Clinical relevance of vascular endothelial growth factor type A (VEGFA) and VEGF receptor type 2 (VEGFR2) gene polymorphism in chronic lymphocytic leukemia

Novel circular RNAs of the apoptosis-related BAX and BCL2L12 genes identified in a chronic lymphocytic leukemia cell line using nanopore sequencing

Circular RNAs (circRNAs), a novel RNA type generated by back-splicing, are key regulators of gene expression, with deregulated expression and established involvement in leukemia. The products of BCL2 and its homologs, including BAX and BCL2L12, are implicated in chronic lymphocytic leukemia (CLL). However, to the best of our knowledge, nothing is known about circRNAs produced by these two genes and their role in CLL. We sought to further elucidate the contribution of BAX and BCL2L12 in CLL by unraveling the identity, localization, and potential role of their circRNAs. Therefore, total RNA from the EHEB cell line and peripheral blood mononuclear cells (PBMCs) of CLL patients and non-leukemic blood donors was extracted and reverse-transcribed using random hexamers. Next, nested PCRs with divergent primers were performed and the purified PCR products were subjected to 3rd generation nanopore sequencing. Nested PCRs were also applied to first-strand cDNAs synthesized from total RNA extracts of PBMCs from CLL patients and non-leukemic blood donors. Lastly, a single-molecule resolution fluorescent in situ hybridization method called circFISH was used to visualize the circRNA distribution in EHEB cells. We discovered several novel circRNAs produced by BAX and BCL2L12, which were characterized by great exon structure diversity. In addition, intriguing findings regarding their formation emerged. Interestingly, visualization of the most abundant circRNAs showed distinct intracellular localization. Moreover, a complex BAX and BCL2L12 circRNA expression pattern was revealed in CLL patients and non-leukemic blood donors. Our data suggest a multifaceted role of BAX and BCL2L12 circRNAs in B-cell CLL.

VEGF-A related SNPs: a cardiovascular context

Cardiovascular diseases (CVDs) are the leading cause of death worldwide. Currently, cardiovascular disease risk algorithms play a role in primary prevention. However, this is complicated by a lack of powerfully predictive biomarkers that could be observed in individuals before the onset of overt symptoms. A key potential biomarker for heart disease is the vascular endothelial growth factor (VEGF-A), a molecule that plays a pivotal role in blood vessel formation. This molecule has a complex biological role in the cardiovascular system due to the processes it influences, and its production is impacted by various CVD risk factors. Research in different populations has shown single nucleotide polymorphisms (SNPs) may affect circulating VEGF-A plasma levels, with some variants associated with the development of CVDs, as well as CVD risk factors. This minireview aims to give an overview of the VEGF family, and of the SNPs reported to influence VEGF-A levels, cardiovascular disease, and other risk factors used in CVD risk assessments.

Clinical Relevance of +936 C>T VEGFA and c.233C>T bFGF Polymorphisms in Chronic Lymphocytic Leukemia

Angiogenesis process contributes to the pathogenesis of B-cell chronic lymphocytic leukemia (B-CLL) being the levels of VEGFA and bFGF higher in patients than in healthy controls. Our aim was to evaluate the implication of angiogenesis factors genetic variants in the predisposition to B-CLL and their association with clinical factors and survival. We performed a population-based case-control study in 224 Spanish B-CLL patients and 476 healthy randomly selected controls to evaluate susceptibility to developing B-CLL. Six polymorphisms were evaluated: rs1109324, rs1547651, rs3025039 (+936 C>T), rs833052 of the VEGFA gene, rs1449683 (c.233C>T) of the bFGF gene and (−710 C>T) of the VEGFR1 gene. The association between clinical parameters and patient outcome was analyzed. Carriers of the CT/TT variants of rs3025039 showed a significant protective effect against developing B-CLL. The CT/TT variants of rs1449683 show a tendency towards the development of the disease and the same variants associated significantly with higher genetic risk and with reduced disease free survival. Moreover, the association persisted in the early-stage disease subgroup. Our study provides evidence of the protective effect of the T/- rs3025039 VEGFA variant against B-CLL development and the association of CT/TT variants of the rs1449683 bFGF gene with genetic risk and an adverse survival.

