A high-temporal resolution technology for dynamic proteomic analysis based on 35S labeling

Phycocyanin Reduces Proliferation of Melanoma Cells through Downregulating GRB2/ERK Signaling

As a type of functional food additive, phycocyanin is shown to have a potential antineoplastic property. However, its underlying anticancer mechanism in melanoma cells remains unknown. We previously reported a 35S in vivo/vitro labeling analysis for dynamic proteomic (SiLAD) technology. It could exclusively detect protein synthesis rates via pulse labeling of newly expressed proteins by 35S, providing a high time-resolution method for analysis of protein variations. In the present study, we performed a time course analysis in A375 melanoma cells after phycocyanin treatment using SiLAD. Protein expression velocities were specifically visualized and their regulation modes were dynamically traced. Strikingly, novel protein synthesis patterns were discovered in the early phase of phycocyanin treatment, suggesting a possible mechanism of phycocyanin regulation. Furthermore, network analysis and phenotype experiments demonstrated that GRB2-ERK1/2 pathway was involved in phycocyanin-mediated regulation process and responsible for the proliferation suppression of melanoma cell, which could be a therapeutic target for malignant melanoma.

CHIP/Stub1 regulates the Warburg effect by promoting degradation of PKM2 in ovarian carcinoma

Tumor cells preferentially adopt aerobic glycolysis for their energy supply, a phenomenon known as the Warburg effect. It remains a matter of debate as to how the Warburg effect is regulated during tumor progression. Here, we show that CHIP (carboxyl terminus of Hsc70-interacting protein), a U-box E3 ligase, suppresses tumor progression in ovarian carcinomas by inhibiting aerobic glycolysis. While CHIP is downregulated in ovarian carcinoma, induced expression of CHIP results in significant inhibition of the tumor growth examined by in vitro and in vivo experiments. Reciprocally, depletion of CHIP leads to promotion of tumor growth. By a SiLAD proteomics analysis, we identified pyruvate kinase isoenzyme M2 (PKM2), a critical regulator of glycolysis in tumors, as a target that CHIP mediated for degradation. Accordingly, we show that CHIP regulates PKM2 protein stability and thereafter the energy metabolic processes. Depletion or knockout of CHIP increased the glycolytic products in both tumor and mouse embryonic fibroblast cells. Simultaneously, we observed that CHIP expression inversely correlated with PKM2 levels in human ovarian carcinomas. This study reveals a mechanism that the Warburg effect is regulated by CHIP through its function as an E3 ligase, which mediates the degradation of PKM2 during tumor progression. Our findings shed new light into understanding of ovarian carcinomas and may provide a new therapeutic strategy for ovarian cancer.

Serum translationally controlled tumor protein is involved in rat liver regeneration after hepatectomy

AIM

The translationally controlled tumor protein (TCTP) has been reported to promote progression of many physiological processes. However, whether TCTP is involved in liver regeneration has been rarely studied. This study aimed to investigate the potential role of serum TCTP in liver regeneration after two-thirds partial hepatectomy.

METHODS

The synthesis rate and accumulated expression of TCTP was assessed by phosphor imaging and Western blot analysis, respectively. The mRNA expression of tctp was analyzed by quantitative real-time PCR. The effect of serum TCTP on hepatocyte proliferation was investigated by bromodeoxyuridine incorporation, liver/body weight ratio, albumin concentration, and histological examination of liver following treatment of rat with anti-TCTP antibody or prokaryotic TCTP protein before hepatectomy. The MTT assay was used to examine effect of TCTP on hepatocyte proliferation in vitro.

RESULTS

The results showed that the expression of intracellular and serum TCTP protein was significantly increased in rats after two-thirds partial hepatectomy. In vivo bromodeoxyuridine labeling assay suggested that treatment with anti-TCTP antibody before hepatectomy significantly decreased hepatocyte proliferation and liver/body weight ratio. The prokaryotic TCTP had a potential promoting effect on hepatocyte proliferation both in vivo and in vitro, although prokaryotic TCTP given to rats prior to hepatectomy did not increase the proliferation ratio or liver/body weight ratio. Furthermore, anti-TCTP antibody pretreatment decreased the expression of cyclin E, cdk2, and interleukin-6 in rat liver.

