Hypoglycemic coma in an elderly adult switched from twice-daily vildagliptin to once-daily glimepiride to improve drug adherence.

BACKGROUND: Elderly adults with diabetes are at increased risk of severe hypoglycemia and hypoglycemic coma due to various conditions including decline in cognitive function, reduced activity of daily living (ADL) and reduced renal function; special cautions are, therefore, recommended to avoid these life-threatening events. CASE PRESENTATION: A 92-year-old female was admitted to our institution because of severe coma. Upon arrival, her serum C-peptide was 1.64 ng/mL despite low plasma glucose (24 mg/dL) and serum glimepiride (40.85 ng/mL). She had past history of compression fracture of her lumbar spine, which substantially affected her ADL. Her score on the dementia assessment sheet for community-based integrated care system-8 items (DASC-8) was 26 points. She had been receiving 12 oral medications for diabetes, essential hypertension, chronic gastritis and constipation from her nearby clinic. Her physician-in-charge had found that she was not taking her medications properly and simplified her prescription regimen to 3 oral medications with vildagliptin 50 mg twice daily replaced by glimepiride 3 mg once daily and asked her son to assist in taking the drugs 6 days before her admission to our hospital. While her consciousness level was improved to some extent, she was transferred to a long-term care bed hospital because it had become too difficult to care for her at home. CONCLUSIONS: It is important to note that anti-diabetes drugs should be carefully selected based on each patient's cognitive function and ADL, and that the reasoning should be shared with the general practitioners involved to avoid severe hypoglycemic events. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13340-021-00510-9.

A novel RFX6 heterozygous mutation (p.R652X) in maturity-onset diabetes mellitus: A case report.

Heterozygous RFX6 mutation has emerged as a potential cause of maturity-onset diabetes mellitus of the young (MODY). A 16-year-old female was diagnosed with diabetes by her family doctor and was referred to our institution for genetic examination. Genetic testing revealed a novel RFX6 heterozygous mutation (NM_173560: exon17: c.1954C>T: p.R652X) in the patient and in her mother and brother. She had no islet-specific autoantibodies and showed a reduced meal-induced response of insulin, glucose-dependent insulinotropic polypeptide, and glucagon-like peptide-1, which is consistent with the phenotype of MODY due to heterozygous RFX6 mutation. In conclusion, we report a case of MODY due to a novel heterozygous mutation, p.R652X.

Comparison of Pregnane X Receptor Antagonists for Enhancing the Antitumor Effect of Cisplatin.

BACKGROUND: Cisplatin is a platinum compound capable of inducing apoptosis of cancer cells. However, cancer cells can become cisplatin-resistant. A recent study showed that a pregnane X receptor (PXR) antagonist, leflunomide, can enhance the antitumor activity of cisplatin and overcome such resistance. This study determined whether PXR antagonists ketoconazole and phenethyl isothiocyanate (PEITC) enhance the antitumor activity of platinum compounds and by which mechanism(s) of action. MATERIALS AND METHODS: Caspase-3 activity, intracellular platinum level, and expression of ATP-binding cassette subfamily C member 2 (ABCC2; previously named multidrug resistance-associated protein 2) were assessed in HepG2 human hepatocellular carcinoma cells exposed to carboplatin or cisplatin with and without PXR antagonist. RESULTS: In combination with platinum compounds, PEITC increased the intracellular platinum level, while ketoconazole induced higher caspase-3 activity. Additionally, PEITC suppressed ABCC2 protein expression. CONCLUSION: These results suggested that ketoconazole and PEITC enhance the antitumor activity of platinum compounds by different and complex mechanisms.

The Involvement of Pregnane X Receptor-regulated Pathways in the Antitumor Activity of Cisplatin.

BACKGROUND/AIM: Nuclear receptors regulate the expression of cellular transporters, which may be contributing factors for cisplatin (CDDP) resistance. This study aimed to clarify whether nuclear receptor ligands could be potentially used as drugs to overcome CDDP resistance. MATERIALS AND METHODS: Caspase-3 activity was measured using a fluorogenic substrate. mRNA levels were determined using real-time polymerase chain reaction. RESULTS: Pregnane X receptor (PXR) showed an expression level change dependent on caspase-3 activation by CDDP in HepG2. Rifampicin, a PXR agonist, reduced the accumulation of CDDP and suppressed growth inhibition and caspase-3 activation in HepG2 after CDDP exposure. Leflunomide, a PXR antagonist, significantly enhanced caspase-3 activation by CDDP in HepG2 and CDDP-resistant HepG2/R. CONCLUSION: These results suggest that PXR can modify the antitumor activity of CDDP, presumably through regulating the expression of transporters, which control intracellular CDDP concentration. Thus, PXR antagonists can be further investigated as potential drugs capable of overcoming CDDP resistance.

Changes in the Expression of Various Transporters as Influencing Factors of Resistance to Cisplatin.

