It has been long recognized that under hypoxia conditions cancer cells reprogram their metabolism through shift from oxidative phosphorylation (OXPHOS) to glycolysis to meet elevated requirements in energy and nutrients for proliferation, migration and survival. However, data accumulated over the last years increasingly evidence that cancer cells can revert from glycolysis to OXPHOS and maintain both reprogrammed and oxidative metabolism even in the same tumor. The phenomenon denoted as cancer cell metabolic plasticity or hybrid metabolism depends on a tumor micro-environment, which is highly heterogeneous and influenced by intensity of vasculature and blood flow, oxygen concentration, nutrient and energy supply, and requires regulatory interplay between multiple oncogenes, transcription factors, growth factors, reactive oxygen species (ROS), etc. Hypoxia-inducible factor-1 (HIF-1) and AMP-activated protein kinase (AMPK) represent key modulators of switch between reprogrammed and oxidative metabolism. The present review focuses on cross-talks between HIF-1, GLUTs, and AMPK and other regulatory proteins including oncogenes such as c-Myc, p53 and KRAS, growth factor-initiated PKB/Akt, PI3K and mTOR signaling pathways and tumor suppressors such as LKB1 and TSC1 in controlling cancer cell metabolism. The multiple switches between metabolic pathways can underlie chemo-resistance to conventional anti-cancer therapy and should be taken into account in choosing molecular targets to discovery novel anti-cancer drugs.