ABB  Vol.3 No.6 A , October 2012
Increased resistance to apoptosis during differentiation and syncytialization of BeWo choriocarcinoma cells
ABSTRACT
Transition from mononuclear villous cytotrophoblast into multinuclear syncytiotrophoblast in the human placenta is accompanied by changes in apoptosis-related proteins and an apparent increased resistance to induced apoptosis. We investigated the specific nature and timing of changes in Bcl-2, Bax, p53, and caspases 3 and 8 in forskolin-treated BeWo choriocarcinoma cells, a model for villous cytotrophoblast differentiation. BeWo cells were treated with forskolin or vehicle alone for up to 72 h and evaluated at 24 h intervals for syncytialization and quantitative expression specific apoptosis-related proteins and mRNAs. Syncytialization was quantified using fluorescent staining of intercellular membranes and enumeration of the percentage of nuclei in multinucleate cells, and differential localization of apoptosis-related proteins to multinuclear or mononuclear cells was determined by quantitative immunofluorescence. Forskolin treatment for up to 72 h resulted in 80% syncytialization, increased expression of Bcl-2 protein (P < 0.01) and mRNA (P < 0.05), and significantly decreased expression of protein and mRNA for Bax, p53, and caspases 3 and 8. Syncytialized cells expressed higher levels of Bcl-2 protein concurrent with increased resistance to cisplatin-induced apoptosis. Thus, syncytialization of BeWo cells was accompanied by altered transcription of apoptotic-related proteins characteristic of increased apoptosis resistance secondary to increased expression of the anti-apoptotic protein Bcl-2 and diminish expression of pro-apoptotic proteins.

Cite this paper
Wei, B. , Xu, C. and Rote, N. (2012) Increased resistance to apoptosis during differentiation and syncytialization of BeWo choriocarcinoma cells. Advances in Bioscience and Biotechnology, 3, 805-813. doi: 10.4236/abb.2012.326100.
References
[1]   Straszewski-Chavez, S.L., Abrahams, V.M. and Mor, G. (2005) The role of apoptosis in the regulation of trophoblast survival and differentiation during pregnancy. Endocrine Reviews, 26, 877-897.

[2]   Heazell, A.E.P. and Crocker, I.P. (2008) Live and let die-regulation of villous trophoblast apoptosis in normal and abnormal pregnancies. Placenta, 29, 772-783.

[3]   Huppertz, B., Frank, H.G., Kingdom, J.C., Reister, F. and Kaufmann, P. (1998) Villous cytotrophoblast regulation of the syncytial apoptotic cascade in the human placenta. Histochemistry and Cell Biology, 110, 495-508.

[4]   Huppertz, B., Frank, H.G., Reister, F., Kingdom, J., Korr, H. and Kaufmann, P. (1999) Apoptosis cascade progresses during turnover of human trophoblast: analysis of villous cytotrophoblast and syncytial fragments in vitro. Laboratory Investigation, 79, 1687-1702.

[5]   Ratts, V.S., Tao, X.J., Webster, C.B., et al. (2000) Expression of BCL-2, BAX and BAK in the trophoblast layer of the term human placenta: a unique model of apoptosis within a syncytium. Placenta, 21, 361-366.

[6]   Huppertz, B., Tews, D.S. and Kaufmann, P. (2001) Apoptosis and syncytial fusion in human placental trophoblast and skeletal muscle. International Review of Cytology, 205, 215–253.

[7]   Danihel, L., Gomolcak, P., Korbel, M., et al. (2002) Expression of proliferation and apoptotic markers in human placenta during pregnancy. Acta Histochemica, 104, 335-338.

[8]   Ishihara, N., Matsuo, H., Murakoshi, H., Laoag-Fernandez, J.B., Samoto, T. and Maruo, T. (2002) Increased apoptosis in the syncytiotrophoblast in human term placentas complicated by either preeclampsia or intrauterine growth retardation. American Journal of Obstetrics and Gynecology, 186, 158-166.

[9]   Ishihara, N., Matsuo, H., Murakoshi, H., Laoag-Fernandez, J., Samoto, T. and Maruo, T. (2000) Changes in proliferative potential, apoptosis and Bcl-2 protein expression in cytotrophoblasts and syncytiotrophoblast in human placenta over the course of pregnancy. Endocrine Journal, 47, 317-327.

[10]   Ka, H. and Hunt, J.S. (2003) Temporal and spatial patterns of expression of inhibitors of apoptosis in human placentas. American Journal of Pathology, 163, 413-422.

[11]   Black, S., Kadyrov, M., Kaufmann, P., Ugele, B., Emans, N. and Huppertz, B. (2004) Syncytial fusion of human trophoblast depends on caspase 8. Cell Death and Differentiation, 11, 90-98.

[12]   Huppertz, B., Frank, H.G. and Kaufmann, P. (1999) The apoptosis cascade -morphological and immunohistochemical methods for its visualization. Anatomy and Embryology (Berl), 200, 1-18.

[13]   Yusuf, K., Smith, S.D., Sadovsky, Y. and Nelson, D.M. (2002) Trophoblast differentiation modulates the activity of caspases in primary cultures of term human trophoblasts. Pediatric Research, 52, 411-415.

[14]   Hu, C., Smith, S.D., Pang, L., Sadovsky, Y. and Nelson, D.M. (2006) Enhanced basal apoptosis in cultured term human cytotrophoblasts is associated with a higher expression and physical interaction of p53 and Bak. Placenta, 27, 978-983.

[15]   Rote, N.S., Chang, J., Katsuragawa, H., Ng, A.K., Lyden, T.W. and Mori, T. (1995) Expression of phosphatidylserine-dependent antigens on the surface of differentiating BeWo human choriocarcinoma cells. American Journal of Reproductive Immunology, 33, 114-121.

[16]   Das, M., Xu, B., Lin, L., Chakrabarti, S., Shivaswamy, V. and Rote, N.S. (2004) Phosphatidylserine efflux and intercellular fusion in a BeWo model of human villous cytotrophoblast. Placenta, 25, 396-407.

 
 
Top