Biological significance and therapeutic implication of resveratrol-inhibited Wnt, Notch and STAT3 signaling in cervical cancer cells

Anticancer Molecular Mechanisms of Resveratrol

Resveratrol is a pleiotropic phytochemical belonging to the stilbene family. Though it is only significantly present in grape products, a huge amount of preclinical studies investigated its anticancer properties in a plethora of cellular and animal models. Molecular mechanisms of resveratrol involved signaling pathways related to extracellular growth factors and receptor tyrosine kinases; formation of multiprotein complexes and cell metabolism; cell proliferation and genome instability; cytoplasmic tyrosine kinase signaling (cytokine, integrin, and developmental pathways); signal transduction by the transforming growth factor-β super-family; apoptosis and inflammation; and immune surveillance and hormone signaling. Resveratrol also showed a promising role to counteract multidrug resistance: in adjuvant therapy, associated with 5-fluoruracyl and cisplatin, resveratrol had additive and/or synergistic effects increasing the chemosensitization of cancer cells. Resveratrol, by acting on diverse mechanisms simultaneously, has been emphasized as a promising, multi-target, anticancer agent, relevant in both cancer prevention and treatment.

Resveratrol Protects SAMP8 Brain Under Metabolic Stress: Focus on Mitochondrial Function and Wnt Pathway

Metabolic stress induced by high-fat (HF) diet leads to cognitive dysfunction and aging, but the physiological mechanisms are not fully understood. Senescence-accelerated prone mouse (SAMP8) models were conducted under metabolic stress conditions by feeding HF for 15 weeks, and the preventive effect of resveratrol was studied. This dietary strategy demonstrates cognitive impairment in SAMP8-HF and significant preventive effect by resveratrol-treated animals. Hippocampal changes in the proteins involved in mitochondrial dynamics optic atrophy-1 protein (OPA1) and mitofusin 2 (MFN2) comprised a differential feature found in SAMP8-HF that was prevented by resveratrol. Electronic microscopy showed a larger mitochondria in SAMP8-HF + resveratrol (SAMP8-HF + RV) than in SAMP8-HF, indicating increases in fusion processes in resveratrol-treated mice. According to the mitochondrial morphology, significant increases in the I-NDUFB8, II-SDNB, III-UQCRC2, and V-ATPase complexes, in addition to that of voltage-dependent anion channel 1 (VDAC1)/porin, were found in resveratrol-treated animals with regard to SAMP8-HF, reaching control-animal levels. Moreover, tumor necrosis factor alpha (TNF-α) and interleukin (IL-6) were increased after HF, and resveratrol prevents its increase. Moreover, we found that the HF diet affected the Wnt pathway, as demonstrated by β-catenin inactivation and modification in the expression of several components of this pathway. Resveratrol induced strong activation of β-catenin. The metabolic stress rendered in the cognitive and cellular pathways altered in SAMP8 focus on different targets in order to act on preventing cognitive impairment in neurodegeneration, and resveratrol can offer therapeutic possibilities for preventive strategies in aging or neurodegenerative conditions.

Resveratrol and STAT inhibitor enhance autophagy in ovarian cancer cells

Autophagic activity reflects cellular response to drug treatment and can be regulated by STAT3 signaling. Resveratrol inhibits STAT3 activation and causes remarkable growth arrest and cell death of ovarian cancer (OC) cells. However, the autophagic status and its relevance with resveratrol’s anti-OC effects remain unclear. We analyzed the states of autophagic activities, the nature of autophagosomes and the levels of autophagy-related proteins (LC-3, Beclin 1 and STAT3) in resveratrol-treated CAOV-3 and OVCAR-3 OC cells using multiple approaches. We elucidated the correlation of STAT3 inhibition with autophagic activity by treating OC cells with an upstream inhibitor of STAT proteins, AG490. Resveratrol efficiently suppressed growth, induced apoptosis and inactivated STAT3 signaling of the two OC cell lines. We found enhanced autophagic activity accompanied with Beclin-1 upregulation and LC3 enzymatic cleavage in resveratrol-treated OC cells. Immunofluorescent (IF) microscopic and IF-based confocal examinations demonstrated the accumulation of cytoplasmic granules co-labeled with LC3 and cytochrome C in resveratrol- or AG490-treated OC cells. Using electron microscopy, we confirmed an increase in autophagosomes and mitochondrial spheroids in either resveratrol- or AG490-treated OC cells. This study demonstrates the abilities of resveratrol to enhance apoptotic and autophagic activities in OC cells, presumably via inactivating STAT3 signaling. Resveratrol or the selective JAK2 inhibitor also leads to mitochondrial turnover, which would be unfavorable for OC cell survival and sensitize OC cells to resveratrol.

