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Curcumin and Cancer

While curcumin is known for many anti-inflammatory abilities, especially fighting pain, it is probably most studied for its ability to fight cancer.

One of the more recent developments in the understanding of cancer has been the ability to identify the markers that show a potential for the disease. This is critical, because cancer can take decades to develop. What starts as a small cellular anomaly can spread to surrounding tissues (or even throughout the body), essentially bumped along by each inflammatory or oxidative stressor that affect it. Over time, the cells develop into tumors, and situation is much harder to reverse.

Curcumin has been shown to prevent and inhibit the formation of tumors in scientific studies. What is remarkable is that curcumin does this through multiple pathways.

Our bodies have a natural ability to fight cancer through the activity of tumor suppressing genes. However, cancer cells can turn off, or silence, these genes, allowing the cancer to grow and spread unchecked. Researchers have now found that one of the ways curcumin fights cancer is by re-awakening these “sleeping genes,” turning them back on to stop cancer. This branch of science is known as epigenetics, and it may hold the answer to treating many types of cancer.

Curcumin has been shown to stop cancer initiation, promotion and progression, meaning that it stops the changes that cause normal cells to become cancerous, stops the replication of cancerous cells (tumor formation), and stops cancerous cells from migrating to other parts of the body (known as metastasis). Published studies on curcumin’s anticancer activity (so far) have found that it can suppress prostate, breast, liver, skin, colon and lung cancer.1-3

Prostate cancer

For example, some of the body’s own detoxifying enxymes, glutathioine S-transferases, are usually deficient in cases of prostate cancer. Without these protective enzymes (specifically an enzyme called GSTP1), the prostate is left to deal with inflammation and oxidative stress essentially on its own. Even a small deficiency has been shown to increase the risk of prostate cancer in scientific studies, so any natural way of boosting this enzyme activity is positive.

Fortunately, curcumin can. In scientific studies (both animal and laboratory studies), curcumin increased GST in prostate tissue, and induced protective phase 2 enzymes in human prostate cancer cell lines. In other studies, supplemental curcumin also boosted the activities of glutathione peroxidase, glutathione reductase, and other natural oxidative stress-reducing enzymes.4-10

So far, research points to curcumin as a potential treatment to stop the progression of prostate cancer if caught in early stages. More work needs to be done, but the signs are very encouraging.

 

Breast cancer

While there are many factors that can lead to the development of breast cancer, including genetic, endocrine, and environmental causes, inflammation and inflammatory markers are seen regardless.

Inflammation induces tumor metabolism. When inflammatory markers, such as tumor necrosis factor-alpha (TNF-a) are overexpressed, cellular DNA is damaged and begins to replicate into tumors. Scientific research has shown that curcumin stops the inflammation and appears to have a direct effect on reducing or inhibiting tumor growth.

In one laboratory study, treatment of breast cancer cell lines (nonmalignant MCF-10a and malignant MCF-7) with curcumin reversed a tumor growth signaling that had been induced by TNF-a.11

In fact, curucmin has also been shown to induce direct apoptosis (programmed cell death) in the malignant MCF-7 breast cancer cell line.12

This is not unusual for curcumin. Besides inhibiting TNF-a, researchers have found that it also inhibits interleukin 1b (IL-1b) and interleukin 6 (IL-6), among others.

Additionally, other cell studies have found that curcumin acts in a dose-dependent manner (the higher the dose, the more activity) against tumor cells that are cultured in an estrogen-containing media (which replicates the growth of tumors in cases of hormone imbalance, frequently seen during menopause). Curcumin “downregulates” the activity of MMP-2 (matrix metalloproteinase-2) -- an enzyme responsible for cell replication that can cause tumor growth under certain conditions – by encouraging the activity of a counter-protein called TIMP-1 (tissue inhibitor of metalloproteinase). It also stops the formation of blood vessels in tumor cells, which would lead to their increased growth. In other words, curcumin appears to be able to set our cellular activity on the right track through a very delicate balancing act.13

Still more research with curcumin and breast cancer shows that curcumin can not only stop tumor cell growth and activity during its administration, but may have effects that last beyond that – even when curcumin is withdrawn. Curcumin also encouraged the death of tumor cells but not healthy cells.14

Colon cancer

Like all cancers, colon cancer has many causes. However, while polyps can account for those with a family history or genetic predisposition to the disease, they only cause a small fraction of the cases.15,16

In fact, constant inflammation of the digestive tract is almost always associated with an increased risk of colon cancers. That’s why diet and medications can be so influential. Highly inflammatory and refined foods tend to boost the levels of harmful markers and activity in the intestines, and lead to polyps and potential tumor growth.

In some cases, non-steroidal anti-inflammatory drugs (NSAIDs) have been found to decrease the risk of colon cancer because of their ability to reduce COX-2 enzyme activity. Of course, these same drugs can cause a lot of other damage in the stomach, liver, and digestive tract, so they really aren’t a long-term option.

