Cancer cells are known to undergo metabolic reprogramming to sustain survival and rapid proliferation, however, it remains to be fully elucidated how oncogenic lesions coordinate the metabolic switch under various stressed conditions. Here we show that deprivation of glucose or glutamine, two major nutrition sources for cancer cells, dramatically activated serine biosynthesis pathway (SSP) that was accompanied by elevated cMyc expression. We further identified that cMyc stimulated SSP activation by transcriptionally upregulating expression of multiple SSP enzymes. Moreover, we demonstrated that SSP activation facilitated by cMyc led to elevated glutathione (GSH) production, cell cycle progression and nucleic acid synthesis, which are essential for cell survival and proliferation especially under nutrient-deprived conditions. We further uncovered that phosphoserine phosphatase (PSPH), the final rate-limiting enzyme of the SSP pathway, is critical for cMyc-driven cancer progression both in vitro and in vivo, and importantly, aberrant expression of PSPH is highly correlated with mortality in hepatocellular carcinoma (HCC) patients, suggesting a potential causal relation between this cMyc-regulated enzyme, or SSP activation in general, and cancer development. Taken together, our results reveal that aberrant expression of cMyc leads to the enhanced SSP activation, an essential part of metabolic switch, to facilitate cancer progression under nutrient-deprived conditions.

In this study, we developed a facile microwave-assisted ethylene glycol approach to synthesize Fe3O4 nanoroses in the presence of the PEO-PPO-PEO block copolymer (P123). The resulting products were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Fourier transform infrared absorption spectroscopy (FT-IR). The characterization results revealed that the Fe3O4 nanoroses were formed by P123 directed assembly of nanoparticles under microwave irradiation. Besides size and morphology-dependent magnetic properties, the as-prepared nanocrystalline Fe3O4 nanoroses exhibited high sensitivity and good reversibility for gas-sensing of ethanol vapor at room temperature. Our results suggest these Fe3O4 nanoroses are promising materials for magnetic and sensing applications.