A novel indole ethyl isothiocyanate (7Me-IEITC) with anti-proliferative and pro-apoptotic effects on platinum-resistant human ovarian cancer cells

Abstract

Objective-A novel indole-ethyl isothiocyanate derivative (7Me-IEITC) was defined as a potent growth-suppressing agent to cell lines derived from ovarian cancers. Key mechanisms of the cellular response in vitro were studied and suggest a potential of 7Me-IEITC as a therapeutic drug.Methods-The viability of ovarian cancer cell lines (SKOV-3, OVCAR-3) in comparison to pancreatic and prostate cancer cell lines, primary fibroblast and immortalized trophoblasts after treatment with 7Me-IEITC was analyzed. Morphological and apoptotic responses of SKOV-3 were studied by fluorescence microscopy (DAPI staining, TUNEL assay). SKOV-3 proliferation was estimated by a standardized BrdU incorporation assay. The phosphorylation of MAP-Kinases, prosurvival factors and the activation of caspases and PARP-1 were analyzed by western blotting. Changes of the mitochondrial transmembrane-potential and in cell cycle progression were studied by FACS analysis. MAP-Kinase and caspase inhibitors were employed in cytotoxicity studies.Results-7Me-IEITC selectively reduced the viability of SKOV-3, OVCAR-3, BXPC-3 and PC-3 cells (IC50 values ≤5μM), while the viability of fibroblasts or trophoblasts remained unaffected at concentrations below 20μM. 7Me-IEITC treatment down-regulated pro-survival kinases and transcription factors (STAT-3, IKKα and NF-κB), caused rapid loss of the mitochondrial transmembrane-potential and inactivation of PARP-1 along with activation of caspases. The use of p38 MAP-Kinase-and caspase-inhibitors suppressed the cytotoxicity of the drug. 7Me-IEITC acted as an anti-proliferative agent and arrested the cell-cycle progression of SKOV-3 in G2/M phase.Conclusion-7Me-IEITC is a potent and growth-suppressing agent to cell lines derived from ovarian cancers by causing de-activation of survival signals, apoptosis, and cell-cycle arrest.

Isothiocyanate NB7M causes selective cytotoxicity, pro-apoptotic signalling and cell-cycle regression in ovarian cancer cells

“…The DTP at the NCI maintains a public accessible database of cytotoxic drugs; a comparison analysis (COMPARE) of known cytotoxic drugs versus NB7M indicated that NB7M is more potent than a variety of clinically relevant drugs, such as cisplatin, oxaloplatin, seliciclib, CNDAC, 5-FU and cyclophosphamide, in most of the NCI 60 cell lines but is less potent than docetaxel, adriamycin and gemcitabine. Our in vitro investigations have shown that NB7M and its synthetic parent compound 7Me-IEITC show overlapping cytotoxic effects with ovarian cancer cell lines OVCAR-3 and SKOV-3 being more sensitive to NB7M as compared to 7Me-IEITC (present manuscript; Singh et al, 2008). This also applies to several neuroblastoma cell lines, while the viability of lung fibroblasts or trophoblast cell lines by either compound is only marginally affected Brard et al, 2008).…”

“…The growth of IGROV1, OVCAR-3, OVCAR-5 was highly affected by 10 mM of the drug (as shown for OVCAR-3 in the cytotoxicity assay performed in our laboratory) and OVCAR-8 and OVCAR-4 responded strongly to treatment, whereas SKOV-3 revealed less but still significant reduction in growth compared to the other five lines tested by the National Cancer Institute (NCI). Taken together, the NCI screen (http:// dtp.nci.nih.gov/screening.html) and our cytotoxicity assays suggest NB7M to be highly and specifically detrimental to cell lines derived from certain tumour types, including ovarian cancer, but less effective against other tumour types and marginally cytotoxic for control cell lines (e.g., TCL-1, HTR-8; Figure 1B and MRC-5 fibroblasts, Singh et al, 2008).…”

“…NB7M and its precursor 7Me-IEITC showed a striking similarity in the expression and/or activation of a multitude of molecular targets, including DNA-PK, Axl, PI-3K, Akt; the MAPKs ERK1/2, p38, JNK; NF-kB and the CDK inhibitor p27 (present manuscript; Singh et al, 2007;Brard et al, 2008;Singh et al, 2008). Many types of tumours are associated with activated oncogenic kinases.…”

Description of the cytotoxic effect of a novel drug Abietyl-Isothiocyanate on endometrial cancer cell lines

“…1b) with increased in-vitro potency as compared to various naturally occurring ITC have been developed. Cytotoxic mechanisms of these compounds include rapid induction of apoptosis, alteration of Mitogen activated protein kinase (MAPK) signaling and cell-cycle inhibitory effects in neuroblastoma [12,13] and ovarian cancer cells [14][15][16].…”

“…Based on our previous structure-activity guided modification of PEITC to identify potent ITC derivatives [12,14,15], in the present manuscript we describe a de novo approach to the structural optimization of PHITC, a synthetic longer chain congener of naturally occurring PEITC leading to the design of Abietyl-Isothiocyanate (ABITC) (Fig. 1c).…”