Sublethal concentrations of the platinum(II) complex [Pt(O,O′‐acac)(γ‐acac)(DMS)] alter the motility and induce anoikis in MCF‐7 cells

Abstract

Background and purpose:We showed previously that a new Pt(II) complex ([Pt(O,O′-acac)(g-acac)(DMS)]) exerted high and fast apoptotic processes in MCF-7 cells. The objective of this study was to investigate the hypothesis that [Pt(O,O′-acac)(gacac)(DMS)] is also able to exert anoikis and alter the migration ability of MCF-7 cells, and to show some of the signalling events leading to these alterations. Experimental approach: Cells were treated with sublethal doses of [Pt(O,O′-acac)(g-acac)(DMS)], and the efficiency of colony initiation and anchorage-independent growth was assayed; cell migration was examined by in vitro culture wounding assay. Gelatin zymography for MMP-2 and -9 activities, Western blottings of MMPs, MAPKs, Src, PKC-e and FAK, after [Pt(O,O′-acac)(g-acac)(DMS)] treatment, were also performed. Key results: Sub-cytotoxic drug concentrations decreased the: (i) anchorage-dependent and -independent growth; (ii) migration ability; and (iii) expression and activity of MMP-2 and MMP-9. [Pt(O,O′-acac)(g-acac)(DMS)] provoked the generation of reactive oxygen species (ROS), and the activation of p38MAPK, Src and PKC-e. p38MAPK phosphorylation, cell anoikis and migration due to [Pt(O,O′-acac)(g-acac)(DMS)] were blocked by PKC-e inhibition. Furthermore, Src inhibition blocked the [Pt(O,O′-acac)(g-acac)(DMS)]-provoked activation of PKC-e, while ROS generation blockage inhibited the activation of Src, and also the decrement of phosphorylated FAK observed in detached [Pt(O,O′-acac)(g-acac)(DMS)]-treated cells. Conclusions and implications:Sublethal concentrations of [Pt(O,O′-acac)(g-acac)(DMS)] induced anoikis and prevented events leading to metastasis via alterations in cell migration, anchorage independency, stromal interactions and MMP activity. Hence, [Pt(O,O′-acac)(g-acac)(DMS)] may be a promising therapeutic agent for preventing growth and metastasis of breast cancer.

The signalling axis mediating neuronal apoptosis in response to [Pt(O,O′-acac)(γ-acac)(DMS)]

“…The different mechanism of action of the new complex, having biological targets, different from those of cisplatin, may render it intrinsically able to evoke less chemo-resistance. Theoretically, this compound could produce, in addition, a broader spectrum of application, since we have assessed its ability to exert also specific antimetastatic responses in vitro [9]. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 (Fig.…”

“…Depending on the specific role of NF-κB in apoptosis, it may regulate the expression of either proapoptotic or antiapoptotic Bcl-2 proteins [45]. However, since in SH-SY5Y and in some neuronal cell types NF-κB is more-commonly associated with pro-apoptotic functions [44,46], and because NF-κB activation plays a pro-apoptotic role also in activation of NAD(P)H oxidase and mitochondrial pathways [9], as often observed in the early stages of apoptosis [52]. Here, inhibition of NAD(P)H oxidase blocks activation of MAPKs, suggesting ROS generation upstream to MAPK activation in SH-SY5Y cells (Fig.…”

“…Recently, a platinum complex containing two acetylacetonate ligands, one O,O'-chelate and the other sigma-linked by methionine in the gamma position, and dimethylsulphide (DMS) in the metal coordination sphere has been synthesized [5] and shown to exhibit interesting biological activities [6][7][8][9].Differently from cisplatin, for which the activity appears to be associated both with its intracellular accumulation and with the formation of DNA adducts [6,7], the cytotoxicity of this new compound is related to the intracellular accumulation only, showing a low reactivity with nucleobases and a specific reactivity with sulphur ligands, suggesting that the cellular targets could be amino acid residues of proteins. The different action mechanism of the new complex, having different biological targets, with respect to cisplatin, may render it intrinsically able to evoke less A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 compared with cisplatin, [Pt(O,O'-acac)(γ-acac)(DMS)] induces less severe changes on fundamental events of neuroarchitecture development, such as no high apoptotic events, less altered granule cell migration and Purkinje cell dendrite growth, suggesting a low neurotoxicity for normal central nervous system [10].…”

The platinum (II) complex [Pt(O,O′-acac)(γ-acac)(DMS)] alters the intracellular calcium homeostasis in MCF-7 breast cancer cells

“…To obtain protein cell extracts and subcellular fractions we used a procedure previously described [22]. Cells were washed twice in ice-cold PBS and harvested in 1 ml of PBS.…”

“…ROS generation was detected by nitroblue tetrazolium (NBT) assay as previously described [22]. NBT (1 mg/ml ) was added to medium of treated MCF-7 and incubations were carried out at 37 °C for 15- …”