Prognostic significance of PUMA in pancreatic ductal adenocarcinoma

Scribble promotes fibrosis-dependent mechanisms of hepatocarcinogenesis by p53/PUMA-mediated glycolysis

BACKGROUNDS AND AIMS

Liver cancer is the sixth most common type of cancer and the fifth leading cause of cancer mortality worldwide. Scribble has been shown to function as a neoplastic tumor suppressor gene in most tumors. Our previous studies reported that down-regulation or mislocalization of Scribble was sufficient to initiate mammary tumorigenesis and NSCLC. Recently, it was reported that Scribble was highly expressed in hepatocellular carcinoma (HCC). We aim to study how it was up-regulated and the contradictory role of Scribble in HCC.

METHODS AND RESULTS

Using a mouse model of carbon tetrachloride (CCl4)-induced liver fibrosis system, we showed that Scribble was over-expressed and which may protect the mice against hepatic fibrosis. Unexpectedly, we found out the potential for Scribble to act as a tumor driver at the advanced stage of N-nitrosodiethylamine (DEN) plus CCl4 induced HCC mice model in vivo. In addition, we observed even higher expression of Scribble in HCC tumors harboring elevated levels of wild-type p53. Most importantly, nuclear translocated Scribble could interact with p53, which lead to enhanced stability and transcriptional activity of p53. Mechanistically, our data suggested that Scribble might drive HCC progression by promoting metabolic regulation of p53 through p53-upregulated modulator of apoptosis (PUMA)-mediated Warburg effect.

CONCLUSIONS

Our data identified the molecular basis of hepatic fibrosis-specific gene expression of polarity gene, such as Scribble. Interestingly, with the progression from fibrosis to cirrhosis to HCC, its nuclear translocation promoted a wild-type p53-mediated cancer metabolic switch and tumor progression in HCC. Taken together, we demonstrated that Scribble was up-regulated and served a protective role in liver fibrosis, while also apparently acting as a tumor driver in fibrosis-dependent hepatocarcinogenesis.

TMT-Based Quantitative Proteomic Analysis Identified Proteins and Signaling Pathways Involved in the Response to Xanthatin Treatment in Human HT-29 Colon Cancer Cells

BACKGROUND

Xanthatin is a plant-derived bioactive sesquiterpene lactone from the Xanthium strumarium L., and it has been used as a traditional Chinese medicine. Recently, many studies have reported that xanthatin has anticancer activity. However, a comprehensive understanding of the mechanism underlying the antitumor effects of xanthatin is still lacking.

OBJECTIVE

To systematically and comprehensively identify the underlying mechanisms of xanthatin on cancer cells, quantitative proteomic techniques were performed.

METHODS

Xanthatin induced HT-29 colon cancer cells death was detected by lactate dehydrogenase (LDH) release cell death assay. Differentially abundant proteins in two groups (control groups and xanthatin treatment groups) of human HT-29 colon cancer cells were identified using tandem mass tag (TMT) quantitative proteomic techniques. All the significant differentially abundant proteins were generally characterized by performing hierarchical clustering, Gene Ontology (GO) enrichment analyses and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. We chose Western blot analysis to validate the candidate proteins in the proteomics results.

RESULTS

A total of 5637 proteins were identified, of which 397 significantly differentially abundant proteins in the groups were quantified. Based on the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses, we found that p53-related signaling played an important role in xanthatin-treated HT-29 colon cancer cells. p53-upregulated modulator of apoptosis (Puma), Sestrin-2 and p14ARF, which were selected from among p53-related signaling proteins, were further validated, and the results were consistent with the tandem mass tag quantitative proteomic results.

CONCLUSION

We first investigated the molecular mechanism underlying the effects of xanthatin treatment on HT-29 colon cancer cells using tandem mass tag quantitative proteomic methods and provided a global comprehensive understanding of the antitumor effects of xanthatin. However, it is necessary to further confirm the function of the differentially abundant proteins and the potentially associated signaling pathways.