Jianpeng Zhang

Metallothionein gene expression under different time in testicular Sertoli and spermatogenic cells of rats treated with cadmium

The rodent testes are generally more susceptible to cadmium (Cd)-induced toxicity than the liver. To clarify the molecular mechanism underlying tissue and cell differences in Cd sensitivity, we compared metallothionein (MT) gene expression, MT protein accumulation, and Cd retention under different times in freshly isolated testicular Sertoli and spermatogenic cells and liver of rats treated with Cd. Adult male Sprague-Dawley rats received a s.c. injection of 4.0 micromol Cd/kg and 1, 3, 6, or 24h later and untreated animals (0h) tissue were sampled and testicular Sertoli and spermatogenic cells isolated. MT1 and MT2 mRNA levels were determined by semi-quantitative RT-PCR analysis followed by densitometry scanning, and MT was estimated by the enzyme-linked immunosorbent assay (ELISA) method. Cadmium content was determined by atomic absorption spectrophotometry. Testicular lesions were not grossly or histologically observed in rats treated with 4.0 micromol Cd/kg. In the present study, we demonstrated that the rat testis indeed expressed MT1 and MT2, the major isoforms. We also found that untreated animals contained relatively high basal levels of both isoform mRNA, which were increased after Cd treatment in liver and peaked at 3h, followed by a decline, in contrast, the mRNA levels in Sertoli cells peaked at 6h. Interestingly, the induction of MT1 mRNA was lower than MT2 mRNA in Sertoli cells and liver of rats treated with Cd. However, the MT1 mRNA levels of spermatogenic cells decreased 0-3h after Cd treatment, followed by an increase; in contrast, MT2 mRNA levels increased 0-3h after Cd treatment, followed by a reduction, but induced extents of them are lower than those of Sertoli cells and liver. Cd exposure substantially increased hepatic MT, but did not increase MT translation in Sertoli and spermatogenic cells. These results indicate: (1) that Cd-induced MT mRNA expression is cell- and time-dependent; (2) that the inability to induce the metal-detoxicating MT protein in response to Cd, might account for higher susceptibility of testes to Cd toxicity and carcinogenesis relative to liver.

Interleukin-11 promotes the progress of gastric carcinoma via abnormally expressed versican.

Versican, a ubiquitous component of the extracellular matrix (ECM), accumulates both in tumor stroma and cancer cells and is highly regulated by various cytokines. The aberrant expression of versican and its isoforms is known to modulate cell proliferation, differentiation, and migration, all of which are features of the invasion and metastasis of cancer; versican is also known to favour the homeostasis of the ECM. Interleukin-11 (IL-11) is an important cytokine that exhibits a wide variety of biological effects in gastric cancer development. Here, we analysed the expression of versican isoforms and found that the major isoforms expressed by both gastric carcinoma tissue and gastric cell lines were V0 and V1, and V1 was significantly higher in gastric carcinoma tissue. The treatment of the gastric cell lines AGS and MKN45 with rhIL-11 resulted in a significant increase in the expression of V0 and V1. Exogenous IL-11 increased migration in AGS and MKN45 cells, whereas these effects were reversed when the expression of V0 and V1 were abolished by siRNA targeting versican V0/V1. Collectively, these findings suggest that the abnormally expressed versican and its isoforms participate, at least in part, in the progress of gastric carcinoma triggered by IL-11.

Glycosylation of the Sodium Channel β4 Subunit is Developmentally Regulated and Involves in Neuritic Degeneration

Aberrant protein glycosylation plays major roles in neurodegenerative diseases, including Parkinsons disease (PD). Glycoproteomics showed that the glycosylation of sodium channel β4 was significantly increased in human brain tissue. β4-specific antibodies reacted in immunoblot assays with the 35- and 38-kDa bands from the membrane fractions isolated from neonatal PD transgenic mice but only with the 35-kDa band of the neonatal wild-type mice. The size of the 38-kDa immunoreactive protein is in close agreement with previously reported, suggesting heavy glycosylation of this protein in adult wild-type and neonatal PD transgenic brain tissues. However, the neonatal wild-type mice membrane fractions only contained the 35-kDa immunoreactive protein, and the additional 38-kDa band was not shown until postnatal day 7. Enzymatic deglycosylation of the membrane preparations only converted the 38-kDa band into a faster migrating protein, which was consistent with heavy glycosylation of this protein. The glycosylated state of β4 was developmentally regulated and was altered in disease state. Neurite outgrowth assay demonstrated that overexpression of deglycosylated mutant β4-MUT accelerated neurite extension and increased the number of filopodia-like protrusions, when compared with β4-WT and the vector. These results suggest that extensive glycosylation of β4 subunit play roles in morphological changes, and the altered glycosylation may be involved in the pathogenesis of PD.

