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Targeting the Warburg Effect to Treat Cancer

There is currently an obesity epidemic that is facing not only the United States, but the entire world. From 1975 to 2016, children and young people’s age standardized mean BMI increased globally, as well as in most regions. The global rate of increase was 0.32 kg/mper decade.1This increase in BMI is not only an issue for health problems related to cholesterol levels and diabetes, but also for cancer. Obesity has been identified as a leading risk factor for cancer development, specifically colorectal cancer (CRC) which has become the fourth leading cause of cancer morbidities worldwide.2,3This has created a clear necessity for novel treatment for those with obesity related CRC. Currently, caloric restriction has been identified as having potential therapeutic effects against CRC, due primarily to its interference with the Warburg effect.4Other studies have been done with energy restriction mimetic agents (ERMAs) in the treatment of various cancers. ERMAs act by selectively targeting cancer cells that are addicted to glycolysis, essentially interfering with the Warburg effect and the need for energy in tumor cells, similar to caloric restriction’s effects. 5,6

A recent publication from Hersi et al. looked to identify ERMAs that could potentially be used as treatment for CRC by affecting the energy machinery of the cancer cells. Doing so could lead to the development of novel treatment that is less cytotoxic, and more potent than current CRC treatments.7,8The basis for the ERMAs being tested within this study was that a hybrid structure that contained an aminothiazole attached to a coumarin core had been reported to target survival signaling in cancers similarly to other ERMAs.8,9In order to identify an ERMA with a high efficacy of cellular metabolic disruption, the authors needed to design and synthesize numerous compounds with the aminothiazole moiety and coumarin core with differing substituents.8

The featured image within this post identifies what substituents made up the various ERMA compounds. Compounds with 9 had a methyl group, 10, had an ethyl group, and 11 had a propyl group. These three categories were further divided with other varying substituents with different properties (e.g. electron donating, electron withdrawing, etc.). Following an initial screening of these compounds based on their cell viability and potency in comparison to OSU-CG5 and OCU-CG12 (ERMA controls), compounds 9f and 9b were selected as the most potent and safest compound, respectively.8These compounds would be tested further for efficacy as anti-cancer treatment. 

Table 2. Synthesized aminothiazole-coumarin ERMA compounds, screened for potency and cell viability. Those compounds which performed well in initial screenings were selected and further tested.

Previously synthesized ERMAs, including OSU-CG5 have shown the induction of energy restriction cellular responses.9Because of this, compounds 9f and 9b were investigated for their energy restriction mediated anticancer activity on two CRC cell lines; HT-29 and HCT116. This was done by determining the expression levels of various metabolically important proteins through Western Blot analysis. These proteins included Akt, AMPK, and beta-TrCP. Results from this experiment were promising. For example, introduction of 9f and 9b showed an enhancement of AMPK activation via phosphorylation in both cell lines. This result is typically a marker of glucose starvation, as AMPK plays a critical role in maintaining redox homeostasis, cell survival and has been characterized as having a role in tumor suppression.10These findings led the authors to further test compounds 9f and 9b’s ability to hinder the Warburg effect.8

A key component of the Warburg effect and its ability to assist growing tumor cells in proliferation, is an increase in glucose uptake for the fermentation of glucose to lactate.11This is why Hersi et al. tested compounds 9f and 9b’s effect on glucose uptake. To do so, CRC cell lines HT-29 and HCT116 were again treated with 9f and 9b at varying concentrations (0.5 – 4.0 mM) for 16 hours, and glucose uptake was measured using Glucose Uptake-Glo Assay.8Results indicated that in both cell lines, glucose uptake was inhibited significantly in a dose-dependent manner. This once again suggests a hindrance of the tumor cells’ energy machinery by the ERMA compounds due to glycolytic interference.8

In addition to the reduction in glucose uptake by the CRC cancer cells as a result of ERMA treatment, the cancer cells also displayed an accumulation of reactive oxygen species (ROS) as a result of a significant decrease in NADPH/NADP+ ratio.8The presence of reactive oxygen species often leads to oxidative stress and eventual cell death, but NADPH is responsible for its detoxification. However, NADPH cannot be regenerated as a result of the CRC cell’s reduction in glucose uptake, and thus cannot detoxify the ROS.12This could lead to extensive cell death, and act as another form of anti-cancer activity as a result of compound 9f and 9b treatment.

