Renal tumors include about 3% of all malignant neoplasia of adulthood. The overwhelming majority of these tumors fall into renal carcinoma (RC). Renal epithelial tumors can be, according to Heidelberg and UICC97 classification, divided into several types. It is a conventional RC, papillary RC, chromophobe RC, RC from the collecting ducts and unclassified type of RC. Benign epithelial tumors are then papillary renal adenoma, renal oncocytoma and metanephric adenoma and related lesions. The histological type of RC is considered to be an important prognostic factor. The distinction between different RC types only via histology finding, however, is problematic in some cases. For these reasons, in order to perform an exact classification of tumors and to determine the prognosis, it is appropriate to obtain further information, e.g. analysis of tumors at the molecular level.

Works based on molecular genetic and cytogenetic data, constitute the classification of each RC type according to changes in the number of individual parts or whole chromosomes. It was found that various histological types include specific losses or gains of some chromosomes. For example, the main marker of the conventional RC is the loss of the short (p) arm of chromosome 3, eventually the gain of chromosome 5q along with the deletion of some of chromosomes 6q, 8p. 9p, 14q, papillary RC in a high percentage of cases obtain at least two of chromosomes 3q, 7, 8, 12, 16, 17 and 20, and chromophobe RCs show the loss of chromosomes 1, 2, 6, 10, 13, and 17.

Probably the most appropriate methodology to obtain comprehensive information on the genetic profile of the sample, is the CGH and its variants. However, this method is relatively expensive. It has specific requirements on the quality of material and, requires special equipment. However, similar information can be obtained using other methods, such as microsatellite analysis (loss of heterozygosity analysis - loss of heterozygosity - LOH) or fluorescence in-situ hybridization (FISH).

Examination

In our laboratory, we perform the detection of losses and gains of genetic material through the analysis of LOH and FISH. For the analysis of LOH when investigating the state of chromosomes 1 and 3, we use microsatellite markers D1S1656 (1q), D3S1300 (3p) and D3S1768 (3p). Fragmentation analysis of the PCR products is carried out on an ABI PRISM 3130xl genetic analyzer and is evaluated by the GeneMapper program (Fig. 1). Then, using the FISH, using centromeric probes and, using locus specific probes of chromosomes 13 and 21, we investigate the state of chromosomes 1, 2, 6, 7, 10, 17 (Fig. 2a, 2b and 2c).

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    Fig.1

    Fragmentation analysis of microsatellite marker D3S1768 (3p): Sample 1- nonmalignant tissue, sample 2, - tumor tissue, LOH is marked by the arrow.

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    Fig.2a

    Examples of interphase FISH on nuclei isolated from the formalin-fixed paraffin-embedded tissue.

    A) monosomy

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    Fig.2b

    Examples of interphase FISH on nuclei isolated from the formalin-fixed paraffin-embedded tissue.

    B) disomy

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    Fig.2c

    Examples of interphase FISH on nuclei isolated from the formalin-fixed paraffin-embedded tissue.

    C) polysomy

References

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