The ins and outs of APC and beta-catenin nuclear transport

Differential Localization of β-Catenin Protein in CTNNB1 Mutant Endometrial Cancers Results in Distinct Transcriptional Profiles

CTNNB1 exon 3 mutation is a well-established driver of nearly 30% of endometrioid endometrial cancers (EECs), and this is associated with worse patient survival. Paradoxically, we have previously demonstrated that mutant β-catenin protein does not robustly localize to the nucleus in these cancers. The purpose of this study was to determine downstream gene expression in these cancers with nuclear or membrane/cytoplasmic mutant β-catenin protein localization. Spatial transcriptomics was performed on tumors with intratumor nuclear and nonnuclear mutant β-catenin, using the protein localization to select for regions of interest (ROIs). Differential expression analysis of all nuclear and nonnuclear ROIs yielded distinct transcriptional profiles based on the localization of β-catenin. Analysis revealed enrichment for Wnt signaling and epithelial-to-mesenchymal transition pathways in nuclear ROIs and hormone signaling in nonnuclear ROIs. Hierarchical clustering yielded 2 clusters comprised of almost entirely nuclear or nonnuclear ROIs. A novel therapeutic target, TROP2, encoded by the TACSTD2 gene, was identified to be altered by Wnt/β-catenin signaling. These data provide evidence for highly heterogeneous intratumor transcriptional profiles dependent on β-catenin protein localization in EEC with CTNNB1 driver mutations. Therefore, reporting of β-catenin immunohistochemistry should include an estimated percentage of tumor with nuclear localization in EEC tumors with exon 3 CTNNB1 mutations.

The Role of Xenobiotics and Anelloviruses in Colorectal Cancer: Mechanisms and Perspectives

Xenobiotics are non-natural chemical compounds to which the human population is exposed. Chronic exposure to certain xenobiotics is associated with various diseases, including cancer development. Anelloviruses (AVs), including Torque Teno Virus (TTV), Torque Teno Mini Virus (TTMV), and Torque Teno Midi Virus (TTMDV), are ubiquitous viruses found in the general population. As no disease has been definitively associated with AVs, they are sometimes referred to as "viruses awaiting a disease". This review explores the potential roles of xenobiotics and AVs in colorectal cancer (CRC) development and suggests a potential interplay between them. Evidence suggests an association between certain xenobiotics (like pesticides, cigarette smoke components, and dietary factors) and CRC, while such an association is less clear for AVs. The high prevalence of AVs suggests these infections alone may be insufficient to disrupt homeostasis; thus, additional factors might be required to promote disease, potentially including cancer.

Molecular landscape of clear cell renal cell carcinoma: targeting the Wnt/β-catenin signaling pathway

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma and is characterized by a complex molecular landscape driven by genetic and epigenetic alternations. Among the crucial signaling pathways implicated in ccRCC, the Wnt/β-catenin pathway plays a significant role in tumor progression and prognosis. This review delves into the molecular basis of ccRCC, highlighting the genetic and epigenetic modifications that contribute to its pathogenesis. We explore the significance of the Wnt/β-catenin pathway, focusing on its role in disease development, particularly the nuclear transport of β-catenin and its activation and downstream effects. Furthermore, we examine the role of antagonist genes in regulating this pathway within the context of ccRCC, providing insights into potential therapeutic targets. Dysregulation of this pathway, which is characterized by abnormal activation and nuclear translocation of β-catenin, plays a significant role in promoting tumor growth and metastasis. We explore the intricate molecular aspects of ccRCC, with a particular emphasis on this topic, underscoring the role of the pathway and emphasizing the importance and relevance of antagonist genes. Understanding the intricate interplay between these molecular mechanisms is crucial for developing innovative strategies to improve ccRCC treatment and patient outcomes.

Bacteroides fragilis Toxin Induces Sequential Proteolysis of E-Cadherin and Inflammatory Response in Mouse Intestinal Epithelial Cell Line

Enterotoxigenic Bacteroides fragilis (ETBF) is an intestinal bacterium that secretes the metalloprotease Bacteroides fragilis toxin (BFT), which induces E-cadherin cleavage and interleukin-8 secretion in human intestinal epithelial cell lines. ETBF-induced E-cadherin cleavage is proposed to be the underlying reason for the promotion of colitis in ETBF-infected mice. However, a BFT-responsive murine cell line has not yet been reported. In the current study, we report that the mouse colonic epithelial cell line CMT93 undergoes E-cadherin ectodomain cleavage, cell rounding, and proliferation in response to BFT treatment. The amino acid sequence of the putative cleavage site of E-cadherin is identical in both BFT-responsive (CMT93) and BFT-nonresponsive (MSIE, CT26, YAMC, and B16) cell lines, suggesting that the E-cadherin amino acid sequence is not responsible for this observation. After E-cadherin ectodomain cleavage, the membrane-bound intracellular E-cadherin domain underwent cleavage by γ-secretase and was subsequently degraded by the proteasome. Moreover, BFT induced the secretion of two chemokines (LIX and KC) and the formation of soluble TNFR1 in the CMT93 cell line. The identification of a BFT-responsive murine cell line may be used to elucidate the mechanism of ETBF pathogenesis in ETBF murine infection models.

Nuclear localization and transactivation of SYS-1/β-catenin is the result of serial gene duplications and subfunctionalizations

β-catenin is a highly conserved multifunctional protein capable of mediating cell adhesion via E-cadherin and transactivation of target genes of the canonical Wnt signaling pathway. The nematode, C. elegans contains four paralogs of β-catenin which are highly specific in their functions. Though similar in overall structure, the four beta-catenins are functionally distinct, each regulating different aspects of development. Of the four, SYS-1 is a key player in Wnt dependent asymmetric cell division (ACD). In ACD, a polarized mother will give rise to a daughter with high nuclear SYS-1 and another with low nuclear SYS-1. Despite sequence dissimilarity, SYS-1 shares a close structural resemblance with human β-catenin where it retains an unstructured amino-terminus (NTD) and 12 armadillo repeats. Using existing genome sequence data from several nematode species, we find that the four β-catenin paralogs result from 3 sequential gene duplications and neofunctionalizations during nematode evolution. SYS-1, however, lacks an unstructured carboxyl-terminus (CTD) that is essential for human β-catenin transactivation processes. This work supports the hypothesis that SYS-1 compensated for the lack of CTD by acquiring novel transactivation domains with cryptic nuclear localization signals in the NTD and the first four armadillo repeats, as shown by transactivation assays in worms and yeast. Furthermore, SYS-1 regulatory domains are not localized to the NTD as in canonical β-catenin and instead spans the entire length of the protein. Truncating SYS-1 abolishes the classical SYS-1 nuclear asymmetry, resulting in daughter cells with symmetrical SYS-1 truncation localization. A screen for SYS-1 physical interactors followed by in vivo SYS-1 localization analyses and effects on cell fate suggest that proper SYS-1 nuclear export is facilitated by XPO-1, while an interaction with IMB-3, an importin β-like protein, suggests import mechanisms. Interestingly, XPO-1 is especially required for lowering SYS-1 in the Wnt-unsignaled nucleus, suggesting a distinct mechanism for regulating asymmetric nuclear SYS-1. In summary, we provide insights on the mechanism of β-catenin evolution within nematodes and inform SYS-1 transactivation and nuclear transport mechanisms.

Transcriptome and Functional Comparison of Primary and Immortalized Endothelial Cells of the Human Choroid Plexus at the Blood-Cerebrospinal Fluid Barrier

The human choroid plexus (CP) is the location of the blood-cerebrospinal fluid (CSF) barrier (BCSFB). Whereas the epithelial cells of the CP mainly contribute to the formation of the BCSFB, the vessels of the CP are built by fenestrated endothelial cells. Still, the CP endothelium can contribute to barrier function. By ectopic expression of human telomerase reverse transcriptase (hTERT) in primary human CP endothelial cells (HCPEnCs), we recently generated and characterized immortalized HCPEnCs (iHCPEnCs). Here, we compared primary cells of the sixth passage (HCPEnCs p6) with a lower (p20) and a higher passage (p50) of iHCPEnCs by transcriptome analysis. A high concordance of HCPEnCs and both passages of iHCPEnCs was observed, as only small proportions of the transcripts examined were significantly altered. Differentially expressed genes (DEGs) were identified and assigned to potentially affected biological processes by gene set enrichment analysis (GSEA). Various components of the endothelial barrier-relevant Wnt signaling were detected in HCPEnCs and iHCPEnCs. Functional analysis of HCPEnCs and iHCPEnCs showed equal marginal activation of Wnt signaling, supporting the downregulation of β-catenin (CTNNB) signaling in CP endothelial cells, and a contribution to the barrier function by the CP endothelium was retained until passage 100 (p100) of iHCPEnCs. Overall, our data support the suitability of iHCPEnCs as an in vitro model of the CP endothelium over extended passages.

