mk-1775 and Colonic-Neoplasms

Wee1 is an oncogenic nuclear kinase, which can regulate the cell cycle as a crucial G2M checkpoint. Overexpression of Wee1 can be observed in various cancer types, which may lead to a poor prognosis, but the potential therapeutic value of Wee1 in colorectal cancer has not been fully studied. In the present study, the role of Wee1 in colonic cancer was investigated. Wee1 inhibition by small interfering RNA was demonstrated to significantly restrain cancer cell proliferation and sensitize the p53 mutant colonic cancer cell lines HT29 and SW480 to the effect of treatment with ionizing radiation. The anticancer effect of the Wee1 inhibitor MK1775 was investigated in these two colonic cancer cell lines. MK1775 was demonstrated to induce significant DNA damage, suppress cell viability and induce apoptosis. In addition, MK1775 sensitized HT29 and SW480 cells to the effect of irinotecan. Annexin V/propidium iodide staining demonstrated that combination therapy can induce increased apoptosis compared with MK1775 or irinotecan monotherapy. The results of western blot analysis also indicated increased expression of the DNA damage marker histone H2AX, and apoptosis‑associated protein cleaved caspase 3, in HT29 and SW480 cells. In conclusion, the present study indicated that Wee1 may be a valuable target for treatment of p53 mutant colonic cancer.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Camptothecin; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Colonic Neoplasms; DNA Damage; Enzyme Inhibitors; Humans; Irinotecan; Mutation; Nuclear Proteins; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; Tumor Suppressor Protein p53

MK-1775 is a potent and selective small molecule Wee1 inhibitor. Previously we have shown that it abrogated DNA damaged checkpoints induced by gemcitabine, carboplatin, and cisplatin and enhanced the anti-tumor efficacy of these agents selectively in p53-deficient tumor cells. MK-1775 is currently in Phase I clinical trial in combination with these anti-cancer drugs. In this study, the effects of MK-1775 on 5-fluorouracil (5-FU) and other DNA-damaging agents with different modes of action were determined. MK-1775 enhanced the cytotoxic effects of 5-FU in p53-deficient human colon cancer cells. MK-1775 inhibited CDC2 Y15 phosphorylation in cells, abrogated DNA damaged checkpoints induced by 5-FU treatment, and caused premature entry of mitosis determined by induction of Histone H3 phosphorylation. Enhancement by MK-1775 was specific for p53-deficient cells since this compound did not sensitize p53-wild type human colon cancer cells to 5-FU in vitro. In vivo, MK-1775 potentiated the anti-tumor efficacy of 5-FU or its prodrug, capecitabine, at tolerable doses. These enhancements were well correlated with inhibition of CDC2 phosphorylation and induction of Histone H3 phosphorylation in tumors. In addition, MK-1775 also potentiated the cytotoxic effects of pemetrexed, doxorubicin, camptothecin, and mitomycin C in vitro. These studies support the rationale for testing the combination of MK-1775 with various DNA-damaging agents in cancer patients.

Topics: Animals; Antibiotics, Antineoplastic; Antimetabolites, Antineoplastic; Antineoplastic Agents, Phytogenic; Apoptosis; Blotting, Western; Camptothecin; Capecitabine; Caspases; Cell Cycle Proteins; Cell Proliferation; Colonic Neoplasms; Deoxycytidine; DNA Damage; Doxorubicin; Flow Cytometry; Fluorouracil; Glutamates; Guanine; Histones; Humans; Immunoenzyme Techniques; Mitomycin; Nuclear Proteins; Pemetrexed; Phosphorylation; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; Rats; Rats, Inbred F344; Rats, Nude; Xenograft Model Antitumor Assays

Topics: Animals; Antineoplastic Agents; Cell Cycle Proteins; Colonic Neoplasms; DNA Damage; Humans; Nuclear Proteins; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones