Mice with human breast cancer tissue and high levels of the Myc cancer-driving gene who received a vitamin B5-deficient diet had slower tumor growth.
According to new research, vitamin B5 (normally associated with cell metabolism) may also be associated with tumor growth. However, this research—published in Nature Metabolism—does not necessarily mean that patients must restrict themselves from all dietary vitamin B5.
“Vitamin B5 is needed for normal body functions,” said Mariia Yuneva, PhD, senior group leader of the Oncogenes and Tumour Metabolism Laboratory at the Francis Crick Institute and co-investigator in the Cancer Grand Challenges Rosetta team, in a press release. “Attempting to restrict access to vitamin B5 to the tumor is a fine balance and could have toxic side effects.”
These findings came from an animal study that aimed to uncover more about tumor metabolism. During the study, investigators from the Cancer Grand Challenges Rosetta team gave mice 2 types of tumor cells: cells with high levels of Myc (Myc-high) or low levels of Myc (Myc-low).The team also transplanted Myc-high and Myc-low human breast cancer tumor tissue into the mice.
Myc is a cancer-driving gene that promotes cancer cell growth, disturbs normal cell processes, and drives nutrient dependency. Normally, tumors will have different levels of Myc expression, leading to low versus high areas of Myc in tumor cells.
The team then used mass spectrometry imaging to evaluate the relationship between vitamin B5 and Myc abundance in tumor cells; they found an association between vitamin B5 and Myc-high cells.
In particular, vitamin B5 promoted tumor cell growth and survival in the human breast cancer cells with high Myc expression. This may occur because Myc increases the number of multivitamin transporters in cells; their role is to allow vitamins to enter cells. When both Myc-high and Myc-low cells had more transporters, the cells allowed more vitamin B5 to enter, according to researchers.
Likewise, more B5 could increase tumor cell growth. Cells convert vitamin B5 into coenzyme A, which is used in metabolic pathways and provides macronutrients (protein, fat, and carbohydrates) that can be used as energy to facilitate tumor cell growth.
“Taking away just 1 vitamin stops a cascade of cancer-driving events,” said Peter Kreuzaler, former postdoctoral researcher in the Oncogenes and Tumour Metabolism Laboratory and now Group Leader at the University of Cologne, in the press release.
In a further analysis, mice with Myc-low and Myc-high tumors, along with mice withtransplanted human breast cancer tissue, who received a vitamin B5-deficient diet had slower tumor growth than those given a standard diet.
Ultimately, however, the investigators said removing dietary vitamin B5 might not wholly benefit patients since vitamins support the immune system and can help defend against tumors. New strategies are looking at weakening the tumor without compromising the immune system.
“While the mice used in this study had a weakened immune system…next steps are to see the impact of removing vitamin B5 within a strong immune system,” Kreuzaler said in the press release.
Yuneva added, “It would be interesting to test how altering vitamin levels make a difference in treatment, or how we can use vitamin B5 metabolism to characterize what type of tumor a person has and whether it will respond to different treatments.”
Reducing vitamin B5 slows breast cancer growth in mice. The Francis Crick Institute. News Release. November 9, 2023. Accessed on November 14, 2023. https://www.eurekalert.org/news-releases/1007257