Mechanism of APC truncation involved in colorectal cancer tumorigenesis (Review)

Adenomatous polyposis coli (APC) is widely recognized as a heavily mutated gene that suppresses tumor growth in colorectal cancer (CRC). Its mutation is considered to be the primary and early event that occurs in the development of CRC. In addition, APC has a crucial role in inhibiting the canonical Wnt signaling pathway. APC mutations in CRC result in the production of shortened gene products. This impairment of β-catenin destruction complexes causes an accumulation of active β-catenin in the cytoplasm and nucleus. In these compartments, β-catenin can bind with DNA-binding proteins of the transcription factor/lymphoid enhancer-binding factor family, thereby activating the Wnt signaling pathway. Consequently, the balance of numerous cellular processes is disrupted, ultimately driving the formation of tumors. There is a growing body of evidence indicating the prevalent occurrence of APC truncation in the majority of CRC cases. Furthermore, it has been observed that these truncated proteins have a crucial role in the activation of the Wnt signaling pathway and the subsequent loss of tumor inhibitory function. This review aimed to provide an overview of the recent advancements in understanding the mechanism behind APC truncation and its association with the onset and progression of CRC.

NDR1/FBXO11 promotes phosphorylation-mediated ubiquitination of β-catenin to suppress metastasis in prostate cancer

Background: Prostate cancer progression hinges on β-catenin's stability and activity, a key factor in epithelial-mesenchymal transition (EMT) and metastasis. This study delves into NDR1-dependent phosphorylation's impact on β-catenin via FBXO11, an E3 ubiquitin ligase, in prostate cancer cells. Methods: Human prostate cancer cell lines underwent various in vitro assays, including real-time PCR, Western blotting, immunoprecipitation, immunofluorescence, and protein stability assays, to explore β-catenin's interactions and post-translational modifications. NDR1 modulation's in vivo efficacy was assessed using a nude mice lung metastasis model. Small-molecule screening identified a potential NDR1 activator, aNDR1, tested for its effects on metastasis via in vitro and in vivo assays. Results: NDR1 phosphorylated β-catenin at Ser33/37, facilitating its interaction with FBXO11. This led to FBXO11-mediated ubiquitination and cytoplasmic degradation of β-catenin, while the NDR1-FBXO11 complex impeded β-catenin nuclear translocation by inducing JNK2 ubiquitination. Thus, NDR1 and FBXO11 jointly regulate β-catenin activity in prostate cancer cells through dual phosphorylation-driven ubiquitination, potentially suppressing EMT. Reduced NDR1 expression inhibited FBXO11 and β-catenin phosphorylation, diminishing β-catenin and JNK2 ubiquitination, promoting EMT and enhancing prostate cancer cell metastasis. The inhibitory effects of aNDR1 on prostate cancer metastasis were validated. Conclusion: The NDR1/FBXO11 axis outlines a non-canonical β-catenin degradation pathway crucial in regulating EMT and prostate cancer cell metastasis. NDR1 activation, particularly with aNDR1, could offer a promising therapeutic avenue against prostate cancer metastasis.

Clinicopathological significance of SOX9 and β-catenin expression in pre-neoadjuvant chemotherapy cases of osteosarcoma: molecular and immunohistochemical study

The molecular pathogenesis of osteosarcoma (OS), the most frequent primary malignant bone tumor of all age groups, is still obscure. Since multidrug chemotherapeutic regimens were introduced in the 1970s, survival rates have been stationary. The Wnt-β-catenin signaling cascade and SOX9 have a significant contribution to skeletal growth, development, and tumorigenesis. In the present work, an attempt was made to examine the role and clinicopathological significance of β-catenin and SOX9 in 46 cases of pre-neoadjuvant chemotherapy OS tissues compared to 10 cases of non-neoplastic bone. The mRNA levels of both markers were assessed by qRT-PCR, and protein levels of β-catenin were analyzed by immunohistochemistry. The results were correlated with different clinicopathological parameters. SOX9 mRNA levels were significantly elevated in OS compared to non-neoplastic bone, and higher levels were significantly associated with the occurrence of fluid-fluid levels (indicating blood-containing cystic spaces) and osteolytic radiological pattern. Although β-catenin mRNA and protein levels were higher in OS compared to non-neoplastic bone, only the protein levels reached statistical significance. Higher β-catenin mRNA levels were significantly associated with tumor size, while higher protein levels were significantly associated with the histologic subtype, mitotic count, and radiological pattern. No significant association was noted with any of the other evaluated parameters. OS showing higher SOX9 mRNA expression and lower β-catenin mRNA and protein expression exhibited longer estimated overall survival times approaching statistical significance. To conclude, while high expression of β-catenin and SOX9 suggests their possible involvement in OS development, their prognostic role may need further research.

Phosphorylated PTTG1 switches its subcellular distribution and promotes β-catenin stabilization and subsequent transcription activity

The Wnt/β-catenin signaling is usually abnormally activated in hepatocellular carcinoma (HCC), and pituitary tumor-transforming gene 1 (PTTG1) has been found to be highly expressed in HCC. However, the specific mechanism of PTTG1 pathogenesis remains poorly understood. Here, we found that PTTG1 is a bona fide β-catenin binding protein. PTTG1 positively regulates Wnt/β-catenin signaling by inhibiting the destruction complex assembly, promoting β-catenin stabilization and subsequent nuclear localization. Moreover, the subcellular distribution of PTTG1 was regulated by its phosphorylation status. Among them, PP2A induced PTTG1 dephosphorylation at Ser165/171 residues and prevented PTTG1 translocation into the nucleus, but these effects were effectively reversed by PP2A inhibitor okadaic acid (OA). Interestingly, we found that PTTG1 decreased Ser9 phosphorylation-inactivation of GSK3β by competitively binding to PP2A with GSK3β, indirectly leading to cytoplasmic β-catenin stabilization. Finally, PTTG1 was highly expressed in HCC and associated with poor patient prognosis. PTTG1 could promote the proliferative and metastasis of HCC cells. Overall, our results indicated that PTTG1 plays a crucial role in stabilizing β-catenin and facilitating its nuclear accumulation, leading to aberrant activation of Wnt/β-catenin signaling and providing a feasible therapeutic target for human HCC.

Cadherins and catenins in cancer: connecting cancer pathways and tumor microenvironment

Cadherin-catenin complexes are integral components of the adherens junctions crucial for cell-cell adhesion and tissue homeostasis. Dysregulation of these complexes is linked to cancer development via alteration of cell-autonomous oncogenic signaling pathways and extrinsic tumor microenvironment. Advances in multiomics have uncovered key signaling events in multiple cancer types, creating a need for a better understanding of the crosstalk between cadherin-catenin complexes and oncogenic pathways. In this review, we focus on the biological functions of classical cadherins and associated catenins, describe how their dysregulation influences major cancer pathways, and discuss feedback regulation mechanisms between cadherin complexes and cellular signaling. We discuss evidence of cross regulation in the following contexts: Hippo-Yap/Taz and receptor tyrosine kinase signaling, key pathways involved in cell proliferation and growth; Wnt, Notch, and hedgehog signaling, key developmental pathways involved in human cancer; as well as TGFβ and the epithelial-to-mesenchymal transition program, an important process for cancer cell plasticity. Moreover, we briefly explore the role of cadherins and catenins in mechanotransduction and the immune tumor microenvironment.

Progress of Wnt Signaling Pathway in Osteoporosis

Osteoporosis, one of the serious health diseases, involves bone mass loss, bone density diminishing, and degeneration of bone microstructure, which is accompanied by a tendency toward bone fragility and a predisposition to fracture. More than 200 million people worldwide suffer from osteoporosis, and the cost of treating osteoporotic fractures is expected to reach at least $25 billion by 2025. The generation and development of osteoporosis are regulated by genetic factors and regulatory factors such as TGF-β, BMP, and FGF through multiple pathways, including the Wnt signaling pathway, the Notch signaling pathway, and the MAPK signaling pathway. Among them, the Wnt signaling pathway is one of the most important pathways. It is not only involved in bone development and metabolism but also in the differentiation and proliferation of chondrocytes, mesenchymal stem cells, osteoclasts, and osteoblasts. Dkk-1 and SOST are Wnt inhibitory proteins that can inhibit the activation of the canonical Wnt signaling pathway and block the proliferation and differentiation of osteoblasts. Therefore, they may serve as potential targets for the treatment of osteoporosis. In this review, we analyzed the mechanisms of Wnt proteins, β-catenin, and signaling molecules in the process of signal transduction and summarized the relationship between the Wnt signaling pathway and bone-related cells. We hope to attract attention to the role of the Wnt signaling pathway in osteoporosis and offer new perspectives and approaches to making a diagnosis and giving treatment for osteoporosis.

Differential expression profiling of onco and tumor-suppressor genes from major-signaling pathways in Wilms' tumor

PURPOSE

Wilms' tumor is the most-frequent malignant-kidney tumor in children under 3-4 years of age and is caused by genetic alterations of oncogenes (OG) and tumor-suppressor genes (TG). Wilms' tumor has been linked to many OG-&-TG. However, only WT1 has a proven role in the development of this embryonic-tumor.

