ACTA ENDOCRINOLOGICA (BUC)

Aims. Resistin has been reported to impair the pancreatic beta cells and associated with insulin resistance. MicroRNAs (miRNAs) are short, endogenously produced non-coding ribonucleotides that bind mRNAs and function mainly as negative regulators in mammals. MiRNAs have been implicated in many diseases, including insulin resistance and diabetes. A considerable body of evidence has indicated an important function for miRNAs in insulin secretion. The current study was designed to investigate the effects of miR-494 in the reductions in insulin secretion attributable to resistin. Methods. Insulin secretion was determined by ELISA, and expressions of genes were identified using quantitative RT-PCR (qRT-PCR) or Western blot analysis. Results. Insulin secretion was significantly reduced by resistin. Overexpression of miR-494 inhibited insulin secretion both in diet culture and high glucose medium in MIN6 cell lines. MiR-494 down-regulated the protein level of STXBP5 by pairing with sites in the 3′UTR. Conclusion. miR-494 is involved in the insulin secretion regulated by resistin via its effects on STXBP5 in MIN6 cells.

Context. Phosphoinositide-3-kinase (PI3K) pathway inhibitors are increasingly used as targeted therapy in malignancies. We discuss here three cases of PI3K inhibitor induced hyperglycemia and discuss the mechanism of action of these medications and treatment of this class side effect. Objectives. Alpelisib (Piqray) is the newest PI3K inhibitor used in conjunction with Fulvestrant to treat specific types of breast cancer. Since PI3K is a critical mediator of insulin signaling, hyperglycemia is an on-target, unfortunate side effect of this treatment. We present a case series of severe hyperglycemia induced by the alpelisib in three women without a history of diabetes. Design. All three women in this study had hormone receptor (HR) positive, human epidermal growth factor receptor 2 (Her2) negative, PI3K mutated breast cancer. They were referred to our clinic by Oncology for alpelisibinduced hyperglycemia. Subjects and Methods. Review of laboratory values and glucometer values were conducted during each visit allowing treatment decisions. Two of these women are actively managed by us for their diabetes. One woman recently died due to progression of malignancy. Results. All three women presented with new onset of severe hyperglycemia after the initiation of PI3K inhibitor, alpelisib. At least one case noted maximal glucose elevation in the hours following drug ingestion. In another, cessation of Alpelisib reversed the hyperglycemia within the span of one week. Conclusion. Hyperglycemia induced by PI3K inhibitors can be recalcitrant and might necessitate interruption of chemotherapy. Optimal glucose-lowering therapy remains unclear as exogenous insulin has the theoretical potential to overcome PI3K inhibition.

Aims. To investigate the changes in the miRNAs and mRNAs expressed in the liver upon induction of “hyperresistinemia”. Methods. We identified mRNA and miRNAs that were differentially expressed between normal and resistin-treated liver tissue using microarrays. Expression was validated using quantitative RT-PCR (qRT-PCR). The putative targets and pathways of the differentially expressed miRNAs and mRNAs were investigated, respectively, using various computational algorithms. In addition, the interactions between differentially expressed miRNAs and mRNAs were analyzed. Results. After the filtration of the signals below the threshold level, we identified 34 miRNAs and 875 genes with expression levels different by more than 1.5-fold and 2.0-fold, respectively, between the two groups. These observations were confirmed by qRT-PCR. Bidirectional prediction analyses showed that the differentially expressed miRNAs may be inversely regulated by their predicted targets. Conclusion. Hyperresistinemia results in changes in the miRNAs and mRNAs expressed in the liver.

We describe clinical features of women with extremely low bone density, and investigate secondary causes of osteoporosis. Our hypothesis was that this population would be enriched in identifiable causes of osteoporosis. We performed a retrospective review of medical records of all women seen at our university over 4 years with T-score on bone densitometry at/below -4 at any site. Historical and fracture details were abstracted. We considered a thorough work up to include Vitamin D, PTH, CBC, chemistry panel, cortisol, transglutaminase, myeloma screen, tryptase and 24-hour urine calcium. Results. 137 women were identified with T-score at/below -4. Percent identified as Asian was 26% (higher than local prevalence of 8%). Average BMI was 21.6 kg/ m2. Clearly identifiable causes of osteoporosis were noted in 57% (inflammatory disorder, glucocorticoid or antacid exposure, prolonged immobilization and alcoholism were most prevalent). Of the remainder, full work up was performed only in 8%. Endocrine consultation and white race predicted thoroughness of secondary work-up. Conclusion. Fragility fractures, leanness and Asian race were common in women with very low T-score. However, few new causes were identified. Underlying etiology was either immediately evident or inadequately studied, especially in minorities.