FOXO3a Activation by HDAC Class IIa Inhibition Induces Cell Cycle Arrest in Pancreatic Cancer Cells.

OBJECTIVES: Pancreatic cancer (PC) is highly aggressive with multiple oncogenic mutations. The efficacy of current chemotherapy is poor, and new therapeutic targets are needed. The forkhead box (FOX) proteins are multidirectional transcriptional factors strongly implicated in malignancies. Their expression is consistently suppressed by several oncogenic pathways such as PI3K/AKT signaling activated in PC. A recent study showed that class IIa histone deacetylases (HDAC) can act as a transcriptional suppressor. In this study, we hypothesized that HDAC class IIa inhibition would upregulate FOXO3a expression, thereby inducing its transcription-dependent antitumor effects. METHODS: We confirmed the change of FOXO3a expression and the effect of the cell growth inhibition by HDAC class IIa inhibition in AsPC-1 cells. Because FOXO3a is subject to ubiquitylation-mediated proteasome degradation, we examined the synergistic activation of FOXO3a by HDAC class IIa selective inhibitor TMP269 combined with proteasome inhibitor carfilzomib. RESULTS: We observed that TMP269 induced FOXO3a expression in a dose-dependent manner and inhibited cell growth in AsPC-1 cells. G1/S arrest was observed. FOXO3a expression was further increased and cell growth inhibition was dramatically enhanced by TMP269 combined with carfilzomib. CONCLUSIONS: Dual inhibition of class IIa HDACs and proteasome could be a promising new strategy for modifying FOXO3a activity against PC.

Fatal case of multiple recurrences of endometrial stromal sarcoma after fertility-sparing management.

Several cases of the uterus being preserved after diagnosis of endometrial stromal sarcoma (ESS) have been reported. Most of these patients were alive and did not experience relapse, but this might have reflected the short follow-up period, given the indolent recurrence of ESS. We report the first fatal case of ESS 10 years after fertility-sparing management. A specimen obtained from the last operation showed loss of estrogen receptor status and expression of c-kit without c-kit or PDGFR-α gene mutations.

A case of idiopathic encapsulating peritoneal sclerosis with intractable ileus successfully treated by surgery and steroid therapy.

Encapsulating peritoneal sclerosis (EPS) occurring without a history of peritoneal dialysis is rare. We report on a patient with idiopathic EPS following intractable ileus who was successfully treated by surgery and postoperative steroid therapy without any sign of recurrence. A 67-year-old woman was referred to our department for further treatment of intractable ileus. Abdominal CT scanning revealed wall thickening of the proximal jejunum. Double-balloon enteroscopy disclosed stenosis of the jejunum at 20 cm anally from the Treitz ligament, although the intestinal mucosa appeared normal without specific biopsy findings. In addition, FDG-PET showed no abnormal accumulation, thus discounting a malignant lesion. Since conservative therapy failed to improve the ileus, we performed an operation on her in order to release the ileus and make a histological diagnosis. Surgical findings included a whitish thickening of the serosa extending to the intestine and the whole mesentery. Accordingly, we made a diagnosis of idiopathic encapsulating peritoneal sclerosis because of her negative history of peritoneal dialysis, laparotomy or peritonitis, in addition to the above-noted findings. Postoperative oral administration of steroid has suppressed EPS recurrence. In patients with intractable ileus, EPS should be added to the list of differential diagnoses, even if they have not undergone peritoneal dialysis.

Redesign of coenzyme B(12) dependent diol dehydratase to be resistant to the mechanism-based inactivation by glycerol and act on longer chain 1,2-diols.

Coenzyme B(12) dependent diol dehydratase undergoes mechanism-based inactivation by glycerol, accompanying the irreversible cleavage of the coenzyme Co-C bond. Bachovchin et al. [Biochemistry16, 1082-1092 (1977)] reported that glycerol bound in the G(S) conformation, in which the pro-S-CH(2) OH group is oriented to the hydrogen-abstracting site, primarily contributes to the inactivation reaction. To understand the mechanism of inactivation by glycerol, we analyzed the X-ray structure of diol dehydratase complexed with cyanocobalamin and glycerol. Glycerol is bound to the active site preferentially in the same conformation as that of (S)-1,2-propanediol, i.e. in the G(S) conformation, with its 3-OH group hydrogen bonded to Serα301, but not to nearby Glnα336. k(inact) of the Sα301A, Qα336A and Sα301A/Qα336A mutants with glycerol was much smaller than that of the wild-type enzyme. k(cat) /k(inact) showed that the Sα301A and Qα336A mutants are substantially more resistant to glycerol inactivation than the wild-type enzyme, suggesting that Serα301 and Glnα336 are directly or indirectly involved in the inactivation. The degree of preference for (S)-1,2-propanediol decreased on these mutations. The substrate activities towards longer chain 1,2-diols significantly increased on the Sα301A/Qα336A double mutation, probably because these amino acid substitutions yield more space for accommodating a longer alkyl group on C3 of 1,2-diols. Database Structural data are available in the Protein Data Bank under the accession number 3AUJ. Structured digital abstract • Diol dehydrase gamma subunit, Diol dehydrase beta subunit and Diol dehydrase alpha subunit physically interact by X-ray crystallography (View interaction).