Identification, molecular characterization and alternative splicing of three novel members of the canine kallikrein (Klk)-related peptidase family

Background/Aim: Kallikrein-related peptidases (KLKs) comprise a serine protease family with prominent roles in tissue physiology and disease pathogenesis, including cancer. Previously, we have characterized canine Klk4-10 and -14. Herein, we continue our efforts by characterizing three novel members of the canine family, i.e. Klk11-13, and investigating their expression in mammary cancer. Materials and Methods: Reverse transcription-polymerase chain reaction (RT-PCR) and DNA sequencing were used for investigating the expression and determining the nucleotide sequence of all transcripts identified, respectively. Results: It was demonstrated that (i) unlike other Klks, (CANFA)Klk12 probably possesses a non-AUG translation initiation codon, (ii) all three Klks undergo alternative splicing, with exon 2 and 3 concurrent elimination serving as the most prominent event, (iii) all transcripts identified were detected in both tumor and normal tissues, yet with different frequencies. Conclusion: Having completed this work, Klk15 is the only gene remaining to experimentally resolve the entire canine Klk family. Our data lay sufficient groundwork for validation studies and await further incorporation into genetic/evolutionary studies with translational impact.