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.

Introduction: The prognostic significance of lymphovascular space invasion (LVSI) in stage IA endometrial cancer remains unclear. The aim of this study was to evaluate the clinical significance of LVSI in stage IA endometrial cancer. Methods: Clinical data of patients with stage IA endometrial cancer who underwent initial surgery at our institution between January 2008 and December 2018 were reviewed retrospectively. Information of patients, surgery, and characteristics of cancer were obtained from medical records and pathological reports. Results: Two hundred ninety-seven patients were enrolled in this study. With a median follow-up of 60 months, 15 patients experienced recurrence (5.1%) and 4 patients died of endometrial cancer (1.3%). The recurrence and mortality rates did not differ significantly between the LVSI-positive and -negative groups (p = 0.07 and p = 0.41, respectively). Recurrence-free survival and endometrial cancer-specific survival also did not differ significantly between these groups (p = 0.11 and p = 0.49, respectively). The 5-year endometrial cancer-specific survival rates for tumors with and without LVSI were 97.0% and 98.9%, respectively. Among patients with low-grade tumors, recurrence-free survival and endometrial cancer-specific survival did not differ significantly between patients with tumors with and without LVSI (p = 0.92 and p = 0.72, respectively). The 5-year endometrial cancer-specific survival rates for low-grade tumors with and without LVSI were 100% and 99.3%, respectively. Conclusion: LVSI was not a prognostic factor of not only stage IA endometrial cancer but also stage IA low-grade cancer.

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.

Background/Objectives: Under the current molecular classification of endometrial cancer, the p53-abnormal group is defined as having the worst prognosis, but the clinicopathological position of low-grade endometrial cancer with p53-abnormal expression relative to high-grade endometrial cancer remains unclear. We previously showed that low-grade endometrial cancer with p53-abnormal expression more closely resembles low-grade endometrial cancer with p53 wild-type expression than high-grade endometrial cancer and that the ERBB2 gene, encoding Human Epidermal Growth Factor Receptor 2 (HER2) protein, is more highly expressed in high-grade endometrial cancer. This study compared HER2 immunohistochemical expression (IHC) among low-grade endometrial cancer with wild-type p53 expression (EC^lop53^wt), low-grade endometrial cancer with p53-abnormal expression (EC^lop53^ab), and high-grade endometrial cancer (EC^hi), in order to characterize EC^lop53^ab. Methods: We retrospectively analyzed 70 endometrial cancer cases treated at Kyushu University Hospital in 1992–2022. Tumors were classified as EC^lop53^wt, EC^lop53^ab, and EC^hi based on histopathology and p53 immunohistochemistry, with EC^hi corresponding to conventional uterine serous carcinoma. HER2 expression was evaluated immunohistochemically using a standardized scoring system (0, 1+, 2+, 3+), and its distribution was compared across the three groups, together with clinicopathological parameters and patient outcomes. Results: EC^hi showed the highest frequency and intensity of HER2 expression, with a substantially larger proportion of HER2 IHC 3+ cases than EC^lop53^wt and EC^lop53^ab (p < 0.0001 and p = 0.0146, respectively). Meanwhile, there was no significant association between EC^lop53^wt and EC^lop53^ab (p = 0.3794). In addition, HER2 IHC 3+ had significant associations with older age (≥60 years) and substantial lymphovascular space invasion (p = 0.0003 and 0.0174, respectively). Conclusions: EC^lop53^ab exhibits HER2 profiles and clinical behavior more similar to EC^lop53^wt, supporting the more nuanced application of molecular classification and HER2-targeted therapy in endometrial cancer.