Protein kinases orchestrate cell cycle regulators in differentiating BeWo choriocarcinoma cells

Potential role of Hematopoietic PBX-Interacting Protein (HPIP) in trophoblast fusion and invasion: Implications in pre-eclampsia pathogenesis

Pre-eclampsia is a known hypertensive disorder of pregnancy. While abnormal placentation and poor trophoblast invasion into maternal endometrium during blastocyst implantation are primary causes of pre-eclampsia, the underlying mechanisms remain elusive. Hematopoietic PBX-Interacting protein (HPIP) is an estrogen receptor (ER) interacting protein that plays a pivotal role in cell proliferation, migration, and differentiation; however, its role in trophoblast functions is largely unknown. In this study, we used BeWo cells as a model system to investigate trophoblast fusion and syncytialization, focusing on the role of HPIP in regulating these critical aspects of trophoblast functions. Herein, we report that HPIP expression declines during forskolin-induced trophoblast fusion in BeWo cells. In support of these observations, HPIP depletion enhanced forskolin-induced human chorionic gonadotropin-β (β-hCG), ERVWE1, and GCM1 expression, markers for trophoblast fusion. Furthermore, silencing of HPIP decreased cell invasion and epithelial to mesenchymal transition (EMT), a prerequisite for syncytialization in BeWo cells. Functional genomic studies further revealed a regulatory role for HPIP in a subset of gene networks involved in trophoblast fusion and EMT. We also uncovered that HPIP is a proteolytic substrate of furin, which is known to promote trophoblast cell fusion. Clinical data further indicated a significantly lower expression level of HPIP in pre-eclampsia subjects than in normal subjects. These findings imply that HPIP inhibits trophoblast fusion while promoting invasion and EMT, and its downregulation in trophoblasts might have implications for pre-eclampsia development.

Regulation of Jun and Fos AP-1 transcription factors by JNK MAPKs signaling cascade in areca nut extract treated KB cells

The edible endosperm of Areca catechu is recognized as a potent carcinogenic agent either consumed alone or in combination with tobacco. Habitual chewing of areca nut leads to orally potential malignant disorders which are highly effective in malignant transformation and thereby lead to oral carcinogenesis. Human buccal epithelial KB carcinoma cells were used as an experimental cell system to inspect the mechanistic act of aqueous extract of areca nut on biochemical status and their implications on transcriptional activation of cancer signaling cascade that could possibly trigger numerous oncogenic players and finally decides the cells fate. Extract treated cells showed reduced viability with altered balance between oxidants and antioxidants which lead to redox status and which is known to distort various biological processes within the cell system. Results of RT-PCR demonstrated decreased expression of BCl2, cell cycle regulators along with Activator Protein -1 (AP-1) components. While Bax, p16 and p21 mRNAs showed increased expression in extract treated KB cells. Likewise, the translational levels of proliferation cell nuclear antigen (PCNA), tumor suppressor p53, retinoblastoma (Rb) and cyclin dependent kinase 4 (CDK4) were decreased along with AP-1 subunits (c-Jun/c-Fos) with increased protein levels of p21 in extract treated KB cells. Further, the downstream activation and regulation of AP-1 transcription factors could be through stress activated c-Jun - N terminal Kinase (JNK) Mitogen Activated Protein Kinases (MAPKs) which downregulated both Jun and Fos mRNA transcripts in areca nut extract exposed KB cells. Thus, outcome of the study provides insights into mechanistic path of pathogenesis of areca related disorders. Further, it could aid in designing new therapeutic modalities that specific targets these oncogenic players and help in disease management.