Kinase-Inactive Glycogen Synthase Kinase 3β Promotes Wnt Signaling and Mammary Tumorigenesis (original) (raw)
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Kinase-Inactive Glycogen Synthase Kinase 3B Promotes Wnt Signaling and Mammary Tumorigenesis
2005
Recent studies have implicated ectopic activation of the Wnt pathway in many human cancers, including breast cancer. B-catenin is a critical coactivator in this signaling pathway and is regulated in a complex fashion by phosphorylation, degradation, and nuclear translocation. Glycogen synthase kinase 3B (GSK3B) phosphorylation of the NH2-terminal domain of B-catenin targets it for ubiquitination and proteosomal degradation. We hypothesized that expression of kinase-inactive GSK3B (KI-GSK3B) in mammary glands would function in a dominant-negative fashion by antago- nizing the endogenous activity of GSK3B and promoting breast cancer development. Consistent with this, we find that KI-GSK3B stabilizes B-catenin expression, catalyzes its localization to the nucleus, and up-regulates the down- stream target gene, cyclin D1, in vitro. In vivo, transgenic mice overexpressing the KI-GSK3B under the control of the mouse mammary tumor virus-long terminal repeat develop mammary tumors with over...
Effect of glycogen synthase kinase-3 inactivation on mouse mammary gland development and oncogenesis
Oncogene, 2014
Many components of the Wnt/β-catenin signaling pathway have critical functions in mammary gland development and tumor formation, yet the contribution of glycogen synthase kinase-3 (GSK-3α and GSK-3β) to mammopoiesis and oncogenesis is unclear. Here, we report that WAP-Cre-mediated deletion of GSK-3 in the mammary epithelium results in activation of Wnt/β-catenin signaling and induces mammary intraepithelial neoplasia that progresses to squamous transdifferentiation and development of adenosquamous carcinomas at 6 months. To uncover possible β-catenin-independent activities of GSK-3, we generated mammaryspecific knockouts of GSK-3 and β-catenin. Squamous transdifferentiation of the mammary epithelium was largely attenuated, however, mammary epithelial cells lost the ability to form mammospheres suggesting perturbation of stem cell properties unrelated to loss of β-catenin alone. At 10 months, adenocarcinomas that developed in glands lacking GSK-3 and β-catenin displayed elevated levels of γ-catenin/plakoglobin as well as activation of the Hedgehog and Notch pathways. Collectively, these results establish the two isoforms of GSK-3 as essential integrators of multiple developmental signals that act to maintain normal mammary gland function and suppress tumorigenesis.
Histopathology, 2013
tumour cells showed an inverse association with histological grade (P = 0.002), Ki67 (P = 0.008) and p53 (P = 0.031), while its relation with ER, erbB2 and caspase-3 was found to be positive (P = 0.007, P = 0.018 and P = 0.03, respectively). Cytoplasmic Wnt1 expression was related to a favourable prognosis within the subgroup of patients with stage II disease (P = 0.032). Conclusions: Wnt1 expression in the invasive tumour cells seems to promote differentiation and apoptosis, while being related inversely to proliferation. Therefore, this suggests its participation in the primary stages of breast carcinogenesis. The latter is supported further by the immunodetection of Wnt1 in in-situ carcinomas.
Oncogene, 2001
Development of strategies for prevention of breast cancer development requires an understanding of the eects of mammary oncogenes on mammary cells at early stages in neoplastic transformation. As mammary oncogenes wnt-1 and int-2 aect dierent signal transduction pathways, we investigated their eects on established mouse mammary epithelial cell lines (MMECLs) re¯ecting early stages in tumorigenesis. Normal interactions between b-catenin and E-cadherin were abrogated in all three immortalized MMECLs and the cells lacked b-catenin-mediated transactivation activity, detectable using a reporter assay, suggesting that alterations in cell adhesion may be very early events in mammary tumorigenesis. Immortalized FSK4 and EL12 cells and hyperplastic TM3 cells were stably transfected with expression vectors encoding wnt-1 or int-2 or the control vector, and drug-selected pooled cells from each line were con®rmed by reverse transcription-polymerase chain reaction to express the transfected oncogene; this expression persisted in the cells analysed in vitro and in vivo. Resultant phenotypic changes depended both on the oncogene and the target mammary cell line. In FSK4 cells, expression of wnt-1 or int-2 resulted in proliferative changes in vitro, including reduced contact inhibition, increased b-catenin expression, and decreased p53 transcriptional activity, but neither oncogene conferred upon those cells the ability to produce tumors in vivo. EL12 cells were highly refractory to the eects of both oncogenes, with the only measurable changes being increased E-cadherin levels induced by both oncogenes and increased proliferation of the int-2-transfected cells in the absence of serum. Parental TM3 cells were phenotypically similar to wnt-1-or int-2-transfected FSK4 cells and displayed an increased rate of proliferation in vitro and markedly increased tumorigenicity in vivo following transfection with int-2 but not with wnt-1. These results suggest that wnt-1 signaling is redundant in the hyperplastic TM3 cells and indicate that wnt-1-induced eects in the immortalized FSK4 and EL12 cells were not sucient to mediate a tumorigenic phenotype. This study showed that the wnt-1 and int-2 oncogenes have similar but distinguishable eects on immortalized MMECLs and that the genetic background of the mammary cells greatly in¯uences the consequences of oncogene expression at early stages of cell transformation. Oncogene (2001) 20, 7645 ± 7657.