Although Hersi et al. provide a great deal of evidence for compounds 9f and 9b having significant anti-cancer activity, there is certainly always room for improvement. The authors suggest that compounds containing electron withdrawing groups at the phenyl ring of the thiazole moiety are more effective than those containing electron donating groups, perhaps there could be a different backbone for which electron withdrawing groups could be placed that would result in a compound that is more potent and less cytotoxic compared to 9f and 9b. Thus, in the future, the authors could screen other potential ERMA compounds for their anti-cancer capabilities. Additionally, other cancer cell lines aside from colorectal could be looked at to determine whether or not this same strategy could be applied to other cancers that act in similar ways.8

Given our class’ recent discussion on the Warburg effect, and its impact on glucose metabolism and cancer development, it’s interesting to see this as a place where researchers see the potential for therapeutics. Given how clear the Warburg effect’s impact is on the progression of cancer, (CRC in particular) it makes a lot of sense that Hersi et al. would investigate the potential for ERMAs to be used as a treatment for obesity linked cancer.

(1)       Abarca-Gómez, L.; Abdeen, Z. A.; Hamid, Z. A.; Abu-Rmeileh, N. M.; Acosta-Cazares, B.; Acuin, C.; Adams, R. J.; Aekplakorn, W.; Afsana, K.; Aguilar-Salinas, C. A.; et al. Worldwide Trends in Body-Mass Index, Underweight, Overweight, and Obesity from 1975 to 2016: A Pooled Analysis of 2416 Population-Based Measurement Studies in 128·9 Million Children, Adolescents, and Adults. The Lancet2017390(10113), 2627–2642. https://doi.org/10.1016/S0140-6736(17)32129-3.

(2)       Stone, T. W.; McPherson, M.; Gail Darlington, L. Obesity and Cancer: Existing and New Hypotheses for a Causal Connection. EBioMedicine201830, 14–28. https://doi.org/10.1016/j.ebiom.2018.02.022.

(3)       Pearson-Stuttard, J.; Zhou, B.; Kontis, V.; Bentham, J.; Gunter, M. J.; Ezzati, M. Worldwide Burden of Cancer Attributable to Diabetes and High Body-Mass Index: A Comparative Risk Assessment. The Lancet Diabetes & Endocrinology20186(6), e6–e15. https://doi.org/10.1016/S2213-8587(18)30150-5.

(4)       O’Flanagan, C. H.; Smith, L. A.; McDonell, S. B.; Hursting, S. D. When Less May Be More: Calorie Restriction and Response to Cancer Therapy. BMC Medicine201715(1), 106. https://doi.org/10.1186/s12916-017-0873-x.

(5)       Pietrocola, F.; Pol, J.; Vacchelli, E.; Rao, S.; Enot, D. P.; Baracco, E. E.; Levesque, S.; Castoldi, F.; Jacquelot, N.; Yamazaki, T.; et al. Caloric Restriction Mimetics Enhance Anticancer Immunosurveillance. Cancer Cell201630(1), 147–160. https://doi.org/10.1016/j.ccell.2016.05.016.

(6)       Kuntz, S.; Mazerbourg, S.; Boisbrun, M.; Cerella, C.; Diederich, M.; Grillier-Vuissoz, I.; Flament, S. Energy Restriction Mimetic Agents to Target Cancer Cells: Comparison between 2-Deoxyglucose and Thiazolidinediones. Biochemical Pharmacology2014,92(1), 102–111. https://doi.org/10.1016/j.bcp.2014.07.021.

