These mutations, together with the newly identified ones in SEC61B and Alpha-1,3-Glucosyltransferase (ALG8), can be found in ∼50% of patients with isolated polycystic liver disease.
Cdc25A expression was analyzed in livers of control and polycystic kidney (PCK) rats, control and polycystic kidney 2 (Pkd2(ws25/-)) mice, healthy individuals, and patients with PLD.
In polycystic kidney disease and polycystic liver disease (PLD), the normally nonproliferative hepato-renal epithelia acquire a proliferative, cystic phenotype that is linked to overexpression of cell division cycle 25 (Cdc25)A phosphatase and cell-cycle deregulation.
In addition, levels of normal hepatocystin and of the glucosidase II alpha subunit are substantially reduced in liver and Epstein-Barr virus-immortalized B lymphoblasts from patients with polycystic liver disease.
However, the activation of TGR5-dependent signalling may also trigger proliferation and apoptosis resistance of cystic cholangiocytes and malignantly transformed cholangiocytes, thus promoting cyst growth in polycystic liver disease or progression of cholangiocarcinoma.
TGR5 contributes to hepatic cystogenesis by increasing cAMP and enhancing cholangiocyte proliferation; our data suggest that a TGR5 antagonist alone or concurrently with somatostatin receptor agonists represents a potential therapeutic approach in polycystic liver disease.(Hepatology 2017;66:1197-1218).
Nevertheless, TGR5 overexpression or constant stimulation of the receptor can promote cholangiocyte proliferation leading to cyst growth in polycystic liver disease or even progression of cholangiocarcinoma.
While TGR5 agonists may improve various aspects of metabolic, inflammatory, and cholestatic liver diseases, TGR5 inhibitors may attenuate disease progression in polycystic liver disease and cholangiocarcinoma.
Genetic defects in polycystin-1 or -2 (PC1 or PC2) cause polycystic liver disease associated with autosomal dominant polycystic kidney disease (PLD-ADPKD).