Hongxia Zhu

High expression of survivin predicts poor prognosis in esophageal squamous cell carcinoma following radiotherapy.

Radiotherapy is one of the main treatments for esophageal squamous cell carcinoma, but there are still no biomarkers to differentiate patients who will benefit from radiation. Although treatment with a combination of radiotherapy with chemotherapy, and/or surgery improves the prognosis of patients, no biomarkers can distinguish between the responses obtained with the combined therapies. Therefore, in this study, we selected patients treated with radiotherapy alone to evaluate survivin as a predictor for radiotherapy. One hundred two biopsy samples collected by endoscopy were immunostained by survivin antibody. Positive staining for survivin was obtained in 60.8% tumor samples. Survivin expression, metastasis, and clinical stage correlated significantly with overall survival. In multivariate analysis, survivin was an independent prognostic factor for predicting overall survival of patients with esophageal cancer. Moreover, in esophageal cancer cell lines, overexpression of survivin reduced the percentage of cell death induced by radiation. Our data indicate that survivin could be a potential predictor to define those patients with esophageal squamous carcinoma who would benefit from radiotherapy.

Protein SUMOylation modification and its associations with disease

SUMOylation, as a post-translational modification, plays essential roles in various biological functions including cell growth, migration, cellular responses to stress and tumorigenesis. The imbalance of SUMOylation and deSUMOylation has been associated with the occurrence and progression of various diseases. Herein, we summarize and discuss the signal crosstalk between SUMOylation and ubiquitination of proteins, protein SUMOylation relations with several diseases, and the identification approaches for SUMOylation site. With the continuous development of bioinformatics and mass spectrometry, several accurate and high-throughput methods have been implemented to explore small ubiquitin-like modifier-modified substrates and sites, which is helpful for deciphering protein SUMOylation-mediated molecular mechanisms of disease.

Antibacterial mechanism of daptomycin antibiotic against Staphylococcus aureus based on a quantitative bacterial proteome analysis

Daptomycin (DAP) is a novel lipopeptide antibiotic which exhibits excellent antibacterial activity against most clinically relevant Gram-positive bacteria, but the DAP-targeting protein molecules against host bacterial infection are far from clear. In order to discover bacterial protein response to DAP treatment, an iTRAQ-based quantitative proteomic analysis was applied to identify differential bacterial proteome profiling of Staphylococcus aureus (S. aureus) ATCC 25923 to 0.125μg/ml DAP exposure. Totally 51 bacterial proteins were significantly changed with DAP treatment, among which 34 proteins were obviously up-regulated and 17 proteins were down-regulated. Meanwhile, 139 bacterial cell membrane (CM) proteins were identified, and 7 CM proteins were significantly altered to decrease CM potential to disrupt bacterial cell membrane. Especially the up-regulation of NDK and down-regulation of NT5 in several S. aureus strains are validated to be a universal variation tendency response to DAP treatment. Under DAP exposure, bacterial membrane potential is decreased and cell membrane is disrupted, and bacterial chromosome is aggregated, which contributes to bacterial DNA rapid release and induces bacteria death within 2-5h. In general, multiple bacterial protein expressions are changed in response to DAP antibiotic exposure, which disrupts host bacterial physiology by multiple cellular levels. To our knowledge, this is the first time to exactly identify infectious bacterial proteins in response to DAP antibiotic action. Our findings help better understand DAP antibacterial mechanism and develop novel DAP derivatives against the upcoming antibiotic-resistant bacterial infection.nnnBIOLOGICAL SIGNIFICANCEnDAP is a novel lipopeptide antibiotic that it exhibits excellent in vitro activity against most clinically relevant Gram-positive bacteria, and the investigations on its pharmaceutical action mode of DAP have dramatically increased in the past decade due to its unique antimicrobial mechanism. However, the target molecules of DAP acting on the infectious bacteria, are far from clear. The state-of-the-art quantitative proteomic technologies provide new avenues to uncover underlying mechanism of antibiotics. Our research main aims to identify bacterial proteome profiling of host strain S. aureus response to DAP treatment through an iTRAQ-based quantitative proteomic analysis, which contributes to understand DAP efficient antibacterial activity and the microbial-antibiotic interactions.

Proteomics progresses in microbial physiology and clinical antimicrobial therapy.