(7)       Mohammadian, M.; Zeynali, S.; Azarbaijani, A. F.; Khadem Ansari, M. H.; Kheradmand, F. Cytotoxic Effects of the Newly-Developed Chemotherapeutic Agents 17-AAG in Combination with Oxaliplatin and Capecitabine in Colorectal Cancer Cell Lines. Res Pharm Sci2017,12(6), 517–525. https://doi.org/10.4103/1735-5362.217432.

(8)       Hersi, F.; Omar, H. A.; Al-Qawasmeh, R. A.; Ahmad, Z.; Jaber, A. M.; Zaher, D. M.; Al-Tel, T. H. Design and Synthesis of New Energy Restriction Mimetic Agents: Potent Anti-Tumor Activities of Hybrid Motifs of Aminothiazoles and Coumarins. Scientific Reports2020,10(1), 1–17. https://doi.org/10.1038/s41598-020-59685-x.

(9)       Arafa, E. A.; Abdelazeem, A. H.; Arab, H. H.; Omar, H. A. OSU-CG5, a Novel Energy Restriction Mimetic Agent, Targets Human Colorectal Cancer Cells in Vitro. Acta Pharmacologica Sinica2014,35(3), 394–400. https://doi.org/10.1038/aps.2013.183.

(10)    Ren, Y.; Shen, H.-M. Critical Role of AMPK in Redox Regulation under Glucose Starvation. Redox Biology2019,25, 101154. https://doi.org/10.1016/j.redox.2019.101154.

(11)    Liberti, M. V.; Locasale, J. W. The Warburg Effect: How Does It Benefit Cancer Cells? Trends Biochem Sci2016,41(3), 211–218. https://doi.org/10.1016/j.tibs.2015.12.001.

(12)    Panieri, E.; Santoro, M. M. ROS Homeostasis and Metabolism: A Dangerous Liason in Cancer Cells. Cell Death & Disease20167(6), e2253–e2253. https://doi.org/10.1038/cddis.2016.105.

11 replies on “Targeting the Warburg Effect to Treat Cancer”

Thanks for such an interesting review that’s so relevant to what we’ve been discussing in class! After the lecture material on the Warburg effect, it was especially enlightening to read about how it can be hijacked for therapeutic effects, essentially using the cancer cells’ own metabolism against itself. Although it seems promising that ERMA compounds 9b and 9f are viable treatments for CRC cell lines, especially in terms of hindering glucose uptake in the first place, I am wondering how selective these compounds are. You mentioned that the authors tested their ERMA compounds in two cell lines specific to CRC, which of course is the first step to figuring out if treatment is even possible, but I’m wondering about the extent to which such a treatment could be selective for just CRC cells if given to a patient. It may be possible to just target the cancerous tissue, in which case my concern would be a non-issue. However, even though non-cancerous cells don’t experience the Warburg effect, they still must take up glucose for “normal” aerobic carbohydrate metabolism; if ERMA compounds inhibit cancer cell metabolism at the point of glucose-uptake, wouldn’t this create an adverse effect for the surrounding healthy cells? This could be my naivete about oncology and cancer treatment coming through, but it did raise an eyebrow for me when thinking about the future of this type of treatment in the clinic. Nonetheless, ERMA compounds 9b and 9f do sound incredibly promising in vitro, and I’m excited to watch how this science develops.

The point you brought up regarding these compounds’ selectivity was also a concern that I had while reading through this article, as well as other related articles. It would make sense to me that the reason that we haven’t seen ERMA compounds be introduced to the general public (given that articles related to ERMA compounds have been published as early as 2013) is that researchers don’t know the entire story related to selectivity. While much of the research with ERMAs is about finding a compound that is effective yet less cytotoxic than other current cancer treatments, I think we are left wondering just how cytotoxic they still are. One thing that I’ve picked out of my research is that because the signaling for glucose uptake is so high in tumor cells, researchers believe that this is a viable target for treatment. I believe only time will tell us how selective these compounds can be, by waiting to see if ERMA compounds reach clinical trials.

