4 research outputs found
The p53 Family of Transcription Factors Represses the Alpha- fetoprotein Gene Expression in Hepatocellular Carcinoma
Background: p53 deletion and mutation as well as upregulation of alpha-fetoprotein (AFP) are hallmarks of hepatocarcinogenesis. p63 and p73 belong to the family of p53-related transcription factors expressing a variety of isoforms. The expression of dominant negative (ΔN) p73 is related to the reduced survival of patients with hepatocellular carcinoma (HCC). In this study, we characterized the interaction between p53 family-dependent signaling pathways and the regulation of AFP at the gene and protein levels as essential determinants of therapeutic response and prognosis in HCC.
Methods: Putative p53-, p63- and p73-binding sites within the AFP gene were identified in silico. Hep3B cells were transfected with plasmids encoding for p53, p63 and p73 to analyze the interplay of the p53 family with AFP. AFP transcription was determined by RT-qPCR. Protein levels of AFP, p53, p63 and p73 were analyzed by Western blot.
Results: Underlining the importance of the crosstalk between the p53 family-dependent pathways and AFP regulation we identified eight novel putative binding sites for the members of the p53 family within the introns 1, 2, 3, 4, 7, 8, 11, and 12 of the AFP gene. Accordingly, full-length isoforms of p53, p63 and p73 efficiently downregulated AFP both on mRNA and protein level. Thus, the p53 family members were identified to be major regulators of AFP repression. Of note, p63 was characterized as a novel and p73 as the most efficient repressor of AFP.
Conclusion: p53 mutation and upregulation of AFP are essential oncogenic events in the development of HCC. Here we show that AFP gene regulation occurs via a combined action of the p53 family members p53, p63 and p73. All three tumor suppressors reduce AFP gene and protein expression. Thus, our findings reveal a novel interaction of p53 family-dependent signaling pathways and AFP regulation at the gene and protein levels in HCC
KCNN4 Expression Is Elevated in Inflammatory Bowel Disease: This Might Be a Novel Marker and Therapeutic Option Targeting Potassium Channels
Background & Aims: The K+ channel KCNN4 is involved in many inflammatory diseases. Previous work has shown that this channel is involved in epithelial ion transport and intestinal restitution. In inflammatory bowel diseases (IBD) a defective epithelial barrier can lead to typical symptoms like secretory diarrhea and the formation of intestinal ulcers. We compared surgical samples from patients with IBD, diverticulitis and controls without inflammation to determine the potential role of KCNN4 as a diagnostic marker and/or therapeutic target. Methods: mRNA-levels of KCNN4 and a control K+ channel were determined in intestinal epithelial cells (IEC) from patients with IBD, diverticulitis and controls. In addition, we performed a Western blot analysis of KCNN4 and a respective control K+ channel in IEC from patients with IBD. Furthermore, we determined epithelial barrier integrity by measuring the flux of fluorescent-labeled dextran beads across a cell monolayer upon incubation with interferon-gamma. Results: KCNN4 mRNA and protein levels were elevated in IEC from patients with Crohn's disease (CD) and ulcerative colitis (UC). Of note, KCNN4 was not elevated in non-IBD intestinal inflammatory conditions e.g. diverticulitis. Of clinical relevance, pharmacological KCNN4 channel openers stabilized epithelial barrier function in vitro. Thus, KCNN4 may have a protective role in IBD and constitute a therapeutic target. Conclusions: Our data demonstrate elevated KCNN4 both at mRNA and protein level in IEC specifically from patients with IBD. Therefore, we conclude that KCNN4 could be used as a novel marker for IBD, especially for the establishment of initial diagnosis. Of therapeutic consequence, we show that pharmacological KCNN4 openers stabilize the epithelial barrier. Thus, KCNN4 might be a novel target to diagnose and treat HBD
Microvascular Disease Associates with Larger Osteocyte Lacunae in Cortical Bone in Type 2 Diabetes Mellitus
ABSTRACT Clinical studies indicate that microvascular disease (MVD) affects bone microstructure and decreases bone strength in type 2 diabetes mellitus (T2D). Osteocytes are housed in small voids within the bone matrix and lacunae and act as sensors of mechanical forces in bone. These cells regulate osteoclastic bone resorption and osteoblastic bone formation as well as osteocytic perilacunar remodeling. We hypothesized that MVD changes morphometric osteocyte lacunar parameters in individuals with T2D. We collected iliac crest bone biopsies from 35 individuals (10 female, 25 male) with T2D with MVD (15%) or without MVD (21%) with a median age of 67 years (interquartile range [IQR] 62–72 years). The participants were included based on c‐peptide levels >700 pmol L−1, absence of anti‐GAD65 antibodies, and glycated hemoglobin (HbA1c) levels between 40 and 82 mmol mol−1 or 5.8% and 9.7%, respectively. We assessed osteocyte lacunar morphometric parameters in trabecular and cortical bone regions using micro‐computed tomography (micro‐CT) at a nominal resolution of 1.2 μm voxel size. The cortical osteocyte lacunar volume (Lc.V) was 7.7% larger (p = 0.05) and more spherical (Lc.Sr, p < 0.01) in the T2D + MVD group. Using linear regression, we found that lacunar density (Lc.N/BV) in trabecular but not cortical bone was associated with HbA1c (p < 0.05, R2 = 0.067) independently of MVD. Furthermore, Lc.V was larger and Lc.Sr higher in the center than in the periphery of the trabecular and cortical bone regions (p < 0.05). In conclusion, these data imply that MVD may impair skeletal integrity, possibly contributing to increased skeletal fragility in T2D complicated by MVD. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research
Characterization of the Dosepix detector with XRF and analog testpulses
Part of 15th International Workshop on Radiation Imaging Detectors (IWORID2013)
Dosepix is a hybrid pixel detector based on the technology of the Medipix and Timepix detectors. The Dosepix detector has a matrix of 16 × 16 square pixels, with the sensor segmented into rows of small (55 μm) and big (220 μm) pixels. In addition to photon counting, the Dosepix detector has a time over threshold mode which permits energy resolved measurements.
In this contribution, we present results of the characterization of the Dosepix detector regarding energy calibration and energy resolution. We calibrated the detectors with X-ray fluorescence (XRF) and analog testpulses. We determined a conversion factor from testpulse amplitude to energy. This work aims to develop a calibration method of the Dosepix detector without the need for radiation. In addition, Monte Carlo simulations with ROSI were carried out to compare energy deposition spectra reconstructed with the radiation-based calibration and with testpulse-based calibration