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

• Published in: BMC cancer Vol. 20; no. 1; p. 32
• Main Authors: Zhang, Ji-Gang, Zhou, He-Ming, Zhang, Xue, Mu, Wan, Hu, Juan-Ni, Liu, Gao-Lin, Li, Qin
• Format: Journal Article
• Language: English
• Published: England BioMed Central 13-01-2020; BMC
• Subjects: Antibiotics; Binding sites; CD34 antigen; Cell adhesion & migration; Cloning; Hepatocellular carcinoma; HIF-1α; Hypoxia; Hypoxia-inducible factor 1; Immunoglobulins; Kinases; Liver cancer; Medical prognosis; Mesenchyme; Mimicry; p21-activated kinase; Phosphorylation; Prognosis; Proteins; Rac1 protein; Rac1/PAK; Rho protein; Rho-associated kinase; RhoA protein; RhoA/ROCK; Signal transduction; siRNA; Tumor cells; Tumors; Vimentin; Vimentin;Vasculogenic mimicry; United States > US; China; HIF-1α; Rac1/PAK; RhoA/ROCK; Vimentin;Vasculogenic mimicry
• ISSN: 1471-2407; 1471-2407
• DOI: 10.1186/s12885-019-6501-8

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