Indolylkojyl methane analogue IKM5 potentially inhibits invasion of breast cancer cells via attenuation of GRP78
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More than 90% of the breast cancer deaths occur due to the metastasis of the cancer cells to secondary organ sites. Increased Glucose-regulated protein 78 (GRP78) expression is critical for epithelial–mesenchymal transition (EMT) and invasion in breast cancer resulting in poor patient survival outcomes. Therefore, there is an urgent need of potential inhibitors of GRP78 for the abrogation of invasion and metastasis in breast cancer.
We investigated the effect of IKM5 (2-(1-(1H-indol-3-yl)octyl)-3-hydroxy-6-(hydroxymethyl)-4H-pyran-4-one) (a novel Indolylkojyl methane analogue) on invasion abilities of human breast cancer cells employing invadopodia formation, Matrigel invasion assays, and mouse models for metastasis. The mechanism underlying the anti-invasive effect of IKM5 was examined through molecular docking, immunoblotting, immunocytochemistry, co-immunoprecipitation analysis, siRNA silencing, and sub-cellular fractionation studies.
Treatment with IKM5 at its sub-toxic concentration (200 nM) suppressed invasion and invadopodia formation, and growth factor-induced cell scattering of aggressive human breast cancer MDA-MB-231, MDA-MB-468, and MCF7 cells. IKM5 spontaneously binds to GRP78 (Ki = 1.35 µM) and downregulates its expression along with the EMT markers MMP-2, Twist1, and Vimentin. Furthermore, IKM5 amplified the expression and nuclear translocation of tumor suppressor Par-4 to control NF-kB-mediated pro-EMT activities. Interestingly, IKM5 disrupts the interaction between GRP78 and TIMP-1 by inhibiting GRP78 in a Par-4-dependent manner. Moreover, IKM5 inhibited tumor growth and lung metastasis at a safe dose of 30 mg/kg/body weight.
Our study warrants IKM5, a potential anticancer agent that can abrogate invasion and metastasis, suggesting its clinical development for the treatment of patients with advanced breast cancer.
KeywordsIKM5 GRP78 EMT Par-4 Invasion Breast cancer
Glucose-regulated protein 78
Matrix metalloproteinase 2
Tissue inhibitor of metalloproteases 1
Prostate apoptosis response 4
Nuclear factor kappa B
We thank our Director, Dr R. A. Vishwakarma (IIIM, Jammu, India), for his encouragement and support to accomplish this work. The study was funded by institutional internal grant (MLP-6002) from Council of Scientific & Industrial Research (CSIR), Govt. of India with publication number IIIM/2297/2019. The authors acknowledge CSIR and Department of Biotechnology (DBT), Ministry of Science and Technology, Government of India for providing fellowships to the research scholars.
Compliance with ethical standards
Conflict of interest
All the authors declare that they have no conflicts of interest.
This article does not contain any studies conducted on human participants by any of the co-authors. Animal studies were approved by the Institutional Animal Ethics Committee (IAEC), CPCSEA, Indian Institute of Integrative Medicine, Jammu, India and performed following all the necessary guidelines of IAEC.
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