Background/aims: This study was conducted to elucidate tumor-induced alterations in pace maker enzymes and possible effects of pre-operative nutritional support on those enzymes in gastrointestinal (GI) cancer patients.
Methodology: Three pacemaker enzymes; phosphoenolpyruvate carboxykinase (PEPck) for gluconeogenesis, malic enzyme for de novo fatty acid synthesis, and lipoprotein lipase (LPL) for triglyceride clearance in liver and adipose tissues were examined in 22 patients with gastrointestinal cancers, both with or without pre-operative total parenteral nutritional support. Five patients with normal nutrition and liver function but undergoing cholecystectomy were used as controls.
Results: Activity of hepatic malic enzyme was significantly decreased (p < 0.05) and activity of hepatic PEPck was slightly elevated in patients with advanced stage cancer. LPL activity in the abdominal subcutaneous tissue was increased by advanced tumor bearing (p < 0.05). Pre-operative total parenteral nutrition for 1 week resulted in significant stimulation of LPL activity in adipose tissue from patients with advanced cancer compared to that from controls (6.53 +/- 4.99 U/g tissue and 1.32 +/- 0.18 U/g tissue, respectively).
Conclusions: Effects of tumor bearing on key regulatory enzymes were evident only at the advanced stages. Pre-operative hyperalimentation may increase fat storage at the peripheral tissue by stimulating tissue LPL activity even at the advanced stage disease.