Quantitative Proteomics Approach to Screening of Potential Diagnostic and Therapeutic Targets for Laryngeal Carcinoma

To discover candidate biomarkers for diagnosis and detection of human laryngeal carcinoma and explore possible mechanisms of this cancer carcinogenesis, two-dimensional strong cation-exchange/reversed-phase nano-scale liquid chromatography/mass spectrometry analysis was used to identify differentially expressed proteins between the laryngeal carcinoma tissue and the adjacent normal tissue. As a result, 281 proteins with significant difference in expression were identified, and four differential proteins, Profilin-1 (PFN1), Nucleolin (NCL), Cytosolic non-specific dipeptidase (CNDP2) and Mimecan (OGN) with different subcellular localization were selectively validated. Semiquantitative RT-PCR and Western blotting were performed to detect the expression of the four proteins employing a large collection of human laryngeal carcinoma tissues, and the results validated the differentially expressed proteins identified by the proteomics. Furthermore, we knocked down PFN1 in immortalized human laryngeal squamous cell line Hep-2 cells and then the proliferation and metastasis of these transfected cells were measured. The results showed that PFN1 silencing inhibited the proliferation and affected the migration ability of Hep-2 cells, providing some new insights into the pathogenesis of PFN1 in laryngeal carcinoma. Altogether, our present data first time show that PFN1, NCL, CNDP2 and OGN are novel potential biomarkers for diagnosis and therapeutic targets for laryngeal carcinoma, and PFN1 is involved in the metastasis of laryngeal carcinoma.

Underexpressed CNDP2 participates in gastric cancer growth inhibition through activating the MAPK signaling pathway.

Increasing evidence suggests that cytosolic non-specific dipeptidase 2 (CNDP2) appears to do more than just perform an enzymatic activity; it is functionally important in cancers as well. Here, we show that the expression of CNDP2 is commonly down-regulated in gastric cancer tissues. The ectopic expression of CNDP2 resulted in significant inhibition of cell proliferation, induction of cell apoptosis and cell cycle arrest, and suppressed gastric tumor growth in nude mice. We further revealed that the reintroduction of CNDP2 transcriptionally upregulated p38 and activated c-Jun NH2-terminal kinase (JNK), whereas the loss of CNDP2 increased the phosphorylation of extracellular signal-related kinase (ERK). These results suggest that CNDP2 acts as a functional tumor suppressor in gastric cancer via activation of the mitogen-activated protein kinase (MAPK) pathway.

S100A11 is a migration-related protein in laryngeal squamous cell carcinoma.

Objective: As a member of the S100 proteins family, the involvement of S100A11 has been suggested in a wide range of biological processes such as cell growth and motility, cell-cycle progression, transcription, differentiation and smooth muscle cell migration. However, the expression of S100A11 and its exact function in laryngeal squamous cell carcinoma (LSCC) have not been elucidated. Methods: The protein and mRNA expression levels of S100A11 were analyzed in primary tumors and matched tumor-adjacent tissues of LSCC by western blotting and semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) or quantitative real time PCR (Q-RT-PCR), respectively. Cell proliferation, colony formation, migration and wound-healing assays were performed to assess whether the knockdown of S100A11 by small interfering RNA (siRNA) could influence the biological behavior of human laryngeal carcinoma Hep-2 cells in vitro. Results: We found that both protein and mRNA levels of S100A11 were overexpressed in laryngeal tumor tissues when compared to the corresponding noncancerous tissues. Further, it was demonstrated that the expression of S100A11 could induce migration but not proliferation of Hep-2 cells. Additionally, S100A11 altered a series of intracellular events, including the down-regulation of epidermal growth factor receptor (EGFR), CD44 and MMP2. Conclusions: These results highlight the significance of S100A11 in LSCC progression and suggest that the dysregulation of S100A11 might contribute to the metastatic progression of LSCC.

Does the expression of versican isoforms contribute to the pathogenesis of neurodegenerative diseases

Classical neurodegenerative diseases such as Alzheimers, Parkinsons, and Huntingtons are most commonly seen in older persons. The incidence rate increases as life expectancy increases. Even though neuronal loss, neuronal death and accumulated toxic proteins are well investigated, the mechanism(s) of neurodegenerative disorders is not yet fully understood. Versican is a large extracellular matrix proteoglycan. Its isoforms are aberrantly expressed in central nervous system injuries. Diverse lines of evidence suggest that versican isoforms play a vital role in regulating neuronal differentiation, maturation, neurite outgrowth, and synaptic transmission. Some toxic proteins may be increased and less sensitive to degeneration due to the chondroitin sulfate (CS) chains of versicans. We propose that the patterns of versican V1 and V2 isoforms act as a fine-tuned mechanism for guiding the change of neural microenvironment, and the unbalanced expression of V1 and V2 isoforms may contribute to the pathogenesis of neurodegenerative diseases. The emergence of versican isoforms indicates that it may explain the pathogenesis of the common sporadic forms of complex diseases.