WNT receptors profile expression in mature blood cells and immature leukemic cells: RYK emerges as a hallmark receptor of acute leukemia.

BACKGROUND: Wnt signaling induces a plethora of intracellular responses that dictate normal or abnormal cellular behavior. Abnormal WNT signaling has been related to the development of leukemogenic processes. In this regard, it is important to know the expression profile of WNT receptors in normal and malignant cells, in order to understand the WNT mechanisms that control the cell behavior. This work aimed to determine the WNT receptors expression profile in normal and leukemia cells. METHODS: Expression of WNT receptors was determined by flow cytometry using leukemia-derived cell lines, peripheral blood cells, and blood marrow samples from healthy volunteers and acute leukemia patients. RESULTS: Despite the heterogenic WNT receptors expression in mature normal blood cells and in immature tumorigenic cells, the RYK receptor was found highly express in leukemia cells, but not in normal cells. RYK expression was found mainly in cells positive to immature markers like CD33, CD13, CD7, and CD117. CONCLUSIONS: Our data show differences in FZD receptors expression between T and B leukemic cells, but both cell types and also myeloblast-derived cells express high levels of RYK. The association of RYK expression with immature markers indicates its possible use as a diagnostic marker or therapeutic target.

[Wnt signalling pathway and cervical cancer]. / Vía de señalización Wnt y cáncer cervicouterino.

Cervical cancer (CC) is a pathology that arises in the cervical epithelium, whose major cause of risk is human papillomavirus (HPV) infection. Due to the fact that HPV infection per se is not enough to generate a carcinogenic process, it has been proposed that alterations in the Wnt signaling pathway are involved in cervical carcinogenesis. The Wnt family consists of 13 receptors and 19 ligands, and it is highly conserved phylogenetically due to its contribution in different biological processes, such as embryogenesis and tissue regeneration. Additionally, this signaling pathway modulates various cellular functions, for instance: cell proliferation, differentiation, migration and cell polarity. This paper describes the Wnt signaling pathways and alterations that have been found in members of this family in different cancer types and, especially, in CC.

El cáncer cervicouterino (CaCU) es una patología que se origina en el epitelio del cuello del útero, cuya principal causa de riesgo es la infección por el virus de papiloma humano (VPH). Sin embargo, dado que la infección por VPH per se no es suficiente para generar un proceso carcinogénico, se ha propuesto que alteraciones en la vía de señalización Wnt están involucradas en la carcinogénesis cervical. La familia Wnt está compuesta por 13 receptores y 19 ligandos, y se encuentra altamente conservada filogenéticamente, puesto que contribuye en diversos procesos biológicos, como la embriogénesis y la regeneración de tejidos. Adicionalmente, esta familia modula diferentes funciones celulares, como la proliferación celular, la diferenciación, la migración y la polaridad celular. En la presente revisión se describen las vías de señalización de Wnt, así como las alteraciones que han sido encontradas en miembros de esta familia en diferentes patologías cancerosas y especialmente en el cáncer cervicouterino.

Restoration of WNT4 inhibits cell growth in leukemia-derived cell lines.

