Regucalcin downregulation in human cancer.

Regucalcin is a unique calcium-binding protein first discovered in rat liver in 1978. Regucalcin has multiple functions as an inhibitor of various cellular signaling pathways that regulate cell activity. The expression of the regucalcin gene can be altered by various physiological and pathological factors such as diet (nutrients), hormones, diabetes, alcohol and drugs. Several transcription factors have been identified on the regucalcin gene, including AP-1, NF1-A1, RGPR-p117, ß-catenin, NF-κB, STAT3 and hypoxia-inducible factor-1α (HIF-1α). Notably, regucalcin plays an important role in the development of several cancers by controlling cell growth. Clinically, many studies have reported that the expression of the regucalcin gene is downregulated in various human cancers. In addition, higher expression of regucalcin in tumor tissue has been associated with longer patient survival, suggesting that regucalcin may act as a potential suppressor of various types of human cancer. Regucalcin may offer a novel therapeutic strategy and diagnostic tool for cancer treatment. However, the underlying mechanism by which regucalcin expression is reduced in human cancer is still unclear. A deeper understanding of regucalcin reduction and function in cancer is needed to discover potential resistance mechanisms and biomarkers, and to improve regucalcin-targeting agents. We review recent findings on regucalcin gene expression in cancer. We discuss the possible mechanisms by which regucalcin expression is downregulated in cancer cells to facilitate understanding of how regucalcin regulates cell growth function. This mini-review may lead to better therapeutic targets with regucalcin.

The overexpressed transcription factor RGPR-p117 suppresses the proliferation of normal rat kidney proximal tubular epithelial NRK-52E cells: Involvement of diverse signaling pathways.

AIMS: RGPR-p117 was originally discovered as a novel transcription factor, which specifically binds to a nuclear factor I (NFI) consensus motif TTGGC(N)6CC in the promoter region of the regucalcin gene. RGPR-p117 is also called as Lztr2 and SEC16B. The role of RGPR-p117 in cell regulation is poorly understood. This study was undertaken to determine whether the overexpression of RGPR-p117 impacts the proliferation of normal rat kidney proximal tubular epithelial NRK-52E cells in vitro. MAIN METHODS: The NRK-52E wild-type cells and RGPR-p117-overexpressing NRK-52E cells were cultured in DMEM containing fetal bovine serum. KEY FINDINGS: The overexpression of RGPR-p117 repressed colony formation and proliferation of NRK-52E cells. Interestingly, RGPR-p117 overexpression blocked cell proliferation promoted by culturing with Bay K 8644, a calcium-entry agonist, and phorbol 12-myristate 13-acetate, an activator of protein kinase C. The depressive effects of RGPR-p117 overexpression on cell proliferation were not occurred by culturing with various inhibitors of cell cycle and intracellular signaling processes. RGPR-p117 overexpression increased the translocation of RGPR-p117 into the nucleus of NRK-52E cells. Mechanistically, RGPR-p117 overexpression diminished the levels of Ras, PI3 kinase, Akt, mitogen-activated protein kinase, and mTOR, while it raised the levels of p53, Rb, p21, and regucalcin. Furthermore, RGPR-p117 overexpression protected cell death caused by apoptosis-inducing factors, suggesting that the suppressive effects of RGPR-p117 on cell growth are independent of cell death. SIGNIFICANCE: The present study demonstrates that the overexpressed transcription factor RGPR-p117 suppresses cell proliferation via targeting diverse signaling processes, suggesting a role of RGPR-p117 in cell regulation.

Regulation of Leukaemia Associated Rho GEF (LARG/ARHGEF12).

The Ras homologous (Rho) protein family of GTPases (RhoA, RhoB and RhoC) are the members of the Ras superfamily and regulate cellular processes such as cell migration, proliferation, polarization, adhesion, gene transcription and cytoskeletal structure. Rho GTPases function as molecular switches that cycle between GTP-bound (active state) and GDP-bound (inactive state) forms. Leukaemia-associated RhoGEF (LARG) is a guanine nucleotide exchange factor (GEF) that activates RhoA subfamily GTPases by promoting the exchange of GDP for GTP. LARG is selective for RhoA subfamily GTPases and is an essential regulator of cell migration and invasion. Here, we describe the mechanisms by which LARG is regulated to facilitate the understanding of how LARG mediates functions like cell motility and to provide insight for better therapeutic targeting of these functions.

Identification of seven novel variants in the ß-globin gene in transfusion-dependent and normal patients.

INTRODUCTION: Abnormality in HBB results in an inherited recessive blood disorder, which can be caused by variants at the transcriptional or translational level affecting the stability and the production of the HBB chain. The severity of the disease relies on the variant's characteristics. This study aimed to identify the common ß-globin HBB variants in the population of the Eastern Province, which has the highest prevalence of blood diseases in Saudi Arabia. MATERIAL AND METHODS: Direct sequence of ß-globin HBB gene, and alpha-globin HBA1 and HBA2 genes was performed on a total of 545 blood samples (transfusion-dependent: 215, 106 men and 109 women; normal healthy subjects: 330, 197 men and 133 women) collected from Saudi Arabian participants in the Eastern region. RESULTS: A total of 36 variants in HBB gene were revealed with 11 variants that have been reported for the first time in Saudi Arabia, including 7 novel variants that have been identified for the first time in HBB gene. The novel variants consisted of two exonic (HBB:c.252C>T; HBB:c.281G>T) and five intronic variants (c.316-183_316-168del; c.315+241T>A; c.315+376T>C; c.316-114C>G; c.315+208T>G) at HBB gene. The novel exonic variants and three (c.316-183_316-168del; c.315+241T>A; c.315+376T>C) intronic variants were co-inherited with α deletion. CONCLUSIONS: This current study updated the HBB gene variations with newly identified variants of HBB gene and co-inheritance with α-globin deletions. The identified ß-globin mutations will strengthen the genetic reference that could aid in characterizing mutations that are associated with phenotype of thalassemia in a specific region.

