I have been doing some experiments testing the sensitivity of Nasopharyngeal carcinoma cells (NPC) to ABT-263 and Maritoclax (MCL-1 selective inhibitor). Treatment with Maritoclax alone is killing the normal NPC epithelial cells at very low doses and same goes to when I combine ABT-263 and Maritoclax. My question is whether it is worth testing this combination in NPC cancer cells as the combination is attacking the normal epithelial cells or should I do some more experiments to validate the toxicity? Thank you
Hi Nethia,
I am also working on drug(cisplatin) on lung cancer cells. It is important for you first to determine the toxicity of any compound that you used onto normal cells. If the drugs killed the normal cells, then it is not worth for you to test it on cancer cells.No point at all.
However, i agree that you need to validated the toxicity of both ABT-263 and MCL-1 .You may try used several normal cells and see if the drugs still affect the normal cells.
As in my cases, i tested the cisplatin on normal lung cells (IMR-90), and it showed no toxicity even up to day 3 (72hrs).
Good Luck!
Hi Nethia,
I am also working on drug(cisplatin) on lung cancer cells. It is important for you first to determine the toxicity of any compound that you used onto normal cells. If the drugs killed the normal cells, then it is not worth for you to test it on cancer cells.No point at all.
However, i agree that you need to validated the toxicity of both ABT-263 and MCL-1 .You may try used several normal cells and see if the drugs still affect the normal cells.
As in my cases, i tested the cisplatin on normal lung cells (IMR-90), and it showed no toxicity even up to day 3 (72hrs).
Good Luck!
Hello Nethia,
I would suggest you lower the dose. don't forget the dose determine the toxicity and poison. consider a lower dose than the dose you are using presently.
you may also change the cell line, it is possible you are using a wrong cell that you don't know or ask someone to help you confirm.
Hi Nethia,
It always depends on how 'important' the normal cells are. I would test on a number of different epithelial cell types.
Cheers,
Nikolas
Hi,
I am a bit confused when you said "normal NPC epithelial cells", do you mean normal nasopharyngeal epithelia cells? maybe you can also test it using more generic cell such as HEK293 to see whether you see a very similar effect.
Best,
Shinghu
Hi,
on top of all the suggestion above, do you have the solvent only control? Sometime, it could be just the solvent that you used is too much. You could prepare your drug in a more concentrated form and therefore reduce the amount of solvent in the culture.
I would suggest that you do a dose response and a time course. Its always good to know your drug effects with dose and time in comparison to the tumour cell lines. I would also suggest using more than one normal epithelial cell lines.
Some normal cells always get killed during chemotherapy, such as the rapidly growing cells of the gut lining epithelial cels and the hair cells causing diarrhea and hair loss, but ofcourse drugs where such effects are minimum would be optimal for therapy.
It's always about identifying a therapeutic window. Many cytotoxic drugs are clinically useful despite being toxic (at some level) to 'normal' cells. Test the toxicity over several logs of concentration. If you do some reading around the topic of IC50 (or IC90) measurement that will probably help.
Hi Nethia
In order to answer your query convincingly, May I ask you to provide following information:
1. What was the minimum toxic concentration of drug?
2. For how much time you treat the cells?
3. What was the IC50?
Why would you want to do it. Just because it can be done is not a reason to do it. High school students can test compounds on cells, you need defined objective(s).
I would recommend the following experiment: Vary the drug concentration (~8-12 serial dilutions) on as many different cell lines as possible and determine the LC50 of the drug for each cell line (LC50 = the concentration of drug that kills 50% of the cells relative to controls treated with just buffer). Hopefully, you will observe a higher LC50 for normal cells than cancer cells. In other words, it should take more drug to kill normal cells than cancer cells. But even if this is not the case, you still might have a good drug depending on other considerations.
In principle, I would agree with Nazilar (above), a drug, without a therapeutic window, (Concentration range, where cancerous cells are more sensitive than healthy cells) is not useful. It can still be worthwhile to continue, if you find another cotreatment compound which might synergize with your substance. So, I would suggest: follow Don and test the full concentration range with and without the second compound. if this does not lead to useable conditions, you may have to change one of the compounds.
