Validation of selected molecular methods for the mutations determination in codons 12 and 13 of K-RAS gene in five Polish oncological research centers

Chorzy na raka jelita grubego z przerzutami mogą osiągnąć korzyść z leczenia panitumumabem jedynie, jeśli w guzie nie stwierdzono mutacji w genie K-RAS. W związku z tym konieczne jest zbadanie statusu tego genu w celu wyłonienia chorych, którzy mogą być poddani takiemu leczeniu. Celem pracy było opracowanie standardowej procedury oznaczania statusu genu K-RAS w materiale izolowanym z bloczków parafinowych. Kolejnym celem była walidacja wybranych technik molekularnych oznaczania mutacji w pięciu ośrodkach w Polsce, w których odbywa się leczenie chorych na raka jelita grubego. Ocenie poddano cztery różne techniki oznaczania mutacji: SSCP, DHPLC, RFLP/PCR i bezpośrednie sekwencjonowanie. Stwierdzono, że wszystkie jednostki uczestniczące w procesie walidacji są odpowiednio przygotowane do podjęcia działalności diagnostycznej w zakresie oznaczania statusu genu K-RAS. Przyjęto następujące zalecenia dla laboratoriów diagnostycznych: 1. Materiał do izolacji DNA powinien zawierać przynajmniej 70% utkania nowotworowego; 2. Ujednolicenie procedury izolacji DNA ze skrawków parafinowych wymaga stosowania gotowego zestawu do izolacji DNA; 3. W przypadku braku jednoznacznego wyniku konieczne jest stosowanie dwóch metod oznaczania mutacji, przy czym jedną z nich powinno być sekwencjonowanie bezpośrednie.Metastatic colorectal cancer patients will benefit from treatment with panitumumab only when they don't have mutation in K-RAS gene. Therefore, estimation of mutational status of K-RAS is necessary for the selection of patients, who should be treated with panitumumab. The aim of this study was to evolve a standard method of estimation of K-RAS mutational status in the material isolated from paraffin blocs. The second aim was the validation of selected molecular methods of K-RAS mutation evaluation in five Polish oncological centers where mCRC patients are treated. Four methods were evaluated: SSCP, DHPLC, RFLP/PCR and direct sequencing. We found that all groups in five selected oncological centers, who took part in the validation process, were well prepared for molecular diagnosis of K-RAS mutational status. The following recommendations for diagnostic laboratories were approved: 1. At least 70% of cancer cells should be present in a tissue for DNA isolation; 2. The method of DNA isolation should be standardized, the most appropriate is usage of DNA isolation kits; 3. In case of equivocal results two independent molecular methods should be employed, one of them should be direct sequencing

The structural and functional analysis of the human HSPA2 gene promoter region

HSPA2 is a human counterpart of the testis-specific rodent Hst70/Hsp70.2 gene. In contrast to the latter, the expression of the human HSPA2 gene is not limited to the testis, and recent data show that human tumor cells can express this gene at significant levels. The characteristics of HSPA2 expression suggests that it can influence the phenotype and survival of cancer cells similarly as overexpression of major members of the HSP70 gene family. Until now, neither the structure of the transcription unit of the human HSPA2 gene has been established nor a functional analysis of its promoter performed. In this study we established that the human HSPA2 gene, in contrast to its rodent counterparts, is intronless and has a single transcription start site. We also show that the same type of HSPA2 transcripts are synthesized in the testes and in cancer cell lines. In order to perform a functional study of the HSPA2 promoter, we used a transient transfection assay and found that the 392 bp fragment upstream of the ATG codon was a minimal region required for efficient transcription, while a 150 bp deletion from the 5' end of this region dramatically reduced the promoter activity. Delineation of the minimal promoter is a basic step toward identifiying the cis and trans elements involved in the regulation of the HSPA2 gene expression in cancer cells

The GC-box is critical for high level expression of the testis-specific Hsp70.2/Hst70 gene

The Hsp70.2/Hst70 gene, which belongs to the 70 kDa heat-shock protein (HSP) family, is expressed specifically in primary spermatocytes and spermatids. The regulatory elements required for a high level of testis-specific expression of the gene are placed between the two major transcription start sites T1 and T2 (approximately 350 and 115 bp upstream of the starting ATG codon). Here we have shown that sequences proximal to the exon1/intron splicing site in the 5' untranslated region of the Hsp70.2/Hst70 gene, which include a highly conserved element called box B, are required for efficient expression of the chloramphenicol acetyltransferase reporter gene in testes of transgenic mice. However, in spite of the drastically reduced overall activity, the stage-specific expression pattern of the transgene was preserved after removal of these sequences. We have also shown that GC-box located downstream of the box B (approximately 210 bp upstream of the starting ATG codon) is indispensable for efficient expression of the Hsp70.2/Hst70 gene promoter in spermatogenic cells. The GC-box specifically binds proteins present in nuclear extracts from testes (putatively Sp1-like factors). A change in the pattern of such GC-box-interacting factors corresponds to activation of the Hsp70.2/Hst70 gene, confirming the importance of this regulatory element

Expression of a constitutively active mutant of heat shock factor 1 under the control of testis-specific hst70 gene promoter in transgenic mice induces degeneration of seminiferous epithelium.

Heat shock activates in somatic cells a set of genes encoding heat shock proteins which function as molecular chaperones. The basic mechanism by which these genes are activated is the interaction of the specific transcription factor HSF1 with a regulatory DNA sequence called heat shock element (HSE). In higher eukaryotes HSF1 is present in unstressed cells as inactive monomers which, in response to cellular stress, aggregate into transcriptionally competent homotrimers. In the present paper we showed that the expression of a transgene encoding mutated constitutively active HSF1 placed under the control of a spermatocyte-specific promoter derived from the hst70 gene severely affects spermatogenesis. We found the testes of transgenic mice to be significantly smaller than those of wild-type males and histological analysis showed massive degeneration of the seminiferous epithelium. The lumen of tubules was devoid of spermatids and spermatozoa and using the TUNEL method we demonstrated a high rate of spermatocyte apoptosis. The molecular mechanism by which constitutively active HSF1 arrests spermatogenesis is not known so far. One can assume that HSF1 can either induce or repress so far unknown target genes involved in germ cell apoptosis