Hiroshi Tomonobe

The BHLHE40‒PPM1F‒AMPK pathway regulates energy metabolism and is associated with the aggressiveness of endometrial cancer

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.

Evaluation of Clinical Significance of Lymphovascular Space Invasion in Stage IA Endometrial Cancer

<b><i>Introduction:</i></b> 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. <b><i>Methods:</i></b> 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. <b><i>Results:</i></b> 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 (<i>p</i> = 0.07 and <i>p</i> = 0.41, respectively). Recurrence-free survival and endometrial cancer-specific survival also did not differ significantly between these groups (<i>p</i> = 0.11 and <i>p</i> = 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 (<i>p</i> = 0.92 and <i>p</i> = 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. <b><i>Conclusion:</i></b> LVSI was not a prognostic factor of not only stage IA endometrial cancer but also stage IA low-grade cancer.