Increased levels of the cardiovascular disease risk biomarkers GDF15 and myostatin in patients with chronic lymphocytic leukemia

Individuals suffering from cancer, including hematological malignancies, are at increased risk of cardiovascular disease (CVD). Elevated levels of several biomarkers in blood are associated with an increased risk of CVD. The aim of this study was to investigate whether a subset of such CVD risk biomarkers was elevated in patients with untreated chronic lymphocytic leukemia (CLL). Blood plasma and serum from 139 CLL patients and 71 healthy age-matched controls were analyzed for 11 proposed CVD risk biomarkers. The CLL cohort displayed a more heterogeneous pattern of biomarker expression compared to controls. The majority, eight out of 11, analyzed CVD risk biomarkers differed significantly in concentrations between CLL patients and controls. Increased levels of the biomarkers GDF15 and myostatin have not previously been reported in CLL. Further prospective studies are warranted to investigate whether these biomarkers predict future cardiovascular events in patients with CLL.

The distribution and potential prognostic value of SMAD protein expression in chronic lymphocytic leukemia

The SMAD proteins are responsible for transducing signals from activated transforming growth factor-beta. This is the first study assessing the expression of SMAD-1/8, SMAD-2/3, SMAD-4, and SMAD-7 in chronic lymphocytic leukemia cells with regard to their clinical significance and potential prognostic value. Overexpression of SMAD-1/8 was observed in 160 chronic lymphocytic leukemia patients compared to 42 healthy volunteers (p = 0.023) and was associated with a more progressive course of the disease (p = 0.016). Moreover, the high expression of SMAD-1/8 correlated with other, well-established prognostic factors, including clinical stage (p = 0.010) and lymphocyte doubling time (p = 0.021). The expression of SMAD-4 was lower in chronic lymphocytic leukemia patients compared with the control group (p = 0.003). Importantly, lower SMAD-4 levels correlated with longer progression-free survival (p = 0.009), progressive course of the disease (p = 0.002), advanced clinical stage (p = 0.0004), elevated beta-2-microglobulin and lactate dehydrogenase levels (p < 0.05), shorter lymphocyte doubling time (p = 0.009), and CD38 antigen expression (p = 0.039). In addition, lower SMAD-4 expression correlated with lower apoptotic index (p = 0.0007) and lower expression of receptors for vascular endothelial growth factors VEGFR-1 and VEGFR-2. A significant association was found between the low expression of inhibitory protein SMAD-7 and both zeta-chain-associated protein kinase 70–negative cells (p = 0.04) and lower apoptotic index (p = 0.004). No differences were observed in SMAD-2/3 expression. In conclusion, our results demonstrate a significant correlation between greater SMAD-1/8 and lower SMAD-4 expression in chronic lymphocytic leukemia cells, as well as more progressive outcome and poor prognosis. These data provide supporting evidence that the expression of SMAD proteins plays an important role in disease development and may be considered as a novel, biologic prognostic factor in this disease.

Molecular cloning, expression analysis and miRNA prediction of vascular endothelial growth factor A (VEGFAa and VEGFAb) in pond loach Misgurnus anguillicaudatus, an air-breathing fish

Vascular endothelial growth factor A (VEGFA) is the most studied and the best characterized member of the VEGF family and is a key regulator of angiogenesis via its ability to affect the proliferation, migration, and differentiation of endothelial cells. In this study, the full-length cDNAs encoding VEGFAa and VEGFAb from pond loach, Misgurnus anguillicaudatus, were isolated. The VEGFAa is constituted by an open reading frame (ORF) of 570bp encoding for a peptide of 189 amino acid residues, a 639bp 5'-untranslated region (UTR) and a 2383bp 3' UTR. The VEGFAb is constituted by an ORF of 687bp encoding for a peptide of 228 amino acid residues, a 560bp 5' UTR and a 1268bp 3' UTR. Phylogenetic analysis indicated that the VEGFAa and VEGFAb of pond loach were conserved in vertebrates. Expression levels of VEGFAa and VEGFAb were detected by RT-qPCR at different development stages of pond loach and in different tissues of 6-month-old, 12-month-old and 24-month-old pond loach. Moreover, eight predicted miRNAs (miR-200, miR-29, miR-218, miR-338, miR-103, miR-15, miR-17 and miR-223) targeting VEGFAa and VEGFAb were validated by an intestinal air-breathing inhibition experiment. This study will be of value for further studies into the function of VEGFA and its corresponding miRNAs, which will shed a light on the vascularization and accessory air-breathing process in pond loach.