Protein kinase CK2 in mammary gland tumorigenesis
Oncogene, 2001
Protein kinase CK2 is a ubiquitous and evolutionarily conserved serine/threonine kinase that is upregulated in many human cancers and can serve as an oncogene in lymphocytes. Recently, we have demonstrated that CK2 potentiates Wnt/b-catenin signaling in mammary epithelial cells. To determine whether CK2 overexpression contributes to mammary tumorigenesis, we have performed comparative studies of human and rat breast cancer specimens and we have engineered transgenic mice with dysregulated expression of CK2a in the mammary gland. We ®nd that CK2 is highly expressed in human breast tumor specimens and in carcinogeninduced rat mammary tumors. Overexpression of CK2a in the mammary gland of transgenic mice, under control of the MMTV-LTR, causes hyperplasia and dysplasia of the female mammary gland. Thirty per cent of the female MMTV-CK2a transgenic mice develop mammary adenocarcinomas at a median of 23 months of age, often associated with Wnt pathway activation, as evidenced by upregulation of b-catenin protein. NF-kB activation and upregulation of c-Myc also occur frequently. Thus, in mice, rats, and humans, dysregulated expression of CK2 is associated with and is capable of contributing to mammary tumorigenesis. Targeted inhibition of CK2 could be useful in the treatment of breast cancer. Oncogene (2001) 20, 3247 ± 3257.
Protein kinase CK2: Signaling and tumorigenesis in the mammary gland
Protein Kinase CK2 — From Structure to Regulation, 2001
Breast cancer is a major cause of cancer death in women, and the genetic abnormalities leading to the common sporadic forms of the disease are still under active investigation. CK2 has been reported to be upregulated in human breast cancer, which these studies confirm; CK2 is also upregulated in rat carcinogen-induced breast tumors. Transgenic mice overexpressing CK2α in the mammary gland develop mammary hyperplasia, dysplasia, and eventually adenocarcinomas, demonstrating that dysregulated expression of CK2 can contribute to transformation of the mammary epithelium. These mammary tumors have evidence of activation of the Wnt and NFκB pathways and upregulation of c-Myc. CK2 is capable of phosphorylating the key signaling molecule in the Wnt pathway, the transcriptional cofactor β-catenin, and regulating its turnover. CK2 is known to phosphorylate IκB and thereby regulate basal NFκB levels; in the mammary cell lines and tumors, CK2 activity correlates with NFκB levels and inhibition of CK2 downregulates NFκB. Thus, CK2 may promote breast cancer through dysregulation of key pathways of transcriptional control in the mammary epithelium, and inhibition of CK2 has a potential role in the treatment of breast and other cancers.
Oncology, 2007
The Wnt/beta-catenin signaling cascade is an important signal transduction pathway in human cancers. Overexpression of beta-catenin and its downstream effector, cyclin D1, is implicated in malignant transformation and acquisition of an invasive tumor phenotype. This study aimed to determine the clinical significance of Wnt/beta-catenin canonical pathway components in breast cancer. Expression of beta-catenin, dishevelled (Dvl) and cyclin D1 was examined in invasive ductal carcinomas (IDCs) of the breast by immunohistochemical analysis. Of the 98 IDCs analyzed, 30% of tumors displayed both nuclear and cytoplasmic staining of Dvl protein, while 52% showed nuclear localization. Loss of cell surface beta-catenin was observed in 66% of breast carcinomas, whereas nuclear expression was observed in 48% IDCs. Cyclin D1 overexpression was observed in 60% IDCs; 31/59 (53%) of these tumors showed nuclear expression of beta-catenin, suggesting upregulation of the canonical Wnt/beta-catenin pathway. Our study demonstrates a significant association between nuclear localization of Dvl and beta-catenin (p < 0.01, OR = 15.8). To our knowledge, this is the first study showing an association between nuclear localization of Dvl and beta-catenin in IDCs and suggests the upregulation of Wnt/beta-catenin pathway components, beta-catenin, Dvl and cyclin D1 in IDCs of the breast.
