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Inhibition of the nicotinic acetylcholine receptors by cobra venom α-neurotoxins: is there a perspective in lung cancer treatment?

Alama A, Bruzzo C, Cavalieri Z, Forlani A, Utkin Y, Casciano I, Romani M - PLoS ONE (2011)

Bottom Line: Nicotine exerts its oncogenic effects through the binding to nicotinic acetylcholine receptors (nAChRs) and the activation of downstream pathways that block apoptosis and promote neo-angiogenesis.The nAChRs of the α7 subtype are present on a wide variety of cancer cells and their inhibition by cobra venom neurotoxins has been proposed in several articles and reviews as a potential innovative lung cancer therapy.Paradoxically α-cobrotoxin from Naja atra showed the tendency to enhance tumor growth although, even in this case, the statistical significance was not reached.In conclusion our results show that, in contrast with other reports, the nAChR inhibitors α-cobratoxin from N. kaouthia and α-cobrotoxin from N. atra neither suppressed tumor growth nor prolonged the survival of the treated animals.

View Article: PubMed Central - PubMed

Affiliation: Lung Cancer Unit, Istituto Nazionale per la Ricerca sul Cancro, IST, Genova, Italy.

ABSTRACT
Nicotine exerts its oncogenic effects through the binding to nicotinic acetylcholine receptors (nAChRs) and the activation of downstream pathways that block apoptosis and promote neo-angiogenesis. The nAChRs of the α7 subtype are present on a wide variety of cancer cells and their inhibition by cobra venom neurotoxins has been proposed in several articles and reviews as a potential innovative lung cancer therapy. However, since part of the published results was recently retracted, we believe that the antitumoral activity of cobra venom neurotoxins needs to be independently re-evaluated.We determined the activity of α-neurotoxins from Naja atra (short-chain neurotoxin, α-cobrotoxin) and Naja kaouthia (long-chain neurotoxin, α-cobratoxin) in vitro by cytotoxicity measurements in 5 lung cancer cell lines, by colony formation assay with α7nAChRs expressing and non-expressing cell lines and in vivo by assessing tumor growth in an orthotopic Non-Obese Diabetic/Severe Combined Immunodeficient (NOD/SCID) mouse model system utilizing different treatment schedules and dosages.No statistically significant reduction in tumor growth was observed in the treatment arms in comparison to the control for both toxins. Paradoxically α-cobrotoxin from Naja atra showed the tendency to enhance tumor growth although, even in this case, the statistical significance was not reached.In conclusion our results show that, in contrast with other reports, the nAChR inhibitors α-cobratoxin from N. kaouthia and α-cobrotoxin from N. atra neither suppressed tumor growth nor prolonged the survival of the treated animals.

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Clonality assay.The cell lines A549 (α7 AChR +) and NCI-H1975 (α7 AChR -) were plated in 35 mm Petri dishes or in 24 wells plates at densities of 150 (A549) and 300 (NCI-H1975) cells/dish and exposed to either long-chain α-neurotoxin from Naja Kaouthia, at concentrations of 15 µM, 7.5 µM, 3.8 µM (A549) and 6 µM, 3 µM, 1.5 µM (NCI-H1975), or short-chain from Naja Atra, at concentrations of 30 µM and 15 µM (both cell lines). Treated cells were then incubated for 7–10 days, until visible colonies formed.
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pone-0020695-g003: Clonality assay.The cell lines A549 (α7 AChR +) and NCI-H1975 (α7 AChR -) were plated in 35 mm Petri dishes or in 24 wells plates at densities of 150 (A549) and 300 (NCI-H1975) cells/dish and exposed to either long-chain α-neurotoxin from Naja Kaouthia, at concentrations of 15 µM, 7.5 µM, 3.8 µM (A549) and 6 µM, 3 µM, 1.5 µM (NCI-H1975), or short-chain from Naja Atra, at concentrations of 30 µM and 15 µM (both cell lines). Treated cells were then incubated for 7–10 days, until visible colonies formed.

Mentions: To confirm and extend this observation we have conducted a colony formation assay with the α7 nAChR+A549 and with the α7 nAChR−NCI-H1975 cell lines . Since the IC50 was not reached with α-cobrotoxin, we utilized the two highest concentrations tested by MTT (15 and 30 µM). For α-cobratoxin we utilized the concentrations corresponding to the IC50 for A549 and NCI-H1975 (7. 5 and 3 µM, respectively) and concentrations corresponding to half and twice the IC50. As shown in Figure 3, the clonogenic activity of the two cell lines was not affected by the treatment and by the presence of the α7 nACh receptor.