METHODS

The study investigates the level of mRNA expression of 16 OGs and 20 TGs involved in key-signaling pathways, including chromatin modification; RAS; APC; Cell Cycle/Apoptosis; Transcriptional Regulation; PI3K; NOTCH-&-HH; PI3K & RAS of 24-fresh Wilms'-tumor cases by capture-and-reporter probe Code-Sets chemistry, as CNVs in these pathway genes have been reported.

RESULTS

Upon extensively investigating, MEN1, MLL2, MLL3, PBRM1, PRDM1, SMARCB1, SETD2, WT1, PTPN11, KRAS, HRAS, NF1, APC, RB1, FUBP1, BCOR, U2AF1, PIK3CA, PTEN, EBXW7, SMO, ALK, CBL, EP300-and-GATA1 were found to be significantly up-regulated in 58.34, 62.5, 79.17, 91.67, 58, 66.66,54, 58.34, 66.67, 75, 62.5, 62.5, 58, 79.17, 79.17, 75, 70.84, 50, 50, 75, 66.66, 62.50, 61.66, 58.34-and-62.50% of cases respectively, whereas BRAF, NF2, CDH1, BCL2, FGFR3, ERBB2, MET, RET, EGFR-and-GATA2 were significantly down regulated in 58, 87.50, 79.16, 54.16, 79.17, 91.66, 66.66, 58.33, 91.66-and-62.50% of cases, respectively. Interestingly, the WT1 gene was five-fold down regulated in 41.66% of cases only.

CONCLUSION

Hence, extensive profiling of OGs and TGs association of major-signaling pathways in Wilms' tumor cases may aid in disease diagnosis. PBRM1 (up-regulated in 91.67% of cases), ERBB2 and EGFR (down-regulated in 91.66 and 91.66% of cases, respectively) could be marker genes. However, validation of all relevant results in a larger number of samples is required.

Intraabdominal sporadic desmoid tumors and inflammation: an updated literature review and presentation and insights on pathogenesis of synchronous sporadic mesenteric desmoid tumors occurring after surgery for necrotizing pancreatitis

Sporadic intra-abdominal desmoid tumors are rare and known to potentially occur after trauma including previous surgery, although knowledge of the underlying pathogenetic mechanism is still limited. We reviewed the recent literature on sporadic intraabdominal desmoids and inflammation as we investigated the mutational and epigenetic makeup of a case of multiple synchronous mesenterial desmoids occurring after necrotizing pancreatitis. A 62-year-old man had four mesenteric masses up to 4.8 cm diameter detected on CT eighteen months after laparotomy for peripancreatic collections from necrotizing pancreatitis. All tumors were excised and diagnosed as mesenteric desmoids. DNA from peripheral blood was tested for a multigene panel. The tumour DNA was screened for three most frequent β-catenin gene mutations T41A, S45F and S45P. Expression levels of miR-21-3p and miR-197-3-p were compared between the desmoid tumors and other wild-type sporadic desmoids. The T41A CTNNB1 mutation was present in all four desmoid tumors. miR-21-3p and miR-197-3p were respectively upregulated and down-regulated in the mutated sporadic mesenteric desmoids, with respect to wild-type lesions. The patient is free from recurrence 34 months post-surgery. The literature review did not show similar studies. To our knowledge, this is the first study to interrogate genetic and epigenetic signature of multiple intraabdominal desmoids to investigate potential association with abdominal inflammation following surgery for necrotizing pancreatitis. We found mutational and epigenetic features that hint at potential activation of inflammation pathways within the desmoid tumor.

Different strategies by distinct Wnt-signaling pathways in activating a nuclear transcriptional response

The Wnt family of secreted glycolipo-proteins signals through multiple signal transduction pathways and is essential for embryonic development and organ development and homeostasis. The Wnt-pathways are conserved and critical in all metazoans. Wnt signaling pathways comprise the canonical Wnt/β-catenin pathway and several non-canonical signaling branches, of which Wnt-Planar Cell Polarity (PCP) signaling and the Wnt/Calcium pathway have received the most attention and are best understood. nterestingly, all Wnt-pathways have a nuclear signaling branch and also can affect many cellular processes independent of its nuclear transcriptional regulation. Canonical Wnt/β-catenin signaling is the most critical for a nuclear transcriptional response, in both development and disease, yet the mechanism(s) on how the "business end" of the pathway, β-catenin, translocates to the nucleus to act as co-activator to the TCF/Lef transcription factor family still remains obscure. Here we discuss and compare the very different strategies on how the respective Wnt signaling pathways activate a nuclear transcriptional response. We also highlight some recent new insights into how β-catenin is translocated to the nucleus via an IFT-A, Kinesin-2, and microtubule dependent mechanism and how this aspect of canonical Wnt-signaling uses ciliary proteins in a cilium independent manner, conserved between Drosophila and mammalian cells.

PSPC1 is a new contextual determinant of aberrant subcellular translocation of oncogenes in tumor progression

Dysregulation of nucleocytoplasmic shuttling is commonly observed in cancers and emerging as a cancer hallmark for the development of anticancer therapeutic strategies. Despite its severe adverse effects, selinexor, a selective first-in-class inhibitor of the common nuclear export receptor XPO1, was developed to target nucleocytoplasmic protein shuttling and received accelerated FDA approval in 2019 in combination with dexamethasone as a fifth-line therapeutic option for adults with relapsed refractory multiple myeloma (RRMM). To explore innovative targets in nucleocytoplasmic shuttling, we propose that the aberrant contextual determinants of nucleocytoplasmic shuttling, such as PSPC1 (Paraspeckle component 1), TGIF1 (TGF-β Induced Factor Homeobox 1), NPM1 (Nucleophosmin), Mortalin and EBP50, that modulate shuttling (or cargo) proteins with opposite tumorigenic functions in different subcellular locations could be theranostic targets for developing anticancer strategies. For instance, PSPC1 was recently shown to be the contextual determinant of the TGF-β prometastatic switch and PTK6/β-catenin reciprocal oncogenic nucleocytoplasmic shuttling during hepatocellular carcinoma (HCC) progression. The innovative nucleocytoplasmic shuttling inhibitor PSPC1 C-terminal 131 polypeptide (PSPC1-CT131), which was developed to target both the shuttling determinant PSPC1 and the shuttling protein PTK6, maintained their tumor-suppressive characteristics and exhibited synergistic effects on tumor suppression in HCC cells and mouse models. In summary, targeting the contextual determinants of nucleocytoplasmic shuttling with cargo proteins having opposite tumorigenic functions in different subcellular locations could be an innovative strategy for developing new therapeutic biomarkers and agents to improve cancer therapy.

Adenomatous polyposis coli in cancer and therapeutic implications

Inactivating mutations of the adenomatous polyposis coli (APC) gene and consequential upregulation of the Wnt signaling pathway are critical initiators in the development of colorectal cancer (CRC), the third most common cancer in the United States for both men and women. Emerging evidence suggests APCmutations are also found in gastric, breast and other cancers. The APC gene, located on chromosome 5q, is responsible for negatively regulating the b-catenin/Wnt pathway by creating a destruction complex with Axin/Axin2, GSK-3b, and CK1. In the event of an APC mutation, b-catenin accumulates, translocates to the cell nucleus and increases the transcription of Wnt target genes that have carcinogenic consequences in gastrointestinal epithelial stem cells. A literature review was conducted to highlight carcinogenesis related to APC mutations, as well as preclinical and clinical studies for potential therapies that target steps in inflammatory pathways, including IL-6 transduction, and Wnt pathway signaling regulation. Although a range of molecular targets have been explored in murine models, relatively few pharmacological agents have led to substantial increases in survival for patients with colorectal cancer clinically. This article reviews a range of molecular targets that may be efficacious targets for tumors with APC mutations.

Direct interaction of β-catenin with nuclear ESM1 supports stemness of metastatic prostate cancer

Wnt/β-catenin signaling is frequently activated in advanced prostate cancer and contributes to therapy resistance and metastasis. However, activating mutations in the Wnt/β-catenin pathway are not common in prostate cancer, suggesting alternative regulations may exist. Here, we report that the expression of endothelial cell-specific molecule 1 (ESM1), a secretory proteoglycan, is positively associated with prostate cancer stemness and progression by promoting Wnt/β-catenin signaling. Elevated ESM1 expression correlates with poor overall survival and metastasis. Accumulation of nuclear ESM1, instead of cytosolic or secretory ESM1, supports prostate cancer stemness by interacting with the ARM domain of β-catenin to stabilize β-catenin-TCF4 complex and facilitate the transactivation of Wnt/β-catenin signaling targets. Accordingly, activated β-catenin in turn mediates the nuclear entry of ESM1. Our results establish the significance of mislocalized ESM1 in driving metastasis in prostate cancer by coordinating the Wnt/β-catenin pathway, with implications for its potential use as a diagnostic or prognostic biomarker and as a candidate therapeutic target in prostate cancer.

