Genes associated with testicular germ cell tumors and testicular dysgenesis in patients with testicular microlithiasis

Testicular microlithiasis (TM) is one of the symptoms of testicular dysgenesis syndrome (TDS). TM is particularly interesting as an informative marker of testicular germ cell tumors (TGCTs). KIT ligand gene (KITLG), BCL2 antagonist/killer 1 (BAK1), and sprouty RTK signaling antagonist 4 (SPRY4) genes are associated with a high risk of TGCTs, whereas bone morphogenetic protein 7 gene (BMP7), transforming growth factor beta receptor 3 gene (TGFBR3), and homeobox D cluster genes (HOXD) are related to TDS. Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis, we investigated allele and genotype frequencies for KITLG (rs995030, rs1508595), SPRY4 (rs4624820, rs6897876), BAK1 (rs210138), BMP7 (rs388286), TGFBR3 (rs12082710), and HOXD (rs17198432) in 142 TGCT patients, 137 TM patients, and 153 fertile men (control group). We found significant differences in the KITLG GG_rs995030 genotype in TM (P = 0.01) and TGCT patients (P = 0.0005) compared with the control. We also revealed strong associations between KITLG_rs1508595 and TM (G allele, P = 0.003; GG genotype, P = 0.01) and between KITLG_rs1508595 and TGCTs (G allele, P = 0.0001; GG genotype, P = 0.0007). Moreover, there was a significant difference in BMP7_rs388286 between the TGCT group and the control (T allele, P = 0.00004; TT genotype, P = 0.00006) and between the TM group and the control (T allele, P = 0.04). HOXD also demonstrated a strong association with TGCTs (rs17198432 A allele, P = 0.0001; AA genotype, P = 0.001). Furthermore, significant differences were found between the TGCT group and the control in the BAK1_rs210138 G allele (P = 0.03) and the GG genotype (P = 0.01). KITLG and BMP7 genes, associated with the development of TGCTs, may also be related to TM. In summary, the KITLG GG_rs995030, GG_rs1508595, BMP7 TT_rs388286, HOXD AA_rs17198432, and BAK1 GG_rs210138 genotypes were associated with a high risk of TGCT development.

[Genetic risk factors for sporadic germ cell testicular tumors]

INTRODUCTION

Approximately 95% of all testicular cancers are testicular germ cell tumors (GCTTs), represented by seminoma and nonseminoma germ cell testicular cancer. There is a hypothesis that the formation of GCTTs begins in early embryogenesis being a part of testicular dysgenesis syndrome (TDS).

AIM

To determine the role of genetic factors in the development of GCTTs.

MATERIALS AND METHODS

We studied the frequency of alleles and genotypes KITLG (rs995030, rs1508595), SPRY4 (rs4624820, rs6897876) and BAK1 (rs210138) in 97 fertile men (control), and 73 patients with GCTTs (34 seminoma and 39 nonseminoma).

RESULTS

GCTTs were statistically significantly associated with KITLG rs1508595 gene (p=0.0003 for allele G, p=0.0014 for genotype GG), and with rs995030 gene (p=0.0031 for genotype GG). When comparing patients with seminoma and control group, statistically significant differences were found for SPRY4 rs4624820 (p=0.0226 for the A and p=0.04 for the AA), for KITLG rs995030 (p=0.0375 for the G and p=0.0282 for GG), rs1508595 (p=0.0306 for G), for BAK1 rs210138 (p=0.0329 for the G and p=0.0219 for the GG). When comparing patients with nonseminoma and fertile men, statistically significant differences were found only for KITLG rs1508595 (p=0.0005 for the G and p=0.0021 for the GG). There was no statistically significant difference between the allele and genotype frequencies of the investigated genes from seminoma and nonseminoma GCTTs patients. However, these groups differed statistically significantly when genotype combinations of the three genes were investigated (p=0,029; OR 3,709 [1.147-11.99]). The combination of genotypes of the three genes was found to increase the risk of GCTTs by 6.5 times (p=0.0005; OR 6.526 [2.078-20.5], and the risk for seminoma was over 12-fold (p<0.0001; OR 12,68 [3,731-43,11].

CONCLUSION

A comprehensive study of genotypes associated with GCTTs in patients with manifested TDS can be used for risk stratification to identify and follow-up high-risk patients, develop approaches to family counseling and treatment, which is the basis for predictive medicine.

[Polymorphisms of KITLG, SPRY4, and BAK1 genes in patients with testicular germ cell tumors and individuals with infertility associated with AZFc deletion of the Y chromosome]

Testicular cancer is the most common form of solid cancer in young men. Testicular cancer is represented by testicular germ cell tumors (TGCTs) derived from embryonic stem cells with different degrees of differentiation in about 95% of cases. The development of these tumors is related to the formation of a pool of male germ cells and gametogenesis. Clinical factors that are predisposed to the development of germ-cell tumors include cryptorchidism and testicular microlithiasis, as well as infertility associated with the gr/gr deletion within the AZFс locus. KITLG, SPRY4, and BAK1 genes affect the development of the testes and gametogenesis; mutations and polymorphisms of these genes lead to a significant increase in the risk of the TGCT development. To determine the relationship between gene polymorphisms and the development of TGCTs, we developed a system for detection and studied the allele and genotype frequencies of the KITLG (rs995030, rs1508595), SPRY4 (rs4624820, rs6897876), and BAK1 (rs210138) genes in fertile men, patients with TGCTs, and patients with infertility that have the AZFс deletion. A significant association of rs995030 of the KITLG gene with the development of TGCTs (p = 0.029 for the allele G, p = 0.0124 for the genotype GG) was revealed. Significant differences in the frequencies of the studied polymorphisms in patients with the AZFc deletion and the control group of fertile men were not found. We showed significant differences in the frequencies for the combination of all high-risk polymorphisms in the control group, patients with the AZFc deletion and patients with TGCTs (p (TGCTs-AZF-control) = 0.0207). A fivefold increase in the frequency of the combination of all genotypes in the TGCT group (p = 0.0116; OR = 5.25 [1.44-19.15]) and 3.7-fold increase was identified in patients with the AZFc deletion (p = 0.045; OR = 3.69 [1.11-12.29]) were revealed. The genotyping of patients with infertility caused by the AZFc deletion can be used to identify individuals with an increased risk of TGCTs.