Heat shock proteins (HSPs) play an important role in folding, intracellular localization and degradation of cellular
proteins. However, the cellular role of HSP27 is not completely understood. The conflicting results have been reported regarding stress-induced nuclear translocation of HSP27. In this study, human
breast cancer cells transiently and stably expressing HSP27-EGFP chimera were utilized to observe the intracellular localization of HSP27. The data show that the transient and stable expression of HSP27-EGFP displayed distinguishingly cellular localization. The nuclear translocalization of HSP27-EGFP was correlated with the presence of
G418. Experiments carried out with different human
breast cancer cell lines revealed clearly different distribution patterns of endogenous HSP27. The subcellular distribution of endogenous HSP27 appeared diffuse throughout the cytoplasm in MDA435 cells. In MCF-7 and SKBR3 cells, the accumulation of the
protein was distinctly seen along the cell membrane and around nucleus. Moreover, the nuclear translocation of endogenous HSP27 was stimulated by
G418 only in MDA435 cells, but not in MCF-7 and SKBR3 cells. Overexpression of HSP27 has been associated with resistance to
cisplatin and
doxorubicin. The correlation of the expression pattern of HSP27 with the drug resistance may need to be investigated. Further studies on the intracellular function of HSP27 may take into account its interaction
proteins in the cells. It may provide useful information for the identification of sensitivity of
carcinoma cells to the chemotherapeutic drugs and development of more specific agents to circumvent HSP27.