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Effects of PHA-665752 and Cetuximab Combination Treatment on In Vitro and Murine Xenograft Growth of Human Colorectal Cancer Cells with KRAS or BRAF Mutations

[ Vol. 18 , Issue. 3 ]

Author(s):

Yi-Tao Jia, Dong-hai Yang, Zhaolong Zhao, Xiao-Hui Bi, Wei-Hua Han, Bo Feng, Jie Zhi, Bin Gu, Zhihui Duan, Jian-Hua Wu, Ying-Chao Ju, Ming-Xia Wang and Zhong-Xin Li*Pages 278-286 (9)

Abstract:


Background: It remains unknown whether blockade of c-Met signaling and epidermal growth factor receptor signaling is effective in suppressing the growth of human colorectal cancer (CRC) cells. In this study, we investigated the effects of the c-Met inhibitor PHA-665752 alone and in combination with cetuximab on the growth of human CRC cells in vitro and in mouse xenografts.

Methods: Human CRC cell lines (Caco2, HCT-116, and HT-29) and mice bearing HCT-116 xenografts were treated with cetuximab in the absence or presence of PHA-665752. Cell viability and apoptosis were examined using the MTT and TUNEL assays, respectively. Vimentin was measured by immunohistochemistry as a marker for epithelial-to-mesenchymal transition. Western blotting was used to determine signaling protein expression levels.

Results: The MTT assay showed that the growth of Caco2, HCT-116, and HT-29 cells was inhibited by PHA-665752 in a dose-dependent manner, but only Caco2 cell growth was suppressed by cetuximab. Combination treatment with PHA-665752 and cetuximab inhibited the proliferation of Caco2 cells and RAS mutant CRC cell lines. However, relative to the PHA-665752-alone treatment group, HT-29 cells with a BRAF mutation showed no noticeable effect. The mean tumor volume in mice treated with cetuximab in combination with PHA-665752 was significantly smaller than that in the mice treated with only cetuximab (P = 0.033) or PHA-665752 (P < 0.01). Similarly, the expression of vimentin in the mice treated with PHA-665752 in combination with cetuximab was significantly lower than that in the mice treated with cetuximab or PHA-665752 alone (P < 0.05 in each case). TUNEL assays revealed that treatment with PHA-665752 in combination with cetuximab markedly increased CRC cell apoptosis. Western blotting analysis of signaling protein expression showed that PHA- 665752 inhibited Met phosphorylation (P < 0.05). In addition, treatment with cetuximab alone or in combination with PHA-665752 effectively inhibited EGFR phosphorylation (P < 0.05).

Conclusion: Combination treatment with PHA-665752 and cetuximab suppressed in vitro and in vivo CRC cell growth more than treatment with either agent alone did.

Keywords:

Colorectal cancer, cetuximab, RAS, BRAF, c-Met, CRC cell lines.

Affiliation:

Department of Oncology, Hebei General Hospital, Shijiazhuang 050051, Hebei, Second Department of Surgery, the Fourth Hospital of Hebei Medical University, Tianshan Road, Shijiazhuang 050011, Hebei, Second Department of Surgery, the Fourth Hospital of Hebei Medical University, Tianshan Road, Shijiazhuang 050011, Hebei, Second Department of Surgery, the Fourth Hospital of Hebei Medical University, Tianshan Road, Shijiazhuang 050011, Hebei, Second Department of Surgery, the Fourth Hospital of Hebei Medical University, Tianshan Road, Shijiazhuang 050011, Hebei, Second Department of Surgery, the Fourth Hospital of Hebei Medical University, Tianshan Road, Shijiazhuang 050011, Hebei, Department of Oncology, Hebei General Hospital, Shijiazhuang 050051, Hebei, Second Department of Surgery, the Fourth Hospital of Hebei Medical University, Tianshan Road, Shijiazhuang 050011, Hebei, Second Department of Surgery, the Fourth Hospital of Hebei Medical University, Tianshan Road, Shijiazhuang 050011, Hebei, Experimental Animal Center, the Fourth Hospital of Hebei Medical University, Shijiazhuang 050011, Hebei, Experimental Animal Center, the Fourth Hospital of Hebei Medical University, Shijiazhuang 050011, Hebei, Department of Pharmacy, the Fourth Hospital of Hebei Medical University, Shijiazhuang 050011, Hebei, Second Department of Surgery, the Fourth Hospital of Hebei Medical University, Tianshan Road, Shijiazhuang 050011, Hebei

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