Additional N-glycosylation mutation in the major hydrophilic region of hepatitis B virus S gene is a risk indicator for hepatocellular carcinoma occurrence in patients with coexistence of HBsAg/anti-HBs

Abstract

The study aimed to determine the association of additional N-glycosylation mutations in the major hydrophilic region (MHR) of hepatitis B virus (HBV) S gene with hepatocellular carcinoma (HCC) occurrence in HBsAg/anti-HBs coexistent patients. A total of 288 HBsAg/anti-HBs coexistent patients and 490 single HBsAg-positive patients were enrolled, including 193 with HCC, 433 with chronic hepatitis B (CHB), and 152 with acute-on-chronic liver failure (ACLF). The HBV S genes were amplified from serum and sequenced. The frequency of additional N-glycosylation mutations was significantly higher in HCC patients (12.37%) than in CHB patients (4.39%) and ACLF patients (2.63%). The frequency escalated by an order of single HBsAg-positive non-HCC (1.61%), single HBsAg-positive HCC (5.98%), HBsAg/anti-HBs coexistent non-HCC (8.01%), and HBsAg/anti-HBs coexistent HCC (22.36%). Twelve kinds of mutations/mutation patterns were detected, five of which have not been reported. Multivariate analysis showed that age > 40 years [OR, 3.005; 95% CI, 1.177−7.674; P = 0.021], alpha-fetoprotein > 10 ng/mL [OR, 4.718; 95% CI, 2.406−9.251; P <0.001], cirrhosis [OR, 6.844; 95% CI, 2.773−16.891, P < 0.001], Hepatitis B e antigen negativity [OR, 2.218; 95% CI, 4.335, P = 0.020], and additional N-glycosylation mutation [OR, 2.831; 95% CI, 1.157−6.929; P = 0.023] were independent risk factors for HCC in HBsAg/anti-HBs coexistent patients. Dynamical analysis showed that the additional N-glycosylation mutations existed 1-4 years prior to HCC occurrence in eight of 18 patients observed. In conclusion, the dditional N-glycosylation mutations together with HBsAg/anti-HBs coexistence might serve as a predictive indicator for HCC occurrence in chronic HBV-infected patients.

N-Glycosylation and N-Glycan Processing in HBV Biology and Pathogenesis

“…Interestingly, these mutations are significantly more frequent in HBsAg/anti-HBsAg antibodies-coexisting patients who develop HCC than in those who do not. Moreover, they are often detected several years before HCC onset, raising the question of a direct involvement of N-linked glycans in disease progression [ 70 ].…”

“…Functional analysis of the newly discovered mutations was further performed in transfected HepG2 cells. However, neither cell proliferation nor migration was affected in cells expressing HBV-S with additional N-linked glycans [ 70 ].…”

The truncated mutant HBsAg expression increases the tumorigenesis of hepatitis B virus by regulating TGF-β/Smad signaling pathway

“…Instead, host cellular immunity and humoral immunity against HBV should be the main reason causing liver damage. It has been reported that the HBsAg produced by some HBV mutants may help virus particles escaping immune surveillance, thus hindering the body’s immune system killing HBV, leading to persistent infection of HBV and continuous liver injury, and finally resulting in the development of liver cirrhosis or even HCC [ 9 , 10 ]. Additionally, HBsAg protein can interfere with some important signaling pathways in hepatocyte, which may induce malignant proliferation of hepatocytes and lead to the occurrence of hepatocellular carcinoma [ 4 , 11 ].…”

Antiviral effects of hepatitis B virus S gene-specific anti-gene locked nucleic acid in transgenic mice

“…HBV contains 4 overlapping open reading frames (ORFs) encoding the polymerase (P), core (C), surface antigen (S), and X proteins[ 29 ]. The S gene region is one of the most important open reading frames of the HBV genome, encoding a protein forming an important part of HbsAg[ 30 , 31 ]. Thus, the S gene is not only closely associated with virus replication, transcription, assembly, and secretion processes, but also with cellular and humoral immune responses induced by the virus.…”