Upregulated miR-665 expression independently predicts poor prognosis of lung cancer and facilitates tumor cell proliferation, migration and invasion.

Non-small cell lung cancer (NSCLC) is one of the leading causes of global cancer-associated mortality. Aberrant microRNAs (miRs) have been reported to be involved in the pathogenesis of various cancer types. The present study aimed to investigate the expression profile and prognostic value of miR-665 in patients with NSCLC, and to analyze its functional role in tumor progression using NSCLC cells. Reverse transcription-quantitative PCR was used to estimate the expression levels of miR-665. Kaplan-Meier survival curves and Cox regression analysis were performed to evaluate the prognostic value of miR-665. The effects of miR-665 on NSCLC cell proliferation, migration and invasion were examined by cell transfection, and the target gene of miR-665 was explored. miR-665 expression was elevated in the tissue and cell samples of NSCLC. This increased miR-665 expression was associated with lymph node metastasis and TNM stage. An independent association between miR-665 and overall survival was identified in patients with NSCLC. When regulating the expression levels of miR-665 in vitro, NSCLC cell proliferation, migration and invasion were enhanced by overexpression of miR-665, but were inhibited by knockdown of miR-665. The luciferase activity results indicated that the protein tyrosine phosphatase receptor type B (PTPRB) was a direct target of miR-665 in NSCLC cells. The present study provided evidence for the clinical significance of a decreased expression of miR-665 in the prognosis of NSCLC. Upregulation of miR-665 contributed to tumor cell proliferation, migration and invasion by targeting PTPRB, suggesting the potential of miR-665 as a candidate therapeutic target for NSCLC treatment.

Contribution of BDNF/TrkB signalling in the rACC to the development of pain-related aversion via activation of ERK in rats with spared nerve injury.

The rostral anterior cingulate cortex (rACC) is a key structure in mediating the negative affective component of chronic pain. Brain-derived neurotrophic factor (BDNF) is known to play a critical role in activity-dependent synaptic plasticity, learning and memory. It has been shown that BDNF signalling in the rACC might be involved in spontaneous pain-related aversion, but its underlying mechanism is still largely unknown. To address this question, we measured the mRNA and protein levels of BDNF in the rACC after nerve injury and found that BDNF expression was markedly higher in nerve-injured rats than in controls. Moreover, we found that conditioned place avoidance (CPA), a behavioural phenotype reflecting pain-related aversion, was acquired in rats with partial sciatic nerve transection. However, a local injection of a BDNF-tropomyosin receptor kinase B (TrkB) antagonist into the rACC completely suppressed this process. Importantly, we found that administration of exogenous BDNF into the rACC of intact rats was sufficient to produce CPA, while selectively blocking phosphorylated extracellular signal regulated kinase (p-ERK) with a mitogen-activated protein kinase (MAPK) inhibitor U0126 completely abolished the acquisition of BDNF-induced CPA. In conclusion, we demonstrate, for the first time, that ERK is an important downstream effector of the BDNF/TrkB-mediated signalling pathway in the rACC that contributes to the development of neuropathic pain-related aversion.