Mutation analysis of the checkpoint kinase 2 gene in colorectal cancer cell lines

Background Checkpoint kinase 2 （CHK2） is a DNA damage-activated protein kinase which is involved in cell cycle checkpoint control, CHK2 gene could be a candidate gene for colorectal cancer susceptibility, But there are few systematic reports on mutation of CHK2 in colorectal cancer. Methods The mutations of all 14 exons of CHK2 in 56 colorectal cancer cell lines were screened systematically, using denaturing high-performance liquid chromatography （DHPLC） to screen the mismatches of the CHK2 exons amplified products, and then the suspected mutant cell lines were scanned by nucleotide sequence analysis. Results VACO400 in CHK2 exon la was suspected to have mutation by DHPLC and confirmed by sequence, but this was nonsense mutation. C106, CX-1, HT-29, SK01, SW480, SW620 and VACO400 in CHK2 exon lb were confirmed to have the same nonsense mutation in 11609 A〉G. DLD-1 and HCT-15 in CHK2 exon 2 were confirmed to have missense mutation R145W, which was heterozygous C〉T missense mutation at nucleotide 433, leading to an Arg〉Trp substitution within the FHA domain. Conclusions The CHK2 mutation in colorectal cancer is a low frequency event, There are just 10 cell lines to have sequence variations in all the 14 exons in 56 colorectal cancer cell lines and only DLD-1/HCT-15 had heterozygous missense mutation. These findings may give useful information of susceptibility of colorectal cancer as single nucleotide polvmorphvsim.

Roscovitine synergizes with conventional chemo-therapeutic drugs to induce efficient apoptosis of human colorectal cancer cells

AIM: To examine the ability of cyclin-dependent kinase inhibitor (CDKI) roscovitine (Rosco) to enhance the antitumor effects of conventional chemotherapeutic agents acting by different mechanisms against human colorectal cancer. METHODS: Human colorectal cancer cells were treat-ed, individually and in combination, with Rosco, taxol, 5-Fluorouracil (5-FU), doxorubicine or vinblastine. The antiproliferative effects and the type of interaction of Rosco with tested chemotherapeutic drugs were de-termined. Cell cycle alterations were investigated by fluorescence-activated cell sorter FACS analysis. Apop-tosis was determined by DNA fragmentation assay. RESULTS: Rosco inhibited the proliferation of tumor cells in a time-and dose-dependent manner. The ef-ficacies of all tested chemotherapeutic drugs were markedly enhanced 3.0-8.42 × 103 and 130-5.28 × 103 fold in combination with 5 and 10 μg/mL Rosco, re-spectively. The combination of Rosco and chemothera-peutic drugs inhibited the growth of human colorectal cancer cells in an additive or synergistic fashion, and in a time and dose dependent manner. Rosco induced apoptosis and synergized with tested chemothera-peutic drugs to induce efficient apoptosis in human colorectal cancer cells. Sequential, inverted sequential and simultaneous treatment of cancer cells with combi-nations of chemotherapeutic drugs and Rosco arrested the growth of human colorectal cancer cells at various phases of the cell cycle as follows: Taxol/Rosco (G2/M-and S-phases), 5-FU/Rosco (S-phase), Dox/Rosco (S-phase) and Vinb/Rosco (G2/M-and S-phases). CONCLUSION: Since the eff icacy of many anticancer drugs depends on their ability to induce apoptotic cell death, modulation of this parameter by cell cycle inhibi-tors may provide a novel chemo-preventive and chemo-therapeutic strategy for human colorectal cancer.