Clinicopathological significance of Notch1 expression in cervical cancer patients: a meta-analysis

Aim: Notch1 expression remains incompatible and contradictory with previous findings on cervical cancer. The purpose of this study is to evaluate the association between Notch1 and cervical cancer. Methods: Available studies were searched from diverse databases and Review Managers 5.3 software was used to perform analysis. Results: A total of 798 samples were included in this meta-analysis. The Notch1 expression in cancer tissues was higher than that in precancer (p = 0.0003) and normal tissues (p < 0.02). However, the difference of Notch1 expression between cancer cases and precancer cases has no statistical significance (p = 0.35). Moreover, lymph node metastasis (p = 0.02) was associated with higher Notch1 expression in cervical cancer. Conclusion: Notch1 over-expression indicated aggressive biological behaviors.

Intermittent cyclic mechanical tension promotes endplate cartilage degeneration via canonical Wnt signaling pathway and E-cadherin/β-catenin complex cross-talk

OBJECTIVE

This study aimed to investigate the role of the Wnt/β-catenin signaling pathway and E-cadherin/β-catenin complex in intermittent cyclic mechanical tension (ICMT)-induced endplate cartilage degeneration.

DESIGN

β-Catenin expression was measured in disc samples obtained from patients with disc degeneration and those with cervical vertebrae fracture or dislocation. Histological staining was performed to examine the disc tissue morphology and extracellular matrix after application of ICMT in vitro and in vivo. Multiple strategies were employed to examine activation of Wnt/β-catenin signaling after ICMT application in vivo and in vitro. Co-immunoprecipitation was performed to examine the interaction between E-cadherin and β-catenin. Pathway-specific inhibitors and an E-cadherin expression plasmid were used to regulate Wnt/β-catenin signaling and E-cadherin expression.

RESULTS

β-Catenin protein expression was elevated significantly, whereas cartilaginous genes were down-regulated in endplate cartilage samples obtained from patients with disc degeneration. ICMT loading led to Wnt/β-catenin signaling activation and the loss of the chondrogenic phenotype of endplate chondrocytes in both an in vivo rabbit model and in vitro endplate chondrocyte culture system. Inhibition of Wnt/β-catenin signaling suppressed the decrease in ICMT-induced cartilaginous gene expression. Furthermore, E-cadherin expression was inhibited by ICMT stimulation, resulting in a decrease in the interaction between E-cadherin and β-catenin proteins. Over-expression of E-cadherin rescued the cartilaginous gene expression by enhancing the interaction between E-cadherin and β-catenin proteins.

CONCLUSIONS

ICMT promotes endplate cartilage degeneration via activation of Wnt/β-catenin signaling and suppression of physical protein-protein interactions between E-cadherin and β-catenin.

Resveratrol Enhances Cardiomyocyte Differentiation of Human Induced Pluripotent Stem Cells through Inhibiting Canonical WNT Signal Pathway and Enhancing Serum Response Factor-miR-1 Axis

Resveratrol (trans-3,5,4′-trihydroxystilbene) (RSV) is a natural polyphenol with protective effects over cardiac tissues and can affect cell survival and differentiation in cardiac stem cells transplantation. However, whether this agent can affect cardiomyocytes (CMs) differentiation of induced pluripotent stem cells (iPSCs) is not yet clear. This study explored whether RSV can affect CMs differentiation of human iPSCs. Under embryoid bodies (EBs) condition, the effect of RSV on the change of pluripotent markers, endoderm markers, mesoderm markers, and ectoderm markers was measured using qRT-PCR. Under CM differentiation culture, the effect of RSV on CM specific markers was also measured. The regulative role of RSV over canonical Wnt signal pathway and serum response factor- (SRF-) miR-1 axis and the functions of these two axes were further studied. Results showed that RSV had no effect on the self-renewal of human iPSCs but could promote mesoderm differentiation. Under CM differentiation culture, RSV could promote CM differentiation of human iPSCs through suppressing canonical Wnt signal pathway and enhancing SRF-miR-1 axis.