TMEM9-v-ATPase Activates Wnt/β-Catenin Signaling Via APC Lysosomal Degradation for Liver Regeneration and Tumorigenesis

BACKGROUND AND AIMS

How Wnt signaling is orchestrated in liver regeneration and tumorigenesis remains elusive. Recently, we identified transmembrane protein 9 (TMEM9) as a Wnt signaling amplifier.

APPROACH AND RESULTS

TMEM9 facilitates v-ATPase assembly for vesicular acidification and lysosomal protein degradation. TMEM9 is highly expressed in regenerating liver and hepatocellular carcinoma (HCC) cells. TMEM9 expression is enriched in the hepatocytes around the central vein and acutely induced by injury. In mice, Tmem9 knockout impairs hepatic regeneration with aberrantly increased adenomatosis polyposis coli (Apc) and reduced Wnt signaling. Mechanistically, TMEM9 down-regulates APC through lysosomal protein degradation through v-ATPase. In HCC, TMEM9 is overexpressed and necessary to maintain β-catenin hyperactivation. TMEM9-up-regulated APC binds to and inhibits nuclear translocation of β-catenin, independent of HCC-associated β-catenin mutations. Pharmacological blockade of TMEM9-v-ATPase or lysosomal degradation suppresses Wnt/β-catenin through APC stabilization and β-catenin cytosolic retention.

CONCLUSIONS

Our results reveal that TMEM9 hyperactivates Wnt signaling for liver regeneration and tumorigenesis through lysosomal degradation of APC.

Cytoskeletal Control and Wnt Signaling-APC's Dual Contributions in Stem Cell Division and Colorectal Cancer

Intestinal epithelium architecture is sustained by stem cell division. In principle, stem cells can divide symmetrically to generate two identical copies of themselves or asymmetrically to sustain tissue renewal in a balanced manner. The choice between the two helps preserve stem cell and progeny pools and is crucial for tissue homeostasis. Control of spindle orientation is a prime contributor to the specification of symmetric versus asymmetric cell division. Competition for space within the niche may be another factor limiting the stem cell pool. An integrative view of the multiple links between intracellular and extracellular signals and molecular determinants at play remains a challenge. One outstanding question is the precise molecular roles of the tumour suppressor Adenomatous polyposis coli (APC) for sustaining gut homeostasis through its respective functions as a cytoskeletal hub and a down regulator in Wnt signalling. Here, we review our current understanding of APC inherent activities and partners in order to explore novel avenues by which APC may act as a gatekeeper in colorectal cancer and as a therapeutic target.

Clinicopathological and molecular analyses of linearly expanded epithelial cells with β-catenin alterations, "β-catenin signature", in the normal fallopian tube

AIMS

Recent advances in next-generation sequencing have made it clear that clonal expansion of cells harbouring driver gene mutations occurs in physiologically normal epithelium. Molecular analysis of tubal epithelium has been almost exclusively confined to the TP53 pathway, which is involved in serous carcinogenesis. Other oncogenic events have not been explored in detail. Here, we report the linear expansion of fallopian tubal epithelial cells exhibiting an altered β-catenin profile (β-catenin signature). Through molecular analyses, we determined the incidence and clinicopathological significance of β-catenin signatures.

METHODS AND RESULTS

We evaluated 64 specimens of surgically removed bilateral fallopian tubes. Thirty-three β-catenin signatures were identified in 13 cases (20.3%); these patients were significantly younger than those without β-catenin signatures (median ages of 44 and 57 years, respectively, P = 0.0317). No correlation between β-catenin signature and any clinical factor was observed. CTNNB1 mutations were detected in three of eight β-catenin signatures when tissues were microdissected and subjected to Sanger sequencing in two representative cases.

CONCLUSIONS

This is the first report of the CTNNB1 mutation in clusters of morphologically bland tubal epithelial cells. The results of this study indicate that β-catenin signatures are common, and they may be a part of diverse molecular alterations occurring in normal tubal epithelium.

HOXA13 promotes colon cancer progression through β-catenin-dependent WNT pathway

Human class I homeobox A13 (HOXA13) was initially identified as a transcription factor and has an important role in embryonic development and malignant transformation. However, the clinical significance and the molecular mechanisms of HOXA13 in colon cancer development and progression are still unknown. In this study, we found that HOXA13 was highly expressed in colon cancer tissues, and its expression was associated with histological grade, T stage, N stage and tumour size. In vitro studies showed that HOXA13 promoted colon cancer cell proliferation, migration and invasion. Bioinformatics analysis revealed that HOXA13 expression was positively correlated with the WNT signalling pathway. In vitro studies showed that HOXA13 promoted the malignant phenotype of colon cancer cells by facilitating the nuclear translocation of β-Catenin. Moreover, XAV939, an inhibitor of β-Catenin, reversed the HOXA13-mediated effects on invasion and proliferation of colon cancer cells. In vivo studies further verified that HOXA13 promoted tumour formation through the Wnt/β-Catenin pathway. Collectively, these results suggest that HOXA13 is a potential oncogene that functions by promoting the nuclear translocation of β-Catenin, thereby maintaining the proliferation and metastasis of colon cancer.

Nuclear Regulation of Wnt/β-Catenin Signaling: It's a Complex Situation

Wnt signaling is an evolutionarily conserved metazoan cell communication pathway required for proper animal development. Of the myriad of signaling events that have been ascribed to cellular activation by Wnt ligands, the canonical Wnt/β-catenin pathway has been the most studied and best understood. Misregulation of Wnt/β-catenin signaling has been implicated in developmental defects in the embryo and major diseases in the adult. Despite the latter, no drugs that inhibit the Wnt/β-catenin pathway have been approved by the FDA. In this review, we explore the least understood step in the Wnt/β-catenin pathway-nuclear regulation of Wnt target gene transcription. We initially describe our current understanding of the importation of β-catenin into the nucleus. We then focus on the mechanism of action of the major nuclear proteins implicated in driving gene transcription. Finally, we explore the concept of a nuclear Wnt enhanceosome and propose a modified model that describes the necessary components for the transcription of Wnt target genes.

Ephrin-B1 Is a Novel Biomarker of Bladder Cancer Aggressiveness. Studies in Murine Models and in Human Samples

Bladder cancer (BC) is the ninth most common cancer worldwide, but molecular changes are still under study. During tumor progression, Epithelial cadherin (E-cadherin) expression is altered and β-catenin may be translocated to the nucleus, where it acts as co-transcription factor of tumor invasion associated genes. This investigation further characterizes E-cadherin and β-catenin associated changes in BC, by combining bioinformatics, an experimental murine cell model (MB49/MB49-I) and human BC samples. In in silico studies, a DisGeNET (gene-disease associations database) analysis identified CDH1 (E-cadherin gene) as one with highest score among 130 BC related-genes. COSMIC mutation analysis revealed CDH1 low mutations rates. Compared to MB49 control BC cells, MB49-I invasive cells showed decreased E-cadherin expression, E- to P-cadherin switch, higher β-catenin nuclear signal and lower cytoplasmic p-Ser33-β-catenin signal, higher Ephrin-B1 ligand and EphB2 receptor expression, higher Phospho-Stat3 and Urokinase-type Plasminogen Activator (UPA), and UPA receptor expression. MB49-I cells transfected with Ephrin-B1 siRNA showed lower migratory and invasive capacity than control cells (scramble siRNA). By immunohistochemistry, orthotopic MB49-I tumors had lower E-cadherin, increased nuclear β-catenin, lower pSer33-β-catenin cytoplasmic signal, and higher Ephrin-B1 expression than MB49 tumors. Similar changes were found in human BC tumors, and 83% of infiltrating tumors depicted a high Ephrin-B1 stain. An association between higher Ephrin-B1 expression and higher stage and tumor grade was found. No association was found between abnormal E-cadherin signal, Ephrin-B1 expression or clinical-pathological parameter. This study thoroughly analyzed E-cadherin and associated changes in BC, and reports Ephrin-B1 as a new marker of tumor aggressiveness.

Role of hyaluronan in regulating self-renewal and osteogenic differentiation of mesenchymal stromal cells and pre-osteoblasts

Objectives

The aim of the study was to investigate the impact of two hyaluronan (HA) formulations on the osteogenic potential of osteoblast precursors.

Materials and methods

Proliferation rates of HA-treated mesenchymal stromal ST2 and pre-osteoblastic MC3T3-E1 cells were determined by 5-bromo-20-deoxyuridine (BrdU) assay. Expression of genes encoding osteogenic differentiation markers, critical growth, and stemness factors as well as activation of downstream signaling pathways in the HA-treated cells were analyzed by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunoblot techniques.