Awesome choice of article Matt! Caloric-restriction mimetics are actually a huge topic of personal interest to me, and have even broader implications beyond fighting cancer, some of which extend into general human longevity (although this phenomenon is obviously intertwined to some extent with the capacity of our bodies to stave off cancer). I think ERMAs (or CRMs) are incredibly exciting as the science surrounding them has profound implications that may even apply to healthy human beings such as ourselves. There are lots of naturally occurring compounds like rapamycin and resveratrol that have demonstrated therapeutic potential for both anti-cancer and longevity-based applications. Do the authors of this paper provide a foundation for why they chose the aminothiazole moiety with the coumarin core in particular? I presume they may have used structural elements of well-characterized naturally-occurring CRMs such as these to inform their structure. Also, did they make use of any sort of computational chemistry to identify their leads, or perhaps a library screen? The authors demonstrate these ERMAs are particularly applicable in the context of colon cancer; as you noted, the authors might have looked at various other cancer cell lines to further understand the applicability of this type of therapy. In class, we discussed how cancers are beginning to be classified based on their shared genetic mutations, rather than the tissue from which they originate. I wonder if there are particular oncogenes or mutations for which ERMAs are especially effective (likely those which modulate our response to nutrient and food availability/deprivation like AMPK), that might make this particular therapeutic route even more broadly applicable.

While the authors make no real mention of why they chose to synthesize ERMA compounds made up of coumarin cores with aminothiazole scaffolds, I think I may see where they developed their rationale from. OSU-CG12, which the authors use as a control in their experiments, shares a scaffold similar to that of an aminothiazole. It is likely that having seen the success of OSU-CG12 as an ERMA, they decided to continue down this same path, only this time utilizing another structure in conjunction with aminothiazole. They ultimately chose coumarin, which has displayed anti-cancer properties from numerous journal articles throughout the early 2010’s. Additionally, I think that the authors chose to focus on CRC cell lines as opposed to other cancers due to its very direct correlation with obesity. Given that dietary control has shown surprising results in terms in limiting proliferation in CRC, it makes a lot of sense that the authors would decide to target this kind of cancer with an ERMA compound.

Wow, what an uncanny relevance to class! It’s nice to see an organic chemistry approach to the oncology topics we cover in BCM 441. When I saw the mention of reactive oxygen species (ROS) buildup in some of the ERMA treatments, I initially thought that would be good for weakening tumors. But, as we all know, cancers have lots of mutations that may change enzymes to produce ROSs as by-products or side reactions, and cancers have mechanisms to deal with them, such as overexpressing the enzymes that neutralize ROSs (superoxide dismutase, glutathione peroxidase, etc.). So even with the lack of free NADPH, I’m skeptical that this has an effect on overall tumor health; further research is necessary, unless maybe you found some in your literature search?
Also, I noticed the two most successful ERMAs were electron withdrawing groups on the phenyl ring, 4-Br and 3-NO2 on ERMA 9. I’m curious why these were so effective and the functionally similar 4-Cl (9c) and 2-NO2 (9h) were not. I know drugs are very specific, so it wouldn’t surprise me if it was something simple like sterics, but I’d like to know if you have any thoughts. Thanks for the review, Matt!

The field of cancer research is certainly one of the most important and impactful fields today and this paper certainly seems to be advancing the field with its work on small molecule inhibitors. You mentioned that the authors test to see the effectiveness of 9b and 9f molecules by measuring their ability to inhibit glucose intake and combat the Warburg effect. As these are cancer cell lines that typically arise from obesity did the authors mention anything about what mechanism might be involved for these molecules to inhibit glucose uptake in these specific cancers? Since we just covered a bit about the insulin pathway in class, I’m interested if you have any idea as to the relationship between Warburg cancer cells and some of the effects of type 2 diabetes or if any of these obesity related cancer cell lines might have been made cancerous from over stimulation of the insulin receptor in some way.

