THE IMPORTANCE OF GENE POLYMORPHISMS IN RANKL/RANK/OPG PATHWAY IN ETIOLOGY OF POSTMENOPAUSAL OSTEOPOROSIS Adam Kamiński1, Karolina Dziekan1, Hubert Wolski2, Radosław Kujawski1, Anna Bogacz1,3, Marcin Ożarowski1,4, Bogusław Czerny1,5, Małgorzata Górska-Paukszta1, Agnieszka Seremak-Mrozikiewicz1,2 1Institute of Natural Fibres and Medicinal Plants, 62-064 Plewiska, Poland 2Division of Perinatology and Women’s Diseases, Poznan University of Medical Sciences, 60-535 Poznan, Poland 3Department of Clinical Pharmacy and Biopharmacy, University of Medical Sciences, 60-781 Poznan, Poland 4Department of Pharmaceutical Botany and Plant Biotechnology, University of Medical Sciences, 61-861 Poznan, Poland 5Department of General Pharmacology and Pharmacoeconomics, Pomeranian Medical University, 70-204 Szczecin, Poland D INTRODUCTION Osteoporosis is a serious metabolic disorder in advanced age with decreased bone mineral density with a significant role of hormonal, environmental and genetic factors. In recent years it has been noted that the processes of growth, maturity, segregation and differentiation of osteoclasts are synchronized and modulated by many factors, in which the key role could play the signal pathway that is directly involved in bone resorption. Currently it is though that in this trail the receptor activator of nuclear factor kappa B (RANK), its ligand (RANKL – receptor activator of nuclear factor - B ligand) and osteoprotegerin (OPG) are involved. It seems that dynamic steadiness between RANKL/RANK and OPG activities determines the regulation of differentiation and activation of osteoclasts, thus significantly affects the metabolism of bone tissue. The RANKL/RANK/OPG trail is directly involved into the proliferation and apoptosis of osteoclasts. The disturbances in RANKL/RANK/OPG system can be major part of postmenopausal osteoporosis etiology. Moreover it has been shown that genes encoding RANKL/RANK/OPG system are closely involved in osteoporosis development. The aim of this study was to investigate the distribution of genotypes of OPG (163A>G, -245T>G, -950T>C, 1181G>C), RANK (575C>T) and RANKL (-643C>T) polymorphisms in the group of postmenopausal women and to determine the connection of examined genetic variants with parameters of the bone turnover and progresses of osteoporosis. However, the TT genotype and T allele of -643C>T polymorphism appeared more frequent in the group with osteoporosis and osteopenia compared to healthy women. We also suggest lack of correlation of the -245T>G, -950T>C and 1181G>C polymorphisms of OPG gene and RANK 575C>T polymorphism with the occurrence of osteoporosis [Tab. 1.]. Tab. 1. The frequency of occurrence of polymorphisms of the OPG, RANK, RANKL genotypes in women with osteoporosis, osteopenia, healthy in postmenopausal and in reproductive age. Genotype Women with osteopenia Women with osteoporosis Women with normal T-score Women in reproductive age Observed value n (%) OPG -163A/G AA 83 (76,9%) 100 (72,5%) 51 (81,0%) 158 (73,1%) AG 22 (20,4%) 37 (26,8%) 11 (17,5%) 53 (24,5%) GG 3 (2,8%) 1 (0,7%) 1 (1,6%) 5 (2,3%) OPG -950T/C TT 38 (36,9%) 41 (30,8%) 15 (25,4%) 85 (29,3%) TC 42 (40,8%) 56 (42,1%) 28 (47,5%) 143 (49,3%) CC 23 (22,3%) 36 (27,1%) 16 (27,1%) 62 (21,4%) RANK 575C/T 12 (20,0%) 15 (34,1%) 3 (11,1%) 46 (28,8%) CT 34 (56,7%) 21 (47,7%) 19 (70,4%) 82 (51,2%) 14 (23,3%) 8 (18,2%) 5 (18,5%) 32 (20,0%) RANKL -643C/T 13 (18,6%) 11 (23,4%) 10 (31,3%) 28 (17,5%) 39 (55,7%) 26 (55,3%) 20 (62,5%) 94 (58,8%) 18 (25,7%) 10 (21,3%) 2 (6,2%) 38 (23,7%) MATERIAL AND METHODS The study included 310 postmenopausal Caucasian women (139 women with osteoporosis, 107 women with osteopenia and 64 healthy women) (Fig. 1.). The bone mineral density (BMD) at the lumbar spine (L1-L4) was measured by dual energy x-ray absorptiometry (DXA). Genetic analysis was performed using PCR-RFLP method. Fig. 1. The characteristics of women in postmenopausal age CONCLUSIONS These findings could suggest a participation of the OPG -163A>G polymorphism in osteoporosis development. Moreover, the RANKL -643C>T polymorphism may have a significant influence on body weight and BMI in postmenopausal women with osteoporosis. REFERENCES Mencej S., Prezelj J., Kocijancic A. et al. Association of NFSF11 gene promoter polymorphisms with bone mineral density in postmenopausal women, Maturitas. 2006; 55 (3) 219–226. Kim J.G., Kim J.H., Kim J.Y. et al. Association between osteoprotegerin (OPG), receptor activator of nuclear factor-kappaB (RANK), and RANK ligand (RANKL) gene polymorphisms and circulating OPG, soluble RANKL levels, and bone mineral density in Korean postmenopausal women, Menopause. 2007; 14 (5) 913–918. Choi J.Y., Shin A., Park S.K. et al. Genetic polymorphisms of OPG, RANK, and ESR1 and bone mineral density in Korean postmenopausal women, Calcif Tissue Int. 2005;77 (3) 152–159. Guo L, Tang K, Quan Z et al. Association between seven common OPG genetic polymorphisms and osteoporosis risk: a meta-analysis. DNA Cell Biol 2014; 33: 29-39. Shang M, Lin L, Cui H. Association of genetic polymorphisms of RANK, RANKL and OPG with bone mineral density in Chinese peri- and postmenopausal women. Clin Biochem 2013; 46: 1493-1501. RESULTS The results showed a higher frequency of heterozygotes AG genotype and mutated G allele of the -163A>G polymorphism in OPG gene in women with osteoporosis. Analysis of the frequency of genotypes and alleles of RANK and RANKL polymorphisms showed no statistically significant differences between study groups.