miR-4775 promotes colorectal cancer invasion and metastasis via the Smad7/TGFß-mediated epithelial to mesenchymal transition.

BACKGROUND: Despite advancements in the diagnosis and treatment of colorectal cancer (CRC), many patients die because of tumor metastasis or recurrence. Therefore, identifying new prognostic markers and elucidating the mechanisms of CRC metastasis and recurrence will help to improve the prognosis of the disease. As dysregulation of microRNAs is strongly related to cancer progression, the aim of this study was to identify the role of miR-4775 in the prognosis of CRC patients and the underling mechanisms involved in CRC progression. METHODS: qPCR and in situ hybridization were used to evaluate the expression of miR-4775 in 544 pairs of paraffin-embedded normal and CRC tissues. Kaplan-Meier analysis with the log-rank test was used for survival analyses. Immunohistochemical staining was applied to investigate the expression of miR-4775-regulated Smad7/TGFß pathway-associated markers. In vitro and in vivo invasion and metastasis assays were used to explore the function of miR-4775 in the progression of CRC. RESULTS: miR-4775 was identified as a high-risk factor for CRC metastasis and recurrence, with high levels predicting poor survival among the 544 studied CRC patients. Furthermore, high miR-4775 expression promoted the invasion of CRC cells as well as metastasis and the epithelial to mesenchymal transition (EMT) via Smad7-mediated activation of TGFß signaling both in vitro and in vivo. Downregulating miR-4775 or overexpressing Smad7 reversed the tumor-promoting roles of miR-4775/Smad7/TGFß in vitro and in vivo. CONCLUSION: miR-4775 promotes CRC metastasis and recurrence in a Smad7/TGFß signaling-dependent manner, providing a new therapeutic target for inhibiting the metastasis or recurrence of the disease.

[Effects of physical factors on neck or shoulder pain and low back pain of adolescents].

OBJECTIVE: To explore the incidence of self-reported neck or shoulder pain (NSP) and lower back pain (LBP) among Chinese adolescents in Shanghai and identify the influencing factors for the incidences of NSP and LBP. METHODS: A total of 3 600 students were selected from 30 high schools randomly chosen from 237 regular full-time high schools registered in Shanghai. From each school, 40 students were selected from each of the tenth, eleventh and twelfth grades for a total of 120 students per school. The questionnaire involved questions pertaining to demographic profiles, learning environment and exercise habits of each student. And it also contained questions regarding the amount of weight carried by each student while commuting to and from school, and it was also used to collect specific information related to the occurrence of NSP and LBP. Logistic regression was performed to analyze the potential risk factors for NSP and LBP. RESULTS: Among 3 600 questionnaires, a total of 2 842 valid ones were returned. The results revealed that the incidence of NSP and LBP in the Chinese adolescent population was 41.1% and 32.8% respectively. Both NSP and LBP were more common in girls than in boys, and 6.3% students reported at least one NSP- or LBP-induced absence from school. A relatively large portion of Chinese adolescents reported experiencing problems such as sedentary behavior (26.7% of the students continued to sit for more than 3 hours after school), a lack of exercise (29.3% exercised less than once each week and 38.2% of students reported that their exercise duration was less than half an hour each time) and overweight backpacks (53.0% complained that their backpack was too heavy). Multivariate logistic regression analysis revealed that gender, grade, physical activity and learning environment were all significantly correlated with the occurrences of NSP and LBP. CONCLUSION: The incidences of NSP and LBP are relatively high among adolescents in Shanghai. And several factors, including sedentary behavior, personal exercise habits and backpack weight, influence the occurrences of NSP and LBP in adolesents.

A simple microdevice for single cell capture, array, release, and fast staining using oscillatory method.

Microchips that perform single cell capture, array, and identification have become powerful tools for single cell studies, which can reveal precise underlying mechanisms among bulk cell populations. However, current single cell capture and on-chip immunostaining methods consume more time and reagent than desired. To optimize this technology, we designed a novel trap structure for single cell capture, array, and release, and meanwhile an oscillatory method was used to perform rapid on-chip cell immunostaining. The trap structure array used equal distribution of lateral flow to achieve single cell array in high velocity flows and decrease the risk of clogging. A length of glass capillary with a sealed bubble was inserted into the outlet so that it could act in a manner analogous to that of a capacitor in an RC circuit. By applying one periodic air pressure to the inlet, oscillation motion was generated, which significantly enhanced the on-chip reaction efficiency. In addition, the oscillation performance could be easily regulated by changing the length of the capillary. The trapped cells could maintain their positions during oscillation; hence, they were able to be tracked in real time. Through our trap microchip, 12 µm microbeads were successfully trapped to form a microarray with a capture efficiency of ∼92.7% and 2 µm microbeads were filtered. With an optimized oscillation condition (Ppush = 0.03 MPa, f = 1 Hz, L = 3 cm), fast on-chip immunostaining was achieved with the advantages of less time (5 min) and reagent (2 µl) consumption. The effectiveness of this method was demonstrated through quantitative microbead and qualitative Caco-2 cell experiments. The device is simple, flexible, and efficient, which we believe provides a promising approach to single cell heterogeneity studies, drug screening, and clinical diagnosis.

MicroRNA-20a-5p promotes colorectal cancer invasion and metastasis by downregulating Smad4.

BACKGROUND: Tumor metastasis is one of the leading causes of poor prognosis for colorectal cancer (CRC) patients. Loss of Smad4 contributes to aggression process in many human cancers. However, the underlying precise mechanism of aberrant Smad4 expression in CRC development is still little known. RESULTS: miR-20a-5p negatively regulated Smad4 by directly targeting its 3'UTR in human colorectal cancer cells. miR-20a-5p not only promoted CRC cells aggression capacity in vitro and liver metastasis in vivo, but also promoted the epithelial-to-mesenchymal transition process by downregulating Smad4 expression. In addition, tissue microarray analysis obtained from 544 CRC patients' clinical characters showed that miR-20a-5p was upregulated in human CRC tissues, especially in the tissues with metastasis. High level of miR-20a-5p predicted poor prognosis in CRC patients. METHODS: Five miRNA target prediction programs were applied to identify potential miRNA(s) that target(s) Smad4 in CRC. Luciferase reporter assay and transfection technique were used to validate the correlation between miR-20a-5p and Smad4 in CRC. Wound healing, transwell and tumorigenesis assays were used to explore the function of miR-20a-5p and Smad4 in CRC progression in vitro and in vivo. The association between miR-20a-5p expression and the prognosis of CRC patients was evaluated by Kaplan-Meier analysis and multivariate cox proportional hazard analyses based on tissue microarray data. CONCLUSIONS: miR-20a-5p, as an onco-miRNA, promoted the invasion and metastasis ability by suppressing Smad4 expression in CRC cells, and high miR-20a-5p predicted poor prognosis for CRC patients, providing a novel and promising therapeutic target in human colorectal cancer.