Effect of polychlorinated biphenyls on oxidation stress in the liver of juvenile GIFT, Oreochromis niloticus

The present study clearly showed that chronic exposure to polychlorinated biphenyls (PCBs) at environmentally relevant concentrations can damage juvenile tilapia livers by modulating antioxidant enzyme activities and gene transcription, which affects toxic bioaccumulation and histological congestion. The results suggest that PCBs caused a decrease in the activity of some hepatic antioxidative and biotransformation enzymes (SOD, CAT, GST, T-GSH, and MDA) in tilapia at 7 days, as well as transcriptional changes (sod, cat, and gst). Except for some antioxidant parameters (T-GSH, GSH/GSSG, T-AOC, and MDA), significant declines and increases occurred at 14 and 21 days, respectively. Most of the antioxidant enzymatic signatures and genotoxicity significantly increased at 14 and 21 days. This study presented evidence that PCBs could result in hepatic toxicity through oxidative stress in the early growth stages of tilapia, and we speculated that oxidative stress plays an important role in embryonic developmental toxicity induced by PCBs.

PRAME promotes in vitro leukemia cells death by regulating S100A4/p53 signaling

OBJECTIVE

PRAME (Preferentially Expressed Antigen in Melanoma) is a tumor-associated antigen recognized by immunocytes, and it induces cytotoxic T cell-mediated responses in melanoma. PRAME is expressed in a wide variety of tumors, but in contrast with most other tumor-associated antigens, it is also expressed in leukemias. The physiologic role of PRAME remains elusive. Recently, it has found PRAME could be involved in the regulation of cell death in leukemias, but the mechanism of the function is unclear. Here, we confirm that PRAME induces leukemias cell death by regulation of S100A4/p53 signaling.

MATERIALS AND METHODS

The pCDNA3-PRAME plasmid and its control were transfected with the KG-1 cells. The pCDNA3-PRAME transfected KG-1 cells were then transiently transfected with S100A4 cDNA or wt-p53 siRNA. The PRAME siRNA and its control were transfected with the K562 cells. The PRAME siRNA transfected K562 cells were then transiently transfected with S100A4 siRNA or pGMp53-Lu. PRAME, S100A4 and P53 were detected by Western blot assay in different time point. Annexin V/propidium iodide and MTT methods were used to detect apoptosis and cell survival rate.

RESULTS

KG-1 cells overexpressing the PRAME gene significantly induces apoptosis and decreases proliferation in vitro, followed by down-regulation of S100A4 and up-regulation of p53. Up-regulation of S100A4 by S100A4 transfection inhibits PRAME-induced p53 up-regulation. Furthermore, up-regulation of S100A4 by S100A4 transfection or down-regulation of p53 by p53 siRNA transfection reduces apoptosis and increases proliferation in vitro. Knockdown of PRAME in K562 cells significantly increases proliferation in vitro, followed by up-regulation of S100A4 and down-regulation of p53. The downregulation of S100A4 by S100A4 siRNA transfection increased p53 expression. Furthermore, downregulation of S100A4 by S100A4 siRNA transfection or up-regulation of p53 by p53 transfection decreases proliferation in vitro.

CONCLUSIONS

Our results suggest that the leukemias expressing high levels of PRAME has a favorable prognosis. PRAME promotes in vitro leukemia cells death by regulating S100A4/p53 signaling.

USP4 promotes invasion of breast cancer cells via Relaxin/TGF-β1/Smad2/MMP-9 signal

OBJECTIVE

Ubiquitin-specific protease 4 (USP4) is a deubiquitinating enzyme with key roles in the regulation of TGF-β1 signaling, suggesting its importance in tumorigenesis. However, the underlying mechanisms causing this are not entirely clear. In the present study, we investigated the effect of USP4 on invasion and tumorigenesis of breast cancer cells, and explored its mechanism.

MATERIALS AND METHODS

Effects of USP4 overexpression or USP4 silencing by small interfering RNA (USP4 siRNA) on invasion of breast cancer MDA-MB-231 and T47D cells in vitro was detected. Using siRNAs and inhibitors to examine the USP4 signaling pathway.

RESULTS

The migration and invasion assays showed that USP4 promotes human breast cancer cell migration and invasion by USP4 overexpression, and knockdown of USP4 by siRNA inhibits human breast cancer cell migration and invasion. Treatment with RLX siRNAs, TGF-β1 siRNAs, Smad2 siRNAs or BB94 (MMPs inhibitor) to USP4-overexpressing breast cancer cells revealed that USP4- induced RLX via TGF-β1 pathway promotes the cell migration and invasion. Further studies demonstrated that USP4-mediated TGF-β1 activation not only enhances the phosphorylation of Smad2 through TGF-β, but also directly upregulate matrix metalloproteinase (MMP)-9-mediated cell migration and invasion of breast cancer cells.

CONCLUSIONS

Therapies targeting the USP4 inhibits invasion of breast cancer cells via Relaxin/TGF-β1/Smad2/MMP-9 signal. These results indicate that USP4 is an attractive target for breast cancer therapy.

YM155 inhibits tumor growth and enhances chemosensitivity to cisplatin in osteosarcoma

OBJECTIVE

Chemoresistance is the principal reason for poor survival and disease recurrence in osteosarcoma patients. Survivin, a family member of the inhibitor of apoptosis proteins, plays an important role in inhibition of apoptosis. Survivin is expressed in a vast majority of human cancers, which is often correlated with poor prognosis in a wide variety of cancer patients. Furthermore, survivin expression is often related with chemoresistance in cancer cells, including osteosarcoma (OS). Here, we evaluated the therapeutic potential of YM155, a selective survivin suppressant alone and in combination with cisplatin using human OS models.

MATERIALS AND METHODS

U-2 OS, SW1353, MG-63 cells were treated with YM155, and/or cisplatin, and cell viability, apoptosis, survivin protein expression levels were then evaluated. Furthermore, the efficacy of YM155 combined with cisplatin was further examined in established xenograft models.

RESULTS

YM155 was sufficient to induce spontaneous apoptosis of OS cells. Combination with YM155 significantly augmented the cytotoxicity of cisplatin in OS cells. Combination treatment of YM155 and cisplatin showed antiproliferative effects and induced a greater rate of apoptosis than the sum of the single-treatment rates and promoted tumor regression in established OS xenograft models.

CONCLUSIONS

Our findings provide evidence that YM155 could act as a survivin inhibitor on OS cells. Chemotherapeutic approaches using YM155 might enhance the benefit of the cisplatin in the treatment of OS cells. YM155 could be further developed as a potential therapeutic agent for the treatment of OS.