The methylation of cytosine at CG sites in the mammalian genome is dynamically reprogrammed during gametogenesis and preimplantation development. It was previously shown that oocyte-derived DNMT1 (a maintenance methyltransferase) is essential for maintaining and propagating CG methylation at imprinting control regions in preimplantation embryos. In mammalian somatic cells, hemimethylated-CG-binding protein UHRF1 plays a critical role in maintaining CG methylation by recruiting DNMT1 to hemimethylated CG sites. However, the role of UHRF1 in oogenesis and preimplantation development is unknown. In the present study, we show that UHRF1 is mainly, but not exclusively, localized in the cytoplasm of oocytes and preimplantation embryos. However, smaller amounts of UHRF1 existed in the nucleus, consistent with the expected role in DNA methylation. We then generated oocyte-specific Uhrf1 knockout (KO) mice and found that, although oogenesis was itself unaffected, a large proportion of the embryos derived from the KO oocytes died before reaching the blastocyst stage (a maternal effect). Whole genome bisulfite sequencing revealed that blastocysts derived from KO oocytes have a greatly reduced level of CG methylation, suggesting that maternal UHRF1 is essential for maintaining CG methylation, particularly at the imprinting control regions, in preimplantation embryos. Surprisingly, UHRF1 was also found to contribute to de novo CG and non-CG methylation during oocyte growth: in Uhrf1 KO oocytes, transcriptionally-inactive regions gained less methylation, while actively transcribed regions, including the imprinting control regions, were unaffected or only slightly affected. We also found that de novo methylation was defective during the late stage of oocyte growth. To the best of our knowledge, this is the first study to demonstrate the role of UHRF1 in de novo DNA methylation in vivo. Our study reveals multiple functions of UHRF1 during the global epigenetic reprogramming of oocytes and early embryos. The methylation of cytosine at CG sites in the mammalian genome is an epigenetic modification that is important for cell differentiation and embryonic development. During oocyte growth, the actively transcribed regions gain both CG and non-CG methylation. However, after fertilization, such methylation is globally erased, except for certain gene control regions and a subset of retrotransposons that retain CG methylation. We examined the role of UHRF1, a protein essential for the maintenance of CG methylation in somatic cells, in oocytes and preimplantation embryos by generating oocyte-specific Uhrf1 gene knockout mice. We found that oocyte-derived maternal UHRF1 protein was important for nuclear localization of DNMT1 (a maintenance DNA methyltransferase) and for CG maintenance methylation, particularly at the imprinting control regions, in preimplantation embryos. Unexpectedly, we found that the gain in CG and non-CG methylation in oocytes was also affected by Uhrf1 knockout in certain genomic regions. To the best of our knowledge, this is the first study to demonstrate a role of UHRF1 in de novo DNA methylation in vivo. Our study reveals multiple functions of UHRF1 during the global epigenetic reprogramming of oocytes and preimplantation embryos.

Ubiquitin-like with PHD and RING finger domains 1 (UHRF1) is a protein essential for the maintenance of DNA methylation in somatic cells. However, UHRF1 is predominantly localized in the cytoplasm of mouse oocytes and preimplantation embryos, where it may play a role unrelated to the nuclear function. We herein report that oocyte-specificUhrf1KO results in impaired chromosome segregation, abnormal cleavage division, and preimplantation lethality of derived embryos. Our nuclear transfer experiment showed that the phenotype is attributable to cytoplasmic rather than nuclear defects of the zygotes. A proteomic analysis of KO oocytes revealed the down-regulation of proteins associated with microtubules including tubulins, which occurred independently of transcriptomic changes. Intriguingly, cytoplasmic lattices were disorganized, and mitochondria, endoplasmic reticulum, and components of the subcortical maternal complex were mislocalized. Thus, maternal UHRF1 regulates the proper cytoplasmic architecture and function of oocytes and preimplantation embryos, likely through a mechanism unrelated to DNA methylation.

