Osteopontin and latent-TGF ß binding-protein 2 as potential diagnostic markers for HBV-related hepatocellular carcinoma.

Chronic Hepatitis B (HB) is the main risk factor for chronic liver disease (CLD) and hepatocellular carcinoma (HCC) in many low-resource countries, where diagnosis is constrained by lack of clinical, histopathological and biomarker resources. We have used proteomics to detect plasma biomarkers that outperform α-Fetoprotein (AFP), the most widely used biomarker for HCC diagnosis in low-resource contexts. Deep-plasma proteome analysis was performed in HCC patients, patients with CLD and in HB-carrier controls from Thailand (South-East Asia) and The Gambia (West-Africa). Mass spectrometry profiling identified latent-transforming growth factor ß binding-protein 2 (LTBP2) and Osteopontin (OPN) as being significantly elevated in HCC versus CLD and controls. These two proteins were further analyzed by ELISA in a total of 684 plasma samples, including 183 HCC, 274 CLD and 227 asymptomatic controls. When combined, LTBP2 and OPN showed an area under the receiver operating curve of 0.85 in distinguishing HCC from CLD in subjects with AFP <20 ng/mL. In a prospective cohort of 115 CLD patients from Korea, increased plasma levels of LTBP2 and/or OPN were detected in plasma collected over 2 years prior to diagnosis in 21 subjects who developed HCC. Thus, the combination of LTBP2 and OPN outperformed AFP for diagnosis and prediction of HCC and may therefore improve biomarker-based detection of HBV-related HCC.

Effects of Δ40p53, an isoform of p53 lacking the N-terminus, on transactivation capacity of the tumor suppressor protein p53.

BACKGROUND: The p53 protein is expressed as multiple isoforms that differ in their N- and C-terminus due to alternative splicing, promoter or codon initiation usage. Δ40p53 lacks the first 39 residues containing the main transcriptional activation domain, resulting from initiation of translation at AUG +40 in fully spliced p53 mRNA or in a specific variant mRNA retaining intron 2. Overexpression of Δ40p53 antagonizes wild-type p53 in vitro. However, animal models of Δ40p53 in mouse or Zebrafish have shown complex phenotypes suggestive of p53-dependent growth suppressive effects. METHODS: We have co-transfected expression vectors for p53 and Δ40p53 in p53-null cell lines Saos-2 and H1299 to show that Δ40p53 forms mixed oligomers with p53 that bind to DNA and modulate the transcription of a generic p53-dependent reporter gene. RESULTS: In H1299 cells, co-expression of the two proteins induced a decrease in transcription with amplitude that depended upon the predicted composition of the hetero-tetramer. In Saos-2, a paradoxical effect was observed, with a small increase in activity for hetero-tetramers predicted to contain 1 or 2 monomers of Δ40p53 and a decrease at higher Δ40p53/p53 ratios. In this cell line, co-transfection of Δ40p53 prevented Hdm2-mediated degradation of p53. CONCLUSION: Δ40p53 modulates transcriptional activity by interfering with the binding of Hdm2 to hetero-tetramers containing both Δ40p53 and p53. These results provide a basis for growth suppressive effects in animal models co-expressing roughly similar levels of p53 and Δ40p53.

Hyperresistinemia and metabolic dysregulation: a risky crosstalk in obese breast cancer.

Breast cancer is the most common malignancy among women worldwide. There is extensive literature on the relationship between body weight and breast cancer risk but some doubts still remain about the role of adipokines per se, the role of insulin and glucose regardless of obesity, as well as the crosstalk between these players. Thus, in this study, we intend to determine the relation between body mass index (BMI), glycaemia, insulinemia, insulin-resistance, blood adipokine levels and tumour characteristics in a Portuguese group of pre- and postmenopausal overweight/obese women with breast cancer. We evaluated clinical and biochemical data in 154 participants, divided in 4 groups: (1) control with BMI <25 kg/m(2), n = 29 (CT); (2) control with BMI >25 kg/m(2), n = 48 (CTOb); (3) breast cancer with BMI <25 kg/m(2), n = 30 (BC); and (4) breast cancer with BMI >25 kg/m(2), n = 47 (BCOb). In women with breast cancer, we also performed tumour characterization. We found that BCOb present increased fasting blood glucose, insulin, resistin and monocyte chemoattractant protein 1, insulin resistance and more aggressive tumours. Notably, this profile is not correlated with BMI, proposing the involvement of other processes than adiposity. Altogether, our results suggest that glucose dysmetabolism, insulin resistance and changes in adipokine secretion, in particular resistin, may be involved in the development and progression of breast cancer in overweight/obese pre- and postmenopausal women.