Results

The investigated HAs strongly stimulated the growth of the osteoprogenitor lines and enhanced the expression of genes encoding bone matrix proteins. However, expression of late osteogenic differentiation markers was significantly inhibited, accompanied by decreased bone morphogenetic protein (BMP) signaling. The expression of genes encoding transforming growth factor-β1 (TGF-β1) and fibroblast growth factor-1 (FGF-1) as well as the phosphorylation of the downstream signaling molecules Smad2 and Erk1/2 were enhanced upon HA treatment. We observed significant upregulation of the transcription factor Sox2 and its direct transcription targets and critical stemness genes, Yap1 and Bmi1, in HA-treated cells. Moreover, prominent targets of the canonical Wnt signaling pathway showed reduced expression, whereas inhibitors of the pathway were considerably upregulated. We detected decrease of active β-catenin levels in HA-treated cells due to β-catenin being phosphorylated and, thus, targeted for degradation.

Conclusions

HA strongly induces the growth of osteoprogenitors and maintains their stemness, thus potentially regulating the balance between self-renewal and differentiation during bone regeneration following reconstructive oral surgeries.

Clinical relevance

Addition of HA to deficient bone or bony defects during implant or reconstructive periodontal surgeries may be a viable approach for expanding adult stem cells without losing their replicative and differentiation capabilities.

Electronic supplementary material

The online version of this article (10.1007/s00784-020-03259-8) contains supplementary material, which is available to authorized users.

Molecular Aspects of Colorectal Adenomas: The Interplay among Microenvironment, Oxidative Stress, and Predisposition

The development of colorectal cancer (CRC) is a multistep process initiated by a benign polyp that has the potential to evolve into in situ carcinoma through the interactions between environmental and genetic factors. CRC incidence rates are constantly increased for young adult patients presenting an advanced tumor stage. The majority of CRCs arise from colonic adenomas originating from aberrant cell proliferation of colon epithelium. Endoscopic polypectomy represents a tool for early detection and removal of polyps, although the occurrence of cancers after negative colonoscopy shows a significant incidence. It has long been recognized that the aberrant regulation of Wingless/It (Wnt)/β-Catenin signaling in the pathogenesis of colorectal cancer is supported by its critical role in the differentiation of stem cells in intestinal crypts and in the maintenance of intestinal homeostasis. For this review, we will focus on the development of adenomatous polyps through the interplay between renewal signaling in the colon epithelium and reactive oxygen species (ROS) production. The current knowledge of molecular pathology allows us to deepen the relationships between oxidative stress and other risk factors as lifestyle, microbiota, and predisposition. We underline that the chronic inflammation and ROS production in the colon epithelium can impair the Wnt/β-catenin and/or base excision repair (BER) pathways and predispose to polyp development. In fact, the coexistence of oxidative DNA damage and errors in DNA polymerase can foster C>T transitions in various types of cancer and adenomas, leading to a hypermutated phenotype of tumor cells. Moreover, the function of Adenomatous Polyposis Coli (APC) protein in regulating DNA repair is very important as therapeutic implication making DNA damaging chemotherapeutic agents more effective in CRC cells that tend to accumulate mutations. Additional studies will determine whether approaches based on Wnt inhibition would provide long-term therapeutic value in CRC, but it is clear that APC disruption plays a central role in driving and maintaining tumorigenesis.

Cleistanthin A inhibits the invasion of MDA-MB-231 human breast cancer cells: involvement of the β-catenin pathway

BACKGROUND

Cleistanthin A (CleA), a natural diphyllin glycoside, has been shown to suppress the invasion of cancer cells, but the underlying mechanisms remain unclear. Here, the inhibitory effect of CleA on the invasion of MDA-MB-231 human breast cancer cells was investigated, and the mechanisms involved were clarified.

METHODS

Cell viability was studied by MTT assay. The migration and invasion of MDA-MB-231 cells were assessed by wound healing assay and transwell assay, respectively. The enzymatic activity of matrix metalloproteinases (MMPs) was detected by gelatin zymography. mRNA and protein levels were detected by qRT-PCR and Western blotting, respectively. Nuclear translocation of β-catenin was observed by immunofluorescence and detected by Western blotting.

RESULTS

CleA effectively inhibited the migration and invasion of MDA-MB-231 cells and suppressed the expression and activation of MMP-2/9. Moreover, the expression and nuclear translocation of β-catenin were reduced by CleA treatment, as well as transcription of the Cyclin D1 and c-myc genes. In addition, the inhibitory effect of CleA on the β-catenin pathway was attributed to the promotion of β-catenin degradation by inhibition of GSK3β phosphorylation. When the phosphorylation of GSK3β was induced by LiCl, the inhibitory effect of CleA on the β-catenin pathway and the invasion of MDA-MB-231 cells were almost reversed.

CONCLUSION

CleA suppressed the invasion of MDA-MB-231 cells, likely through the β-catenin pathway.

Hyperglycemia-induced ubiquitination and degradation of β-catenin with the loss of platelet endothelial cell adhesion molecule-1 in retinal endothelial cells

OBJECTIVE

Increased retinal vascular permeability is one of the earliest manifestations of diabetic retinopathy. The aim of this study was to investigate the role of hyperglycemia-induced platelet endothelial cell adhesion molecule-1 loss on retinal vascular permeability via the β-catenin pathway.

METHODS

Type I diabetes was induced in male Wistar rats using streptozotocin injections, with age-matched non-diabetic rats as controls. Rat retinal microvascular endothelial cells were grown under normal or high glucose conditions for 6 days. Small interfering Ribonucleic Acid was used to knock down platelet endothelial cell adhesion molecule-1 in rat retinal microvascular endothelial cells for loss-of-function studies. Retinas and rat retinal microvascular endothelial cells were subjected to Western blot, immunofluorescence labeling, and co-immunoprecipitation analyses to assess protein levels and interactions. A biotinylated gelatin and fluorescein isothiocyanate-avidin assay was used for retinal endothelial cell permeability studies.

RESULTS

β-catenin, β-catenin/platelet endothelial cell adhesion molecule-1 interaction, active Src homology 2 domain-containing protein tyrosine phosphatase were significantly decreased, while β-catenin ubiquitination levels and endothelial permeability were significantly increased, in hyperglycemic retinal endothelial cells. Similar results were observed with platelet endothelial cell adhesion molecule-1 partial knockdown, where β-catenin and active Src homology 2 domain-containing protein tyrosine phosphatase levels were decreased, while phospho-β-catenin and retinal endothelial cell permeability were increased.

CONCLUSION

Platelet endothelial cell adhesion molecule-1 loss may contribute to increased retinal endothelial cell permeability by attenuating β-catenin levels under hyperglycemic conditions.

Effects of chronic unpredictable mild stress induced prenatal stress on neurodevelopment of neonates: Role of GSK-3β

Prenatal stress (PNS) has gained attention with regard to its impact on hippocampal neurogenesis in neonates which serves as a risk factor for postnatal neurodevelopmental deficits. Evidences from animal models have suggested that depression responsive hypothalamic-pituitary-adrenal (HPA) axis and its hormonal response via cortisol, is responsible for critical neurodevelopmental deficits in the offspring which is transduced due to gestational stress. But knowledge in the area of assessing the effects of maternal chronic unpredictable mild stress (CUMS) on neurogenesis and expression of some key signaling molecules in the offsprings are limited. We have used Wistar rats to induce PNS in offsprings by maternal CUMS during pregnancy. Prefrontal cortex (PFC) and hippocampus were assessed for biomarkers of oxidative stress, neurogenesis, neurodevelopmental signaling molecules and DNA damage in the male Wister offsprings. Our investigations resulted in sufficient evidences which prove how maternal psychological stress has widespread effect on the fetal outcomes via major physiological alteration in the antioxidant levels, neurogenesis, signaling molecules and DNA damage. PNS leads to the upregulation of GSK-3β which in turn inhibited mRNA and protein expressions of sonic hedgehog (SHH), β-catenin, Notch and brain derived neurotrophic factor (BDNF). The study explored multifaceted signaling molecules especially, GSK-3β responsible for crosstalks between different neurodevelopmental molecules like SHH, Notch, BDNF and β-catenin affecting neurodevelopment of the offsprings due to PNS.

Kinesin-2 and IFT-A act as a complex promoting nuclear localization of β-catenin during Wnt signalling

Wnt/Wg-signalling is critical signalling in all metazoans. Recent studies suggest that IFT-A proteins and Kinesin-2 modulate canonical Wnt/Wg-signalling independently of their ciliary role. Whether they function together in Wnt-signalling and their mechanistic role in the pathway remained unresolved. Here we demonstrate that Kinesin-2 and IFT-A proteins act as a complex during Drosophila Wg-signalling, affecting pathway activity in the same manner, interacting genetically and physically, and co-localizing with β-catenin, the mediator of Wnt/Wg-signalling on microtubules. Following pathway activation, Kinesin-2/IFT-A mutant cells exhibit high cytoplasmic β-catenin levels, yet fail to activate Wg-targets. In mutant tissues in both, Drosophila and mouse/MEFs, nuclear localization of β-catenin is markedly reduced. We demonstrate a conserved, motor-domain dependent function of the Kinesin-2/IFT-A complex in promoting nuclear translocation of β-catenin. We show that this is mediated by protecting β-catenin from a conserved cytoplasmic retention process, thus identifying a mechanism for Kinesin-2/IFT-A in Wnt-signalling that is independent of their ciliary role.

