Genetic alterations in adult T-cell leukemia/lymphoma
CANCER SCIENCE
Authors: Kogure, Yasunori; Kataoka, Keisuke
Abstract
Adult T-cell leukemia/lymphoma (ATL) is a peripheral T-cell neoplasm with a dismal prognosis. It is caused by human T-cell leukemia virus type-1 (HTLV-1) retrovirus. A long latency period from HTLV-1 infection to ATL onset suggests that not only HTLV-1 proteins, such as Tax and HBZ, but also additional genetic and/or epigenetic events are required for ATL development. Although many studies have demonstrated the biological functions of viral genes, alterations of cellular genes associated with ATL have not been fully investigated. Recently, a largescale integrated genetic analysis revealed the entire landscape of somatic aberrations in ATL. This neoplasm is characterized by frequent gain-of-function alterations in components of the T-cell receptor/NF-kappa B signaling pathway, including activating mutations in the PLCG1, PRKCB, CARD11 and VAV1 genes, and CTLA4-CD28 and ICOS-CD28 fusions. Importantly, molecules associated with immune surveillance, such as HLA-A/B, CD58 and FAS, are affected recurrently. Among them, one notable lesion occurs as frequent structural variations that truncate the PD-L1 3'-untranslated region, leading to its overexpression. Other genetic targets include transcription factors (IRF4, IKZF2, and GATA3) and chemokine receptors (CCR4, CCR7 and GPR183), which are functionally relevant in normal T cells. A substantial proportion of ATL cases show widespread accumulation of repressive epigenetic changes, such as trimethylation of histone H3 lysine 27 and DNA hypermethylation of CpG islands, which coordinately modulate multiple pathways, including Cys2-His2 zinc finger genes involved in silencing retroelements. Here we review the current understanding of the genetic/epigenetic aberrations in ATL, focusing on their relevance in its molecular pathogenesis.
Prediction of blood-based biomarkers and subsequent design of bisulfite PCR-LDR-qPCR assay for breast cancer detection
BMC CANCER
Authors: Bacolod, Manny D.; Huang, Jianmin; Giardina, Sarah F.; Feinberg, Philip B.; Mirza, Aashiq H.; Swistel, Alexander; Soper, Steven A.; Barany, Francis
Abstract
Background: Interrogation of site-specific CpG methylation in circulating tumor DNAs (ctDNAs) has been employed in a number of studies for early detection of breast cancer (BrCa). In many of these studies, the markers were identified based on known biology of BrCa progression, and interrogated using methyl-specific PCR (MSP), a technique involving bisulfite conversion, PCR, and qPCR.MethodsIn this report, we are demonstrating the development of a novel assay (Multiplex Bisulfite PCR-LDR-qPCR) which can potentially offer improvements to MSP, by integrating additional steps such as ligase detection reaction (LDR), methylated CpG target enrichment, carryover protection (use of uracil DNA glycosylase), and minimization of primer-dimer formation (use of ribose primers and RNAseH2). The assay is designed to for breast cancer-specific CpG markers identified through integrated analyses of publicly available genome-wide methylation datasets for 31 types of primary tumors (including BrCa), as well as matching normal tissues, and peripheral blood.ResultsOur results indicate that the PCR-LDR-qPCR assay is capable of detecting similar to 30 methylated copies of each of 3 BrCa-specific CpG markers, when mixed with excess amount unmethylated CpG markers (similar to 3000 copies each), which is a reasonable approximation of BrCa ctDNA overwhelmed with peripheral blood cell-free DNA (cfDNA) when isolated from patient plasma. The bioinformatically-identified CpG markers are located in promoter regions of NR5A2 and PRKCB, and a non-coding region of chromosome 1 (upstream of EFNA3). Additional bioinformatic analyses would reveal that these methylation markers are independent of patient race and age, and positively associated with signaling pathways associated with BrCa progression (such as those related to retinoid nuclear receptor, PTEN, p53, pRB, and p27).ConclusionThis report demonstrates the potential utilization of bisulfite PCR-LDR-qPCR assay, along with bioinformatically-driven biomarker discovery, in blood-based BrCa detection.