Human Dachshund homologue 1 (DACH1) is a key component of the Retinal Determination Gene Network (RDGN), originally identified in Drosophila Melanogaster eye specification. In mammals DACH1 governs morphogenetic processes at early growth stages, cell differentiation and tissue homeostasis. Recent studies demonstrated that aberrant expression of RDGN members is involved in the tumorigenic process of different human cancers. However, the role of DACH1 in cancer onset and progression is still controversial. Four alternatively spliced transcripts encoding different isoforms have been described for human DACH1 gene with different molecular weight (100 kDa, 95 kDa, 75kDa and ~52/57 kDa) (AyresJA, Genomics 2001) even though no studies have been conducted so far on the role of different DACH1 isoforms in human cancers. In our present study, we want to elucidate the role of full-length DACH1 isoform (DACH1FL) in prostate tumorigenic process, the molecular mechanisms underlying its over-expression in prostate carcinoma (PCa) cell line PC3 and its expression level in human PCa samples. We are studying the expression and subcellular distribution of DACH1 in normal and tumor prostate (PCa) tissues by human PCa biopsies with different tumor stages by immunohistochemistry. On the basis of these data, we will analyze these primary tumor and normal samples by western blot to identify the presence of different DACH1 splicing variants. In addition, our aim is to investigate the functional role of DACH1 full-length isoform (DACH1FL) in modulating radioresistance in prostate cancer cell line PC3. The ultimate goal of this project is to define DACH1FL as a prognostic marker in prostate cancer.
In mammals DACH1 governs morphogenetic processes at early growth stages, cell differentiation and tissue homeostasis 3. Recent studies demonstrated that aberrant expression of RDGN members is involved in the tumorigenic process of different human cancers, from its beginning to its progression. Indeed, some works have described DACH1 as a tumor suppressor, others as an oncogene. In our present study, we aimed to elucidate the role of DACH1 in PCa, focusing our attention to DACH1 full-length isoform.
Due to its intrinsic radioresistance, prostate cancer (PCa) frequently recurs after external-beam radiotherapy (EBRT). Human Dachshund homologue 1 (DACH1) accounts for the carcinogenesis of various cancers with opposite roles, depending on tumor types. Four alternatively spliced transcripts encoding different DACH1 isoforms were described but their role in human cancers is still unknown. In this project we will elucidate the role of DACH1 isoforms in prostate tumorigenic process, the molecular mechanisms underlying its over-expression in PCa cell line PC3 and its expression level in human PCa biopsies with different tumor stages. As DACH1 can antagonize EMT, a process closely associated to PCa radioresistance, we also will investigate a potential correlation of DACH1FL with radioresistance, that has not been investigated yet. Since our preliminary results revealed that RWPE-1 cells, a cell line derived from normal human prostate, express different DACH1 isoform from that expressed by PC3 cells, we will over-express the PC3 isoform in the normal RWPE1 with the aim to verify the conversion to the oncogenic phenotype in DACH1FL-transfected prostate normal cells. Finally, our ultimate goal is to define the oncogenic role of DACH1FL in PCa and that it could represent a novel diagnostic and prognostic marker in prostate cancer, being the last one the most sought-after goal in PCa.