Inhibition of the nicotinic acetylcholine receptors by cobra venom α-neurotoxins: is there a perspective in lung cancer treatment?

Alama A, Bruzzo C, Cavalieri Z, Forlani A, Utkin Y, Casciano I, Romani M - PLoS ONE (2011)

Clonality assay.The cell lines A549 (α7 AChR +) and NCI-H1975 (α7 AChR -) were plated in 35 mm Petri dishes or in 24 wells plates at densities of 150 (A549) and 300 (NCI-H1975) cells/dish and exposed to either long-chain α-neurotoxin from Naja Kaouthia, at concentrations of 15 µM, 7.5 µM, 3.8 µM (A549) and 6 µM, 3 µM, 1.5 µM (NCI-H1975), or short-chain from Naja Atra, at concentrations of 30 µM and 15 µM (both cell lines). Treated cells were then incubated for 7–10 days, until visible colonies formed.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3113800&req=5

pone-0020695-g003: Clonality assay.The cell lines A549 (α7 AChR +) and NCI-H1975 (α7 AChR -) were plated in 35 mm Petri dishes or in 24 wells plates at densities of 150 (A549) and 300 (NCI-H1975) cells/dish and exposed to either long-chain α-neurotoxin from Naja Kaouthia, at concentrations of 15 µM, 7.5 µM, 3.8 µM (A549) and 6 µM, 3 µM, 1.5 µM (NCI-H1975), or short-chain from Naja Atra, at concentrations of 30 µM and 15 µM (both cell lines). Treated cells were then incubated for 7–10 days, until visible colonies formed.
Mentions: To confirm and extend this observation we have conducted a colony formation assay with the α7 nAChR+A549 and with the α7 nAChR−NCI-H1975 cell lines . Since the IC50 was not reached with α-cobrotoxin, we utilized the two highest concentrations tested by MTT (15 and 30 µM). For α-cobratoxin we utilized the concentrations corresponding to the IC50 for A549 and NCI-H1975 (7. 5 and 3 µM, respectively) and concentrations corresponding to half and twice the IC50. As shown in Figure 3, the clonogenic activity of the two cell lines was not affected by the treatment and by the presence of the α7 nACh receptor.

Bottom Line: Nicotine exerts its oncogenic effects through the binding to nicotinic acetylcholine receptors (nAChRs) and the activation of downstream pathways that block apoptosis and promote neo-angiogenesis.The nAChRs of the α7 subtype are present on a wide variety of cancer cells and their inhibition by cobra venom neurotoxins has been proposed in several articles and reviews as a potential innovative lung cancer therapy.Paradoxically α-cobrotoxin from Naja atra showed the tendency to enhance tumor growth although, even in this case, the statistical significance was not reached.In conclusion our results show that, in contrast with other reports, the nAChR inhibitors α-cobratoxin from N. kaouthia and α-cobrotoxin from N. atra neither suppressed tumor growth nor prolonged the survival of the treated animals.

View Article: PubMed Central - PubMed

Affiliation: Lung Cancer Unit, Istituto Nazionale per la Ricerca sul Cancro, IST, Genova, Italy.

ABSTRACT
Nicotine exerts its oncogenic effects through the binding to nicotinic acetylcholine receptors (nAChRs) and the activation of downstream pathways that block apoptosis and promote neo-angiogenesis. The nAChRs of the α7 subtype are present on a wide variety of cancer cells and their inhibition by cobra venom neurotoxins has been proposed in several articles and reviews as a potential innovative lung cancer therapy. However, since part of the published results was recently retracted, we believe that the antitumoral activity of cobra venom neurotoxins needs to be independently re-evaluated.We determined the activity of α-neurotoxins from Naja atra (short-chain neurotoxin, α-cobrotoxin) and Naja kaouthia (long-chain neurotoxin, α-cobratoxin) in vitro by cytotoxicity measurements in 5 lung cancer cell lines, by colony formation assay with α7nAChRs expressing and non-expressing cell lines and in vivo by assessing tumor growth in an orthotopic Non-Obese Diabetic/Severe Combined Immunodeficient (NOD/SCID) mouse model system utilizing different treatment schedules and dosages.No statistically significant reduction in tumor growth was observed in the treatment arms in comparison to the control for both toxins. Paradoxically α-cobrotoxin from Naja atra showed the tendency to enhance tumor growth although, even in this case, the statistical significance was not reached.In conclusion our results show that, in contrast with other reports, the nAChR inhibitors α-cobratoxin from N. kaouthia and α-cobrotoxin from N. atra neither suppressed tumor growth nor prolonged the survival of the treated animals.

Show MeSH
Related in: MedlinePlus