IFT-A proteins and Kinesin-2 modulate canonical Wnt/Wg-signalling independent of their ciliary role, but how is unclear. Here, the authors show that Kinesin-2 and IFT-A act as a complex to promote nuclear translocation of β-catenin in Drosophila and mouse MEF Wnt signalling independent of its ciliary role.

Multiple roles of Adenomatous Polyposis Coli gene in Wnt Signalling - a Computational Model

The Adenomatous Polyposis Coli (APC) gene is a multifunctional gene that plays a major role in regulating the Wnt signalling pathway. The Wnt pathway, when activated by Wnt signalling molecules, initiates cell division. Mutation of APC disrupts the regulation and causes continuous activation of the Wnt pathway even in the absence of Wnt signals, thus causing uncontrolled cell proliferation. APC regulates the Wnt pathway by controlling the formation of the nuclear complex β-catenin/TCF that initiates the transcription of the Wnt target genes. There are at least five mechanisms by which APC can regulate the formation of the β-catenin/TCF complex: This paper presents a computational model for the Wnt pathway that explicitly includes the above five roles of APC in regulating β-catenin/TCF formation. We use this computational model to perform in-silico experiments to study the effect of different functional losses of APC on the level of β-catenin/TCF complex. The simulations also demonstrate the different outcomes that could be expected when the system is governed by different hypotheses.

Frequently rearranged and overexpressed δ-catenin is responsible for low sensitivity of prostate cancer cells to androgen receptor and β-catenin antagonists

The mechanism of prostate cancer (PCa) progression towards the hormone refractory state remains poorly understood. Treatment options for such patients are limited and present a major clinical challenge. Previously, δ-catenin was reported to promote PCa cell growth in vitro and its increased level is associated with PCa progression in vivo. In this study we show that re-arrangements at Catenin Delta 2 (CTNND2) locus, including gene duplications, are very common in clinically significant PCa and may underlie δ-catenin overexpression. We find that δ-catenin in PCa cells exists in a complex with E-cadherin, p120, and α- and β-catenin. Increased expression of δ-catenin leads to its further stabilization as well as upregulation and stabilization of its binding partners. Resistant to degradation and overexpressed δ-catenin isoform activates Wnt signaling pathway by increasing the level of nuclear β-catenin and subsequent stimulation of Tcf/Lef transcription targets. Evaluation of responses to treatments, with androgen receptor (AR) antagonist and β-catenin inhibitors revealed that cells with high levels of δ-catenin are more resistant to killing with single agent treatment than matched control cells. We show that combination treatment targeting both AR and β-catenin networks is more effective in suppressing tumor growth than targeting a single network. In conclusion, targeting clinically significant PCa with high levels of δ–catenin with anti-androgen and anti β-catenin combination therapy may prevent progression of the disease to a castration-resistant state and, thus, represents a promising therapeutic strategy.

Identification of a noncanonical function for ribose-5-phosphate isomerase A promotes colorectal cancer formation by stabilizing and activating β-catenin via a novel C-terminal domain

Altered metabolism is one of the hallmarks of cancers. Deregulation of ribose-5-phosphate isomerase A (RPIA) in the pentose phosphate pathway (PPP) is known to promote tumorigenesis in liver, lung, and breast tissues. Yet, the molecular mechanism of RPIA-mediated colorectal cancer (CRC) is unknown. Our study demonstrates a noncanonical function of RPIA in CRC. Data from the mRNAs of 80 patients’ CRC tissues and paired nontumor tissues and protein levels, as well as a CRC tissue array, indicate RPIA is significantly elevated in CRC. RPIA modulates cell proliferation and oncogenicity via activation of β-catenin in colon cancer cell lines. Unlike its role in PPP in which RPIA functions within the cytosol, RPIA enters the nucleus to form a complex with the adenomatous polyposis coli (APC) and β-catenin. This association protects β-catenin by preventing its phosphorylation, ubiquitination, and subsequent degradation. The C-terminus of RPIA (amino acids 290 to 311), a region distinct from its enzymatic domain, is necessary for RPIA-mediated tumorigenesis. Consistent with results in vitro, RPIA increases the expression of β-catenin and its target genes, and induces tumorigenesis in gut-specific promotor-carrying RPIA transgenic zebrafish. Together, we demonstrate a novel function of RPIA in CRC formation in which RPIA enters the nucleus and stabilizes β-catenin activity and suggests that RPIA might be a biomarker for targeted therapy and prognosis.

The pentose phosphate pathway generates NADPH, pentose, and ribose-5-phosphate by RPIA for nucleotide synthesis. Deregulation of RPIA is known to promote tumorigenesis in liver, lung, and breast tissues; however, the molecular mechanism of RPIA-mediated CRC is unknown. Here, we demonstrate a role of RPIA in CRC formation distinct from its role in these other tissues. We showed that RPIA is significantly elevated in CRC. RPIA increased cell proliferation and oncogenicity via activation of β-catenin, with RPIA entering the nucleus to form a complex with APC and β-catenin. Further investigation suggested that RPIA protects β-catenin by preventing its phosphorylation, ubiquitination, and subsequent degradation. In addition, the C-terminus of RPIA (amino acids 290 to 311), a portion of the protein not previously characterized, is necessary for RPIA-mediated tumorigenesis. Finally, we observed that transgenic expression of RPIA increases the expression of β-catenin and its target genes and induces tumorigenesis. Our findings suggest that RPIA can enter the nucleus and associate with APC/β-catenin, and suggest precise treatment of human CRC by targeting its nonenzymatic domain.

Loss of CDX2 gene expression is associated with DNA repair proteins and is a crucial member of the Wnt signaling pathway in liver metastasis of colorectal cancer

Caudal type homeobox 2 (CDX2) has been well-established as a diagnostic marker for colorectal cancer (CRC); however, less is known about its regulation, particularly its potential interactions with the DNA repair proteins, adenomatous polyposis coli (APC) and β-catenin, in a non-transcriptional manner. In the present study, the protein expression of CDX2 was analyzed, depending on the expression of the DNA repair proteins, mismatch repair (MMR), O6-methylguanine DNA methyltransferase (MGMT) and excision repair cross-complementing 1 (ERCC1), and its importance in Wnt signaling was also determined. A total of 101 liver metastases were punched into tissue microarray (TMA) blocks and serial sections were cut for immunohistochemistry. For each protein, an immunoreactive score was generated according to literature data and the scores were fitted to TMA. Subsequently, statistical analysis was performed to compare the levels of expression with each other and with clinical data. CDX2 loss of expression was observed in 38.5% of the CRC liver metastasis cases. A statistically significant association between CDX2 and each of the investigated MMRs was observed: MutL Homolog 1 (P<0.01), MutS protein Homolog (MSH) 2 (P<0.01), MSH6 (P<0.01), and postmeiotic segregation increased 2 (P=0.040). Furthermore, loss of MGMT and ERCC1 was also associated with CDX2 loss (P=0.039 and P<0.01, respectively). In addition, CDX2 and ERCC1 were inversely associated with metastatic tumor size (P=0.038 and P=0.027, respectively). Sustained CDX2 expression was associated with a higher expression of cytoplasmic/membranous β-catenin and with nuclear APC expression (P=0.042 and P<0.01, respectively). In conclusion, CDX2 loss of expression was not a rare event in liver metastasis of CRC and the results suggested that CDX2 may be involved in mechanisms resulting in the loss of DNA repair protein expression, and in turn methylation; however, its exact function in this context remains to be elucidated.

Angiogenesis in a 3D model containing adipose tissue stem cells and endothelial cells is mediated by canonical Wnt signaling

Adipose-derived stromal cells (ASCs) have gained great attention in regenerative medicine. Progress in our understanding of adult neovascularization further suggests the potential of ASCs in promoting vascular regeneration, although the specific cues that stimulate their angiogenic behavior remain controversial. In this study, we established a three-dimensional (3D) angiogenesis model by co-culturing ASCs and endothelial cells (ECs) in collagen gel and found that ASC-EC-instructed angiogenesis was regulated by the canonical Wnt pathway. Furthermore, the angiogenesis that occurred in implants collected after injections of our collagen gel-based 3D angiogenesis model into nude mice was confirmed to be functional and also regulated by the canonical Wnt pathway. Wnt regulation of angiogenesis involving changes in vessel length, vessel density, vessel sprout, and connection numbers occurred in our system. Wnt signaling was then shown to regulate ASC-mediated paracrine signaling during angiogenesis through the nuclear translocation of β-catenin after its cytoplasmic accumulation in both ASCs and ECs. This translocation enhanced the expression of nuclear co-factor Lef-1 and cyclin D1 and activated the angiogenic transcription of vascular endothelial growth factor A (VEGFA), basic fibroblast growth factor (bFGF), and insulin-like growth factor 1 (IGF-1). The angiogenesis process in the 3D collagen model appeared to follow canonical Wnt signaling, and this model can help us understand the importance of the canonical Wnt pathway in the use of ASCs in vascular regeneration.

