Expression of HOXA10 in endometrial hyperplasia and adenocarcinoma and regulation by sex hormones in vitro

Loss of HOXA10 causes endometrial hyperplasia progressing to endometrial cancer

Endometrial cancer is the fourth most common malignancy in women and the precursor lesion is endometrial hyperplasia. HOXA10 is a transcription factor that plays key roles in endometrial functions such as the endowment of receptivity, embryo implantation, and trophoblast invasion. Herein, using testicular transgenesis, we developed transgenic mice that expressed a shRNA against HOXA10 and there was a nearly 70% reduction in the expression of HOXA10 in these animals. We observed that downregulation of HOXA10 led to the development of endometrial hyperplasia in the young animals (3 months), and as they aged (>1 year), most animals developed well-differentiated endometrial adenocarcinoma. In the endometrium of animals with reduced HOXA10, there was increased proliferation and elevated levels of ERα and ERβ. In parallel, there was increased expression of Wnt4 and β-Catenin, SOX9, and YAP1. We propose that chronic reduction in HOXA10 expression disrupts multiple pathways in the uterus that aids in the development of endometrial hyperplasia which progresses to endometrial cancer with age.

Metformin reduces androgen receptor and upregulates homeobox A10 expression in uterine endometrium in women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) causes anovulation and is associated with a reduced clinical pregnancy rate. Metformin, which is widely used for treating PCOS, can lead to successful pregnancy by restoring the ovulation cycle and possibly improving endometrial abnormality during the implantation period. However, the mechanism by which metformin improves endometrial abnormality remains unknown. Women with PCOS have an aberrant expression of steroid hormone receptors and homeobox A10 (HOXA10), which is essential for embryo implantation in the endometrium.

METHODS

In this study, we examined whether metformin affects androgen receptor (AR) and HOXA10 expression in PCOS endometrium in vivo and in human endometrial cell lines in vitro. Expression of AR and HOXA10 was evaluated by immunohistochemistry, fluorescent immunocytochemistry, and western blot analysis.

RESULTS

AR expression was localized in both epithelial and stromal cells; however, HOXA10 expression was limited to only stromal cells in this study. In women with PCOS, 3 months after metformin treatment, the expression of AR was reduced in epithelial and stromal cells in comparison to their levels before treatment. In contrast, HOXA10 expression in the stromal cells with metformin treatment increased in comparison to its level before treatment. Further, we showed that metformin counteracted the testosterone-induced AR expression in both Ishikawa cells and human endometrial stromal cells (HESCs); whereas, metformin partly restored the testosterone-reduced HOXA10 expression in HESCs in vitro.

CONCLUSIONS

Our results suggest that metformin may have a direct effect on the abnormal endometrial environment of androgen excess in women with PCOS.

TRIAL REGISTRATION

The study was approved by the Ethical Committee of Fukushima Medical University (approval no. 504, approval date. July 6, 2006), and written informed consent was obtained from all patients. https://www.fmu.ac.jp/univ/sangaku/rinri.html.

LncHOXA10 drives liver TICs self-renewal and tumorigenesis via HOXA10 transcription activation

Background

Liver cancer is one of the most deadly cancers in the world. There are various cells in liver tumor bulk, including liver tumor initiating cells (TICs), which account for liver tumorigenesis, drug resistance, relapse and metastasis. The homeobox (HOX) transcription factors play critical roles in many physiological and pathological processes, while, their roles in liver TICs and liver tumorigenesis remain unknown.

Methods

An unbiased screening was performed using online-available datasets. Liver TICs were sorted by FACS using surface markers CD133, CD13 and EPCAM, or enriched by oncosphere formation assay. TIC self-renewal was examined by oncosphere formation and tumor initiation assay. Loss of function and gain of function assays were performed to examine the role of lncRNA. RNA pulldown, RNA immunoprecipitation, ChIP, Western blot and double FISH were used to explore the molecular mechanism of lncRNA.

Results

Here, we examined the expression pattern of HOX transcription factors, and found HOXA10 was overexpressed in liver cancer samples. Moreover, a divergent lncRNA of HOXA10 (termed lncHOXA10 hereafter) was also highly expressed in liver cancer and liver TICs. LncHOXA10 drove liver TIC self-renewal and liver tumorigenesis through HOXA10-dependent manner. LncHOXA10 interacted with SNF2L and recruited NURF chromatin remodeling complex to HOXA10 promoter, and thus initiated the transcription of HOXA10. Through HOXA10 transcriptional regulation, lncHOXA10 activated HOXA10 in liver TICs. LncHOXA10-HOXA10 signaling can be targeted to eliminate liver TICs. Altogether, lncHOXA10 drove HOXA10 expression and thus promoted liver TIC self-renewal.

Conclusion

HOXA10 was the most highly expressed HOX transcription factor in liver cancer and liver TICs. LncHOXA10 drove the transcriptional activation of HOXA10. This work revealed the important role of HOX transcription factor in liver TIC self-renewal and added a new layer for liver TIC regulation.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0921-y) contains supplementary material, which is available to authorized users.

Methylation of the HOXA10 homeobox gene promoter is associated with endometrial cancer: a pilot study

Methylation in the promoter region represents an epigenetic mechanism that silences expression of various homeobox genes in cancers. We compare the methylation profile of HOXA10 promoter gene in 19 histologically proven endometrioid cancers and 27 normal endometrial tissues. Endometrial cancer tissue displays significantly higher methylation status in HOXA10 gene promoter than normal tissue, suggesting a possible role of epigenetic changes in HOXA10 gene regulation in tumorigenesis. Further studies in human tissue and cell lines are necessary to validate these preliminary results and to investigate HOXA10 expression according to methylation status in endometrial cancer.