Hypoxic induction of vasculogenic mimicry in hepatocellular carcinoma: role of HIF-1 α, RhoA/ROCK and Rac1/PAK signaling.

Abstract

BACKGROUND:

Vasculogenic mimicry (VM), defined as a capability of aggressive tumor Cells to mimic embryonic vasculogenic networks, caused poor prognosis in hepatocellular carcinoma (HCC). Rho kinases (ROCK), p21-activated kinase (PAK), hypoxia or epithelial-mesenchymal transition (EMT) contributed to the VM potential. However, the details underlying these biological behaviors have not been completely elucidated.

METHODS:

Kaplan-Meier analysis was conducted to predict relationship with hypoxia Inducible factor (HIF-1α), EMT related markers: Vimentin and patient prognosis. CD34/periodic acid-Schiff (PAS) double staining was examined to differentiate VM-positive (VM+) and VM-negative (VM-) samples. Cells were cultured under controlled hypoxic environments (1% O2) or normoxic conditions. The effect of hypoxia on RhoA/ROCK, Rac1/PAK and EMT were evaluated by real time-qPCR and western blot. HIF-1α small interfering RNA (siRNA), overexpressed or short hairpin RNA (shRNA) of ROCK and kinase inhibitors were used to explore the effect of HIF-1α, RhoA/ROCK, Rac1/PAK and Vimentin on VM.

RESULTS:

HIF-1α or Vimentin was upregulated in VM+ HCC tissues, compared to non-cancerous tissues (P < 0.01), and patients with high expression of HIF-1α or Vimentin had worse prognosis (P < 0.001). We showed hypoxia induced RhoA/ROCK and Rac1/PAK signaling transduction, and EMT could be repressed by HIF-1α siRNA. Notably, RhoA/ROCK or Rac1/PAK stabilized HIF-1α in hypoxia, whereas HIF-1α did not significantly altered RhoA/ROCK or Rac1/PAK signaling in hypoxia. Moreover, we found distinct roles of ROCK1, ROCK2 and PAK in regulating Vimentin phosphorylation.

CONCLUSIONS:

RhoA/ROCK and Rac/PAK signaling played crucial roles in hypoxia-induced VM via Ser72 and Ser56 Vimentin phosphorylation in HCC.

• Authors: Ji-Gang Zhang, He-Ming Zhou, Xue Zhang, Wan Mu, Juan-Ni Hu, Gao-Lin Liu, Qin Li
• Journal: BMC cancer (BMC Cancer) Vol. 20 Issue 1 Pg. 32 (Jan 13 2020) ISSN: 1471-2407 [Electronic] England
• PMID: 31931758 (Publication Type: Journal Article)

Chemical References

• Biomarkers
• HIF1A protein, human
• Hypoxia-Inducible Factor 1, alpha Subunit
• RAC1 protein, human
• Vimentin
• RHOA protein, human
• p21-Activated Kinases
• rac1 GTP-Binding Protein
• rhoA GTP-Binding Protein

Topics

• Adult
• Aged
• Biomarkers
• Carcinoma, Hepatocellular (metabolism, mortality, pathology)
• Disease Progression
• Epithelial-Mesenchymal Transition
• Female
• Humans
• Hypoxia (metabolism)
• Hypoxia-Inducible Factor 1, alpha Subunit (metabolism)
• Immunohistochemistry
• Kaplan-Meier Estimate
• Liver Neoplasms (metabolism, mortality, pathology)
• Male
• Middle Aged
• Neoplasm Metastasis
• Neoplasm Staging
• Neovascularization, Pathologic (metabolism)
• Prognosis
• Signal Transduction
• Vimentin (metabolism)
• p21-Activated Kinases (metabolism)
• rac1 GTP-Binding Protein (metabolism)
• rhoA GTP-Binding Protein (metabolism)