ABSTRACT
BACKGROUND: The energy supply of certain cancer cells depends on aerobic glycolysis rather than oxidative phosphorylation. Our previous studies have shown that withaferin A (WA), a lactone compound derived from Withania somnifera, suppresses skin carcinogenesis at least partially by stabilizing IDH1 and promoting oxidative phosphorylation. Here, we have extended our studies to evaluate the anti-tumor effect of WA in liver cancer. METHODS: Differential expression of glycolysis-related genes between liver cancer tissues and normal tissues and prognosis were verified using an online database. Glycolysis-related protein expression was detected using western blot after overexpression and knockdown of IDH1 and mitochondrial membrane potential assay based on JC-1, and mitochondrial complex I activity was also detected. The inhibitory effect of WA on the biological functions of HepG2 cells was detected along with cell viability using MTT assay, scratch assay, clone formation assay, glucose consumption and lactate production assay. Western blot and qRT-PCR were used to detect the expression of proteins and genes related to IDH1, p53 and HIF1α signaling pathways. RESULTS: We first identified that IDH1 expression was downregulated in human liver cancer cells compared to normal liver cells. Next, we found that treatment of HepG2 cells with WA resulted in significantly increased protein levels of IDH1, accompanied by decreased levels of several glycolytic enzymes. Furthermore, we found that WA stabilized IDH1 proteins by inhibiting the degradation by the proteasome. The tumor suppressor p53 was also upregulated by WA treatment, which played a critical role in the upregulation of IDH1 and downregulation of the glycolysis-related genes. Under hypoxic conditions, glycolysis-related genes were induced, which was suppressed by WA treatment, and IDH1 expression was still maintained at higher levels under hypoxia. CONCLUSION: Taken together, our results indicated that WA suppresses liver cancer tumorigenesis by p53-mediated IDH1 upregulation, which promotes mitochondrial respiration, thereby inhibiting the HIF-1α pathway and blocking aerobic glycolysis.
Subject(s)
Glycolysis , Hypoxia-Inducible Factor 1, alpha Subunit , Isocitrate Dehydrogenase , Liver Neoplasms , Signal Transduction , Tumor Suppressor Protein p53 , Withanolides , Humans , Withanolides/pharmacology , Tumor Suppressor Protein p53/metabolism , Tumor Suppressor Protein p53/genetics , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Glycolysis/drug effects , Liver Neoplasms/drug therapy , Liver Neoplasms/metabolism , Liver Neoplasms/pathology , Signal Transduction/drug effects , Isocitrate Dehydrogenase/genetics , Isocitrate Dehydrogenase/metabolism , Cell Proliferation/drug effects , Hep G2 Cells , Gene Expression Regulation, Neoplastic/drug effects , Carcinogenesis/drug effectsABSTRACT
Self-healing hydrogels were prepared from hydrazide functionalized poly(aspartic acid) (PAsp). The polymer succinimide (PSI) was reacted with hydrazine and ethanolamine successively to obtain water soluble poly(aspartic acid) derivatives with hydrazide functional groups (PAEH). The hydrogel was prepared by cross-linking PAEH with poly(ethylene glycol) dialdehyde (PEG DA) under mild conditions without addition of catalyst. The rheological property and the self-healing property of the hydrogels were investigated intensively. The in vitro toxicity experiment showed the hydrogels have good bio-compatibility and the doxorubicin (DOX)-loaded hydrogels showed controlled release profile. Importantly, the hydrogel can still be degraded based on poly(aspartic acid) backbone. The bio-degradable poly(amino acid) based on self-healing hydrogel could have great potential application in bioscience including tissue repairing, drug loading and release.