Clinical microbial identification plays an important role in optimizing the management of infectious diseases and provides diagnostic and therapeutic support for clinical management. Microbial proteomic research is aimed at identifying proteins associated with microbial activity, which has facilitated the discovery of microbial physiology changes and host–pathogen interactions during bacterial infection and antimicrobial therapy. Here, we summarize proteomic-driven progresses of host–microbial pathogen interactions at multiple levels, mass spectrometry-based microbial proteome identification for clinical diagnosis, and antimicrobial therapy. Proteomic technique progresses pave new ways towards effective prevention and drug discovery for microbial-induced infectious diseases.

SUMOylation of IQGAP1 promotes the development of colorectal cancer

IQGAP1 is a conserved multifunctional protein implicated in tumorigenesis. An aberrant expression of IQGAP1 widely exists in many cancers, but the SUMOylation modification of IQGAP1 in carcinogenesis is unknown by now. Here we first time explore biological functions of IQGAP1 SUMOylation in promoting colorectal cancer progression inxa0vitro and inxa0vivo. The expression of IQGAP1 and its SUMOylation level are both increased in human colorectal carcinoma (CRC) cells and tissues. IQGAP1 is mainly SUMOylated by SUMO1 at the K1445 residue, which could stabilize IQGAP1 by reducing protein ubiquitination. IQGAP1 SUMOylation improves CRC cell growth, cell migration and tumorigenesis inxa0vivo through activating the phosphorylation of ERK, MEK and AKT. While the SUMOylation site mutation at K1445 of IQGAP1 greatly reduces CRC cell proliferation, migration ability and tumor growth of CRC-xenograft mice by suppressing phosphorylation of ERK, MEK and AKT. Our findings discover the IQGAP1 SUMOylation is a novel regulatory mechanism to enhance tumorigenesis and development of CRC inxa0vitro and inxa0vivo.

Downregulation of ARHGDIA contributes to human glioma progression through activation of Rho GTPase signaling pathway.

The protein ARHGDIA has been found to play distinct roles in cancer progression for several tumors. However, it remains elusive whether and how ARHGDIA plays functions in human glioma. In this study, we discovered that ARHGDIA is much downregulated in human glioma; meanwhile, its expression negatively correlates with glioma malignancy and positively relates to prognosis of glioma patients. It has independent predictive value of ARHGDIA expression level for overall survival of human glioma patients. Glioma patients with ARHGDIA-positive expression have a longer overall survival time than ARHGDIA-negative patients. Knockdown of ARHGDIA promotes cell proliferation, cell cycle progression, and cell migration due to the activation of Rho GTPases (Rac1, Cdc42, and RhoA) and Akt phosphorylation, whereas overexpression of ARHGDIA suppresses cell growth, cell cycle progression, and cell migration. ARHGDIA is a potential prognostic marker and therapeutic target for human glioma.

SILAC–based quantitative MS approach for real-time recording protein-mediated cell-cell interactions

In tumor microenvironment, interactions among multiple cell types are critical for cancer progression. To understand the molecular mechanisms of these complex interplays, the secreted protein analysis between malignant cancer cells and the surrounding nonmalignant stroma is a good viewpoint to investigate cell-cell interactions. Here, we developed two stable isotope labeling of amino acids in cell culture (SILAC)-based mass spectrometry (MS)/MS approaches termed spike-in SILAC and triple-SILAC to quantify changes of protein secretion level in a cell co-cultured system. Within the co-culture system of CT26 and Ana-1 cells, the spike-in SILAC and triple-SILAC MS approaches are sensitive to quantitatively measure protein secretion changes. Three representative quantified proteins (Galectin-1, Cathepsin L1 and Thrombospondin-1) by two SILAC-based MS methods were further validated by Western blotting, and the coming result matched well with SILACs’. We further applied these two SILACs to human cell lines, NCM460 and HT29 co-culture system, for evaluating the feasibility, which confirmed the spike-in and triple SILAC were capable of monitoring the changed secreted proteins of human cell lines. Considering these two strategies in time consuming, sample complexity and proteome coverage, the triple-SILAC way shows more efficiency and economy for real-time recording secreted protein levels in tumor microenvironment.

