the safety and pharmacokinetics of YM155, a potent, selective survivin inhibitor, in combination with erlotinib in patients with EGFR TKI refractory advanced non-small cell lung cancer (NSCLC). METHODS: The pimary objectives were to evaluate the safety and tolerability of YM155 at escalating doses (3.6, 4.8, 6.0, and 8.0 mg/m2/days) administered every 3 weeks as continuous intravenous infusion over 168 h in combination with erlotinib at a fixed dose (150 mg, once a day). Secondary objectives were to assess the pharmacokinetics of YM155, antitumor activity, and the relationship between biomarkers and efficacy. The changes in survivin expression in biopsied tumor pre- and post-YM155 administration and serum cytokine levels were also analyzed. RESULTS: Fifteen patients were treated. The most common YM155-related adverse event was the presence of urine microalbumin, whereas grades 3/4 toxicities were rare. One patient who received 4.8  mg/m2/days YM155 developed a dose-limiting grade 2 serum creatinine elevation. YM155 exposure in plasma showed dose proportionality across all dose ranges tested. No pharmacokinetic interaction occurred between YM155 and erlotinib. The serum cytokines IL-8, G-CSF, and MIP-1b showed decreasing trends in patients who achieved progression-free survival of ≥ 12 weeks. Durable stable disease for ≥ 24 weeks was observed in two patients. CONCLUSION: Up to 8.0 mg/m2/days YM155 administered every 3 weeks in combination with erlotinib exhibited a favorable safety profile and moderate clinical efficacy. These results suggest that inhibiting survivin is a potential therapeutic strategy for select patients with EGFR TKI refractory NSCLC. TRIAL REGISTRATION: UMIN000031912 at UMIN Clinical Trials Registry (UMIN-CTR).

Novel small-molecule LG1836 inhibits the in vivo growth of castration-resistant prostate cancer.

BACKGROUND: Androgen deprivation therapy (ADT) is the mainstay of treatment for castration-resistant prostate cancer (CRPC). Unfortunately, although ADT initially prolongs survival, most patients relapse and develop resistance. Clinical failure of these treatments in CRPC highlights the urgent need to develop novel strategies to more effectively block androgen receptor (AR) signaling and target other oncogenic factors responsible for ADT resistance. METHODS: We developed a small-molecule compound LG1836 and investigated the in vitro and in vivo activity of LG1836 against CRPC in cellular and animal models. RESULTS: LG1836 exhibits potent in vitro cytotoxicity in CRPC cells. Mechanistic studies demonstrated that LG1836 inhibits the expression of AR and AR variant 7, partially mediated via proteasome-dependent protein degradation. LG1836 also suppresses survivin expression and effectively induces apoptosis in CRPC cells. Significantly, as a single agent, LG1836 is therapeutically efficacious in suppressing the in vivo growth of CRPC in the subcutaneous and intraosseous models and extends the survival of tumor-bearing mice. CONCLUSIONS: These preclinical studies indicate that LG1836 is a promising lead compound for the treatment of CRPC.

The SMAC mimetic LCL161 is a direct ABCB1/MDR1-ATPase activity modulator and BIRC5/Survivin expression down-regulator in cancer cells.

Upregulation of ABCB1/MDR1 (P-gp) and BIRC5/Survivin promotes multidrug resistance in a variety of human cancers. LCL161 is an anti-cancer DIABLO/SMAC mimetic currently being tested in patients with solid tumors, but the molecular mechanism of action of LCL161 in cancer cells is still incompletely understood. It is still unclear whether LCL161 is therapeutically applicable for patients with ABCB1-overexpressing multidrug resistant tumors. In this study, we found that the potency of LCL161 is not affected by the expression of ABCB1 in KB-TAX50, KB-VIN10, and NTU0.017 cancer cells. Besides, LCL161 is equally potent towards the parental MCF7 breast cancer cells and its BIRC5 overexpressing, hormone therapy resistance subline MCF7-TamC3 in vitro. Mechanistically, we found that LCL161 directly modulates the ABCB1-ATPase activity and inhibits ABCB1 multi-drug efflux activity at low cytotoxic concentrations (i.e. 0.5xIC50 or less). Further analysis revealed that LCL161 also decreases intracellular ATP levels in part through BIRC5 downregulation. Therapeutically, co-treatment with LCL161 at low cytotoxic concentrations restored the sensitivity to the known ABCB1 substrate, paclitaxel, in ABCB1-expressing cancer cells and increased the sensitivity to tamoxifen in MCF7-TamC3 cells. In conclusion, LCL161 has the potential for use in the management of cancer patients with ABCB1 and BIRC5-related drug resistance. The findings of our study provide important information to physicians for designing a more "patient-specific" LCL161 clinical trial program in the future.

