Three steps mutation model of carcinogenesis

Hox gene dysregulation in acute myeloid leukemia

ABSTRACT: 

In humans, class I homeobox genes (HOX genes) are distributed in four clusters. Upstream regulators include transcriptional activators and members of the CDX family of transcription factors. HOX genes encode proteins and need cofactor interactions, to increase their specificity and selectivity. HOX genes contribute to the organization and regulation of hematopoiesis by controlling the balance between proliferation and differentiation. Changes in HOX gene expression can be associated with chromosomal rearrangements generating fusion genes, such as those involving MLL and NUP98, or molecular defects, such as mutations in NPM1 and CEBPA for example. Several miRNAs are involved in the control of HOX gene expression and their expression correlates with HOX gene dysregulation. HOX genes dysregulation is a dominant mechanism of leukemic transformation. A better knowledge of their target genes and the mechanisms by which their dysregulated expression contributes to leukemogenesis could lead to the development of new drugs.

RUNX1-MTG16 fusion gene in acute myeloblastic leukemia with t(16;21)(q24;q22): case report and review of the literature

We report here a 73-year old female who was admitted for hematomas, dyspnea, and fever. Hematological data showed pancytopenia with 9% blast cells positive for CD13, CD33, CD34, HLAD2, and myeloperoxydase. A diagnosis of acute myeloid leukemia (AML) type 2 (FAB classification) was made. Banding cytogenetic techniques performed on bone marrow cells showed a 48,XX,+8,+9,del(9)(q22q33)x2 ,t(16;21)(q24;q22)[20]/46,XX[2] karyotype. Fluorescence in situ hybridization (FISH) with BACs covering the RUNX1 (alias AML1) (band 21q22) and MTG16 (band 16q24) gene showed a fusion of both genes. The t(16;21)(q24;q22) has been described in 16 AML cases, including ours. Eleven patients had received chemotherapy for a previous cancer, most of them were been treated with DNA-topoisomerase II inhibitors known to be associated with chromosomal translocations involving the RUNX1 gene. The significant homology between MGT16 and MTG8 suggests that the RUNX1-MTG16 fusion gene induced by the t(16;21)(q24;q22) is a variant of the RUNX1-MTG8 that shares similar activity.

Cytogenetic findings in cervical carcinoma. A statistical approach

Cytogenetic analysis with banding techniques was attempted in 150 cervical carcinomas, including in situ carcinoma, large cell keratinizing tumors, large cell nonkeratinizing tumors, small cell nonkeratinizing tumors, and adenocarcinomas. Monte Carlo simulations were used to determine which numerical and structural aberrations were nonrandomly involved in the tumorous process and to attempt to correlate specific abnormalities with specific histologic types. Results showed that several chromosomes are nonrandomly involved in cervical carcinomas and that some are more specifically associated with particular histologic subtypes. Therefore, cervical carcinoma appear to include a large spectrum of malignancies, each particular histologic type involving different genes. If some cytogenetic changes may be considered general events related to the carcinogenesis process, other rearrangements are presumably more specific processes arising in more committed stem cells.