CONCLUSION

These findings suggest serum TCTP is involved in rat liver regeneration through promoting hepatocyte proliferation.

"Omics" in pharmaceutical research: overview, applications, challenges, and future perspectives

In the post-genomic era, biological studies are characterized by the rapid development and wide application of a series of "omics" technologies, including genomics, proteomics, metabolomics, transcriptomics, lipidomics, cytomics, metallomics, ionomics, interactomics, and phenomics. These "omics" are often based on global analyses of biological samples using high through-put analytical approaches and bioinformatics and may provide new insights into biological phenomena. In this paper, the development and advances in these omics made in the past decades are reviewed, especially genomics, transcriptomics, proteomics and metabolomics; the applications of omics technologies in pharmaceutical research are then summarized in the fields of drug target discovery, toxicity evaluation, personalized medicine, and traditional Chinese medicine; and finally, the limitations of omics are discussed, along with the future challenges associated with the multi-omics data processing, dynamics omics analysis, and analytical approaches, as well as amenable solutions and future prospects.

Triple labeling with three thymidine analogs reveals a well-orchestrated regulation of hepatocyte proliferation during liver regeneration

AIM

  After a two-thirds partial hepatectomy (PHx) in rodents, the remaining cells will proliferate and restore the lost liver mass within 7 days. Previous studies have proved that the residual hepatocytes proliferate in a synchronous manner. However, the existing data can not reflect the chronicle of individual hepatocytes proliferation during liver regeneration.

METHODS

  In this study, a combination of pulse and continuous labeling using three thymidine analogs, Bromodeoxyuridine (BrdU), Chlorodeoxyuridine (CldU) and Iododeoxyuridine (IdU), were used to analyze the cell proliferation of rat liver after PHx. This strategy allows us to follow an individual cell for more than one cell cycle and to define how many cells and which cells undergo multiple divisions.

RESULTS

  The residual hepatocytes clustered into three subpopulations to initiate the proliferation sequentially, and the corresponding percentage of each was 32%, 17%, and 36%. Meanwhile, the remaining 15% of hepatocytes never proliferated. In addition, the periportal hepatocytes were the first to respond to PHx stimulation and re-proliferated synchronously at 54 h. Furthermore, at least 11% of residual hepatocytes were identified to divide thrice or more.

CONCLUSION

  Based on the present analysis, we concluded a sequential model of the initial proliferation in residual hepatocytes, and for the first time, quantitatively elucidated the proliferation manner of three subpopulations during liver regeneration.

Proteomic analysis to display the effect of low doses of erythropoietin on rat liver regeneration

AIMS

Several groups found different impact of erythropoietin (EPO) on liver regeneration. Both pro-proliferative as well as anti-proliferative and non-proliferative activities have been reported using high dosage of EPO. Systemic administration of high doses of this cytokine is a clinical concern due to risk of thrombosis. Herein, we applied EPO in low dosages and investigated whether it can stimulate liver regeneration after liver resection.

MAIN METHODS

Parameters of liver regeneration were assessed 3 days after 70% hepatectomy by means of immunochemistry and proteomics. EPO was given twice in low dosages (200 and 600 IU/kg BW).

KEY FINDINGS

We showed that EPO facilitated hepatic regeneration in rats. Enhanced hepatocyte proliferation (Ki67, BrdU-positive cells) was observed in all EPO-treated groups. By performing Differential Proteomic analysis, we identified two proteins which resulted sensitive to EPO treatment after hepatectomy: Peroxiredoxin-1 and glutathione S-transferase Mu 1.

SIGNIFICANCE

Based on our results, low doses of rhEPO increase the hepatic regenerative capacity after partial hepatectomy in rats by enhancing hepatocyte proliferation and acting on antioxidant enzymes. Both proteins identified by proteomic analysis have not previously been associated with liver regeneration and will aid in the understanding of EPO's regenerative response having clinical implications to treat liver failure.