Zhaowen Zhang

BACKGROUND: Accumulating evidence indicates that circular RNAs (circRNAs) act as microRNA (miRNA) sponges to directly inhibit specific miRNAs and alter their ability to regulate gene expression at the post-transcriptional level; this mechanism is believed to occur in various cancers. However, the expression level, precise function and mechanism of circ_001680 in colorectal carcinoma (CRC) are largely unknown. METHODS: qRT-PCR was used to detect the expression of circ_001680 and miR-340 in human CRC tissues and their matched normal tissues. Bioinformatics analyses and dual-fluorescence reporter assays were used to evaluate whether circ_001680 could bind to miR-340. Circ_001680 overexpression and knockdown cell lines were constructed to investigate the proliferation and migration abilities in vivo and in vitro through function-based experiments, including CCK8, plate clone formation, transwell, and wounding healing assays. The relationships among circ_001680, miR-340 and BMI1 were investigated by bioinformatics analyses, dual-fluorescence reporter system, FISH, RIP and RNA pull down assays. Sphere forming assays and flow cytometry analyses were used to assess the effect of circ_001680 on the stemness characteristics of CRC cells. RESULTS: Circ_001680 was more highly expressed in of CRC tissue than in matched adjacent normal tissues from the same patients. Circ_001680 was observed to enhance the proliferation and migration capacity of CRC cells. Furthermore, dual-fluorescence reporter assays confirmed that circ_001680 affects the expression of BMI1 by targeting miR-340. More importantly, we also found that circ_001680 could promote the cancer stem cell (CSC) population in CRC and induce irinotecan therapeutic resistance by regulating the miR-340 target gene BMI1. CONCLUSIONS: Our results demonstrated that circ_001680 is a part of a novel strategy to induce chemotherapy resistance in CRC through BMI1 upregulation. Moreover, circ_001680 may be a promising diagnostic and prognostic marker to determine the success of irinotecan-based chemotherapy.

A clinically-related animal model of Parkinson's disease (PD) may enable the elucidation of the etiology of the disease and assist the development of medications. However, none of the current neurotoxin-based models recapitulates the main clinical features of the disease or the pathological hallmarks, such as dopamine (DA) neuron specificity of degeneration and Lewy body formation, which limits the use of these models in PD research. To overcome these limitations, we developed a rat model by stereotaxically (ST) infusing small doses of the mitochondrial complex-I inhibitor, rotenone, into two brain sites: the right ventral tegmental area and the substantia nigra. Four weeks after ST rotenone administration, tyrosine hydroxylase (TH) immunoreactivity in the infusion side decreased by 43.7%, in contrast to a 75.8% decrease observed in rats treated systemically with rotenone (SYS). The rotenone infusion also reduced the DA content, the glutathione and superoxide dismutase activities, and induced alpha-synuclein expression, when compared to the contralateral side. This ST model displays neither peripheral toxicity or mortality and has a high success rate. This rotenone-based ST model thus recapitulates the slow and specific loss of DA neurons and better mimics the clinical features of idiopathic PD, representing a reliable and more clinically-related model for PD research.

BACKGROUND: The abnormal expression of glutathione S-transferase P1 (GSTP1) is associated with the progression of several tumor types. However, its role and molecular mechanism in the progression of colorectal cancer (CRC) are largely unknown. OBJECTIVES: To examine the effect of GSTP1 in CRC and determine its possible mechanisms. MATERIAL AND METHODS: In the present study, immunohistochemistry (IHC) and the quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis were used to detect the expression of GSTP1 and signal transducer and activator of transcription 3 (STAT3) in CRC tissues. Western blotting was applied to detect the expression of GSTP1 and proteins of the Janus kinase (JAK)-STAT3 pathway in different CRC cell lines. The interaction and co-localization of GSTP1 and STAT3 were detected using co-immunoprecipitation (co-IP) and immunofluorescence (IF) in the SW620 cell line. RESULTS: A positive correlation was identified between the expression of GSTP1 and STAT3 in human CRC tissues. The overexpression of GSTP1 promoted the proliferation, invasion and metastasis of CRC cells by upregulating STAT3. The GSTP1 and STAT3 can directly bind to and regulate each other. The interaction between them is regulated by the upstream gene called F-box only protein 8 (FBX8). CONCLUSIONS: The present study demonstrated that GSTP1 could enhance the expression of STAT3 to promote the proliferation, invasion and metastasis of CRC cells, which provides a potential therapeutic target for the clinical treatment of CRC.