67-kDa laminin receptor increases cGMP to induce cancer-selective apoptosis
Motofumi Kumazoe, Kaori Sugihara, Shuntaro Tsukamoto, Yuhui Huang, Yukari Tsurudome, Takashi Suzuki, Yumi Suemasu, Naoki Ueda, Shuya Yamashita, Yoonhee Kim, Koji Yamada, Hirofumi Tachibana
Motofumi Kumazoe, Kaori Sugihara, Shuntaro Tsukamoto, Yuhui Huang, Yukari Tsurudome, Takashi Suzuki, Yumi Suemasu, Naoki Ueda, Shuya Yamashita, Yoonhee Kim, Koji Yamada, Hirofumi Tachibana
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Research Article

67-kDa laminin receptor increases cGMP to induce cancer-selective apoptosis

Abstract

The 67-kDa laminin receptor (67LR) is a laminin-binding protein overexpressed in various types of cancer, including bile duct carcinoma, colorectal carcinoma, cervical cancer, and breast carcinoma. 67LR plays a vital role in growth and metastasis of tumor cells and resistance to chemotherapy. Here, we show that 67LR functions as a cancer-specific death receptor. In this cell death receptor pathway, cGMP initiated cancer-specific cell death by activating the PKCδ/acid sphingomyelinase (PKCδ/ASM) pathway. Furthermore, upregulation of cGMP was a rate-determining process of 67LR-dependent cell death induced by the green tea polyphenol (–)-epigallocatechin-3-O-gallate (EGCG), a natural ligand of 67LR. We found that phosphodiesterase 5 (PDE5), a negative regulator of cGMP, was abnormally expressed in multiple cancers and attenuated 67LR-mediated cell death. Vardenafil, a PDE5 inhibitor that is used to treat erectile dysfunction, significantly potentiated the EGCG-activated 67LR-dependent apoptosis without affecting normal cells and prolonged the survival time in a mouse xenograft model. These results suggest that PDE5 inhibitors could be used to elevate cGMP levels to induce 67LR-mediated, cancer-specific cell death.

Authors

Motofumi Kumazoe, Kaori Sugihara, Shuntaro Tsukamoto, Yuhui Huang, Yukari Tsurudome, Takashi Suzuki, Yumi Suemasu, Naoki Ueda, Shuya Yamashita, Yoonhee Kim, Koji Yamada, Hirofumi Tachibana

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Figure 2

67LR acts as a death receptor via cancer-specific cGMP upregulation.

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67LR acts as a death receptor via cancer-specific cGMP upregulation. (A)...
(A) Effect of EGCG on cGMP levels in normal PBMCs and primary MM cells for 3 hours. (B) U266 cells were preincubated with anti-67LR antibody (20 μg/ml) or IgM control antibody (20 μg/ml), then treated or not with 10 μM EGCG for 3 hours. (C) Effect of the sGC inhibitor NS-2028 on cGMP upregulation. U266 cells were preincubated or not with 5 μM NS-2028 for 1 hour, then treated or not with 10 μM EGCG for 3 hours. (D) Effect of NS-2028 on cell death induced by EGCG. U266 cells were preincubated or not with 5 μM NS-2028 for 1 hour, then treated or not with 10 μM EGCG for 96 hours. (E) Effect of NS-2028 on EGCG-induced ASM activation, measured by TLC analyses. U266 cells were preincubated or not with 5 μM NS-2028 for 1 hour, then treated or not with 10 μM EGCG for 3 hours. (F) U266 cells were treated with 10 μM EGCG or its analogs for 3 hours, and cGMP levels in cells were measured using a competitive immunoassay. n = 3 per group. All data are mean ± SEM.