Salinomycin enhances radiotherapy sensitivity and reduces expressions of BIRC5 and NEIL2 in nasopharyngeal carcinoma.

OBJECTIVE: The aim of this study was to investigate the effects of salinomycin (Sal) on expressions of baculoviral IAP repeat-containing 5 (BIRC5) and Nei endonuclease VIII-like 2 (NEIL2) and radiotherapy sensitivity of nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS: Human NPC CNE-2 cell lines were used as research objects in this study. Subsequently, the cells received intervention with Sal at different concentrations, radioactive rays at different doses and Sal combined with radioactive rays. The growth inhibition rate of CNE-2 cells was detected via methyl thiazolyl tetrazolium (MTT) assay. The dose-effect relations of Sal, radioactive rays and combination therapy with the inhibitory effect on CNE-2 cells were obtained. CNE-2 cells receiving intervention with Sal at an appropriate concentration or radioactive rays at an appropriate dose alone and Sal combined with radioactive rays were used as intervention groups (Sal group, Radiation group and Combination group). However, those added with an equal amount of DMSO were set as Control group. Next, the cycle, apoptosis and apoptotic morphology of CNE-2 cells were observed via flow cytometry and Hoechst assay, respectively. Moreover, the expressions of apoptosis-related proteins Caspase-3, B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein (Bax), as well as BIRC5 and NEIL2 proteins in CNE-2 cells were determined using Western blotting. RESULTS: Under the intervention with Sal or radioactive rays alone, the growth inhibition rate of CNE-2 cells rose in a concentration/dose-dependent manner. With the increase in Sal concentration in combination therapy, the growth inhibition rate of CNE-2 cells significantly increased (p<0.05). Compared with Control group, Sal group, Radiation group, and Combination group exhibited remarkably lower colony formation rate, higher proportion of CNE-2 cells in the G2/M phase, enhanced apoptosis of CNE-2 cells with nuclear fragmentation, increased expressions of pro-apoptotic proteins Caspase-3 and Bax, decreased expression of anti-apoptotic protein Bcl-2, and lower protein expressions of BIRC5 and NEIL2 in cells (p<0.05). Compared with Radiation group, the Combination group had significantly decreased colony formation rate, increased proportion of CNE-2 cells in the G2/M phase, enhanced apoptosis of CNE-2 cells with more nuclear fragmentation and other apoptosis characteristics, increased expressions of pro-apoptotic proteins Caspase-3 and Bax, decreased expression of anti-apoptotic protein Bcl-2, and decreased protein expressions of BIRC5 and NEIL2 in cells (p<0.05). CONCLUSIONS: Sal enhances the radiotherapy sensitivity of NPC and reduces the protein expressions of BIRC5 and NEIL2 in cells.

5-aminolevulinic-acid-mediated sonodynamic therapy improves the prognosis of melanoma by inhibiting survivin expression.

BACKGROUND: This study aimed to evaluate the relationship between survivin expression and melanoma after 5-aminolevulinic acid (5-ALA)-mediated sonodynamic therapy. METHODS: Immunohistochemistry was used to detect survivin protein expression in human melanoma clinical samples. Subsequently, the effects of 5-ALA-mediated sonodynamic therapy were determined by measuring the volume of melanoma xenografts and the bodyweights of melanoma-bearing nude mice. The MTT assay was used to detect the viability of melanoma B16-F10 cells under the action of 5-ALA-mediated sonodynamic therapy, and Western blotting and PCR were used to detect survivin expression in melanoma cells and in the melanoma-xenograft model. RESULTS: Survivin expression was significantly upregulated in human melanoma tissues compared with that of non-melanoma tissues. In the in vivo case, 5-ALA-mediated sonodynamic therapy significantly delayed tumor growth, prolonged the survival of mice, and inhibited the expression of survivin. In the in vitro case, 5-ALA-mediated sonodynamic therapy inhibited B16-F10 cell proliferation and decreased survivin expression at both protein and mRNA levels. CONCLUSION: Our results suggest that 5-ALA-mediated sonodynamic therapy inhibited B16-F10 cell proliferation and melanoma-xenograft growth and prolonged survival of melanoma-bearing nude mice, which might be through downregulation of survivin expression.