The role of nicotinamide mononucleotide (NMN) in cancer has been controversial. There is some evidence showing that NMN protects against cancer, whereas others show that NMN has a role in promoting cancer.

Cui and colleagues from the University of Shanghai for Science and Technology tested whether nicotinamide mononucleotide (NMN) could inhibit the formation and growth of lung cancer in mice. Their article was published in the journal Materials Chemistry Frontiers with results suggesting that supplementation with NMN does not significantly affect lung cancer formation or growth. “In this work, we found that NMN treatment may have little effect on lung cancer,” said the researchers in the article.

Pre-treatment Did Not Prevent Lung Cancer Tumor Formation in Young Mice

The researchers were interested in whether tumor formation was affected by NMN. To test this, the research team from China pre-treated four-week-old mice with either standard salt or NMN (500 mg/kg) twice a day for two weeks by injection before inoculation with mouse lung cancer cells. They then monitored tumor formation for the next three weeks.

The scientists found that NMN pre-treatment did not prevent lung cancer tumor formation in mice. All mice injected with cancer-causing cells formed tumors, whether treated with either NMN or standard salt. Also, the team found no difference in tumor size between these groups, suggesting that NMN does not affect lung cancer growth either.

(Pan et al., 2020 | Materials Chemistry Frontiers) NMN injections did not prevent tumor formation in mice. The left figure shows that tumors formed in all of the mice injected with salt or NMN, suggesting that NMN had no effect on tumor formation. The right figure indicates no differences between tumor volumes in mice given salt or NMN, indicating that NMN had no effect on tumor growth size in formed tumors.

NMN Did Not Curtail Lung Cancer Growth But Reduced Mouse Weight

The researchers also wanted to know if NMN affected tumor growth once the tumor had already formed. To test this, the researchers injected mice with tumor-inducing cells at four weeks of age, and then NMN or salt was injected four weeks later for two weeks.

The researchers found that NMN treatment didn’t inhibit lung cancer growth but can reduce the weight of the mice. According to scientists, the rate of tumor growth was the same for the mice treated with standard salt to represent typical tumor progression and NMN. There were no obvious signs of reduced tumor size in the mice following NMN treatment, but the team found weight loss in the mice after NMN treatment. NMN treatment also had no effect on cellular levels of molecular markers for inflammation that contribute to tumor progression, which indicated that NMN did not inhibit tumor growth.

(Pan et al., 2020 | Materials Chemistry Frontiers) NMN did not stop tumor growth but was linked to weight reductions in mice. The bottom right figure indicates no significant differences in tumor volume between mice given salt or NMN, which meant that NMN did not slow tumor growth. The bottom right figure shows how administering NMN significantly reduced body weight 9 and 10 weeks into the experiment.

“Our findings indicate that NMN does not prevent formation of lung cancer or restrain tumor growth…nor does it promote tumor growth,” said the researchers in the article. “NMN may have beneficial effects on obesity and overweight induced diseases based on our findings.”

Does Aging Influence Effect on Lung Cancer?

Since NAD+ levels gradually decline during aging, it’s possible that the higher cellular NAD+ levels of these younger mice could have influenced the results in some way. Future studies could examine mouse models of cancer in aged mice to see if NMN influences tumor formation and progression differently across age groups. It is also an open question whether different doses, continual administration, and the timing of NMN injections have any influence on tumors.

Effects on Lung Cancer in Humans

It’s unclear if these results will apply to humans. Clinical studies are needed to examine if these results will replicate in people. If these findings do translate to humans, that would mean that NMN supplementation, although possibly leading to weight loss, would do little to prevent or treat lung cancer.