BHLHE40 is a basic helix-loop-helix transcription factor that is involved in multiple cell activities including differentiation, cell cycle, and epithelial-to-mesenchymal transition. While there is growing evidence to support the functions of BHLHE40 in energy metabolism, little is known about the mechanism. In this study, we found that BHLHE40 expression was downregulated in cases of endometrial cancer of higher grade and advanced disease. Knockdown of BHLHE40 in endometrial cancer cells resulted in suppressed oxygen consumption and enhanced extracellular acidification. Suppressed pyruvate dehydrogenase (PDH) activity and enhanced lactated dehydrogenase (LDH) activity were observed in the knockdown cells. Knockdown of BHLHE40 also led to dephosphorylation of AMPKα Thr172 and enhanced phosphorylation of pyruvate dehydrogenase E1 subunit alpha 1 (PDHA1) Ser293 and lactate dehydrogenase A (LDHA) Tyr10. These results suggested that BHLHE40 modulates PDH and LDH activity by regulating the phosphorylation status of PDHA1 and LDHA. We found that BHLHE40 enhanced AMPKα phosphorylation by directly suppressing the transcription of an AMPKα-specific phosphatase, PPM1F. Our immunohistochemical study showed that the expression of BHLHE40, PPM1F, and phosphorylated AMPKα correlated with the prognosis of endometrial cancer patients. Because AMPK is a central regulator of energy metabolism in cancer cells, targeting the BHLHE40‒PPM1F‒AMPK axis may represent a strategy to control cancer development.

Immune checkpoint inhibitors (ICIs) enhance antitumoral immune mechanisms and are used to treat various types of solid tumors including those that are microsatellite instability (MSI)-high. Uterine endometrial cancer is one of the most frequent tumor types that shows MSI-high, and, consequently, opportunities to use ICIs for endometrial cancer treatment are increasing. While using ICIs, it is important to monitor and manage various immune-related adverse events (irAEs). Here, we report two cases of secondary adrenal insufficiency during treatment of endometrial cancer with pembrolizumab. Both cases showed appetite loss and general fatigue after the 6th or 12th cycle of pembrolizumab. They were admitted to our hospital because of remarkable hyponatremia. Both cases showed no adrenocorticotropic hormone (ACTH) or cortisol response to CRH loading tests. Other pituitary hormone levels were normal, and MRI revealed no sign of hypophysitis in either patient. They were diagnosed with secondary adrenal insufficiency due to isolated ACTH deficiency and recovered soon after the administration of hydrocortisone and hydration. Thus, we should be aware of irAEs with the use of ICIs. In particular, adrenocortical insufficiency is sometimes lethal without appropriate treatment. Because the clinical symptoms are fatigue, appetite loss, and nausea, patients might be misjudged to have symptoms related to cancer. Checking serum morning cortisol before ICIs use and monitoring serum sodium levels could provide clues to diagnose secondary adrenal insufficiency.

• LG-ESS is a rare and indolent uterine tumor which has remarkable sensitivity to hormonal agents. • We presented the case of recurrent LG-ESS that was effectively and safely treated with Dienogest. • Dienogest may be useful for the treatment of LG-ESS that is resistant to other progestins.

Background: A molecular classification of endometrial cancer was developed based on an analysis of The Cancer Genome Atlas. In this classification, the group characterized by abnormal p53 immunohistochemical expression showed the poorest prognosis. However, there may be no need to apply a molecular classification in low-grade endometrial cancer. In this study, we investigated the clinical significance of abnormal p53 immunohistochemical expression in low-grade endometrial cancer. Methods: We obtained nine frozen samples of endometrial cancer [low-grade endometrial cancer with wild-type p53 expression (EC^lop53^wt group): n = 3, low-grade endometrial cancer with abnormal p53 expression (EC^lop53^ab group): n = 3, and high-grade endometrial cancer (EC^hi group): n = 3]. RNA sequencing was performed for each sample. All the samples passed RNA quality control. In addition, an immunohistochemical analysis was performed for 44 formalin-fixed paraffin-embedded samples. Results: Differentially expressed genes were identified in the RNA sequencing results (1811 genes between the EC^lop53^ab group and the EC^hi group, and 1088 genes between the EC^lop53^ab group and the EC^lop53^wt group). In a principal component analysis, the EC^lop53^ab group was more similar to the EC^lop53^wt group than to the EC^hi group. In the immunohistochemical analysis, L1CAM expression was significantly less frequently observed in the EC^lop53^ab group than in the EC^hi group. Moreover, p21 expression tended to be more frequently observed in the EC^lop53^ab group than in the EC^hi group. Conclusions: In this study, the RNA sequencing and immunohistochemical results revealed that the EC^lop53^ab group is a separate entity from the EC^hi group. While the abnormal p53 group is considered the most prognostically unfavorable in molecular classification, these findings suggest that routine molecular profiling is not necessary for patients with low-grade endometrial cancer. However, there is insufficient evidence to modify adjuvant treatment in low-grade endometrial cancer patients. Further investigation is needed on the clinical application of molecular classification to low-grade endometrial cancer.