BACKGROUND: Changes in the expression of transporters have been reported as factors in resistance to cisplatin (CDDP). This study was designed to clarify whether CDDP-resistant strains isolated from a cell line had the same characteristics, and whether these characteristics could be therapeutic targets. MATERIALS AND METHODS: Intracellular platinum levels were determined by the inductively-coupled plasma method. mRNA expression levels were determined using the real-time polymerase chain reaction. RESULTS: Some CDDP-resistant HepG2 cell lines exhibited changes in the expression of copper transporter 1, multidrug resistant protein (MRP)2, and/or MRP3, resulting in decreased intracellular platinum amounts, while others showed no change in platinum accumulation. Expression of these transporters was not necessarily maintained in a constant direction within the cell population isolated from the same origin. CONCLUSION: These results suggest that the CDDP-resistant tumors caused by a decrease in intracellular platinum content consist of a heterogeneous cell population showing expression changes of several transporters.

Alteration of molecular assembly of peroxiredoxins from hyperthermophilic archaea.

Peroxiredoxin from Pyrococcus horikoshii (PhPrx) is a decameric protein formed by ring-type assembly of five dimers. To engineer the quaternary structure of PhPrx, we created a mutant PhPrx (PhPrx6m) by introducing six point mutations designed to dissociate PhPrx into dimers. Although PhPrx6m was a dimer in solution, the six dimers assembled into a dodecamer following crystallization. In the crystal structure, PhPrx6m was overoxidized, and the peroxidatic cysteine was in sulfonic acid form and two cysteines in the C-terminal region were linked by an intramolecular disulfide bond. Thus, we characterized the wild-type PhPrx overoxidized by hydrogen peroxide (PhPrxPer). Analytical ultracentrifugation showed that PhPrxPer had a higher molecular mass in solution than PhPrx. This was confirmed by analysis of the crystal structure of PhPrxPer, which was found to form a ring-type dodecamer composed of six dimers. The monomeric structures of PhPrx6m and PhPrxPer differed from that of PhPrx in the relative orientation of two domains, reflecting the number of dimers in the ring-type assembly. Unlike PhPrx, homologous peroxiredoxin from Aeropyrum pernix (ApPrx) did not undergo hexameric association. This property can be explained by the stronger connection between the two domains in ApPrx due to its C-terminal extension relative to PhPrx.

Intracellular uptake of an antitumor-active azole-bridged dinuclear platinum(II) complex in cisplatin-resistant tumor cells.

A cationic azolato-bridged dinuclear platinum(II) complex, [{cis-Pt(NH3)2}2(µ-OH)(µ-methyl-pyrazolate)]2+ (4M-PzPt), was developed to overcome resistance to cisplatin (CDDP). This study aimed to assess the cytotoxicity of 4M-PzPt against a CDDP-resistant cell line, H4-II-E/CDDP, and compare the intracellular accumulation of CDDP and 4M-PzPt. H4-II-E and H4-II-E/CDDP displayed similar sensitivity to 4M-PzPt; however, the sensitivity of H4-II-E/CDDP to CDDP was approximately 19-fold lower than that of H4-II-E. The difference in the sensitivity to both platinum complexes corresponded with the difference in the amount of intracellular platinum accumulation after exposure to CDDP or 4M-PzPt in both cell lines. In H4-II-E, HepG2, and HuH-7 cells, the intracellular uptake of CDDP and 4M-PzPt occurred via active transport and passive transport. Results of co-exposure with the transport inhibitors ouabain, tetraethylammonium, and cimetidine indicated that the intracellular uptake of CDDP was dependent on Na+/K+-ATPase and that of 4M-PzPt was dependent on organic cation transporters (OCTs), probably OCT1. This study suggested that 4M-PzPt could inhibit the growth of a CDDP-resistant tumor via an intracellular uptake mechanism different from that of CDDP.

Death-resistant and nonresistant malignant human cell lines under anoxia in vitro.

BACKGROUND: Erythropoietin supports the survival of erythroblasts. We previously demonstrated that 24 malignant human cell lines expressed erythropoietin and its receptor and that erythropoietin secretion was enhanced under anoxia. In this study, we examined the viability of 22 of these cell lines excluding two leukemia cell lines under anoxia. METHODS: Twenty-two cancer cell lines of various origins were cultured under anoxia or normoxia for 4 days, and their viability was examined at 1-day intervals. The levels of lactate and ATP were measured. The expressions of hypoxia-inducible transcription factor 1alpha (HIF-1alpha) and Bcl-2 family proteins were examined by western blotting analysis. The cellular and mitochondrial features were examined by microscopy. RESULTS: Eleven of the 22 cancer cell lines examined showed 80% to 100% cell viability after 4 days under anoxia; 2 cell lines showed similar viability for 3 days, 3 cell lines showed similar viability for 2 days, and 6 cell lines showed similar viability for 1 day or less. These 11 death-resistant cell lines, which secrete various amounts of erythropoietin under anoxia, produced significantly more lactate during 2 days under anoxia than under normoxia, with ATP levels about 60% of those before anoxia. ATP returned to the normal level when normoxia was restored after 4 days of anoxia. However, the nonresistant cell lines responded to anoxia by yielding significantly more lactate without a reduction of the ATP level. The expression patterns of Bcl-2 family proteins revealed that apoptosis-inhibiting signals predominated over proapoptotic signals in the death-resistant cells under anoxia. CONCLUSION: The majority of the cancer cell lines examined survived under anoxia in vitro, through the Pasteur effect, in a dormant state without direct support of erythropoietin.