If you are trying to find a drug agianst NPC, no to testing the combination. Unless for some mystical reasons Marticlax is toxic in vitro (cell culture) but not in vivo (no due to useless PK) , while adding to the effectiveness of ABT for in vivo NPC model. If you are academically curious - the question will become: is the combination against NPC is synergistic, additive or antagonistic. Toxicity experimetns with combo will give you the results you expect.
Dear Nethia
Yes you should use this toxic substance against cancer cells (different types of cancer cells). If it proves toxic for cancer cell, you then can modify the dose or the chemical composition 0f this substance in order to find safe drug against cance.
Yes I recomme
Cancer cells are not necessarily the only ones that need to be killed, there are some instances where it is necessary to kill normal cells. Showing differential sensitivity among normal and cancer cells to your drug is worth scientific information and someone may find it useful for their project. So I agree with those who suggest trying the drug and drug combinations on cancer cells. Furthermore, dose response may not be as simple as non-toxic, toxic and maximal doses, I would suggest also suggest comparing dose responses at very low doses, as near zero as possible. You may also find interesting differences in cell response at the very low dose.
Dear
you can that drug and measures its efficiency for inhibiting cancer cells and toxicity
Dear Nethia,
If your compound negatively affects your normal control cells in dose response titration at very low concentration, it might be worth to continue to test similar compounds of the same class, which might not be harmful to your control cell on the cancer cells, or to modify the compound chemically in a way that reduces its toxicity to controls.
In my opinion, anti-tumor agents must be specific killing cancer cells.
Agree with Don and Thomas above as a way forward. I would argue, what defines a normal cell in in vitro cell culture anyway? Any cell that grows on a plastic dish can hardly be described as 'normal', eh? [N.B. I used to use HUVEC cells for my toxicity assays (short term culture)]. The real deal killers for drug development are hERG liability and CYP, aren't they? Getting back to your NPC cells, have you tried 3D culture? you can get amazingly different results in 3D (not Soft Agar or Matrigel, other matrices are available)....
There is not enough information to accurately answer your question, but I will raise some issues. 1) How "normal" are your normal cells? Are you convinced they are a good model? 2) "Normal" cells derived from same tissue are not the most relevant concern for chemotherapy toxicity, bone marrow and intestinal epithelial cells are usually more relevant. 3) relative toxicity in the in vivo situation cannot often be predicted by cell culture experiments. In summary, I would not give up on the project based on the data you have presented.
There is an old saying that the chief difference between pharmacology and toxicology is dose! The reaction of patients to chemotherapy due to toxicity on "normal" cells is such that quite often therapy has to be discontinued. Just because a drug is used to treat cancer does not mean it only affects cancer cells, it really a trade off between the damage to normal cells and tumour cells, and any differential in toxicity between tumour and normal cells is worth investigating. Consequently I would perform the studies. Also you are using cells in vitro which will be different to cells in vivo so if there is a difference in vitro it is worth looking at, but bear in mind what Adam has said regarding what constitutes normal cells and that there is a world of difference between in vitro and in vivo toxicity.
good luck!
If you are using an immortalized cell line it is very likely to see some amount of kill off. If the amount of cells being killed is not significant in comparison to your control then I believe a simple explanation (DMSO tends to kill cells) can suffice. In the case of MCF-10As, they are positive for hTERT which is known to be up regulated in many cancer cell types. The compounds we use in our lab target hTERT through inhibition. So, we do see a small decrease in "normal" cellular viability that may be associated with the inactivation of hTERT. I'd say go ahead and test your cancer cells, preform real time PCR to assess the mRNA levels of a few common genes associated with cell survival and maintenance and determine if there are any abnormalities (ex: up-regulation of hTERT) in your "normal cells" that could suffice as an explanation for why your cells are dying. You may also find that the cancer cells are dying more in comparison to your control cells.
Yes, if you find the drug is 10-50 fold more toxic to the cancer cells, it would be useful.
yes , you can by using several concentrations to measure the toxicity and its efficiency to inhibit the cancer cells by DNA fragmentation or apoptosis
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