Twa1/Gid8 is a β-catenin nuclear retention factor in Wnt signaling and colorectal tumorigenesis

Hyperactivation of Wnt/β-catenin signaling is one of the major causes of human colorectal cancer (CRC). A hallmark of Wnt signaling is the nuclear accumulation of β-catenin. Although β-catenin nuclear import and export have been widely investigated, the underlying mechanism of β-catenin's nuclear retention remains largely unknown. Here, we report that Twa1/Gid8 is a key nuclear retention factor for β-catenin during Wnt signaling and colorectal carcinogenesis. In the absence of Wnt, Twa1 exists together with β-catenin in the Axin complex and undergoes ubiquitination and degradation. Upon Wnt signaling, Twa1 translocates into the nucleus, where it binds and retains β-catenin. Depletion of Twa1 attenuates Wnt-stimulated gene expression, dorsal development of zebrafish embryos and xenograft tumor growth of CRC cells. Moreover, nuclear Twa1 is significantly upregulated in human CRC tissues, correlating with the nuclear accumulation of β-catenin and poor prognosis. Thus, our results identify Twa1 as a previously undescribed regulator of the Wnt pathway for promoting colorectal tumorigenesis by facilitating β-catenin nuclear retention.

SATB2/β-catenin/TCF-LEF pathway induces cellular transformation by generating cancer stem cells in colorectal cancer

Recent studies have demonstrated the involvement of colorectal cancer (CRC) stem cells (CSC) in transformation, cancer progression and metastasis. The main goal of this paper was to examine the molecular mechanisms by which SATB2 induced malignant transformation of colorectal epithelial cells. SATB2 induced malignant transformation and these transformed cells gained the characteristics of CSCs by expressing stem cell markers (CD44, CD133, LGR5 and DCLK1) and transcription factors (c-Myc, Nanog and Sox2). Overexpression of SATB2 in normal colorectal epithelial cells increased cell motility, migration and invasion, which were associated with an increase in N-cadherin and Zeb1, and decrease in E-cadherin expression. SATB2 overexpression also upregulated XIAP and cyclin D1, suggesting its role in cell survival and cell cycle. Furthermore, the expression of SATB2 was positively correlated with β-catenin expression in CRC. In contrary, depletion of SATB2 inhibited cell proliferation, colony formation, cell motility and expression of β-catenin, Snail, Slug, Zeb1 and N-cadherin, and upregulated E-cadherin. Furthermore, SATB2 silencing inhibited the expression of stem cell markers, pluripotency maintaining transcription factors, cell cycle and cell proliferation/survival genes and TCF/LEF targets. Finally, β-catenin/TCF-LEF pathway mediated the biological effects of SATB2 in CSCs. These studies support the role of SATB2/β-catenin/TCF-LEF pathway in transformation and carcinogenesis.

SATB2/β-catenin/TCF-LEF pathway induces cellular transformation by generating cancer stem cells in colorectal cancer

Recent studies have demonstrated the involvement of colorectal cancer (CRC) stem cells (CSC) in transformation, cancer progression and metastasis. The main goal of this paper was to examine the molecular mechanisms by which SATB2 induced malignant transformation of colorectal epithelial cells. SATB2 induced malignant transformation and these transformed cells gained the characteristics of CSCs by expressing stem cell markers (CD44, CD133, LGR5 and DCLK1) and transcription factors (c-Myc, Nanog and Sox2). Overexpression of SATB2 in normal colorectal epithelial cells increased cell motility, migration and invasion, which were associated with an increase in N-cadherin and Zeb1, and decrease in E-cadherin expression. SATB2 overexpression also upregulated XIAP and cyclin D1, suggesting its role in cell survival and cell cycle. Furthermore, the expression of SATB2 was positively correlated with β-catenin expression in CRC. In contrary, depletion of SATB2 inhibited cell proliferation, colony formation, cell motility and expression of β-catenin, Snail, Slug, Zeb1 and N-cadherin, and upregulated E-cadherin. Furthermore, SATB2 silencing inhibited the expression of stem cell markers, pluripotency maintaining transcription factors, cell cycle and cell proliferation/survival genes and TCF/LEF targets. Finally, β-catenin/TCF-LEF pathway mediated the biological effects of SATB2 in CSCs. These studies support the role of SATB2/β-catenin/TCF-LEF pathway in transformation and carcinogenesis.

The connections of Wnt pathway components with cell cycle and centrosome: side effects or a hidden logic?

Wnt signaling cascade has developed together with multicellularity to orchestrate the development and homeostasis of complex structures. Wnt pathway components - such as β-catenin, Dishevelled (DVL), Lrp6, and Axin-- are often dedicated proteins that emerged in evolution together with the Wnt signaling cascade and are believed to function primarily in the Wnt cascade. It is interesting to see that in recent literature many of these proteins are connected with cellular functions that are more ancient and not limited to multicellular organisms - such as cell cycle regulation, centrosome biology, or cell division. In this review, we summarize the recent literature describing this crosstalk. Specifically, we attempt to find the answers to the following questions: Is the response to Wnt ligands regulated by the cell cycle? Is the centrosome and/or cilium required to activate the Wnt pathway? How do Wnt pathway components regulate the centrosomal cycle and cilia formation and function? We critically review the evidence that describes how these connections are regulated and how they help to integrate cell-to-cell communication with the cell and the centrosomal cycle in order to achieve a fine-tuned, physiological response.

Dalbinol, a rotenoid from Amorpha fruticosa L., exerts anti-proliferative activity by facilitating β-catenin degradation in hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a highly malignant tumor, and the main cause of treatment failure is malignant proliferation. Aberrations in Wnt/β-catenin signaling are associated with HCC development. Despite the improvements in overall survival made over the past decade from the advent of molecularly targeted therapies, these treatments do not have efficacy in all patients with different pathogeneses. Therefore, there is a demand for novel chemotherapeutic agents for HCC. To this end, we built a natural compound library and screened out a rotenoid named dalbinol from the seeds of Amorpha fruticosa L. Our data demonstrated that dalbinol inhibited the growth of HepG2, HepG2/ADM and Huh7 cells in a concentration-dependent manner. Pharmacological experiments also showed that dalbinol suppressed growth and induced apoptosis in these HCC cell lines in vitro. Furthermore, we found that dalbinol promoted β-catenin degradation, which was mediated by the ubiquitin-proteasome pathway. To summarize, our results illustrate that dalbinol inhibited HCC cell growth by facilitating β-catenin degradation through the ubiquitin-proteasome pathway. Hence, we propose that dalbinol will be a promising agent for the treatment of HCC subtypes with aberrant Wnt/β-catenin pathway activation.

Inhibition of Wnt signaling induces amyloidogenic processing of amyloid precursor protein and the production and aggregation of Amyloid-β (Aβ)42 peptides

Alzheimer's disease (AD) is the most common neurodegenerative disorder and the most frequent cause of dementia in the aged population. According to the amyloid hypothesis, the amyloid-β (Aβ) peptide plays a key role in the pathogenesis of AD. Aβ is generated from the amyloidogenic processing of amyloid precursor protein and can aggregate to form oligomers, which have been described as a major synaptotoxic agent in neurons. Dysfunction of Wnt signaling has been linked to increased Aβ formation; however, several other studies have argued against this possibility. Herein, we use multiple experimental approaches to confirm that the inhibition of Wnt signaling promoted the amyloidogenic proteolytic processing of amyloid precursor protein. We also demonstrate that inhibiting Wnt signaling increases the production of the Aβ₄₂ peptide, the Aβ₄₂ /Aβ₄₀ ratio, and the levels of Aβ oligomers such as trimers and tetramers. Moreover, we show that activating Wnt signaling reduces the levels of Aβ₄₂ and its aggregates, increases Aβ₄₀ levels, and reduces the Aβ₄₂ /Aβ₄₀ ratio. Finally, we show that the protective effects observed in response to activation of the Wnt pathway rely on β-catenin-dependent transcription, which is demonstrated experimentally via the expression of various 'mutant forms of β-catenin'. Together, our findings indicate that loss of the Wnt signaling pathway may contribute to the pathogenesis of AD.

Multiple Roles of APC and its Therapeutic Implications in Colorectal Cancer

Adenomatous polyposis coli (APC) is widely accepted as a tumor suppressor gene highly mutated in colorectal cancers (CRC). Mutation and inactivation of this gene is a key and early event almost uniquely observed in colorectal tumorigenesis. Alterations in the APC gene generate truncated gene products, leading to activation of the Wnt signaling pathway and deregulation of multiple other cellular processes. It has been a mystery why most patients with CRC retain a truncated APC protein, but accumulating evidence suggest that these C terminally truncated APC proteins may have gain of function properties beyond the well-established loss of tumor suppressive function. Here, we will review the evidence for both the loss of function and the gain of function of APC truncations and how together they contribute to CRC initiation and progression.

