Pyruvate kinase M2 is a novel diagnostic marker and predicts tumor progression in human biliary tract cancer

BACKGROUND:

The early diagnosis of biliary tract cancer (BTC) remains challenging, and there are few effective therapies. This study investigated whether the M2 isotype of pyruvate kinase (M2‐PK), which serves as the key regulator of cellular energy metabolism in proliferating cells, could play a role in the diagnosis and therapy of BTC.

METHODS:

Plasma and bile M2‐PK concentrations were measured by enzyme‐linked immunosorbent assay in 88 patients with BTC, 79 with benign biliary diseases, and 17 healthy controls. M2‐PK expression was assayed in a BTC tissue array by immunohistochemistry. The role of M2‐PK in tumor growth, invasion, and angiogenesis was evaluated in BTC cell lines by retrovirus‐mediated M2‐PK transfection and short hairpin RNA silencing techniques.

RESULTS:

Sensitivity (90.3%) and specificity (84.3%) of bile M2‐PK for malignancy were significantly higher than those for plasma M2‐PK and serum carbohydrate antigen 19‐9. M2‐PK expression was specific for cancer cells and correlated with microvessel density. M2‐PK positivity was a significant independent prognostic factor by multivariable analysis. Transfection of M2‐PK in a negatively expressed cell line (HuCCT‐1 cells) increased cell invasion, whereas silencing in an M2‐PK–positive cell line (TFK cells) decreased tumor nodule formation and cellular invasion. A significant increase in endothelial tube formation was noted when supernatants from M2‐PK–transfected cells were added to an in vitro angiogenesis assay, whereas supernatants from silenced cells negated endothelial tube formation.

CONCLUSIONS:

Bile M2‐PK is a novel tumor marker for BTC and correlates with tumor aggressiveness and poor outcome. Short hairpin RNA–mediated inhibition of M2‐PK indicates the potential of M2‐PK as a therapeutic target. Cancer 2013. © 2012 American Cancer Society.