Here again, curucmin has been shown to reduce COX-2 and 5-LOX expression in colon cancer cells. For COX-2 inhibition, a scientific study showed that curcumin reduced COX-2 activity by 66% and inhibited benign tumors that otherwise could have developed into cancerous growths.17

Other studies have found equally strong results with curcumin, but along different cellular pathways. Curcumin inhibits the ability of cancer cells to migrate into surrounding tissues, and works with other traditional chemotherapeutic agents to stop colon cancer cell growth. In fact, in one study, a combination of curcumin and 5-fluorouracil reduced COX-2 expression in a human colon cancer cell line by 6-fold. The researchers noted a synergistic effect of the two treatments.18,19

In fact, several studies have combined curcumin with conventional therapies in hopes to help offset side effects and enhance the effectiveness of the overall treatment. Exciting research from Wayne State University in Detroit, Mich., demonstrated that curcumin enhanced the effectiveness of the chemotherapy agent 5-fluorouracil against colon cancer. They even recommended including curcumin to this treatment regimen for people with colon cancer, because one of their goals is to lower the dosage of chemotherapy in those patients with advanced colon cancer. They believe adding curcumin may also prove to help prevent cancer recurrence in these high-risk individuals.20

Other work regarding curcumin and colon cancer has focused on a field of study called “epigenetics”.

Researchers at MD Anderson Hospital have investigated epigenetic activity and curcumin’s anti-tumor properties, in this case concerning colon cancer, but the results are certainly applicable toward other cancers as well.

Epigenetics is a fascinating realm of study. It delves into the ways that our genes are influenced by our diet and environment, and looks at which factors turn certain genes on and which factors turn them off. In other words, while we may have genetic tendencies toward certain health concerns, we can actually do something about it.

When cancer cells flourish it is due, in part, to a process called “methylation”. Methylation silences our body’s own defense mechanisms by shutting down genes that are designed to naturally suppress tumors. But curcumin has been shown to change that. In this study, it was able to “reawaken” the formerly “sleeping genes” that keep cancerous tumors from growing and spreading.21

Other cancers

Curcumin has positively shown to influence healthy cell growth and tumor inhibition in other cancers as well, including liver, lung, pancreatic, and skin cancer.

For liver cancer, curcumin inhibits the same enzyme activity (MMP-2) that builds tumors in breast cancer tissue. It also induced the expression PPAR-gamma, a receptor that helps the body metabolize fatty acids and glucose and stop the overproduction of liver cells. Researchers noting the ability of curcumin to stop inhibit extracellular growth consider the botanical extract to be a “potential candidate for the treatment of hepatic fibrosis.”22

Pancreatic cancer, one of the most notoriously difficult cancers to detect and treat has often been called “the silent killer”. It is often found only after it has spread to other parts of the body.

Several cellular studies have demonstrated that curcumin can kill pancreatic cancer cells. In a recent study from M.D. Anderson hospital, curcumin was combined with the chemotherapy agent gemcitabine. Like other studies combining curcumin and chemotherapeutic agents, the researchers concluded that curcumin enhanced the anti-tumor effects of the drug.23

Other cancers such as ovarian, lung, and skin have also responded to curcumin therapy. Combining curcumin with chemotherapy proved effective in studies involving lung cancer tissue. A topical curcumin showed benefits in cases of skin tumors. Researchers at M.D. Anderson combined curcumin with the chemotherapy drug docetaxel to successfully kill ovarian cancer cells. Here, as in other cancers, curcumin targeted NF-kB, inhibiting its overexpression.24

Recently, researchers also demonstrated that curcumin has anticancer effects against glioma brain cancer cells, and other cellular studies have shown that curcumin induces apoptosis in leukemia cells, and may be a natural agent for preventing relapse.25-28

Successful preliminary research has also been done with curcumin on bladder cancer, as well as head and neck cancer.29

Curcumin and Cancer: The Future of Treatment

Curcumin has clearly been shown to prevent and inhibit cancer development in a number of studies, and fulfills the four key pathway requirements for cancer fighting that researchers look for, because curcumin can:

  1. Inhibit cellular proliferation = stop the cancer cells from dividing and spreading
  2. Differentiate between cells = able to tell cancer cells from normal tissue cells
  3. Encourage apoptosis = cell death and destruction by immune system cells
  4. Anti-angiogenesis = cut off the blood supply to cancer cells

A substance that can modulate one or more of these factors is considered promising. Curcumin has been shown to influence all four pathways by positively impacting these three key bodily systems:

  1. Stimulates immunity so the body can kill cancer cells and stop them from multiplying
  2. Balances inflammatory responses to reduce inflammation
  3. Improves detoxification so the body can eliminate cancer cells

Whereas the present day cancer drugs are specific for one type of cancer, curcumin has been shown in preclinical studies to be effective for virtually all forms of human cancers. While common chemotherapuetic drugs cause serious side effects, curcumin produces none. Common anticancer drugs are immunosuppressive. Curcumin is an immunorestorer.

Curcumin has also been shown to increase the activity of cancer drugs and to decrease drug resistance in cancer cells (meaning it helps cancer drugs kill tumors more efficiently). Additionally, it protects normal cells from the toxic effects of chemotherapy drugs and radiation treatments. Taking curcumin in combination with chemotherapy drugs may mean less of the toxic drugs are required, but the results will be better, with significantly reduced side effects.

Furthermore, the common anticancer drugs cannot cross the blood brain barrier. Curcumin can.

While a direct answer to stopping cancer may still be a long ways off, and require more research, it is clear that curcumin makes a strong case as a chemopreventive and a natural therapeutic agent that combines well with conventional approaches.

 

References:

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