Roles of the WWOX in pathogenesis and endocrine therapy of breast cancer

Antineoplastic Nature of WWOX in Glioblastoma Is Mainly a Consequence of Reduced Cell Viability and Invasion

Following the discovery of WWOX, research has moved in many directions, including the role of this putative tumor suppressor in the central nervous system and related diseases. The task of determining the nature of WWOX in glioblastoma (GBM) is still considered to be at the initial stage; however, the influence of this gene on the GBM malignant phenotype has already been reported. Because most of the available in vitro research does not consider several cellular GBM models or a wide range of investigated biological assays, the present study aimed to determine the main processes by which WWOX exhibits anticancer properties in GBM, while taking into account the phenotypic heterogeneity between cell lines. Ectopic WWOX overexpression was studied in T98G, DBTRG-05MG, U251MG, and U87MG cell lines that were compared with the use of assays investigating cell viability, proliferation, apoptosis, adhesion, clonogenicity, three-dimensional and anchorage-independent growth, and invasiveness. Observations presenting the antineoplastic properties of WWOX were consistent for T98G, U251MG, and U87MG. Increased proliferation and tumor growth were noted in WWOX-overexpressing DBTRG-05MG cells. A possible explanation for this, arrived at via bioinformatics tools, was linked to the TARDBP transcription factor and expression differences of USP25 and CPNE2 that regulate EGFR surface abundance. Collectively, and despite various cell line-specific circumstances, WWOX exhibits its anticancer nature mainly via a reduction of cell viability and invasiveness of glioblastoma.

The Yin and Yang of ERBB4: Tumor Suppressor and Oncoprotein

ERBB4 (HER4) is a member of the ERBB family of receptor tyrosine kinases, a family that includes the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3). EGFR and ERBB2 are oncoproteins and validated targets for therapeutic intervention in a variety of solid tumors. In contrast, the role that ERBB4 plays in human malignancies is ambiguous. Thus, here we review the literature regarding ERBB4 function in human malignancies. We review the mechanisms of ERBB4 signaling with an emphasis on mechanisms of signaling specificity. In the context of this signaling specificity, we discuss the hypothesis that ERBB4 appears to function as a tumor suppressor protein and as an oncoprotein. Next, we review the literature that describes the role of ERBB4 in tumors of the bladder, liver, prostate, brain, colon, stomach, lung, bone, ovary, thyroid, hematopoietic tissues, pancreas, breast, skin, head, and neck. Whenever possible, we discuss the possibility that ERBB4 mutants function as biomarkers in these tumors. Finally, we discuss the potential roles of ERBB4 mutants in the staging of human tumors and how ERBB4 function may dictate the treatment of human tumors. SIGNIFICANCE STATEMENT: This articles reviews ERBB4 function in the context of the mechanistic model that ERBB4 homodimers function as tumor suppressors, whereas ERBB4-EGFR or ERBB4-ERBB2 heterodimers act as oncogenes. Thus, this review serves as a mechanistic framework for clinicians and scientists to consider the role of ERBB4 and ERBB4 mutants in staging and treating human tumors.

WWOX suppresses proliferation and induces apoptosis via G2 arrest and caspase 3 pathway in nasopharyngeal carcinoma cells

BACKGROUND

WWOX plays crucial roles in various tumors. However, so far, minimal research into the role of WWOX in the development of nasopharyngeal carcinoma (NPC) has been reported. The present study investigates the effects of WWOX overexpression on cell proliferation, migration, and invasion in human NPC cell line CNE1.

MATERIALS AND METHODS

A lentiviral vector carrying WWOX was transfected into CNE1 cells. The mRNA abundances of WWOX, MMP9, E-cadherin and WWOX protein were detected using quantitative RT-PCR and Western blotting in the transfected cells compared with the control cells (cells transfected using the empty vector and untransfected cells), respectively. Cell proliferation rates were assessed by plate colony formation assays and methyl thiazolyl tetrazolium (MTT). Cell migration and invasion were tested through wound healing assays and/or transwell migration and invasion assays. Cell cycle progression and apoptosis assays were performed by flow cytometry. The protein abundances of activated fragments of caspase-3, cleaved caspase-3 and AKT, phosphorylated p-AKT (Ser473) were measured using Western blotting.

RESULTS

Overexpression of WWOX significantly inhibited cell proliferation, migration and invasion and induced apoptosis. Moreover, WWOX overexpression led to cell proliferation inhibition via induction of cell cycle arrest in G2/M phase. WWOX suppressed migration and invasion via downregulation of MMP9 and upregulation of E-cadherin. Meanwhile, WWOX could downregulate the phosphorylation of Akt protein kinase and upregulate cleavage of Caspase-3, contributing to inhibition of proliferation and promotion of apoptosis.

CONCLUSION

WWOX gene may be a novel target for gene therapy in NPC.

