BackgroundPrevious studies suggest that certain transition metal complexes, such as cisplatin, are efficacious for treating various cancer types, including ovarian, lung, and breast.MethodsIn order to further evaluate ruthenium (Ru) complexes as potential anti-cancer agents, we synthesized and evaluated Ru-arene complexes. Two complexes with the general formula [Ru (η6-p-cym) (N–N) Cl]+ were tested for their abilities to inhibit cancer cells.ResultsThe complex with o-phenylenediamine as the N–N ligand (o-PDA) significantly inhibited growth of breast (MDA-MB-231, MCF-7, SKBR-3, and SUM149), lymphoma (Raji), melanoma (Bowes), and osteosarcoma (HT1080); however, the complex with o-benzoquinonediimine (o-BQDI) was ineffective except for SUM149. In contrast, o-PDA failed to inhibit growth of human breast epithelial cells, MCF-10A. Treatment of MDA-MBA-231 cells with o-PDA resulted in a significant reduction of productions of PDGF-AA, GM-CSF, and VEGF-A proteins at the transcriptional levels. Finally, we demonstrated that o-PDA synergistically inhibited MDA-MB-231 cell growth with cyclophosphamide but not doxorubicin or paclitaxel.ConclusionThese results suggest that Ru-arene complexes are promising anti-cancer drugs that inhibit progression and metastasis by blocking multiple processes for breast and other types of cancer.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-0797-9) contains supplementary material, which is available to authorized users.
Previous studies demonstrated that transition metal complexes inhibit cancer cell growth. We have examined a series of ruthenium (Ru (II)) complexes for their ability to inhibit growth of breast cancer cells. Among three complexes with the general formula [Ru(η6-p-cym)(N-N)Cl]+ tested for their abilities to inhibit MDA-MB-231 cell growth, the complex with o-phenalyenediamine (o-pda) as the bidentate nitrogen donor (N-N) ligand, [Ru(η6-p-cym)(o-pda)Cl]+, showed significant inhibitory activity in both a concentration- and a time-dependent manners. Although [Ru(η6-p-cym)(o-pda)Cl]+ inhibited growth of various human cancer types such as MCF-7 (breast), SK-Br3 (breast), B-cell lymphoma (Raji), osteosarcoma (HT1080), and melanoma (Bowes) cells, two TN breast cancer cells, HCC1806 and HCC38, were resistant to this treatment, suggesting cell-type specific functions of [Ru(η6-p-cym)(o-pda)Cl]+ for inhibiting cell growth. When MDA-MB-231 cells were treated with [Ru(η6-p-cym)(o-pda)Cl]+, both cleavage of caspase-3 and release of HMGB-1 into conditioned medium increased in a concentration dependent manner, suggesting [Ru(η6-p-cym)(o-pda)Cl]+ induced both apoptosis and necrosis processes. Importantly, [Ru(η6-p-cym)(o-pda)Cl]+ synergistically inhibited MDA-MB-231 cell growth with cyclophosphamide but not doxorubicin and paclitaxel. These results suggest that [Ru(η6-p-cym)(o-pda)Cl]+ is a potent tumor growth inhibitor per se and enhances tumoricidal activity of chemotherapeutic agents such as cyclophosphamide. Thus, Ru (II) complexes are promising anti-cancer drugs which could be used alone and/or in combination with chemotherapeutic agents for breast cancer patients. The opinion and assertions contained herein are the private views of the authors and are not to be construed as official or as representing the views of the Department of the Army or the Department of Defense.
Citation Format: Joji Iida, Marc L Prazo, Yifeng Lu, Elisabeth T Bell-Loncella, Craig D Shriver. Structure-activity relationship of ruthenium (Ru) complexes to inhibit breast cancer growth and metastasis [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P6-02-09.
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