Aurora-B and HDAC synergistically regulate survival and proliferation of lymphoma cell via AKT, mTOR and Notch pathways

Aurora-B is a protein kinase that functions mainly in the attachment of the mitotic spindle to the centromere. Overexpression of Aurora-B causes unequal distribution of genetic information, creating aneuploidy cells, a hallmark of cancer. Histone deacetylases (HDACs) are a class of enzymes that remove acetyl groups from a ε-N-acetyl lysine amino acid on a histone, allowing the histones to wrap the DNA more tightly, thus globally regulating gene transcription. Additionally, these HDACs can also modify non-histone proteins. Inhibition of HDACs is a potent strategy for cancer treatment. Here, we report that inhibition of Aurora-B and HDAC exerts similar tumor suppressive effects in cells. Knockdown of Aurora-B or inhibition of HDAC achieved the same effect on repression of cell proliferation. Furthermore, we found that the tumor suppressive effect of Aurora-B and HDAC inhibition is due to the induction of cell cycle arrest and/or apoptosis. Mechanistically, we demonstrated that Aurora-B and HDAC can cooperatively regulate AKT, mTOR and Notch pathways.

Effects of doxorubicin mediated by gold nanoparticles and resveratrol in two human cervical tumor cell lines

Green synthesis of gold nanoparticles capped with resveratrol (GNPs) and their physical and chemical characterization by UV-vis spectra, FTIR, DLS, XRD, TEM and AFM are reported. The GNPs are highly stable, with average diameter of about 20 nm. Then, supramolecular nanoassemblies of GNPs and doxorubicin (Dox), Dox-GNPs complexes, were prepared and morphologically characterized. The stability of these Dox nanocomplexes is high in phosphate buffer saline as estimated by UV-vis spectra, TEM and AFM analysis. Effects of resveratrol (Resv), Resv-Dox mixtures, GNPs and Dox-GNPs complexes on HeLa and CaSki cells, after 24h drug incubation, were assessed using MTT cell viability assay. Results showed strong anticancer activity for Resv-Dox mixtures and Dox-GNPs complexes in the two human cervical carcinoma cell lines. Clearly, both Resv and GNPs can mediate the anticancer activity of Dox at its very low concentration of 0.1 μg/mL, reaching the cytotoxicity of Dox alone, at its concentration up to 20 times higher. Cytotoxic effects of Resv-Dox mixtures and Dox-GNPs complexes have been found for the first time in HeLa and CaSki cells. Furthermore, the apoptosis induction in HeLa and CaSki cells was evidenced for Resv-Dox mixtures and Dox-GNPs complexes by flow cytometry using Annexin V-FITC/propidium iodide cellular staining. For CaSki cells, the apoptosis was also demonstrated, mainly for the treatment with Dox-GNPs complexes, by MTT formazan cellular staining visualized in phase contrast microscopy. Our results provide strong evidence that novel drug delivery vehicles developed on Dox-GNPs nanocomplexes and Resv could have wide applications in cancer diagnosis and treatment.

Analysis of the intricate relationship between chronic inflammation and cancer

Deregulated inflammatory response plays a pivotal role in the initiation, development and progression of tumours. Potential molecular mechanism(s) that drive the establishment of an inflammatory-tumour microenvironment is not entirely understood owing to the complex cross-talk between pro-inflammatory and tumorigenic mediators such as cytokines, chemokines, oncogenes, enzymes, transcription factors and immune cells. These molecular mediators are critical linchpins between inflammation and cancer, and their activation and/or deactivation are influenced by both extrinsic (i.e. environmental and lifestyle) and intrinsic (i.e. hereditary) factors. At present, the research pertaining to inflammation-associated cancers is accumulating at an exponential rate. Interest stems from hope that new therapeutic strategies against molecular mediators can be identified to assist in cancer treatment and patient management. The present review outlines the various molecular and cellular inflammatory mediators responsible for tumour initiation, progression and development, and discusses the critical role of chronic inflammation in tumorigenesis.

