Abstract for presentation at 11th International Congress of Human Genetics

Transfection of a PAC contig covering the lung cancer critical region at 3p21.3 discloses the complexity of functional analysis of homozygous deletion regions

  • Arja ter Elst, Department of Medical Genetics, University Medical Center Groningen, The Netherlands
  • Bea Hiemstra, Department of Medical Genetics, University Medical Center Groningen, The Netherlands
  • Pieter van der Vlies, Department of Medical Genetics, University Medical Center Groningen, The Netherlands
  • Anneke van der Veen, Department of Medical Genetics, University Medical Center Groningen, The Netherlands
  • Gerard te Meerman, Department of Medical Genetics, University Medical Center Groningen, The Netherlands
  • Frans Gerbens, Department of Medical Genetics, University Medical Center Groningen, The Netherlands
  • Klaas Kok, Department of Medical Genetics, University Medical Center Groningen, The Netherlands
  • Charles Buys, Department of Medical Genetics, University Medical Center Groningen, The Netherlands

    • Purpose: Localization of tumor suppressor activity in the 3p21.3 LUCA region.
    Methods: We covered this 19 genes-containing 3p21.3 lung cancer tumor suppressor region with 8 overlapping PACs in which the genes are likely accompanied by their promoters. The PACs were used to transfect cells from an SCLC cell line readily causing tumors in nude mice. Per PAC we selected 2 transfectants with a low number of PAC copies integrated at a single site. The transfectants were s.c. injected into nude mice to investigate whether the integrated sequences suppressed the tumor-inducing capacity of the original SCLC cell line.
    Results: PAC-specific gene expression could be demonstrated in the transfectants. All PAC integration sites were different. Transfection and integration of exogenous DNA per se appeared to induce a genome-wide instability. One of two transfectants with integration of mere vector sequences and both transfectants with integration of the same PAC from the centromeric part of the 3p21.3 region caused smaller tumors that did the other transfectants or the original SCLC cells.
    Conclusions: Occasionally, instability due to the introduction of exogenous DNA may lead to chromosomal rearrangements interfering with cell growth and proliferation. This might explain the smaller tumors caused by one transfectant with only vector integration. For the two transfectants with the same centromeric PAC, the sole pair of transfectants that caused smaller tumors, this mechanism seems less likely. The tumor-suppressing effect may rather be attributed to the content - genes, regulatory sequences, miRNA - of this very PAC.

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