High Expression of HIF-1α, BNIP3 and PI3KC3: Hypoxia-Induced Autophagy Predicts Cholangiocarcinoma Survival and Metastasis

Abstract

Hypoxia and autophagy are known to facilitate tumor progression. We here aimed to investigate the role ofhypoxia-associated autophagy in cholangiocarcinoma (CCA) survival and metastasis. Immunostaining of hypoxicresponsiveproteins (HIF-1α and BNIP3) and a key regulator of autophagy (PI3KC3) were examined in CCAtissues and their expression levels were compared with clinicopathological parameters. A hypoxia mimickingcondition (CoCl2 treatment) was also tested regarding CCA cell functions. Our results showed that HIF-1α (66%),BNIP3 (44%) and PI3KC3 (46%) showed strong staining in human CCA tissues. Positive expression of HIF-1α(p=0.033), BNIP3 (p=0.040) and PI3KC3 (p=0.037) was significantly correlated with lymph node metastasis.HIF-1α was well associated with BNIP3 (r=0.3, p<0.01) and PI3KC3 (r=0.2, p<0.01). The survival rates ofpatients who were positive with HIF-1α (p=0.047) or co-expressed HIF-1α and BNIP3 (p=0.032) or HIF-1α andPI3KC3 (p=0.043) were significantly greater than in the negative groups. CCA cells treated with CoCl2 showedan increase in HIF-1α, BNIP3, PI3KC3 and LC3-II, with increased cell migration and pFAK levels. These datasuggest that hypoxia associated autophagy enhances CCA metastasis, resulting in a poor prognosis of CCA.