MAML1: a coregulator that alters endometrial epithelial cell adhesive capacity

A short peptide encoded by long non-coding RNA small nucleolar RNA host gene 6 promotes cell migration and epithelial-mesenchymal transition by activating transforming growth factor-beta/SMAD signaling pathway in human endometrial cells

BACKGROUND

Endometrial dysfunction is closely correlated with the development of multiple severe gynecological disorders including intrauterine adhesion. Accumulating evidence supports that some long non-coding RNAs (lncRNAs) have peptide-coding potential. In this text, the peptide-coding ability of lncRNA SNHG6 was examined. Also, the effects of an SNHG6-encoded peptide on the viability and migration of human endometrial stromal cells (hESCs) and human endometrial epithelial cells (hEECs) and related molecular mechanisms were explored.

METHODS

The peptide-encoding potential of SNHG6 was predicted by FuncPEP and getorf databases and validated by western blot assay. Cell viability was tested by cell counting kit-8 assay. Cell migratory ability was examined by wound healing and transwell migration assays. Protein levels of genes were measured by western blot assay.

RESULTS

Prediction analysis suggested that SNHG6 had the potential peptide-coding ability and multiple open-reading frames (ORFs). Western blot validated that SNHG6 ORF#1 and ORF#2 could translate into short peptides. SNHG6 ORF#2 overexpression facilitated cell migration and epithelial-mesenchymal transition (EMT) in hESCs and hEECs, while these effects were abrogated by transforming growth factor-beta (TGF-β)/SMAD signaling inhibitor GW788388. Moreover, GW788388 inhibited the increase of p-SMAD2 and p-SMAD3 levels induced by SNHG6 ORF#2 in hESCs. SNHG6 ORF#2-encoded peptide did not influence endometrial stromal and epithelial cell viability.

CONCLUSIONS

LncRNA SNHG6 ORF#1 and ORF#2 could translate into small peptides and SNHG6 ORF#2 overexpression promoted cell migration and EMT by activating the TGF-β/SMAD pathway in hESCs and hEECs, suggesting the potential roles of SNHG6-encoded peptides in the development of endometrial stromal and epithelial cells and related gynecological diseases.

Elucidated tumorigenic role of MAML1 and TWIST1 in gastric cancer is associated with Helicobacter pylori infection

BACKGROUND

Epithelial-mesenchymal transition (EMT) has a fundamental role in tumor initiation, progression, and metastasis. Helicobacter pylori (HP) induces EMT and thus causes gastric cancer (GC) by deregulating multiple signaling pathways involved in EMT. TWIST1 and MAML1 have been confirmed to be critical inducers of EMT via diverse signaling pathways such as Notch signaling. This study aimed to investigate for the first time possible associations between TWIST1/MAML1 mRNA expression levels, HP infection, and clinicopathological characteristics in GC patients.

METHOD

TWIST1 and MAML1 mRNA expression levels were evaluated in tumoral and adjacent normal tissues in 73 GC patients using the quantitative reverse transcription PCR (RT-qPCR) method. PCR technique was also applied to examine the infection with HP in GC samples.

RESULTS

Upregulation of TWIST1 and MAML1 expression was observed in 35 (48%) and 34 (46.6%) of 73 tumor samples, respectively. Co-overexpression of these genes was found in 26 of 73 (35.6%) tumor samples; meanwhile, there was a significant positive correlation between MAML1 and TWIST1 mRNA expression levels (P < 0.001). MAML1 overexpression exhibited meaningful associations with advanced tumor stages (P = 0.006) and nodal metastases (P ˂ 0.001). 34 of 73 (46.6%) tumors tested positive for HP, and meanwhile, MAML1 expression was positively related with T (P = 0.05) and grade (P = 0.0001) in these HP-positive samples. Increased TWIST1 expression was correlated with patient sex (P = 0.035) and advanced tumor grade (P = 0.017) in HP-infected tumors. Furthermore, TWIST1 and MAML1 expression levels were inversely linked with histologic grade in HP-negative tumor samples (P = 0.021 and P = 0.048, respectively).

CONCLUSION

We propose TWIST1 and MAML1 as potential biomarkers of advanced-stage GC that determine the characteristics and aggressiveness of the disease. Based on accumulating evidence and our findings, they can be introduced as promising therapeutic targets to modify functional abnormalities in cells that promote GC progression. Moreover, HP may enhance GC growth and metastasis by disrupting TWIS1/MAML1 expression patterns and related pathways.

Jagged1 regulates endometrial receptivity in both humans and mice

The human endometrium undergoes cycle-dependent changes and is only receptive to an implanting blastocyst within a narrow window of 2-4 days in the mid-secretory phase. Such functional changes require delicate interplay between a diversity of factors including cytokines and signaling pathways. The Notch signaling pathway members are expressed in human endometrium. We have previously demonstrated that Notch ligand Jagged1 (JAG1) localizes in the endometrial luminal epithelium (LE) and is abnormally reduced in infertile women during receptivity. However, the functional consequences of reduced JAG1 production on endometrial receptivity to implantation of the blastocyst are unknown. This study aimed to determine the role of JAG1 in regulating endometrial receptivity in humans and mice. Knockdown of JAG1 in both primary human endometrial epithelial cells and Ishikawa cells significantly reduced their adhesive capacity to HTR8/SVneo (trophoblast cell line) spheroids. We confirmed that in human endometrial epithelial cells, JAG1 interacted with Notch Receptor 3 (NOTCH3) and knockdown of JAG1 significantly reduced the expression of Notch signaling downstream target HEY1 and classical receptivity markers. Knockdown of Jag1 in mouse LE significantly impaired blastocyst implantation. We identified ten genes (related to tight junction, infertility, and cell adhesion) that were differentially expressed by Jag1 knockdown in LE in mice. Further analysis of the tight junction family members in both species revealed that JAG1 altered the expression of tight junction components only in mice. Together, our data demonstrated that JAG1 altered endometrial epithelial cell adhesive capacity and regulated endometrial receptivity in both humans and mice likely via different mechanisms.