Acquisition Of Genetic Aberrations Research Articles

Acquisition of Genetic Aberrations During the Progression of High-Grade Intraepithelial Lesions/Micro-Invasive Squamous Cancers to Widely Invasive Cervical Squamous Cell Cancer.

Acquisition of genetic aberrations during cervical carcinogenesis in individual patients is poorly documented. To provide a comparative analysis of high-grade squamous intraepithelial lesions (n = 7) and pT1a squamous cancers (n = 1) and their recurrences, subsequent widely invasive cancers, and metastases developed during 1-24 years. Archival tissues of 8 patients were analyzed immunohistochemically for reserve-cell origin, human papillomavirus genotypes, mutations in 50 cancer genes, and chromosomal copy number variations. Intraepithelial lesions arose either from cytokeratin 17- or 7-expressing reserve cells. All preinvasive and invasive tumors carried human papillomavirus high-risk genotypes and lacked somatic mutations. Chromosomal copy number variations were identified in all intraepithelial lesions and invasive cancers. Four of 8 high-grade intraepithelial lesions progressed to invasive cancer after incomplete treatment, and 4 of 8 invasive cancers arose de novo after in sano resection. Four of 8 cancers carried mutations with high mutational frequency (PIK3CA E545K [n = 2]; PIK3CA and SMAD1 [n = 1]; HRAS, RB1, and EGFR [n = 1]), as did their corresponding regional metastases. One nonmetastasized cancer had a subclonal PIK3CA mutation, and an initially nonmutated, low-stage cancer developed ovarian metastases with PIK3CA amplification. One patient had neither mutations nor metastases. The patient with treated PIK3CA E545K-mutated pT1a cancer developed a subsequent nonmutated intraepithelial lesion that progressed to invasive cancer with a subclonal PIK3CA-H1047R mutation. Cancer-related deaths in 4 of 8 (50%) patients occurred independent of mutational status or metastatic disease. Recurrences arose after persistent or de novo human papillomavirus infection of residual reserve cells or squamous metaplasia. Activating driver mutations were identified in invasive cancers only. High mutational load correlated with metastases, which in turn represented clonal disease.

Molecular landscape of immune pressure and escape in aplastic anemia.

Idiopathic aplastic anemia (IAA) pathophysiology is dominated by autoreactivity of human leukocyte antigen (HLA)-restricted T-cells against antigens presented by hematopoietic stem and progenitor cells (HSPCs). Expansion of PIGA and HLA class I mutant HSPCs have been linked to immune evasion from T-cell mediated pressures. We hypothesized that in analogy with antitumor immunity, the pathophysiological cascade of immune escape in IAA is initiated by immunoediting pressures and culminates with mechanisms of clonal evolution characterized by hits in immune recognition and response genes. To that end, we studied the genetic and transcriptomic make-up of the antigen presentation complexes in a large cohort of patients with IAA and paroxysmal nocturnal hemoglobinuria (PNH) by using single-cell RNA, high throughput DNA sequencing and single nucleotide polymorphism (SNP)-array platforms. At disease onset, HSPCs displayed activation of selected HLA class I and II-restricted mechanisms, without extensive inhibition of immune checkpoint apparatus. Using a newly implemented bioinformatic framework we found that not only class I but also class II genes were often impaired by acquisition of genetic aberrations. We also demonstrated the presence of novel somatic alterations in immune genes possibly contributing to the evasion from the autoimmune T-cells. In contrast, these hits were absent in myeloid neoplasia. These aberrations were not mutually exclusive with PNH and did not correlate with the accumulation of myeloid-driver hits. Our findings shed light on the mechanisms of immune activation and escape in IAA and define alternative modes of clonal hematopoiesis.

Acquisition of Genetic Aberrations by Activation-Induced Cytidine Deaminase (AID) during Inflammation-Associated Carcinogenesis

Genetic abnormalities such as nucleotide alterations and chromosomal disorders that accumulate in various tumor-related genes have an important role in cancer development. The precise mechanism of the acquisition of genetic aberrations, however, remains unclear. Activation-induced cytidine deaminase (AID), a nucleotide editing enzyme, is essential for the diversification of antibody production. AID is expressed only in activated B lymphocytes under physiologic conditions and induces somatic hypermutation and class switch recombination in immunoglobulin genes. Inflammation leads to aberrant AID expression in various gastrointestinal organs and increased AID expression contributes to cancer development by inducing genetic alterations in epithelial cells. Studies of how AID induces genetic disorders are expected to elucidate the mechanism of inflammation-associated carcinogenesis.