Oncogene, 2002
The Wnt/b-catenin signaling pathway controls cell fate and neoplastic transformation. Expression of an endogenous stabilized b-catenin (DE3 b-catenin) in mammary epithelium leads to the transdifferentiation into epidermis-and pilar-like structures. Signaling molecules in the canonical Wnt pathway upstream from b-catenin induce glandular tumors but it is not clear whether they also cause squamous transdifferentiation. To address this question we have now investigated mammary epithelium from transgenic mice that express activating molecules of the Wnt pathway: Wnt10b, Int2/Fgf3, CK2a, DE3 b-catenin, Cyclin D1, and dominant negative (dn) GSK3b. Cytokeratin 5 (CK5), which is expressed in both mammary myoepithelium and epidermis, and the epidermis-specific CK1 and CK6 were used as differentiation markers. Extensive squamous metaplasias and widespread expression of CK1 and CK6 were observed in DE3 b-catenin transgenic mammary tissue. Wnt10b and Int2 transgenes also induced squamous metaplasias, but expression of CK1 and CK6 was sporadic. While CK5 expression in Wnt10b transgenic tissue was still confined to the lining cell layer, its expression in Int2 transgenic tissue was completely disorganized. In contrast, cytokeratin expression in CK2a, dnGSK3b and Cyclin D1 transgenic mammary tissues was similar to that in DE3 bcatenin tissue. In support of transdifferentiation, expression of hard keratins specific for hair and nails was observed in pilar tumors. These results demonstrate that the activation of Wnt signaling components in mammary epithelium induces not only glandular tumors but also squamous differentiation, possibly by activating LEF-1, which is expressed in normal mammary epithelium.
Proceedings of The National Academy of Sciences, 2003
Breast cancer is a genetically and clinically heterogeneous disease, and the contributions of different target cells and different oncogenic mutations to this heterogeneity are not well understood. Here we report that mammary tumors induced by components of the Wnt signaling pathway contain heterogeneous cell types and express early developmental markers, in contrast to tumors induced by other signaling elements. Expression of the Wnt-1 protooncogene in mammary glands of transgenic mice expands a population of epithelial cells expressing progenitor cell markers, keratin 6 and Sca-1; subsequent tumors express these markers and contain luminal epithelial and myoepithelial tumor cells that share a secondary mutation, loss of Pten, implying that they arose from a common progenitor. Mammary tumors arising in transgenic mice expressing -catenin and c-Myc, downstream components of the canonical Wnt signaling pathway, also contain a significant proportion of myoepithelial cells and cells expressing keratin 6. Progenitor cell markers and myoepithelial cells, however, are lacking in mammary tumors from transgenic mice expressing Neu, H-Ras, or polyoma middle T antigen. These results suggest that mammary stem cells and͞or progenitors to mammary luminal epithelial and myoepithelial cells may be the targets for oncogenesis by Wnt-1 signaling elements. Thus, the developmental heterogeneity of different breast cancers is in part a consequence of differential effects of oncogenes on distinct cell types in the breast.
Wnt-signalling pathway in ovarian epithelial tumours: increased expression of �-catenin and GSK3�
Brit J Cancer, 2003
Beta-catenin is involved in both cell -cell adhesion and in transcriptional regulation by the Wingless/Wnt signalling pathway. Alterations of components of this pathway have been suggested to play a central role in tumorigenesis. The present study investigated, by immunohistochemistry and immunoblotting, the protein expression and localisation of b-catenin, adenomatous polyposis coli (APC), glycogen synthase kinase 3b (GSK3b) and lymphocyte enhancer factor-1 (Lef-1) in normal human ovaries and in epithelial ovarian tumours in vivo and in vitro. Immortalised human ovarian surface epithelium and ovarian cancer cell cells (OVCAR-3) expressed b-catenin, APC, GSK3b and Lef-1. Nuclear staining of b-catenin and Lef-1 were demonstrated only in OVCAR-3 cells. There were significant increases of b-catenin and GSK3b, while APC was reduced in ovarian cancer compared to the normal ovary. Beta-catenin and Lef-1 were coimmunoprecipitated in ovarian tumours, but not in the normal ovary. Nuclear localisation of b-catenin or Lef-1 could not be demonstrated in the normal ovary or in the ovarian tumours. The absence of nuclear localisation of b-catenin could be due to an increased binding to the cadherin -a-catenin cell adhesion complex. In fact, we have earlier reported an increased expression of E-cadherin in ovarian adenocarcinomas. In summary, this study demonstrates an increase in the expression of components of the Wingless/Wnt pathway in malignant ovarian tumours. The increase suggests a role for this signalling pathway in cell transformation and in tumour progression. However, it remains to be demonstrated whether it is an increased participation of b-catenin in transcriptional regulation, or in the stabilisation of cellular integrity, or both, that is the crucial event in ovarian tumorigenesis.