Sage Advice Blog


November 10, 2017

Alex Speers ND, MS


Within a single tumor, there are a variety of different cell types. One type, called cancer stem cells, or CSCs, are unique because when they divide, they can produce a variety of different cell types in addition to producing more stem cells. This is important because it means that if CSCs are present within a tumor, that tumor has a potential source for any cell type it needs to sustain itself and grow.


Now consider what happens when we try to kill a growing tumor. Even if a treatment successfully kills a significant number of cancer cells, that tumor may still be able to regrow if CSCs remain alive. Think of cancer like a weed, growing wildly inside the body. CSCs are the root, and as any good gardener knows, if you don’t kill the root, there’s a good chance that weed will eventually grow back.


Some researchers have theorized that this small subgroup of cancer cells are the primary culprits behind cancer growth, cancer metastasis (spread of cancer throughout the body), cancer recurrence after treatment, and the development of treatment resistance, whereby a tumor no longer responds to treatment. Clearly, CSCs are a significant obstacle in the fight against cancer and as a result, targeting these cells has become a focus in the development of new cancer therapies.


Recently, researchers found that CSCs could be identified and distinguished from other cancer cells by their high mitochondrial mass. Mitrochondria are found within every cell in our body (except red blood cells) and are responsible for producing the energy our cells need to function. Discovering this, these same researchers set out to investigate whether they could kill CSCs by targeting their mitochondria.


What they found was that CSCs could effectively be killed using an integrative approach. First, they treated cancer cells with the antibiotic doxycycline, which acts by disrupting normal mitochondrial function. Initially, the researchers found that they could kill CSCs from several cancer types (ovarian, prostate, lung, breast, pancreatic, melanoma, glioblastoma) using only doxycycline. With continued use of doxycycline however, the researchers noticed that some CSCs began to develop resistance to doxycycline, escaping its anti-cancer effects.


Next, the researchers treated doxycycline-resistant CSCs with ascorbic acid, otherwise known as vitamin C. What they found was that adding vitamin C resulted in the death of 90-100% of the doxycycline-resistant CSCs. Furthermore, the doxycycline-resistant CSCs were 4-10 times more susceptible to vitamin C compared to normal CSCs, suggesting a synergy between the two agents.


With any cell study, it’s important to remember that the results don’t always translate to humans because we’re talking about isolated cells in a laboratory, far removed from a living, breathing human being. It is worth noting, however, that this combination has been studied in humans before, albeit for a different condition. A previous study of women with chlamydial cervicitis infections found that combining vitamin C with doxycycline and TMP-sulfa (another antibiotic) resulted in a cure rate that was 5 times higher than using antibiotics alone. In addition, there is a growing body of evidence on the safe use of high-dose intravenous vitamin C in patients with cancer (which will be discussed in a future blog). The present cell study suggests a potential new integrative approach to target CSCs and future research is warranted to validate these findings.


De Francesco EM, Bonuccelli G, Maggiolini M, Sotgia F, and Lisanti MP. Vitamin c and doxycycline: a synthetic lethal combination therapy targeting metabolic flexibility in cancer stem cells (CSCs). Oncotarget. 2017;8(40):67269-67286.


DISCLAIMER: These statements have not been evaluated by the Food and Drug Administration. There are no financial ties to any supplement companies, pharmaceutical companies, or to any of the products mentioned in this post. This post is not meant to treat, cure, prevent, or diagnose conditions or diseases and is meant for educational purposes. As always, please consult your doctor before trying any new treatments or supplements.

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