Advanced glycation end products and diabetic nephropathy: a comparative study using diabetic and normal rats with methylglyoxal-induced glycation.

Hyperglycemia-related advanced glycation end product (AGE) formation is a key mechanism in diabetic nephropathy. Since methylglyoxal (MG) is a potent AGE precursor, we aimed to assess the role of MG-related AGE formation in the progression of renal damages. A comparative study between Wistar (W, normal) and Goto-Kakizaki (GK, nonobese type 2 diabetic) rats was performed at 6 and 14 months old and after 14 weeks of MG administration to 6-month-old rats. Diabetic rats showed progressive structural, biochemical, and functional alterations, including AGE, albuminuria, and tissue hypoxia, which were partially mimicked by MG administration to young GK rats. Aged Wistar rats had an impairment of some parameters, whereas MG administration caused a phenotype similar to young GK rats, including oxidative stress, impaired apoptotic and angiogenic markers, and structural lesions. MG accumulation specifically impaired several of the renal disease markers progressively observed in diabetic rats, and thus, it contributes to the progression of diabetic nephropathy.

Reduction of methylglyoxal-induced glycation by pyridoxamine improves adipose tissue microvascular lesions.

Background and Aims. Adipose tissue dysfunction results from many factors, including glycation-induced microvascular damages. We tested the usefulness of inhibiting methylglyoxal-induced glycation to adipose tissue microvasculature in this work, using the antioxidant and dicarbonyl scavenger drug pyridoxamine. Methods. A group of Wistar rats was treated daily with methylglyoxal (MG, 75 mg/Kg/day, 8 weeks). Half of this group was treated with pyridoxamine in the following 4 weeks (Pyr) (100 mg/Kg/day) and the other half did not have any further treatment (MG). A group of Wistar rats without MG treatment was used as control (C). Results. MG group showed decreased HDL cholesterol and increased plasma free fatty acids levels, what was reverted by pyridoxamine. MG also caused an increase of tissue CEL levels (glycation marker), as well as increased staining of PAS and Masson Trichrome-positive components. Pyridoxamine led to CEL and TGF- ß levels similar to those observed in control rats and inhibited the accumulation of PAS and Masson Trichrome-positive components. MG caused a decrease of Bcl-2/Bax ratio (marker of apoptosis) and vWF staining (microvascular marker), what was partially reverted by the treatment with pyridoxamine. Conclusions. Preventing methylglyoxal-induced accumulation of glycated and fibrotic materials using pyridoxamine improves the microvascular lesions of the adipose tissue.

Pyridoxamine reverts methylglyoxal-induced impairment of survival pathways during heart ischemia.

BACKGROUND AND AIMS: Increased levels of advanced glycation end-products (AGE) and their precursors, such as methylglyoxal (MG), in patients with diabetes may account for impaired response to heart ischemia. Pyridoxamine is a derivate of vitamin B6, which has been shown to reduce AGE formation. Our goal was to assess the role of pyridoxamine in protecting from MG-induced impaired heart response to ischemia. METHODS: Wistar rats were subjected to MG administration (WM), MG plus pyridoxamine (WMPyr), or no treatment (W). Half of the hearts from each group were submitted to ischemia and the other half were perfused as control. The levels of CEL, Bcl-2, Bax, and total and phosphorylated forms of JNK and Akt were determined. RESULTS: Methylglyoxal led to higher levels of AGE and AGE receptor (RAGE) than in the W group. During ischemia, MG caused an impairment of survival pathways and Bcl-2/Bax ratio, a marker of apoptosis. Pyridoxamine treatment decreased glycation and restored the activation of JNK and Akt during ischemia. These events were followed by levels of Bcl-2/Bax ratio similar to W group. CONCLUSION: Methylglyoxal-induced AGE accumulation impairs the activation of cell survival pathways during ischemia. Pyridoxamine-induced decrease of glycation inhibited the effects of MG accumulation in the heart, suggesting that it can be of added value to usual diabetic therapy.