EBV-LMP1 regulating AKT/mTOR signaling pathway and WWOX in nasopharyngeal carcinoma

Our previous studies found the expression of tumor suppressor gene WWOX was reduced in nasopharyngeal carcinoma (NPC), and WWOX expression gradually declined with the progress and lymph node metastasis in patients. These suggested that WWOX was related with the development of NPC. AKT/mTOR signaling pathway was considered the primary pathway of cancer cell survival. AKT/mTOR pathway and WWOX had been found to be closely related. NPC was closely related to infection of Epstein-Barr virus (EBV). The study mainly used oncogene LMP1 of EBV as a starting point to explore whether LMP1 regulated the AKT/mTOR signaling pathway and WWOX gene. Western blot and qPCR were used to detect the expression of AKT/mTOR pathway (AKT, p-AKT, p70S6K and p-p70S6K) and WWOX in nasopharyngeal carcinoma cell lines CNE1 and CNE1-LMP1, and accessed relationship of LMP1 with AKT/mTOR and WWOX. Research of correlation between LMP1 and WWOX gene expression suggested that in CNE1-LMP1 cells, WWOX gene and protein levels were decreased compared with CNE1 cells (P=0.025, P=0.042, respectively). The difference was statistically significant, and suggested that LMP1 expression correlated with WWOX. Research of correlation between LMP1 and AKT/mTOR signaling pathway demonstrated that when cell line CNE1-LMP1 was compared with CNE1 in AKT/mTOR pathway key protein of AKT, p-AKT, p70S6K and p-p70S6K expression, P values were 0.075, 0.008, 0.124, 0.034, respectively, and expression of p-AKT, p-p70S6K in CNE1-LMP1 were higher than CNE1, which were significantly different from each other. It suggested AKT/mTOR pathway was regulated by LMP1. WWOX gene and AKT/mTOR signaling pathway were regulated by the EBV-LMP1 oncogene.

WW domain-binding protein 2: an adaptor protein closely linked to the development of breast cancer

The WW domain is composed of 38 to 40 semi-conserved amino acids shared with structural, regulatory, and signaling proteins. WW domain-binding protein 2 (WBP2), as a binding partner of WW domain protein, interacts with several WW-domain-containing proteins, such as Yes kinase-associated protein (Yap), paired box gene 8 (Pax8), WW-domain-containing transcription regulator protein 1 (TAZ), and WW-domain-containing oxidoreductase (WWOX) through its PPxY motifs within C-terminal region, and further triggers the downstream signaling pathway in vitro and in vivo. Studies have confirmed that phosphorylated form of WBP2 can move into nuclei and activate the transcription of estrogen receptor (ER) and progesterone receptor (PR), whose expression were the indicators of breast cancer development, indicating that WBP2 may participate in the progression of breast cancer. Both overexpression of WBP2 and activation of tyrosine phosphorylation upregulate the signal cascades in the cross-regulation of the Wnt and ER signaling pathways in breast cancer. Following the binding of WBP2 to the WW domain region of TAZ which can accelerate migration, invasion and is required for the transformed phenotypes of breast cancer cells, the transformation of epithelial to mesenchymal of MCF10A is activated, suggesting that WBP2 is a key player in regulating cell migration. When WBP2 binds with WWOX, a tumor suppressor, ER transactivation and tumor growth can be suppressed. Thus, WBP2 may serve as a molecular on/off switch that controls the crosstalk between E2, WWOX, Wnt, TAZ, and other oncogenic signaling pathways. This review interprets the relationship between WBP2 and breast cancer, and provides comprehensive views about the function of WBP2 in the regulation of the pathogenesis of breast cancer and endocrine therapy in breast cancer treatment.

WWOX inhibits the invasion of lung cancer cells by downregulating RUNX2

The WW domain-containing oxidoreductase (WWOX) is a tumor suppressor that is lost or decreased in most human tumors. The role of WWOX in human lung carcinoma invasion is still not clear. This study aimed to elucidate the potential role of WWOX in lung cancer cell invasion. WWOX mRNA levels in human lung cancers and lung cancer cell lines were assayed by quantitative real-time PCR. WWOX in lung cancer cell lines was manipulated by transfection of expression vector or small interfering RNA. Cell migration and invasion were assessed by wound healing and/or transwell migration and invasion assays. The protein levels of WWOX, E-cadherin and RUNX2 were analyzed by western blot or immunofluorescence. WWOX expression is inversely correlated to invasiveness of lung cancer. WWOX overexpression in highly invasive H1299 cells reduced cell motility and invasiveness, and inhibited the expression of RUNX2 and its target gene matrix metalloproteinase-9 (MMP-9). Silencing WWOX in less invasive NL9980 cells resulted in opposite effects. Overexpressing RUNX2 in H1299 or silencing RUNX2 in NL9980 cells reversed the effects of WWOX. These results suggested that WWOX inhibited the invasive phenotype of lung cancer through downregulating the expression of RUNX2.