The Role of the PERK/eIF2α/ATF4/CHOP Signaling Pathway in Tumor Progression During Endoplasmic Reticulum Stress.

Hypoxia is a major hallmark of the tumor microenvironment that is strictly associated with rapid cancer progression and induction of metastasis. Hypoxia inhibits disulfide bond formation and impairs protein folding in the Endoplasmic Reticulum (ER). The stress in the ER induces the activation of Unfolded Protein Response (UPR) pathways via the induction of protein kinase RNA-like endoplasmic reticulum kinase (PERK). As a result, the level of phosphorylated Eukaryotic Initiation Factor 2 alpha (eIF2α) is markedly elevated, resulting in the promotion of a pro-adaptive signaling pathway by the inhibition of global protein synthesis and selective translation of Activating Transcription Factor 4 (ATF4). On the contrary, during conditions of prolonged ER stress, pro-adaptive responses fail and apoptotic cell death ensues. Interestingly, similar to the activity of the mitochondria, the ER may also directly activate the apoptotic pathway through ER stress-mediated leakage of calcium into the cytoplasm that leads to the activation of death effectors. Apoptotic cell death also ensues by ATF4-CHOP- mediated induction of several pro-apoptotic genes and suppression of the synthesis of anti-apoptotic Bcl-2 proteins. Advancing molecular insight into the transition of tumor cells from adaptation to apoptosis under hypoxia-induced ER stress may provide answers on how to overcome the limitations of current anti-tumor therapies. Targeting components of the UPR pathways may provide more effective elimination of tumor cells and as a result, contribute to the development of more promising anti-tumor therapeutic agents.

Efficiency of Base Excision Repair of Oxidative DNA Damage and Its Impact on the Risk of Colorectal Cancer in the Polish Population.

DNA oxidative lesions are widely considered as a potential risk factor for colorectal cancer development. The aim of this work was to determine the role of the efficiency of base excision repair, both in lymphocytes and in epithelial tissue, in patients with CRC and healthy subjects. SNPs were identified within genes responsible for steps following glycosylase action in BER, and patients and healthy subjects were genotyped. A radioisotopic BER assay was used for assessing repair efficiency and TaqMan for genotyping. Decreased BER activity was observed in lymphocyte extract from CRC patients and in cancer tissue extract, compared to healthy subjects. In addition, polymorphisms of EXO1, LIG3, and PolB may modulate the risk of colorectal cancer by decreasing (PolB) or increasing (LIG3 and EXO1) the chance of malignant transformation.

Recessive missense mutations in LAMB2 expand the clinical spectrum of LAMB2-associated disorders.

Congenital nephrotic syndrome is clinically and genetically heterogeneous. The majority of cases can be attributed to mutations in the genes NPHS1, NPHS2, and WT1. By homozygosity mapping in a consanguineous family with isolated congenital nephrotic syndrome, we identified a potential candidate region on chromosome 3p. The LAMB2 gene, which was recently reported as mutated in Pierson syndrome (microcoria-congenital nephrosis syndrome; OMIM #609049), was located in the linkage interval. Sequencing of all coding exons of LAMB2 revealed a novel homozygous missense mutation (R246Q) in both affected children. A different mutation at this codon (R246W), which is highly conserved through evolution, has recently been reported as causing Pierson syndrome. Subsequent LAMB2 mutational screening in six additional families with congenital nephrotic syndrome revealed compound heterozygosity for two novel missense mutations in one family with additional nonspecific ocular anomalies. These findings demonstrate that the spectrum of LAMB2-associated disorders is broader than previously anticipated and includes congenital nephrotic syndrome without eye anomalies or with minor ocular changes different from those observed in Pierson syndrome. This phenotypic variability likely reflects specific genotypes. We conclude that mutational analysis in LAMB2 should be considered in congenital nephrotic syndrome, if no mutations are found in NPHS1, NPHS2, or WT1.

mut0 methylmalonic acidemia: eleven novel mutations of the methylmalonyl CoA mutase including a deletion-insertion mutation.

Methylmalonic aciduria (MMA) is an autosomal-recessive disorder caused by inadequate function of methylmalonyl-CoA mutase (MCM), a nuclear-encoded, mitochondrial enzyme that uses adenosylcobalamin as a cofactor. Biochemical cell studies have delineated phenotypic variants: mut(0) phenotypes in which there is no detectable enzymatic activity and mut- phenotypes in which there is residual cobalamin-dependent activity. Mutation screening in MMA has led to the detection of 30 disease-specific mutations. In 14 patients with the mut(0) phenotype we found 11 novel mutations (K54X, A137V, F174S, 620insA, G203R, Q218H, A535P, H627R, 2085delG and 2270del4/ins5), 6 of them homozygous, consisting of 1 nonsense, 6 missense, 1 splice site, and 3 frame shift mutations. The position in relation to different functional domains in MCM allow for an interpretation of the identified mutations. Hum Mutat 16:179, 2000.

[Trial application of transfection tests in feasibility studies for transforming DNA in white blood cells of patients with chronic lymphatic leukemia]. / Próba zastosowania testów transfekcyjnych w badaniach wlasciwosci transformujacych DNA z krwinek bialych chorych na przewlekla bialaczke limfatyczna.

Transfection technique with the use of high molecular DNA was applied for the investigations of peripheral blood white cells DNA transforming properties in patients with chronic lymphatic leukemia B. Using transfection tests in liquid medium (focus assay) and colony forming in soft agar, the differences in L(tk-) cells transformation were noted following an addition of neoplastic DNA. Medium collected over transformants has shown mitogen properties in micro-mitogen tests on cells BALB/c 3T3. No correlation between clinical stage of the disease and the results of tests was observed.