Small-Molecule Inhibitors Targeting Protein SUMOylation as Novel Anticancer Compounds

SUMOylation, one of post-translational modifications, is covalently modified on lysine residues of a target protein through an enzymatic cascade reaction similar to protein ubiquitination. Along with identification of many SUMOylated proteins, protein SUMOylation has been proven to regulate multiple biologic activities including transcription, cell cycle, DNA repair, and innate immunity. The dysregulation of protein SUMOylation and deSUMOylation modification is linked with carcinogenesis and tumor progression. The SUMOylation-associated enzymes are usually elevated in various cancers, which function as cancer biomarkers to relate to poor outcomes for patients. Considering the significance of protein SUMOylation in regulating diverse biologic functions in cancer progression, numerous small-molecule inhibitors targeting protein SUMOylation pathway are developed as potentially clinical anticancer therapeutics. Here, we systematically summarize the latest progresses of associations of small ubiquitin-like modifier (SUMO) enzymes with cancers and small-molecular inhibitors against human cancers by targeting SUMOylation enzymes. We also compared the pros and cons of several special anticancer inhibitors targeting SUMO pathway. As more efforts are invested in this field, small-molecule inhibitors targeting the SUMOylation modification pathway are promising for development into novel anticancer drugs.

Downregulation of ATP1A1 promotes cancer development in renal cell carcinoma

BackgroundAberrant expression of Na+/K+-ATPase α1 subunit (ATP1A1) is widely observed in multiple types of tumors, and its tissue-specific expression relates to cancer development. However, the functions and molecular mechanisms in renal cell carcinoma (RCC) are not fully understood.MethodsWe investigated the ATP1A1 expression changes and possible roles in RCC through a quantitative proteomic approach and an integrative biochemical assessment. We detected ATP1A1 in RCC with LC–MS/MS, and further validated its expression with immunohistochemical analyses of 80 pairs of the RCC tumor and non-tumor tissues samples. The association of ATP1A1 expression with RCC pathology was statistically analyzed. Cell proliferation, migration and apoptosis were measured by CCK-8, boyden chamber assay and flow cytometry, respectively. The production of reactive oxygen species (ROS) was labeled with a single staining using a commercial kit, and was further detected with flow cytometry.ResultsThe ATP1A1 shows a significantly decreased expression in human RCC tissues than in the adjacent non-tumor tissues. The RCC patients with ATP1A1-positive expression exhibit longer overall survival time than the ATP1A1-negative patients. The exogenous overexpression of ATP1A1 inhibits RCC cell proliferation and cell migration by increasing the production of ROS. In addition, ATP1A1-mediated Raf/MEK/ERK signaling pathway is suppressed in RCC cells, indicating the possible occurrence of induced cell apoptosis.ConclusionsOur in vitro and in vivo data of ATP1A1 inhibitory roles in RCC progression suggest that ATP1A1 is a potential novel suppressor protein for renal cancer.

Combined assessment of low PGRMC1/positive ATP1A1 levels has enhanced prognostic value for renal cell carcinoma

Progesterone receptor membrane componentxa01 (PGRMC1) and Na+/K+‑ATPasexa0α1 subunit (ATP1A1) are two proteins associated with the clinical prognosis of renal cell carcinoma (RCC) and RCC cell proliferation. However, the two proteins have been previously studied independently, and their combined influence on the clinical outcome of RCC remains unclear. The present study suggests that the combined expression levels of PGRMC1 and ATP1A1 (PGRMC1/ATP1A1) are associated with the clinical prognosis of RCC patients. RCC patients with low PGRMC1/positive ATP1A1 levels exhibited the best overall survival (OS) outcomes (103.08±1.85xa0months). The high PGRMC1/negative ATP1A1 group demonstrated the worst prognosis (73.1±8.87xa0months). The low PGRMC1/positive ATP1A1 group had the highest 7‑year OS rate (92.3%). The high PGRMC1/negative ATP1A1 group had the lowest 7‑year OS rate (46.7%). Although PGRMC1 and ATP1A1 both act on AKT phosphorylation in RCC cells, their expression levels are independent of each other. Moreover, the synergistic suppressive roles of PGRMC1 downregulation combined with ATP1A1 upregulation exhibit more efficient tumor inhibition potentials on RCC cells. Therefore, combined assessment of the two biomarkers (PGRMC1/ATP1A1) shows enhanced prognostic ability for RCC.