A series of polymethyl-substituted piperidines linked to either a 6-methoxy-1,2,3,4-tetrahydronaphthalen-1-yl or a 6-methoxynaphthalen-1-yl moiety was generated with the aim of verifying a previously generated hypothesis: tetralin and naphthalene nuclei confer opposite activity at the 1 receptor. Compounds 6, 9 and 10 displayed appreciable affinity at both  subtypes, but none of the novel compounds displayed significant antiproliferative activity in MCF7wt and MCF71 cell lines. The effect on bradikynin-triggered Ca2+ mobilization was studied as a methodology to suggest sigma receptors mediated activity.

A major limitation of cancer treatment is the ability of cancer cells to develop resistance to chemotherapeutic drugs, by the establishment of multidrug resistance. Here, we characterize MC70 as ABC transporters inhibitor and anticancer agent, alone or with chemotherapy. MC70 was analyzed for its interaction with ABCB1, ABCG2 and ABCC1 by specific transport assays. In breast and colon cancer cell lines, cell growth and apoptosis were measured by MTT assay and DNA laddering Elisa kit, respectively. Cell cycle perturbation and cellular targets modulation were analyzed by Flow-cytometry and Western blotting, respectively. MC70 interacted with ABC transporters. In breast cancer cells, MC70 slightly inhibited cell proliferation strongly enhancing doxorubicin effectiveness. By contrast, MC70 was found to inhibit cell growth in colon cancer cells without affecting doxorubicin efficacy and in combination with topoisomerase I inhibitors it could be a promising therapeutic approach. What is more, it was also observed that MC70 induced apoptosis, canceled in favor of necrosis when given in combination with high doses of doxorubicin. MC70 inhibited cell migration probably through its interaction with sigma-1 receptor. Modulations of i) cell cycle, ii) pAkt and the phosphorylation of the three MAPKs were highlighted, while any activity was excluded at transcription level, thus accounting for the phenotypic effects observed. MC70 might be considered as a new potential anticancer agent capable to i) enhance chemotherapy effectiveness and ii) to play a contributory role in the treatment of chemotherapy resistant tumors.

We have measured, in the edible frog (Pelophylax kl. esculentus), the effect of two fungicides (8-hydroxyquinoline and captan), and four herbicides (DCMU, glyphosate, paraquat, and propachlor) on the short-circuit current, whose value gives an estimate of the net ion transport taking place across isolated skin. Glyphosate and paraquat treatment produced a modest increase in short-circuit current, corresponding to 2.6±0.7 and 4.6±0.8 μA·cm−2, whereas the other substances had a more sustained effect, ranging from 9.1±0.6 (propachlor) to 14.8±0.9 μA·cm−2 (captan), which is mainly attributable to an increase in the Na+ absorption, and, to a lesser extent, Cl− secretion. The increase in short-circuit current after pesticide treatment, was partially abolished by AF12198, indomethacin, SC58125, SQ 22536, and W7; these results suggest that pesticides, independently from their chemical structure, induce the release of interleukin-1, which triggers the activity of cyclooxygenase-2, whose products, via a concentration in intracellular cAMP and Ca2+ concentration, increase Na+ absorption. The resulting Na+ disequilibrium must be compensated for by other epithelia, with the only consequence being the dissipation of energy. However, our results are important because they indicate that pesticides interact with the basic cellular machinery, which is responsible for the myriad of biological functions of different cell types.

Background A number of σ receptor ligands have been demonstrated to possess antidepressant-like effect in some experimental paradigms (e.g. forced swim test, tail suspension test, olfactory bulbectomy model, conditioned fear stress). The objective of the present study was to find out whether PB190 and PB212, new σ1 receptor ligands, show the effects in some models predictive of antidepressant activity. Methods The impact of PB190 and PB212 on the immobility time in the forced swim test (FST) and tail suspension test (TST) was assessed in C57BL/6J male mice. Extracellular bradykinin triggers a transient increase in intracellular calcium concentration by activating the phospholipase C/IP3 pathway. The intracellular calcium concentration was estimated with the dual wavelength ratiometric probe Fura-2. Results In the FST model, PB190 showed a moderate antidepressant-like effect (only in the dose of 3 mg/kg) which was enhanced by joint treatment with amantadine (AMA), 10 mg/kg (inactive per se). The decrease in the immobility time induced by the combined treatment with PB190 and AMA was counteracted by PB212 and by BD1047, a σ1-receptor antagonist. The in vitro studies indicated that Ca2+-response was increased by 1 μM PB190, like by the σ1-agonist (+)-pentazocine, while 1 μM PB212 behaved line σ1-antagonist, BD1063. On the other hand, 100 μM PB190 negatively affected the Ca2+-response after bradykinin. Conclusions The obtained results: 1/indicated that in the in vivo conditions PB190 behaved as a σ1-receptor agonist while PB212 counteracted its effect, confirming the in vitro data; 2/gave support to the hypothesis that σ1-receptors might be one of possible mechanisms by which drugs induce antidepressant-like activity; 3/revealed that this effect may be potentiated by NMDA receptor antagonists, e.g. AMA.

Sigma-1 receptors are specifically located at the endoplasmic reticulum–mitochondrion interface, but upon stimulation by ligands or under prolonged cellular stress, they translocate to other areas of the cell. Sigma-1 receptors are involved in the regulation of intracellular [Ca2+] by affecting the Ca2+-influx or the release from intracellular stores. In SK-N-SH cells, we measured the affinity of 4-methyl-1-[4-(6-methoxynaphthalen-1-yl)butyl]piperidine (PB212) at sigma-1 receptor by using a competition binding assay with specific radioligand; we obtained a Ki value = 316 ± 19 nM. PB212 also showed an antiproliferative effect in SK-N-SH cells (EC50 = 32 ± 4 μM) but had no effect in MCF7 cells, which only express sigma-2 receptor; these findings suggest that PB212 behaves as a sigma-1 receptor antagonist. We have studied the effect of PB212 on Ca2+ homeostasis of the SK-N-SH cell line with the fluorescent probe Fura-2. 100 μM PB212 induced a Ca2+-efflux from the endoplasmic reticulum through the inositol (1, 4, 5)-trisphosphate (IP3) receptor. Moreover, [PB212] ranging from 1 to 100 μM reduced the Ca2+-response, triggered by carbachol or bradykinin that engage the phospholipase C/IP3 pathway; such a response is generally increased by sigma-1 receptor agonists. On the other hand, PB212 did not reduce the Ca2+-response mediated by IP3 in LoVo cells, which do not express neither sigma-1 nor sigma-2 receptors, and in MCF7 cells. The fact that the activity of the sigma-1 receptor can be experimentally modulated by agonists and antagonists supports the intriguing hypothesis that some endogenous molecules, unknown at the moment, modulate the sigma-1 receptor and its cellular targets.