Antiproliferative effects and molecular mechanisms of troglitazone in human cervical cancer in vitro

We investigated the effects of troglitazone on human cervical cancer SiHa cells and its mechanisms of action. SiHa cells were incubated with different concentrations of troglitazone (100, 200, or 400 μg/mL) for 24, 48, and 72 hours. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl) 2,5-diphenyltetrazolium bromide (MTT) assay; cell cycle and apoptosis were detected by flow cytometry; and morphology of SiHa cells was observed under an inverted microscope. pcDNA3.1 and pcDNA3.1-Skp2 plasmids were constructed and then transfected into SiHa cells. Protein expression was analyzed by Western blotting. Troglitazone inhibited the proliferation of SiHa cells in a time- and concentration-dependent manner. Troglitazone caused G0/1 phase arrest but failed to reduce apoptosis in SiHa cells. Troglitazone significantly increased expression of p27 but decreased Skp2 expression. Skp2 overexpression inhibited the role of troglitazone in increasing expression of p27, and the cell cycle inhibitory effect of troglitazone. Troglitazone can inhibit SiHa cell viability by affecting cell cycle distribution but not apoptosis, and Skp2 and p27 may play a critical role.

Ubiquitin E3 ligase MARCH7 promotes ovarian tumor growth

Ubiquitin E3 ligase MARCH7 is involved in T cell proliferation and neuronal development. We found that expression of MARCH7 was higher in ovarian cancer tissues than normal ovarian tissues. Silencing MARCH7 decreased cell proliferation, migration, and invasion. Ectopic expression of MARCH7 increased cell proliferation, migration and invasion. Silencing MARCH7 prevented ovarian cancer growth in mice. Silencing MARCH7 inhibited NFkB and Wnt/β-catenin pathway. In agreement, ectopically expressed MARCH7 activated NFkB and Wnt/β-catenin pathways. Finally, MARCH7 was regulated by miR-101. Thus, MARCH7 is oncogenic and a potential target (oncotarget) for ovarian cancer therapy.

Association Study of Single-Nucleotide Polymorphisms of STAT2/STAT3/IFN-γ Genes in Cervical Cancer in Southern Chinese Han Women

OBJECTIVE

Interferon-γ (IFN-γ) and signal transducers and activators of transcription (STATs) each play an important role in carcinogenesis associated with viral infection. Cervical cancer is almost invariably associated with infection by human papillomavirus (HPV), and previous studies suggested that dysregulation of the signal pathway involved in IFN-γ and STATs is associated. Our objective was to evaluate the association of SNPs in STAT2, STAT3, and IFN-γ with cervical cancer susceptibility in Chinese Han women in Hunan province.

MATERIALS AND METHODS

Genomic DNA was extracted from peripheral blood samples of 234 cervical cancer patients and 216 healthy female controls. STAT2 and STAT3 genotyping was performed using polymerase chain reaction-restriction enzyme (PCR-RE) analysis. IFN-γ genotyping was detected by PCR-amplification of specific allele (PASA).

RESULTS

For STAT2 rs2066807 polymorphisms, there was no significant difference of genotype distribution (P=0.827) and allele frequencies (P=0.830, OR=1.09, 95% CI: 0.51-2.31) between cases and controls. For STAT3 rs957970 polymorphisms, there was no significant difference of genotype distribution (P=0.455) and allele frequencies (P=0.560, OR=0.92, 95% CI: 0.71-1.20) between cases and controls. For IFN-γ +874A/T polymorphisms, there was no significant difference of genotype distribution (P=0.652) and allele frequencies (P=0.527, OR=1.12, 95% CI: 0.79-1.59) between cases and controls.

CONCLUSION

These results suggest that polymorphisms in STAT2, STAT3 and IFN-γ genes are not likely to be strong predictors of cervical cancer in Han women in southern China.

Functions of Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) in Gynecologic Disorders

Peroxisome proliferator-activated receptor gamma (PPARγ) is a member of a class of nuclear hormone receptors intimately involved in the regulation of expression of myriad genes that regulate energy metabolism, cell differentiation, apoptosis, and inflammation. Although originally discovered as a pivotal regulator of adipocyte differentiation, the roles that PPARγ plays in gynecological disorders are still unknown. There are a number of studies on the functions of PPARγ and its agonists in gynecological disorders. In this mini-review, we provide a brief summary of the advances in recent years.

