Vol. 26, No. 1, 2004 (March)
	Content

IMMUNOHISTOCHEMICAL ANALYSIS OF S6K1 AND S6K2 EXPRESSION IN HUMAN BREAST TUMORS

Liliya O. Savinska¹, Valeriy V. Lyzogubov², Vasyliy S. Usenko², Galina V. Ovcharenko¹, Olena N. Gorbenko¹, Mykola V. Rodnin¹, Mariya I. Vudmaska¹, Petro V. Pogribniy³, Ramziya G. Kyyamova¹, Ganna G. Panasyuk^1,4, Ivan O. Nemazanyy¹, Milan S. Malets⁵, Sergey S. Palchevskyy¹, Ivan T. Gout^1,6, Valeriy V. Filonenko^1,*

¹Institute of Molecular Biology and Genetics, NAS of Ukraine, Kyiv, Ukraine
²Morphological Laboratory "Biontec", Dniepropetrovsk, Ukraine
³R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, NAS of Ukraine, Kyiv, Ukraine
⁴National University "Kyiv-Mohylyanskaya Academy", Kyiv, Ukraine
⁵Kyiv Municipal Oncological Hospital, Kyiv, Ukraine
⁶University College London, Department of Biochemistry and Molecular Biology, London WC1E 6BT, United Kingdom

Abstract. Aim: To express recombinant S6K2 in baculovirus expression system; to purify large quantities of recombinant S6K2 for biochemical studies; to generate and characterise specific MABs against recombinant S6K2; to study the patterns S6K1 and S6K2 expression and subcellular localization in normal, benign and malignant breast tissues. Methods: Recombinant baculovirus, expressing wild type S6K2 was generated using Bac-to-Bac system (Invitrogen); recombinant S6K was purified from infected Sf9 cells using affinity purification approach; monoclonal antibodies against recombinant S6K2 were generated; the specificity of generated MABs towards recombinant and endogenous S6K2 were examined by ELISA, Western blotting, immunoprecipitation and immuhohistochemical staining; imunnohistochemical detection of S6K1 and S6K2 in human breast tissues was performed using specific monoclonal antibodies towards S6K1 and S6K2. Results: Large amounts of enzymatically active S6K2 were purified using baculovirus expression system; highly purified preparations of S6K2 were used to generate and characterize anti-S6K2 MABs; elevated levels of S6K1 and S6K2 were found in breast tumors when compared to normal breast tissues; S6K2 is frequently localized in the nuclei of ademocarcinoma tissues, but rarely in fibroademona or "normal" breast tissues. Conclusion: Production of recombinant S6K2 in large amount and generation of specific monoclonal antibodies towards S6K2 has provided us with excellent tools to study the function and regulation of this important signalling molecule in normal and cancer cells. Immunnohistochemical analysis of S6K1 and S6K2 expression in normal and malignant breast clearly indicates that both kinases are overexpressed in breast tumors, when compared to "normal" tissues. The retention of S6K2 in the nuclei of malignant cells may be caused by disregulation of nucleocytoplasmic shuttling and could subsequently affect cell growth and proliferation.

Key Words: Ribosomal S6 kinases, monoclonal antibodies, signal transduction, disregulation, breast cancer.

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