Transcriptional Profiles in Liver from Mice Treated with Hepatotumorigenic and Nonhepatotumorigenic Triazole Conazole Fungicides: Propiconazole, Triadimefon, and Myclobutanil

Conazoles are environmental and pharmaceutical fungicides. The present study relates the toxicological effects of conazoles to alterations of gene and pathway transcription and identifies potential modes of tumorigenic action. In a companion study employing conventional toxicological bioassays ( Allen et al., 2006 ), male CD-1 mice were fed triadimefon, propiconazole, or myclobutanil in a continuous oral-dose regimen for 4, 30, or 90 days. These conazoles were found to induce hepatomegaly, to induce high levels of hepatic pentoxyresorufin-O-dealkylase activity, to increase hepatic cell proliferation, to decrease serum cholesterol, and to increase serum triglycerides. Differentially expressed genes and pathways were identified using Affymetrix GeneChips. Gene-pathway associations were obtained from the Kyoto Encyclopedia of Genes and Genomes, Biocarta, and MetaCore compendia. The pathway profiles of each conazole were different at each time point. In general, the number of altered metabolism, signaling, and growth pathways increased with time and dose and were greatest with propiconazole. All conazoles had effects on nuclear receptors as evidenced by increased expression and enzymatic activities of a series of related cytochrome P450s (CYP). A subset of altered genes and pathways distinguished the three conazoles from each other. Triadimefon and propiconazole both altered apoptosis, cell cycle, adherens junction, calcium signaling, and EGFR signaling pathways. Triadimefon produced greater changes in cholesterol biosynthesis and retinoic acid metabolism genes and in selected signaling pathways. Propiconazole had greater effects on genes responding to oxidative stress and on the IGF/P13K/AKt/PTEN/mTor and Wnt-β-catenin pathways. In conclusion, while triadimefon, propiconazole, and myclobutanil had similar effects in mouse liver on hepatomegaly, histology, CYP activities, cell proliferation, and serum cholesterol, genomic analyses revealed major differences in their gene expression profiles.

Construction and Experimental Validation of a Petri Net Model of Wnt/β-Catenin Signaling

The Wnt/β-catenin signaling pathway is important for multiple developmental processes and tissue maintenance in adults. Consequently, deregulated signaling is involved in a range of human diseases including cancer and developmental defects. A better understanding of the intricate regulatory mechanism and effect of physiological (active) and pathophysiological (hyperactive) WNT signaling is important for predicting treatment response and developing novel therapies. The constitutively expressed CTNNB1 (commonly and hereafter referred to as β-catenin) is degraded by a destruction complex, composed of amongst others AXIN1 and GSK3. The destruction complex is inhibited during active WNT signaling, leading to β-catenin stabilization and induction of β-catenin/TCF target genes. In this study we investigated the mechanism and effect of β-catenin stabilization during active and hyperactive WNT signaling in a combined in silico and in vitro approach. We constructed a Petri net model of Wnt/β-catenin signaling including main players from the plasma membrane (WNT ligands and receptors), cytoplasmic effectors and the downstream negative feedback target gene AXIN2. We validated that our model can be used to simulate both active (WNT stimulation) and hyperactive (GSK3 inhibition) signaling by comparing our simulation and experimental data. We used this experimentally validated model to get further insights into the effect of the negative feedback regulator AXIN2 upon WNT stimulation and observed an attenuated β-catenin stabilization. We furthermore simulated the effect of APC inactivating mutations, yielding a stabilization of β-catenin levels comparable to the Wnt-pathway activities observed in colorectal and breast cancer. Our model can be used for further investigation and viable predictions of the role of Wnt/β-catenin signaling in oncogenesis and development.

Curcumin Nanoformulation for Cervical Cancer Treatment

Cervical cancer is one of the most common cancers among women worldwide. Current standards of care for cervical cancer includes surgery, radiation, and chemotherapy. Conventional chemotherapy fails to elicit therapeutic responses and causes severe systemic toxicity. Thus, developing a natural product based, safe treatment modality would be a highly viable option. Curcumin (CUR) is a well-known natural compound, which exhibits excellent anti-cancer potential by regulating many proliferative, oncogenic, and chemo-resistance associated genes/proteins. However, due to rapid degradation and poor bioavailability, its translational and clinical use has been limited. To improve these clinically relevant parameters, we report a poly(lactic-co-glycolic acid) based curcumin nanoparticle formulation (Nano-CUR). This study demonstrates that in comparison to free CUR, Nano-CUR effectively inhibits cell growth, induces apoptosis, and arrests the cell cycle in cervical cancer cell lines. Nano-CUR treatment modulated entities such as miRNAs, transcription factors, and proteins associated with carcinogenesis. Moreover, Nano-CUR effectively reduced the tumor burden in a pre-clinical orthotopic mouse model of cervical cancer by decreasing oncogenic miRNA-21, suppressing nuclear β-catenin, and abrogating expression of E6/E7 HPV oncoproteins including smoking compound benzo[a]pyrene (BaP) induced E6/E7 and IL-6 expression. These superior pre-clinical data suggest that Nano-CUR may be an effective therapeutic modality for cervical cancer.

5-Hydroxytryptamine promotes hepatocellular carcinoma proliferation by influencing β-catenin

5-Hydroxytryptamine (5-HT), a neurotransmitter and vasoactive factor, has been reported to promote proliferation of serum-deprived hepatocellular carcinoma (HCC) cells but the detailed intracellular mechanism is unknown. As Wnt/β-catenin signalling is highly dysregulated in a majority of HCC, this study explored the regulation of Wnt/β-catenin signalling by 5-HT. The expression of various 5-HT receptors was studied by quantitative real-time polymerase chain reaction (qPCR) in HCC cell lines as well as in 33 pairs of HCC tumours and corresponding adjacent non-tumour tissues. Receptors 5-HT1D (21/33, 63.6%), 5-HT2B (12/33, 36.4%) and 5-HT7 (15/33, 45.4%) were overexpressed whereas receptors 5-HT2A (17/33, 51.5%) and 5-HT5 (30/33, 90.1%) were reduced in HCC tumour tissues. In vitro data suggests 5-HT increased total β-catenin, active β-catenin and decreased phosphorylated β-catenin protein levels in serum deprived HuH-7 and HepG2 cells compared to control cells under serum free medium without 5-HT. Activation of Wnt/β-catenin signalling was evidenced by increased expression of β-catenin downstream target genes, Axin2, cyclin D1, dickoppf-1 (DKK1) and glutamine synthetase (GS) by qPCR in serum-deprived HCC cell lines treated with 5-HT. Additionally, biochemical analysis revealed 5-HT disrupted Axin1/β-catenin interaction, a critical step in β-catenin phosphorylation. Increased Wnt/β-catenin activity was attenuated by antagonist of receptor 5-HT7 (SB-258719) in HCC cell lines and patient-derived primary tumour tissues in the presence of 5-HT. SB-258719 also reduced tumour growth in vivo. This study provides evidence of Wnt/β-catenin signalling activation by 5-HT and may represent a potential therapeutic target for hepatocarcinogenesis.

Mathematical and Statistical Techniques for Systems Medicine: The Wnt Signaling Pathway as a Case Study

The last decade has seen an explosion in models that describe phenomena in systems medicine. Such models are especially useful for studying signaling pathways, such as the Wnt pathway. In this chapter we use the Wnt pathway to showcase current mathematical and statistical techniques that enable modelers to gain insight into (models of) gene regulation and generate testable predictions. We introduce a range of modeling frameworks, but focus on ordinary differential equation (ODE) models since they remain the most widely used approach in systems biology and medicine and continue to offer great potential. We present methods for the analysis of a single model, comprising applications of standard dynamical systems approaches such as nondimensionalization, steady state, asymptotic and sensitivity analysis, and more recent statistical and algebraic approaches to compare models with data. We present parameter estimation and model comparison techniques, focusing on Bayesian analysis and coplanarity via algebraic geometry. Our intention is that this (non-exhaustive) review may serve as a useful starting point for the analysis of models in systems medicine.

Colorectal Carcinogenesis, Radiation Quality, and the Ubiquitin-Proteasome Pathway

Adult colorectal epithelium undergoes continuous renewal and maintains homeostatic balance through regulated cellular proliferation, differentiation, and migration. The canonical Wnt signaling pathway involving the transcriptional co-activator β-catenin is important for colorectal development and normal epithelial maintenance, and deregulated Wnt/β-catenin signaling has been implicated in colorectal carcinogenesis. Colorectal carcinogenesis has been linked to radiation exposure, and radiation has been demonstrated to alter Wnt/β-catenin signaling, as well as the proteasomal pathway involved in the degradation of the signaling components and thus regulation of β-catenin. The current review discusses recent progresses in our understanding of colorectal carcinogenesis in relation to different types of radiation and roles that radiation quality plays in deregulating β-catenin and ubiquitin-proteasome pathway (UPP) for colorectal cancer initiation and progression.