Inhibition of STAT3 signaling as critical molecular event in resveratrol-suppressed ovarian cancer cells

Background

Resveratrol exerts inhibitory effects on ovarian cancer cells, while its underlying mechanism and critical molecular target(s) have been lesser known. Activations of Wnt, Notch and STAT3 signaling are frequent in ovarian cancers/OCs and supposed to be important for OC formation and progression, while the impacts of resveratrol on these signaling pathways in OC cells remain obscure.

Methods

In this study, two human ovarian cancer cell lines, OVCAR-3 and CAOV-3, were treated by 120 μM resveratrol and their responses to the treatment and the statuses of Wnt, Notch and STAT3 signaling in them were analyzed by multiple experimental approaches. Selective inhibitors of Wnt, Notch or STAT3 signaling were employed to treat OVCAR-3 and CAOV-3 cells to elucidate the significance of individual signaling pathways for ovarian cancers.

Results

The results demonstrated distinct inhibitory effects of resveratrol on human ovarian cancer cells in terms of remarkable G1 phase accumulation, increased apoptosis fraction and concurrent suppression of Wnt, Notch and STAT3 signaling as well as their downstream cancer-related gene expression. Treatments with Wnt, Notch or STAT3 selective inhibitor revealed that only AG490, a JAK-specific inhibitor, inhibits OVCAR-3 and CAOV-3 cells in the extent as similar as that of resveratrol.

Conclusion

Our results suggest the significance of STAT3 activation in the maintenance and survival of ovarian cancer cells. The activated STAT3 signaling is the critical molecular target of resveratrol. Resveratrol would be a promising candidate in the management of ovarian cancers, especially the ones with resistance to conventional therapeutic agents.

Resveratrol ameliorates high glucose and high-fat/sucrose diet-induced vascular hyperpermeability involving Cav-1/eNOS regulation

Vascular endothelial hyperpermeability is one of the manifestations of endothelial dysfunction. Resveratrol (Res) is considered to be beneficial in protecting endothelial function. However, currently, the exact protective effect and involved mechanisms of Res on endothelial dysfunction-hyperpermeability have not been completely clarified. The aim of present study is to investigate the effects of Res on amelioration of endothelial hyperpermeability and the role of caveolin-1 (Cav-1)/endothelial nitric oxide synthase (eNOS) pathway. Adult male Wistar rats were treated with a normal or high-fat/sucrose diet (HFS) with or without Res for 13 weeks. HFS and in vitro treatment with high glucose increased hyperpermeability in rat aorta, heart, liver and kidney and cultured bovine aortic endothelial cells (BAECs), respectively, which was attenuated by Res treatment. Application of Res reversed the changes in eNOS and Cav-1 expressions in aorta and heart of rats fed HFS and in BAECs incubated with high glucose. Res stimulated the formation of NO inhibited by high glucose in BAECs. Beta-Cyclodextrin (β-CD), caveolae inhibitor, showed the better beneficial effect than Res alone to up-regulate eNOS phosphorylative levels, while NG-Nitro-77 L-arginine methyl ester (L-NAME), eNOS inhibitor, had no effect on Cav-1 expression. Our studies suggested that HFS and in vitro treatment with high glucose caused endothelial hyperpermeability, which were ameliorated by Res at least involving Cav-1/eNOS regulation.

Interference of Notch 2 inhibits the progression of gliomas and induces cell apoptosis by induction of the cell cycle at the G0/G1 phase

Glioblastoma is the most common type of malignant brain tumor with a poor prognosis. The Notch signaling pathway is often aberrantly activated in glioma cells. In order to determine the expression of Notch 2 and to evaluate its possible prognostic value in malignant glioblastoma, specimens from 32 patients and 20 controls were analyzed using immunohistochemical staining and reverse transcription quantitative polymerase chain reaction. The expression of Notch 2 in the glioma tissues was significantly higher compared with that in the normal brain tissues (P<0.01). Subsequently, endogenous Notch 2 interference was effectively performed by specific small hairpin (sh)RNA in the glioma cancer cell line U251. The results from an MTT assay and from Annexin V-fluorescein isothiocyanate/propidium iodide staining indicated that interference of Notch 2 significantly inhibited the proliferation and induced the apoptosis of U251 cells. In addition, the cell cycle was analyzed using flow cytometry and the results revealed that Notch 2 shRNA induced cell cycle arrest at the G0/G1 phase in U251 cells. Additionally, proteins associated with the cell cycle and cell proliferation were detected using western blot analysis. The data demonstrated that the expression of P21, cyclin D and phosphorylated retinoblastoma was significantly inhibited in the Notch 2 shRNA-transfected U251 cells. The results of the present study provide further insights into the effects of Notch 2 and a molecular reference for brain tumor therapy.

