No abstract

Embryo implantation is a complex initial step in establishment of a successful pregnancy. Many mRNAs have been shown to be differentially expressed in the rat uterus during embryo implantation. However, the expression profiles of microRNAs (miRNAs), a key post-transcriptional regulator of gene expression, in the rat uterus between the pre-receptive and receptive phases are still unknown. Here, an miRNA microarray was used to examine differential expression of miRNAs in the rat uterus between the pre-receptive and receptive phases. Twenty-eight miRNAs were up-regulated and 29 miRNAs were down-regulated at least twofold during the receptive phase in rat uterus; these results were confirmed by Northern blotting. miR-29a was only highly expressed in rat uterus during the implantation period, and activation of delayed implantation and artificial decidualization enhanced the miR-29a level. Further investigation revealed that both the pro-apoptotic factor genes Bak1 and Bmf and the anti-apoptotic factor gene Bcl-w are targets of miR-29a. There was weak binding between miR-29a and the 3 0 UTR of the anti-apoptotic factor gene Mcl1. Over-expression of miR-29a inhibited the late apoptosis of endometrial stromal cells, which may be due to the stronger binding capacity between miR-29a and the 3 0 UTR of pro-apoptotic factors than that between miR-29a and the 3 0 UTR of anti-apoptotic factors. Collectively, miR-29a plays an important role during embryo implantation by regulating both pro-apoptotic and anti-apoptotic factors. miR-29a may predominantly bind pro-apoptotic factors, leading to inhibition of cell apoptosis.

Numerous studies have focused on the development of novel and innovative approaches for the treatment of peripheral nerve injury using artificial nerve guide conduits. In this study, we attempted to bridge 3.5-cm defects of the sciatic nerve with a longitudinally oriented collagen conduit (LOCC) loaded with human umbilical cord mesenchymal stem cells (hUC-MSCs). The LOCC contains a bundle of longitudinally aligned collagenous fibres enclosed in a hollow collagen tube. Our previous studies showed that an LOCC combined with neurotrophic factors enhances peripheral nerve regeneration. However, it remained unknown whether an LOCC seeded with hUC-MSCs could also promote regeneration. In this study, using various histological and electrophysiological analyses, we found that an LOCC provides mechanical support to newly growing nerves and functions as a structural scaffold for cells, thereby stimulating sciatic nerve regeneration. The LOCC and hUC-MSCs synergistically promoted regeneration and improved the functional recovery in a dog model of sciatic nerve injury. Therefore, the combined use of an LOCC and hUC-MSCs might have therapeutic potential for the treatment of peripheral nerve injury.

BackgroundFolic acid (FA) supplementation before and during the first trimester can reduce the risk of occurrence of preterm delivery (PTD). Preconception body mass index (BMI) is also associated with PTD. This study aimed to investigate the combined effect of FA supplements and preconception BMI on the risk of PTD.MethodsThe data of a cohort from 2010–2011 that was obtained through a preconception care service in China was used (including 172,206 women). A multivariable regression model was used to investigate the association between maternal preconception conditions and the risk of PTD. The interaction of preconception BMI and FA supplementation was measured by a logistic regression model.ResultsTaking FA supplements in the preconception period or in the first trimester reduced the risk of PTD (odds ratio [OR] = 0.58 and OR = 0.61, respectively). Women with an abnormal BMI had an increased risk of PTD (OR = 1.09, OR = 1.10, and OR = 1.17 for underweight, overweight, and obese, respectively). Preconception BMI showed an interaction with the protective effect of FA supplementation for PTD. With regard to the interaction of FA supplementation, the adjusted odds ratio (aOR) was 0.57 (95 % CI: 0.51, 0.64) in underweight women, 0.85 (95 % CI: 0.73, 0.98) in overweight women, and 0.77 (95 % CI, 0.65, 0.91) in obese women. Preconception BMI also showed an interaction with the time of FA supplementation. Women with a normal BMI who began to take FA supplements in the preconception period had the lowest risk of PTD (aORs: 0.58 vs. 0.65 beginning in the first trimester). The aORs at preconception and the first trimester in the underweight group were 0.56 vs. 0.60. The aORs at preconception and the first trimester were 0.94 vs. 0.65 and 1.15 vs. 0.60 in the overweight and obesity groups, respectively.ConclusionsIn our study, FA supplements reduced the risk of PTD, while abnormal BMI raised the risk of PTD, although higher BMI categories did not have this higher risk once adjusted analysis was conducted. The protective effect of FA supplementation for PTD was reduced in women with overweight or obesity. To get better protection of FA supplementation, women with normal BMI or underweight should begin to use in preconception, while women with overweight or obesity should begin to use after conception.

a b s t r a c tIn a previous study, via microRNA microarray analysis we found that miR-98 is differentially expressed in rat uteri during the peri-implantation period (unpublished data). However, the role of miR-98 in rat embryo implantation remains elusive. Here, we found that the level of miR-98 is lower on day 5 and 6 of gestation (g.d. 5-6) than that on g.d. 3-4 and g.d. 7-8 in rat. MiR-98 expression is significantly decreased by delayed implantation. Down-regulation of miR-98 promotes ESC proliferation and inhibits apoptosis. Up-regulation of miR-98 displays opposite effects. Further investigation revealed that miR-98 can bind to the 3 0 -untranslated region (3 0 -UTR) of B-cell lymphoma-extra large (Bcl-xl) to inhibit Bcl-xl translation. Collectively, down-regulation of miR-98 in rat uterus during the receptive phase is linked to the increase of cell proliferation via targeting Bcl-xl.

The mutation of K-RAS represents one of the most frequent genetic alterations in cancer. Targeting of downstream effectors of RAS, including of MEK and ERK, has limited clinical success in cancer patients with K-RAS mutations. The reduced sensitivity of K-RAS-mutated cells to certain MEK inhibitors (MEKi) is associated with the feedback phosphorylation of MEK by C-RAF and with the reactivation of mitogen-activated protein kinase (MAPK) signaling. Here, we report that the RAF dimer inhibitors lifirafenib (BGB-283) and compound C show a strong synergistic effect with MEKi, including mirdametinib (PD-0325901) and selumetinib, in suppressing the proliferation of K-RAS-mutated non-small-cell lung cancer and colorectal cancer (CRC) cell lines. This synergistic effect was not observed with the B-RAF V600E selective inhibitor vemurafenib. Our mechanistic analysis revealed that RAF dimer inhibition suppresses RAF-dependent MEK reactivation and leads to the sustained inhibition of MAPK signaling in K-RAS-mutated cells. This synergistic effect was also observed in several K-RAS mutant mouse xenograft models. A pharmacodynamic analysis supported a role for the synergistic phospho-ERK blockade in enhancing the antitumor activity observed in the K-RAS mutant models. These findings support a vertical inhibition strategy in which RAF dimer and MEKi are combined to target K-RAS-mutated cancers, and have led to a Phase 1b/2 combination therapy study of lifirafenib and mirdametinib in solid tumor patients with K-RAS mutations and other MAPK pathway aberrations.Abbreviations CR, complete regression; CRC, colorectal cancer; EOHSA, excess over highest single agent; MAPK, mitogen-activated protein kinase; MEKi, MEK inhibitors; NFA, negative feedback amplified; NSCLC, non-small-cell lung cancer; PR, partial regression; TGI, tumor growth inhibition; WT, wild-type.