The actress speaks out against cancer and her upcoming role in Disney's edgy version of "Rapunzel."

mandy_moore.jpgTonight in the Stand Up to Cancer (S↑2C) telethon, actress/singer Mandy Moore will reprise a role she's become accustomed to off screen: humanitarian. Moore's battled malaria with Population Services International and promoted World Water Day, among her many causes. In 2008, Moore (in a S↑2C tee, at right) appeared at the first landmark event that raised more than $100 million for cancer research, and two years later, she's back again, taking your donations and speaking out against these deadly diseases.

On screen, Moore has played a teenager afflicted with leukemia in Walk to Remember and a woman in need of a colostomy in Grey's Anatomy. These are serious issues for someone who was once referred to as a "pop princess." This Thanksgiving, she'll play Disney princess Rapunzel in Tangled — but don't call her character normal."She's not the typical femme fatale or the typical Disney princess even, because: A) She doesn't know she's a princess," Moore told MTV News. "I think she sort of has this inkling that something isn't quite right in her life, [but] she's just really sort of motivated to find out what else is out there beyond this crazy tower she's lived in for 18 years. Having said that, she's very independent, she can take care of herself, and she's definitely come up with really entertaining ways to keep herself busy."

When the movie giant failed to attract a male audience to its last film, The Princess and the Frog, they switched the Brothers Grimm fairytale title Rapunzel to Tangled. Some critics have said they're not fooling anyone.

Moore said, "I think I was initially a bit taken aback [by the title change], only because people know the story of Rapunzel, so when you say you're working on Rapunzel, it's sort of a no-brainer, you don't have to explain it to people. But as the title sort of sunk in, I understood the decision behind changing it. The movie is so great and so cute, and people are going to see the trailer and know what the story is about. I guess you sort of have to leave it up to the brains at the top. They know what they're doing."

And we'll leave you, Moore, to attracting donations for cancer research. To catch the actress and others, tune in to all major networks tonight at 8 EST.