Molecular Genetic Evidence for Different Clonal Origin of Components of Human Renal Angiomyolipomas

Abstract

Renal angiomyolipoma is a benign neoplasm composed of variable proportions of blood vessels, smooth muscle, and adipose tissue. Smooth muscle, adipose tissue, blood vessels, and adjacent normal kidney tissue were separately microdissected from sections prepared from formalin-fixed, paraffin-processed tissues from angiomyolipomas from 18 women. X chromosome inactivation analysis using the methylation pattern at exon 1 of the human androgen receptor gene on chromosome Xq11-12 was used to study the clonal origin of each component. Nonrandom inactivation of X chromosomes was found in six of the 15 informative tumors. The smooth muscle and adipose tissue showed differing patterns of nonrandom inactivation of X chromosomes in five angiomyolipomas and the same pattern of nonrandom inactivation of X chromosomes in one. Samples from the blood vessels showed random inactivation of X chromosomes in all informative cases. Our data showed that the adipose tissue and smooth muscle cells of renal angiomyolipoma are both monoclonal but may arise independently. The coexistence of tumor subclones with morphologic heterogeneity can lead to the formation of a clinically detectable tumor.

Clonal relationships between epidermotropic metastatic melanomas and their primary lesions: a loss of heterozygosity and X-chromosome inactivation-based analysis

“…PCR amplification and gel electrophoresis were performed as described previously. [27][28][29][30][31] The criterion for allelic loss was complete or nearly complete (Z75%) absence of one allele in tumor DNA. [27][28][29][32][33][34] PCRs for each polymorphic microsatellite marker were repeated at least twice from the same DNA preparations, and the same results were obtained.…”

“…Nonrandom X-chromosome inactivation was defined as a complete or nearly complete (Z75%) absence of an AR allele after HhaI digestion, which indicated a predominance of one allele. 30,31,35,36 Tumors were considered to be of the same clonal origin if the same AR allelic inactivation pattern was detected in both the primary melanoma and its corresponding epidermotropic metastatic melanomas. Conversely, tumors were considered to be of independent origin if alternate predominance of AR alleles after HhaI digestion (different allelic inactivation patterns) was detected in the primary and metastatic melanoma components.…”

Clonal X-chromosome inactivation suggests that splenic cord capillary hemangioma is a true neoplasm and not a subtype of splenic hamartoma

“…21 X-chromosome inactivation analysis was performed as previously described. 22 Briefly, DNA samples were prepared from the lesional tissue and control normal spleen sections from the same patients. The sample was analyzed with and without digestion with HhaI restriction endonuclease.…”

Analysis of loss of heterozygosity and X chromosome inactivation in spleens with myeloproliferative disorders and acute myeloid leukemia

“…Laser-assisted microdissection was performed (Figure 1), separating neoplastic myeloid proliferations from normal control tissues (residual lymphoid tissues) on unstained sections using a PixCell II Laser Capture Microdissection system (Arcturus Engineering, Mountain View, CA, USA), as previously described. [9][10][11][12][13][14] …”

“…PCR amplification and gel electrophoresis were performed as previously described. [9][10][11][12][13][14] The criterion for allelic loss was complete or nearly complete absence of one allele in tumor DNA. [9][10][11][12][13][14] PCRs for each polymorphic microsatellite marker were repeated at least twice from the same DNA preparations and the same results were obtained.…”