BACKGROUND: WNT signaling pathways are significantly altered during cancer development. Vertebrates possess two classes of WNT signaling pathways: the "canonical" WNT/ß-catenin signaling pathway, and the "non-canonical" pathways including WNT/Ca²âº and WNT/Planar cell polarity [PCP] signaling. WNT4 influences hematopoietic progenitor cell expansion and survival; however, WNT4 function in cancer development and the resulting implications for oncogenesis are poorly understood.The aim of this study was twofold: first, to determine the expression of WNT4 in mature peripheral blood cells and diverse leukemia-derived cells including cell lines from hematopoietic neoplasms and cells from patients with leukemia; second, to identify the effect of this ligand on the proliferation and apoptosis of the blast-derived cell lines BJAB, Jurkat, CEM, K562, and HL60. METHODS: We determined WNT4 expression by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) in peripheral blood mononuclear cells (PBMCs) and T- and B-lymphocytes from healthy individuals, as well as from five leukemia-derived cell lines and blasts derived from patients with leukemia. To analyze the effect of WNT4 on cell proliferation, PBMCs and cell lines were exposed to a commercially available WNT4 recombinant human protein. Furthermore, WNT4 expression was restored in BJAB cells using an inducible lentiviral expression system. Cell viability and proliferation were measured by the addition of WST-1 to cell cultures and counting cells; in addition, the progression of the cell cycle and the amount of apoptosis were analyzed in the absence or presence of WNT4. Finally, the expression of WNT-pathway target genes was measured by qRT-PCR. RESULTS: WNT4 expression was severely reduced in leukemia-derived cell lines and blasts derived from patients with leukemia. The exposure of cell lines to WNT4 recombinant protein significantly inhibited cell proliferation; inducing WNT4 expression in BJAB cells corroborated this observation. Interestingly, restoration of WNT4 expression in BJAB cells increased the accumulation of cells in G1 phase, and did not induce activation of canonical WNT/ß-catenin target genes. CONCLUSIONS: Our findings suggest that the WNT4 ligand plays a role in regulating the cell growth of leukemia-derived cells by arresting cells in the G1 cell cycle phase in an FZD6-independent manner, possibly through antagonizing the canonical WNT/ß-catenin signaling pathway.

Peripheral T-lymphocytes express WNT7A and its restoration in leukemia-derived lymphoblasts inhibits cell proliferation.

BACKGROUND: WNT7a, a member of the Wnt ligand family implicated in several developmental processes, has also been reported to be dysregulated in some types of tumors; however, its function and implication in oncogenesis is poorly understood. Moreover, the expression of this gene and the role that it plays in the biology of blood cells remains unclear. In addition to determining the expression of the WNT7A gene in blood cells, in leukemia-derived cell lines, and in samples of patients with leukemia, the aim of this study was to seek the effect of this gene in proliferation. METHODS: We analyzed peripheral blood mononuclear cells, sorted CD3 and CD19 cells, four leukemia-derived cell lines, and blood samples from 14 patients with Acute lymphoblastic leukemia (ALL), and 19 clinically healthy subjects. Reverse transcription followed by quantitative Real-time Polymerase chain reaction (qRT-PCR) analysis were performed to determine relative WNT7A expression. Restoration of WNT7a was done employing a lentiviral system and by using a recombinant human protein. Cell proliferation was measured by addition of WST-1 to cell cultures. RESULTS: WNT7a is mainly produced by CD3 T-lymphocytes, its expression decreases upon activation, and it is severely reduced in leukemia-derived cell lines, as well as in the blood samples of patients with ALL when compared with healthy controls (p ≤0.001). By restoring WNT7A expression in leukemia-derived cells, we were able to demonstrate that WNT7a inhibits cell growth. A similar effect was observed when a recombinant human WNT7a protein was used. Interestingly, restoration of WNT7A expression in Jurkat cells did not activate the canonical Wnt/ß-catenin pathway. CONCLUSIONS: To our knowledge, this is the first report evidencing quantitatively decreased WNT7A levels in leukemia-derived cells and that WNT7A restoration in T-lymphocytes inhibits cell proliferation. In addition, our results also support the possible function of WNT7A as a tumor suppressor gene as well as a therapeutic tool.

Activation of the calpain/cdk5/p25 pathway in the girus cinguli in Parkinson's disease.

The mechanisms involved in neuronal loss in Parkinson's disease (PD) are not known, although recent studies performed in PD experimental models suggest that cdk5/p25 plays a predominant role. In the present study, we examined the gyrus cinguli of cases with PD and compared them with age-matched controls, and we demonstrated an activation of the calpain/cdk5 pathway. We found an increase in the p25/p35 immunoreactivity ratio and in the expression of transcription factor E2F-1. Our results implicate the cdk5/p25 pathway and re-entry into the cell cycle in the process of neuronal loss in patients with PD.