Genetic disorder prenatal diagnosis and pregnancy termination practices among high consanguinity population, Saudi Arabia.

The prevalence of consanguineous marriage and genetic disorders are high in Saudi Arabia. There were records on the practices of Saudis toward prenatal diagnosis (PND) and termination of pregnancy (TOP), however the sample sizes are small. This study has targeted the Saudi Arabian community and family history of genetic disorders to determine the practices toward PND and TOP. The cross-sectional survey was conducted among Saudis (n = 2761) to determine their practices toward reproductive-decision making. Regression analysis was conducted to identify the association of the limiting factors, relative merits and family history on the outcomes. Total of 2507 participants returned completed questionnaire. The practice towards PND (68%) were more favorable than TOP (33%). PND was found to be a good opportunity for early diagnosis and gives parent's choice. Education, history with affected baby, prior knowledge and religious belief were significant deciding factors of PND and TOP. Down syndrome (n = 161) and sickle cell anemia (n = 152) were commonly available genetic disorder among participant's family. Respondents with autistic cases in their family have higher acceptance rate for TOP. Non-consanguineous are more willing to consider TOP than consanguineous. Participants with abnormal fetus, aged of > 36 years, married and educated Saudis were more likely consider TOP. Though, religion is the most influencing factor for not accepting TOP, comparatively willingness to PND and TOP have increased recently. Awareness campaigns about PND and TOP may increase the chances of accepting prenatal genetic diagnosis.

Quantitative assessment of changes in cell growth, size and morphology during telomere-initiated cellular senescence in Saccharomyces cerevisiae.

Telomerase-deficient cells of the budding yeast S. cerevisiae experience progressive telomere shortening and undergo senescence in a manner similar to that seen in cultured human fibroblasts. The cells exhibit a DNA damage checkpoint-like stress response, undergo changes in size and morphology, and eventually stop dividing. In this study, a new assay is described that allowed quantitation of senescence in telomerase-deficient est2 cells with applied statistics. Use of the new technique revealed that senescence was strongly accelerated in est2 mutants that had homologous recombination genes RAD51, RAD52 or RAD54 co-inactivated, but was only modestly affected when RAD55, RAD57 or RAD59 were knocked out. Additionally, a new approach for calculating population doublings indicated that loss of growth capacity occurred after approximately 64 generations in est2 cells but only 42 generations in est2 rad52 cells. Phase contrast microscopy experiments demonstrated that senescing est2 cells became enlarged in a time-dependent manner, ultimately exhibiting a 60% increase in cell size. Progressive alterations in physical properties were also observed, including striking changes in light scattering characteristics and cellular sedimentation rates. The results described herein will facilitate future studies of genetic and environmental factors that affect telomere shortening-associated cell senescence rates using the yeast model system.

Hemoglobin A2 (HbA2) has a measure of unreliability in diagnosing ß-thalassemia trait (ß-TT).

INTRODUCTION: Detection of ß-thalassemia trait or carriers (ß-TT) depends significantly on an increase in Hemoglobin A2 (HbA2) levels, which is found at low levels (<3%) in normal healthy individuals and elevated levels (≥3.5%) in ß-TT individuals. The study was designed to evaluate the reliability of the diagnostic parameter HbA2 in the differentiation of ß-TT and non-ß-TT in Saudis. METHODS: The widely used high performance liquid chromatography (Variant II Bio-Rad) was used to measure HbA2 levels in blood. Sanger sequencing was used to screen the variation in globin genes (HBB, HBD, HBA1, and HBA2). All the study subjects were divided into ßTT and non-ßTT (wild) categories based on the presence or absence of HBB variations and further sub-divided into false positive, true positive, false negative, and true negative, based on HbA2 values. RESULTS: Out of 288 samples, 96 had HBB gene mutations. Of the 96 ß-TT samples, sickle cell trait (SCT) samples (n = 58) were excluded, while the remaining (38 ß-TT) were included in the detailed analysis: seven subjects with the HBB mutation had normal HbA2 (<3%), and three were borderline (3.1-3.9%). The remainder (n = 28) had an elevated HbA2 level (>4%). Based on HbA2 analysis alone, both these groups would be incorrectly diagnosed as normal. Similarly, of the 189 non-ß-TT samples, 179 had normal HbA2, eight had borderline HbA2, and two had a HbA2 level above 4%. Based on HbA2 analysis alone, borderline and >4% HbA2 individuals, negative for ß-TT, can be incorrectly diagnosed as carriers. CONCLUSION: Given the percentage of samples falling in the HbA2 "borderline" and "normal" categories, it can be concluded that HbA2 has a measure of unreliability in the diagnosis of ß-thalassemia carriers.