While different ERMA compounds have been shown to target various mechanisms within glycolysis, I think that 9b and 9f are following from OSU-CG12, and are actually targeting multiple different mechanisms. My basis for this thought is that the authors don’t seem to mention a specific mechanism within the article, rather they state that the ERMAs target cellular metabolism and activate the cellular stress response. Thus, do to 9b and 9f’s structural and experimental similarity with OSU-CG12, I’m led to believe that the two will act similarly in terms of mechanisms. The mechanisms targeted by OSU-CG12 include Act signaling, glucose uptake, and transcription of genes associated with glycolysis. Additionally, there are still ongoing experiments aimed at deterring what other mechanisms OSU-CG12 is involved in. I think you have also brought up an interesting point regarding obesity related cancer cell lines and the insulin receptor. While I’m unsure if these two are related in the way you have presented, it would seem that cancer causes an over expression of insulin receptors. I would be curious to see if this relationship goes both ways.

Hi Matt! You did a wonderful job providing a summary of such an interesting paper! The authors have explained how they were successful in inhibiting the Warburg effect in two colorectal cancer cell lines, but has this treatment been tested in humans? If so, how effective is it in terms of killing off all cancer cells? If not, do you think it is possibly due to mechanistic reasons? Perhaps the mechanism of the reducing glucose uptake is affecting non-cancer cells as well.

I am a little confused about the reasoning behind why the specific compounds (9f and 9b) were effective. The authors suggested that the compounds with electron withdrawing groups are more effective than the compounds with electron donating groups. However, you mentioned that the cell lines were treated with 9f and 9b at varying concentrations and both were effective. Although both compounds had electron withdrawing groups on them, do you think the concentration is a bigger factor or is it solely just because of the electron withdrawing groups (i.e. a lower concentration of a certain electron withdrawing groups could be as effective as a higher concentration one)? I think it’s interesting how they compared a halogen and a nitro group because the halogen does have some electron donating characteristics, even though the withdrawing effects win.

Really cool review Matt! This was, in my opinion, the most directly relevant review of what we have been studying in class. From what I can tell it seems that they have a small molecule inhibitor that really puts the breaks on glucose metabolism and results in a variety of dysfunctions including the inhibition of glucose transport, cofactor reduction, and enzyme disfunction, however, I was unsure, this may be negligence on my part if they identify a particular mechanism of action through which their small molecule acts. The authors say that ERMAs act as signals for the breakdown of cellular metabolism, however, they do not identify if this is through inhibition, action as a transcription factor, or some other method. Your insight would be much appreciated.

This is a great review on a paper that relates so closely to material we covered in class. Obesity is certainly a massive health concern and this is one of those interesting examples where a healthy lifestyle has the potential to influence you much later in life. It’s hard to perceive the consequences that our habits may have on us decades into the future but this paper exemplifies the importance of taking health initiatives, like reducing childhood obesity, seriously as it may prevent colorectal cancer, among numerous other issues, and the need for treatment in the future. This paper provides evidence for compounds 9b and 9f to be potentially utilized as treatments for colorectal cancer but I worry about side effects that may occur. Could these compounds affect healthy tissues and end up causing a lot of unintended damage which would eliminate them as a viable treatment? I presume most colorectal cancers, especially related to obesity, present with the Warburg effect. However, are there ones that don’t exhibit this effect and how, if at all, would these compounds impact those cancer cells? There is obviously still a need for continued research into this method of treatment, but the authors have shown promising results thus far.

Hey Matt, this was a very interesting and relevant post, thank you for sharing. I may have missed something in my quick read of the article, but what effects do these ERMAs have on normal cells? You mention in your post that these ERMAs selectively target cancer cells, which makes me think that they are able to avoid interactions with normal cells. In my quick read of the article, I did not see the authors explanation for how or why this occurs, and I am wondering if in your background research you came across any reason for this. If these ERMAs can selectively target cancer cells with no major negative effects on normal cells, then these ERMAs may provide another means of treating CRC among other cancers, which would be especially significant considering the low cost of synthesizing these compounds. What did you find in your background research about how ERMAs interact with normal cells, and what implications does this have for clinical use? Thanks!

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