Abstract 2031: Effects of (-)-epigallocatechin-3-gallate on EGFR or ALK driven lung cancer models.
Authors: Honda Yoshihiro , Takigawa Nagio , Ichihara Eiki , Ninomiya Takashi , Kubo Toshio , Ochi Nobuaki , Yasugi Masayuki , Murakami Toshi , Tanimoto Mitsune , Kiura Katsuyuki 
Published: August 2014

There has been considerable evidence that (-)-epigallocatechin-3-gallate (EGCG) inhibited enzyme activities and signal transduction pathways, resulting in the suppression of cell proliferation and enhancement of apoptosis, as well as the inhibition of cell invasion, angiogenesis and metastasis. EGCG has been shown to bind directly to several receptors including epidermal growth factor receptor (EGFR) and to inhibit the functions. EGFR tyrosine kinase inhibitors such as geﬁtinib and ALK inhibitors such as crizotinib are effective for non-small cell lung cancer harboring activating EGFR mutations and ALK fusion genes, respectively. However, even in the patients with an initial response to the drug, acquired resistance develops after 6-12 months. In this study, we investigated effects of EGCG on EGFR or ALK driven lung cancer models.

We used four lung cancer cell lines: PC-9, RPC-9, H1975 and H2228. RPC-9 cells that acquired EGFR T790M mutation were established from parental PC-9 cells harboring EGFR exon 19 deletion mutation in our laboratory. RPC-9 cells that showed a 400-fold resistance to gefitinib compared with parental PC-9 cells. H1975 cells have L858R point mutation in exon 21 with T790M. H2228 cells harbor EML4-ALK fusion genes. Growth inhibition was measured using MTT assay. The drug concentration required to inhibit the growth of tumor cells by 50% (IC50) for 96 h exposure was used to evaluate the effectiveness of EGCG. Protein expression was determined by Western blotting. The IC50s (mean + standard deviation) were 46 + 7.0 μM for PC-9 cells, 37 + 3.6 μM for RPC-9 cells, 32 + 0.6 μM for H1975 cells and 57 + 7.6 μM for H2228 cells: the four cell lines have similar sensitivity to EGCG. Phosphorylated (p)EGFR, pAKT and pERK in RPC-9 and H1975 cells were suppressed by EGCG (50 or 100 μM). pALK, pAKT and pERK in H2228 cells were also inhibited by EGCG (50 or 100μM).

The antitumor effect of EGCG was examined using mouse xenograft model. PC-9, RPC-9, H1975, and H2228 cells (2 × 106) were injected s.c. into the backs of the athymic mice at 7 wk of age. At about 1 week after injection, mice harboring about 5 - 10 mm tumor size were randomly assigned into one of two groups that received either EGCG or vehicle. The tumor sizes (mm3; mean + standard deviation) of PC-9 on day 42 were 1114 + 478 (n = 10) in EGCG group and 2803 + 973 (n = 9) in control group (p &lt; 0.05). Similarly, the xenograft tumors of RPC-9, H1975 and H2228 cells in EGCG-treated groups were significantly smaller than those in vehicle-treated groups, respectively. The numbers of tumor blood vessels of xenograft tissues, which were evaluated by immunohistochemistry using CD31 antibody, in EGCG-treated mice were significantly reduced than those in vehicle-treated mice.

In conclusion, these preclinical data suggest that EGCG may be effective for both EGFR-driven in spite of T790M presence and ALK-driven lung tumors.

Citation Format: Yoshihiro Honda, Nagio Takigawa, Eiki Ichihara, Takashi Ninomiya, Toshio Kubo, Nobuaki Ochi, Masayuki Yasugi, Toshi Murakami, Mitsune Tanimoto, Katsuyuki Kiura. Effects of (-)-epigallocatechin-3-gallate on EGFR or ALK driven lung cancer models. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2031. doi:10.1158/1538-7445.AM2013-2031