Resveratrol inhibits the proliferation of human melanoma cells by inducing G1/S cell cycle arrest and apoptosis

Resveratrol (Res), a natural plant extract, is an effective inducer of cell apoptosis and cell cycle arrest in multiple carcinoma cell types, which has been demonstrated by its ability to inhibit the proliferation of multiple human tumor cells in vitro. Although Res possesses chemopreventive properties against several types of cancer, the molecular mechanism underlying its anticancer activity remains to be fully elucidated. The present study demonstrated that Res induced cell cycle arrest and inhibited the proliferation of human melanoma A375 (IC50=23 µM after 48 h; P<0.05) and SK-MEL-31 (IC50=15 µM after 48 h; P<0.05) cells. Western blot analysis demonstrated that Res induced the apoptosis of human melanoma A375 and SK-MEL-31 cells by upregulating the expression of Bcl-2-associated X protein and B-cell lymphoma 2, possibly via the p53 pathway and activation of caspase-9 and caspase-3.

Smilax China root extract detoxifies nicotine by reducing reactive oxygen species and inducing CYP2A6

Resveratrol has a beneficial effect of lowering reactive oxygen species (ROS) and reduces cellular oxidative stress. We hypothesized that ethanol extract of Smilax china root (EESC) rich in resveratrol (RES) and oxyresveratrol (OXY) could reduce ROS caused by nicotine and promoting nicotine turnover by induction of CYP2A6. The amount of cotinine converted from nicotine was quantified by the direct barbiturate assay method. Expression of CYP2A6 was unregulated by RES, OXY, or EESC, respectively. Pretreatment of RES (50, 100, and 250 μM), OXY (50, 100, and 250 μM), and RES+OXY (50 and 100 μM) inhibited cytotoxicity and ROS production caused by nicotine in a dose-dependent manner. EESC pretreatment (1.8 mg/mL) increased cell viability by 1.5-fold higher than the control (nicotine only), and lowered cellular ROS levels. A significant amount of the conversion of nicotine to cotinine was observed in EESC pretreatment by CYP2A6 induction in HepG2 cells. These results suggested that hepatic induction of CYP2A6 and ROS reduction by EESC activate nicotine metabolism and reduce cellular oxidative stress.

PRACTICAL APPLICATION

Nicotine exposure due to smoking is very concerning because it is the major factor for lung diseases and cardiovascular disorders. It is necessary to examine natural ingredients that can detoxify from nicotine to cotinine as well as neutralize free radicals induced from nicotine. Results from the current study suggest potential applications of Smilax china root for detoxification of nicotine in the food industry.

Targeting the Wnt pathway in human cancers: therapeutic targeting with a focus on OMP-54F28

The Wnt signaling pathways are a group of signal transduction pathways that play an important role in cell fate specification, cell proliferation and cell migration. Aberrant signaling in these pathways has been implicated in the development and progression of multiple cancers by allowing increased proliferation, angiogenesis, survival and metastasis. Activation of the Wnt pathway also contributes to the tumorigenicity of cancer stem cells (CSCs). Therefore, inhibiting this pathway has been a recent focus of cancer research with multiple targetable candidates in development. OMP-54F28 is a fusion protein that combines the cysteine-rich domain of frizzled family receptor 8 (Fzd8) with the immunoglobulin Fc domain that competes with the native Fzd8 receptor for its ligands and antagonizes Wnt signaling. Preclinical models with OMP-54F28 have shown reduced tumor growth and decreased CSC frequency as a single agent and in combination with other chemotherapeutic agents. Due to these findings, a phase 1a study is nearing completion with OMP-54F28 in advanced solid tumors and 3 phase 1b studies have been opened with OMP-54F28 in combination with standard-of-care chemotherapy backbones in ovarian, pancreatic and hepatocellular cancers. This article will review the Wnt signaling pathway, preclinical data on OMP-54F28 and other Wnt pathway inhibitors and ongoing clinical trials.