Estrogen-receptor-related receptors and hormone-dependent cancers

Regulation of the expression of the estrogen related receptors (ERRs)

Estrogen related receptors (ERRα, β and γ in mammals) are orphan members of the nuclear receptor superfamily acting as transcription factors. ERRs are expressed in several tissues and cells and they display various physiological and pathological functions, controlling, amongst others and depending on the receptor, bone homeostasis, energy metabolism, embryonic stem cell pluripotency, and cancer progression. In contrast to classical nuclear receptors, the activities of the ERRs are not controlled by a natural ligand. Regulation of their activities thus rely on other means such as post-translational modification or availability of transcriptional co-regulators. In addition, regulation of their mere expression under given physiological or pathological conditions is a particularly important level of control. Here we discuss the mechanisms involved in the regulation of ERRs expression and the reported means to impact on it using pharmacological approaches.

A Systematic Analysis of Factors Localized to Damaged Chromatin Reveals PARP-Dependent Recruitment of Transcription Factors

Localization to sites of DNA damage is a hallmark of DNA damage response (DDR) proteins. To identify DDR factors, we screened epitope-tagged proteins for localization to sites of chromatin damaged by UV laser microirradiation and found >120 proteins that localize to damaged chromatin. These include the BAF tumor suppressor complex and the amyotrophic lateral sclerosis (ALS) candidate protein TAF15. TAF15 contains multiple domains that bind damaged chromatin in a poly-(ADP-ribose) polymerase (PARP)-dependent manner, suggesting a possible role as glue that tethers multiple PAR chains together. Many positives were transcription factors; > 70% of randomly tested transcription factors localized to sites of DNA damage, and of these, ∼90% were PARP dependent for localization. Mutational analyses showed that localization to damaged chromatin is DNA-binding-domain dependent. By examining Hoechst staining patterns at damage sites, we see evidence of chromatin decompaction that is PARP dependent. We propose that PARP-regulated chromatin remodeling at sites of damage allows transient accessibility of DNA-binding proteins.

The effects of PGC-1α on the proliferation and energy metabolism of malignant endometrial cancer cells

Background

It is well known that peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) plays an important role in tissue energy metabolism. However, the roles of PGC-1α in malignant endometrial cancer remain unknown.

Methods

Forty cases of endometrial carcinoma, 15 cases with proliferative endometrial tissues, and 21 cases with normal endometrial tissues were collected. Real-time polymerase chain reaction was used to detect the mRNA levels of PGC-1α and estrogen-related receptor gamma (ERRγ). ELISA (enzyme-linked immunosorbent assay) was used to detect the concentrations of pyruvate kinase and isocitrate dehydrogenase. The results were analyzed using medical statistical methods.

Results

The mRNA levels of PGC-1α and ERRγ in the endometrial carcinoma tissues and hyperplasic endometrial tissues were significantly greater than those in the normal endometria. The mRNA levels of PGC-1α and ERRγ in the endometrial carcinoma patients with type 2 diabetes were higher than those in patients without diabetes. The mRNA levels of PGC-1α and ERRγ in the endometrial adenocarcinomas increased with clinical staging, depth of myometrial invasion, and increases in the number of metastatic lymph nodes. The PGC-1α mRNA level was positively correlated with ERRγ in the endometrial carcinoma tissues. The mRNA levels of PGC-1α were positively correlated with the concentrations of pyruvate kinase and isocitrate dehydrogenase in the endometrial carcinoma tissues, and similar results were found for ERRγ.

Conclusion

Our results suggested that the upregulation of PGC-1α and ERRγ in endometrial cancer might be a requirement for cancer cell energy metabolism, which contributes to the development of endometrial cancer.