"Haemochromatotic" characteristics of the human BEL-7402 cell line

Comparison of structure and the synergistic anti-hepatocellular carcinoma effect of three polysaccharides from vinegar-baked Radix Bupleuri

Three polysaccharides from Vinegar-baked Radix Bupleuri (VR) and their combined effects were studied. VRP3-3 was a branched polysaccharide with a molecular weight (Mw) of 16.05 kDa characterized by 1,5 linked-α-Araf, 1,2,4 linked-α-Rhap and 1,4 linked-α-GalpA as main chain with a small amount of esterification and acetylation groups. And side chains were connected to the O-3 of Araf, O-4 of Rhap. VRP2-3 had a Mw of 95.35 kDa, its backbone comprised of 1,2 linked-α-Galp, 1,4 linked-β-GalpA(O-Ac), 1,2,4 linked-α-Rhap and 1,5 linked α-Araf. The residues of 1,4 linked-β-Galp,1,3 linked-β-Galp and 1,6 linked-β-D-Galp were connected at O-4 of α-L-Rhap and O-3 of α-L-Araf as its side chain. VRP2-4 was a pectin polysaccharide with a Mw of 57.90 kDa. Its main chain was constituted of 1,4 linked-α-Galp, 1,4 linked-α-GalpA(OMe), 1,4 linked-α-GalpA and 1,2,4 linked-α-Rhap, with some acetylation. As the major side chain, 1,5 linked-α-Araf was connected to O-4 of α-Rhap, a small amount of t-α-Galp and t-α-Manp were also included. VRP3-3 showed superior synergistic effect in combination with paclitaxel, methotrexate and cisplatin than the other two polysaccharides. The VR polysaccharide with a ~16 kDa molecular weight, a larger polymerization degree of arabinan in the backbone and the triple helix structure are the key structures for activity. Together, our findings clarify the pharmacodynamic basis of VR and provide promising adjuvants for Hepatocellular Carcinoma (HCC) chemotherapy.

Identification of novel non-HFE mutations in Chinese patients with hereditary hemochromatosis

BACKGROUNDS

Hereditary hemochromatosis (HH) is mainly caused by homozygous p.C282Y mutations in HFE in the Caucasians. We recently reported non-HFE mutations constitute the major cause of HH in Chinese. However, there is still a relatively high proportion of cases with primary iron overload from unexplained causes. We aimed to explore novel non-HFE mutations in Chinese patients with primary iron overload.

METHODS

Whole exome sequence was conducted to screen mutations in novel HH-related genes in the 9 cases with unexplained primary iron overload. Then the representative candidate genes were screened for mutations in another cohort of 18 HH cases. The biological function of the selected genes and variants were analyzed in vitro.

RESULTS

Whole exome sequencing of 9 cases with unexplained primary iron overload identified 42 missense variants in 40 genes associated with iron metabolism pathway genes such as UBE2O p.K689R and PCSK7 p.R711W. Subsequent Sanger sequencing of the UBE2O and PCSK7 genes in the 27 cases with primary iron overload identified p.K689R in UBE2O, p.R711W and p.V143F in PCSK7 at frequency of 2/27,1/27 and 2/27 respectively. In vitro siRNA interference of UBE2O and PCSK7 resulted in down-regulated HAMP mRNA expression. Adenovirus generation of UBE2O p.K689R in cell lines resulted in increased expression of SMAD6 and SMAD7 and downregulation of p-SMAD1/5 and HAMP expression, and the reduction of hepcidin level.

CONCLUSIONS

Our study identified a series of novel candidate non-HFE mutations in Chinese patients with HH. These may provide insights into the genetic basis of unexplained primary iron overload.

A novel SLC40A1 p.Y333H mutation with gain of function of ferroportin: A recurrent cause of haemochromatosis in China

BACKGROUND & AIMS

Haemochromatosis type 4, also known as ferroportin disease, is an autosomal dominant genetic disorder caused by pathogenic mutations in the SLC40A1 gene, which encodes ferroportin 1 (FPN1). We have identified a novel SLC40A1 p.Y333H mutation in our previous study. In the present study, we tried to investigate the frequency and pathogenicity of the SLC40A1 p.Y333H mutation in haemochromatosis in China.

METHODS

Patients were analysed for SLC40A1 p.Y333H as well as mutations in the other classic haemochromatosis-related genes by Sanger sequencing. To analyse iron export capacity of the SLC40A1 p.Y333H mutant, the 293T cells were transfected with the SLC40A1 p.Y333H construct and then treated with hepcidin after exposure to ferric ammonium citrate. Cellular localization of mutant FPN1, expression of FPN1 and intracellular ferritin were analysed by immunofluorescence and Western blotting.

RESULTS

Of 22 unrelated cases with primary iron overload, three cases (3/22, 13.6%) harboured the SLC40A1 p.Y333H, with no missense mutations identified in any other classical haemochromatosis-related genes including HFE, HJV, HAMP and TFR2. Pedigree analysis showed that three probands and the son of one proband had haemochromatosis of stage 3, while the son of another proband with age of 16 showed elevated transferrin saturation but normal serum ferritin level. In vitro studies showed the mutant p.Y333H ferroportin was resistant to hepcidin, affecting the subsequent internalization and degradation of FPN1, and was associated with ferroportin gain of function.

CONCLUSIONS

The SLC40A1 p.Y333H mutation is associated with gain of function of ferroportin, representing one of the major aetiological factors of haemochromatosis in China.