Vitamin E in plant seeds could halt prostate, lung cancer, says Purdue scientist

December 14, 2004

WEST LAFAYETTE, Ind. - The form of vitamin E found in many plant seeds - but not in most manufactured nutritional supplements - might halt the growth of prostate and lung cancer cells, according to a Purdue University study.

A team led by Qing Jiang (pronounced "ching zhang") has found that gamma-tocopherol, which occurs naturally in walnuts, pecans, sesame seeds, and in corn and sesame oils, inhibits the proliferation of lab-cultured human prostate and lung cancer cells. The vitamin's presence interrupts the synthesis of certain fatty molecules called sphingolipids, important components of cell membranes. However, the gamma-tocopherol leaves healthy human prostate cells unaffected, which could give it value as an anticancer agent.

"This is the first time gamma-tocopherol has been shown to induce death in lab-grown human cancer cells while leaving healthy cells alone," said Jiang, who is an assistant professor of foods and nutrition in the College of Consumer and Family Sciences. "This could be wonderful news for cancer patients if the effect can be reproduced in animal models. But because most nutritional supplements contain only alpha-tocopherol, a different form of vitamin E that alone does not have these anticancer properties, it may be better to supplement the diet with mixed forms of vitamin E. The study shows that the anticancer effect is enhanced when mixed forms are used."

Jiang's research appears in the current (week of Dec. 13) online edition of the scientific journal Proceedings of the National Academy of Sciences. She co-authored the paper with Jeffrey Wong, Henrik Fyrst, Julie D. Saba and Bruce N. Ames of the Children's Hospital Oakland Research Institute in Oakland, Calif.

Scientists have been studying vitamin E for more than three-quarters of a century, but most efforts have focused largely on alpha-tocopherol, one of eight known forms in the vitamin's family. Alpha-tocopherol was found early on to have the most beneficial effects on laboratory animals fed diets deficient in vitamin E, and also is the major form found in body tissues. For these reasons, it has been nearly the only form of the vitamin to be included in most manufactured nutritional supplements.

"Since then, alpha-tocopherol has justifiably earned a good reputation as an antioxidant, which helps to fight against damage caused by unwanted free radicals," Jiang said. "But its familiarity has perhaps attracted research away from the other seven forms of vitamin E, and since gamma-tocopherol is the vitamin's most commonly occurring natural form in the American diet, I grew interested in it a few years ago."

In 2000 another study by Jiang and colleagues found that gamma-tocopherol inhibits inflammation, which had already been implicated in cancer development. They theorized that it might retard the progress of cancer and cardiovascular disease, and to test their hypothesis they exposed cultures of cancerous prostate and lung cells to the vitamin. Normal prostate epithelial cells were used as a control group.

"We discovered that as we increased the quantity of gamma-tocopherol, the cancer cells grew more slowly," Jiang said. "But the normal prostate cells were not affected and grew normally. This could indicate that the vitamin could be used to target lung and prostate cancer cells without the damaging side effects of chemotherapy."

The study also revealed that gamma-tocopherol caused cell death by interrupting sphingolipid synthesis.

"This is also a novel discovery," Jiang said. "Although there have been prior indications that some form of vitamin E may cause cell death in some mouse cell lines, we are the first to provide a mechanism for such an effect."

Gamma-tocopherol, though rarely available in vitamin pills, is nevertheless found in abundance in the typical American diet. Many nuts are rich in it, including walnuts and pecans, as are cooking oils such as corn and sesame oil.

Though Jiang said she would be cautious about using food sources to slow prostate or lung cancer's progress in humans, she said that high-risk groups such as older men could benefit from supplementation - if carried out with prudence.

"Foods rich in gamma-tocopherol are also rich in fats, and some products bring other hazards as well," she said. "Corn oil, for example, is rich in linolic acid, which has been shown to promote certain types of cancer in some studies. But sesame seeds and pecans seem to be good all-around choices."

Jiang said the next step for her research team would be testing the effect of gamma-tocopherol and mixed forms of vitamin E on animal cancers.

"Although this discovery is promising, we do not yet know whether gamma-tocopherol has any effect on cancer in living creatures," she said. "We hope that future research not only will clarify whether gamma-tocopherol could have applications in human cancer treatment, but also will show how we might supplement the body with the vitamin to prevent cancer from developing in the first place. These questions will continue to direct our work."
-end-
This research was funded in part by the National Institutes of Health.

Writer: Chad Boutin, 765-494-2081, cboutin@purdue.edu

Source: Qing Jiang, 765-494-2483 or 496-6407, qjiang@purdue.edu

Related Web site: Online paper in Proceedings of the National Academy of Sciences: http://www.pnas.org/papbyrecent.shtml

Purdue University

Related Lung Cancer Articles from Brightsurf:

State-level lung cancer screening rates not aligned with lung cancer burden in the US
A new study reports that state-level lung cancer screening rates were not aligned with lung cancer burden.

The lung microbiome may affect lung cancer pathogenesis and prognosis
Enrichment of the lungs with oral commensal microbes was associated with advanced stage disease, worse prognosis, and tumor progression in patients with lung cancer, according to results from a study published in Cancer Discovery, a journal of the American Association for Cancer Research.

New analysis finds lung cancer screening reduces rates of lung cancer-specific death
Low-dose CT screening methods may prevent one death per 250 at-risk adults screened, according to a meta-analysis of eight randomized controlled clinical trials of lung cancer screening.

'Social smokers' face disproportionate risk of death from lung disease and lung cancer
'Social smokers' are more than twice as likely to die of lung disease and more than eight times as likely to die of lung cancer than non-smokers, according to research presented at the European Respiratory Society International Congress.

Lung cancer therapy may improve outcomes of metastatic brain cancer
A medication commonly used to treat non-small cell lung cancer that has spread, or metastasized, may have benefits for patients with metastatic brain cancers, suggests a new review and analysis led by researchers at St.

Cancer mortality continues steady decline, driven by progress against lung cancer
The cancer death rate declined by 29% from 1991 to 2017, including a 2.2% drop from 2016 to 2017, the largest single-year drop in cancer mortality ever reported.

Cancer-sniffing dogs 97% accurate in identifying lung cancer, according to study in JAOA
The next step will be to further fractionate the samples based on chemical and physical properties, presenting them back to the dogs until the specific biomarkers for each cancer are identified.

Lung transplant patients face elevated lung cancer risk
In an American Journal of Transplantation study, lung cancer risk was increased after lung transplantation, especially in the native (non-transplanted) lung of single lung transplant recipients.

Proposed cancer treatment may boost lung cancer stem cells, study warns
Epigenetic therapies -- targeting enzymes that alter what genes are turned on or off in a cell -- are of growing interest in the cancer field as a way of making a cancer less aggressive or less malignant.

Are you at risk for lung cancer?
This question isn't only for people who've smoked a lot.

Read More: Lung Cancer News and Lung Cancer Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.