Livin and Bcl-2 expression in high-grade osteosarcoma

Abstract

Aims: The evaluation of prognosis in patients with osteosarcoma is limited to clinical parameters. Although numerous molecular markers have been studied, none are currently in routine clinical use. The aim of this study was to determine if Livin and Bcl-2, acting as antiapoptotic proteins through different mechanisms, are expressed in osteosarcoma, and whether they can be used as prognostic markers in human osteosarcoma.

Methods: Tumor specimens of 29 patients with high-grade central osteosarcoma, with complete clinical follow-up for a minimum of 5 years, were studied. The localization and distribution of Livin and Bcl-2 were investigated using immunohistochemistry. Results were correlated with the histological response to chemotherapy, 5-year disease-free and 5-year overall survival.

Results: Bcl-2 was expressed only in the cytoplasm of 16/29 cases and there was no statistically significant correlation between expression and any of the studied parameters. Livin was detected in 17/29 cases, in the cytoplasm of all 17 and in the nucleus of only 3 cases. Nuclear expression was significantly correlated with a decreased overall survival (P < 0.0002) compared with those patients without nuclear expression.

Conclusions: The results of this study indicate that Bc1-2 and Livin are highly expressed in osteosarcoma cells and that possibly, the evaluation of nuclear Livin expression might be a useful prognostic marker in osteosarcoma.

Fig. 1

Mechanisms of apoptosis. There are two main mechanisms of apoptosis mediated through caspases: (1) the extrinsic pathway, triggered by death activators from outside the cell, which activate death receptors; (2) the intrinsic (mitochondrial) pathway, triggered by internal signals (death signals). There are also caspase-independent mechanisms of apoptosis (such as AIF-triggered apoptosis) Bax, Bak proapoptotic molecules that belong to the Bcl-2 family, DED death effector domain, AIF apoptosis inducing factor (released from mitochondria inducing apoptosis by a caspase-independent mechanism), Apaf-1 apoptosis activating factor-1 (forms an apoptosome together with cytochrome c, dATP and procaspase 9, which leads to initiator caspase 9 activation)

Fig. 2

a Cytoplasmic staining for Livin. b Nuclear staining for Livin. c Cytoplasmic staining for Bcl-2 in a high-grade osteosarcoma. Original magnification ×400

Fig. 3

Kaplan–Meier survival analysis of osteosarcoma patients according to nuclear expression of Livin (P = 0.0002) in tumor cells. The dashed line represents positive staining for nuclear Livin