Nanostructural study of human tumour transformed tissues by X-ray diffraction methods using synchrotron radiation
- Dr. Alvina VAZINA
- Dr. Alvina VAZINA (Institute of theoretical and experimental biophysics, RAS)
The work is dedicated to investigating the nanostructural organization of proteoglycans in different physiological states of biological tissues of human and animals. Experimental samples of human tissues obtained during biopsies, surgeries and pathologoanatomic revisions; samples of breast cancer tissue were obtained from mammary gland division of Blokhin’s Onkological Scientific Center of Russian Ministry of Health. We used also unique collection of tumor transformed epithelial tissues from respiratory tracts of liquidators engaged in elimination of the disaster sequels on the Chernobyl A-plant obtained from Pulmonogical Research Institute. X-ray diffraction and fluorescence study of biological tissues with using synchrotron radiation were carried out on the channel K1.3 of the “Siberia-2” storage ring at NRC “Kurchatovsky Institute”, Moscow (on the constructed and created by us small-angle stations DICSI) and on the channel 3b of VEPP-3 at INP SD RAS, Novosibirsk, and also on SAXS/WAXS station of European Synchrotron Radiation Facility at Grenoble, France. Small-angle X-ray patterns of epithelial tissue, both intact and pathologically transformed, display a large number of sharp diffraction rings at spacing of 4.5 nm and its higher orders caused by the proteoglycans of extracellular matrix of tissue. The period of identity at spacing of 4.65 (± 0.15) nm is attributed by us to regular attachment of olygosaccharide chains to the protein core of giant proteoglycan molecules [A.A.Vazina et al., NIM, 2005, A543, 297-301]. A correlation between the integrated intensity of X-ray patterns and elemental content of tissue is observed. It is experimentally shown that the structure of proteoglycans can be reversibly transformed by metal cations and chelating agents, and that calcium is the major element in the mineral composition of tissue. In cancer transformed tissues intensity of diffuse scattering and diffraction rings of 4.5 nm varies in a wide range and correlates with change of calcium content in the diseased tissues, a significant change in elemental content is detected, up to 200 times increase in the concentration of calcium is found. The final stage of disease is characterized by a significant increase in small-angle diffuse scattering; Debye rings are never registered. Treating the tissue with chelating agents such as EGTA and EDTA, in this case turns out to be ineffective, suggesting the irreversibility of the structural transformation of the extracellular matrix. Thus, the problem of cancerogenesis should be looked at in two aspects: investigation of the mechanisms of normal cell transformation which is initiated by DNA damage (mutations), and the stages of tumor progression, processes of malignant cell proliferation, invasion and metastasis which lead to numerous malignant tumors. X-ray study of tissues indicates that it may be possible to use diffraction characteristics of proteoglycan structures as novel markers of pathological transformation of tissues. The research was supported by RFBR-Moscow region Grant #14-44-03667.