GLI transcription factors have important roles in intracellular signaling cascade, acting as the main mediators of the HH-GLI signaling pathway. This is one of the major developmental pathways, regulated both canonically and non-canonically. Deregulation of the pathway during development leads to a number of developmental malformations, depending on the deregulated pathway component. The HH-GLI pathway is mostly inactive in the adult organism but retains its function in stem cells. Aberrant activation in adult cells leads to carcinogenesis through overactivation of several tightly regulated cellular processes such as proliferation, angiogenesis, EMT. Targeting GLI transcription factors has recently become a major focus of potential therapeutic protocols.

The aim of the study was to determine (1) the frequency and type of mutations in the coding region of the GJB2 gene (sequencing), (2) the frequency of splice site mutation IVS1 + 1G > A in the GJB2 gene (multiplex ligation–dependent probe amplification analysis), (3) possible copy number changes in the GJB2, GJB3, GJB6, and WFS1 genes (multiplex ligation–dependent probe amplification analysis), and (4) the frequency of del(GJB6-D13S1830) in the GJB6 gene in 58 unrelated patients with nonsyndromic hearing loss from Croatia. About 44.8% of our patients presented with mutation in the GJB2 gene. We identified seven sequence variations. Six of them had previously been reported as disease related (35delG, W24X, V37I, L90P, 313del14, and IVS1 + 1G > A), and we report here for the first time one novel variant, −24A > C. We detected the greatest frequency of 35delG allele compared to the other alleles (35.3%). Allelic frequencies of other common mutations accounted for 2.6–0.9% of analyzed chromosomes. Neither GJB6 deletion nor copy number changes in the GJB2, GJB3, GJB6, and WFS1 genes were found. The 35delG/35delG genotype was associated with severe to profound hearing loss in 94% of 35delG homozygotes. High mutation rate (44%) indicates that testing of the GJB2 gene will clarify the genetic cause in almost half of the cases of recessive nonsyndromic hearing loss in Croatia.

Unlike other tumours, TP53 is rarely mutated in melanoma; however, it fails to function as a tumour suppressor. We assume that its functions might be altered through interactions with several families of proteins, including p53/p73, NME and GLI. To elucidate the potential interplay among these families we analysed the expression profiles of aforementioned genes and proteins in a panel of melanoma cell lines, metastatic melanoma specimens and healthy corresponding tissue. Using qPCR a higher level of NME1 gene expression and lower levels of Δ40p53β, ΔNp73, GLI1, GLI2 and PTCH1 were observed in tumour samples compared to healthy tissue. Protein expression of Δ133p53α, Δ160p53α and ΔNp73α isoforms, NME1 and NME2, and N′ΔGLI1, GLI1FL, GLI2ΔN isoforms was elevated in tumour tissue, whereas ∆Np73β was downregulated. The results in melanoma cell lines, in general, support these findings. In addition, we correlated expression profiles with clinical features and outcome. Higher Δ133p53β and p53α mRNA and both GLI1 mRNA and GLI3R protein expression had a negative impact on the overall survival. Shorter overall survival was also connected with lower p53β and NME1 gene expression levels. In conclusion, all examined genes may have implications in melanoma development and functional inactivity of TP53.