LOS ANGELES—Skateboarder Tony Hawk, actor Shemar Moore and other celebrities said they joined in a three-network cancer telethon on Friday because the disease had touched or taken the lives of loved ones.

Hawk, who lost his father to lung cancer 15 years ago and a close friend to a brain tumor last month, called the timing of the Stand Up to Cancer telethon “poetic.”

“I’m here doing whatever they ask of me,” he told reporters before the telethon began. “As long as I don’t have to sing or dance, it’s all good.”

Stand Up to Cancer, a fund- and awareness-raising organization, organized the unprecedented, star-studded live telethon airing simultaneously on ABC, NBC and CBS on Friday night.

Moore, who said his uncle’s wife waged a successful three-year fight against cancer, was eager to answer phones for the cause.

“I’m gonna be sweet-talking some people and trying to reach into their pockets,” said Moore, who stars on CBS’ “Criminal Minds.”

Jennifer Nettles of Sugarland said her boyfriend’s father died of cancer recently and her brother has been diagnosed with the disease. Sugarland, Melissa Etheridge and others were to close the show with a retooled version of Etheridge’s “I Run for Love”—changed to “I Stand for Life.”

“I hope I’m going to be able to get through it without crying,” Nettles said, noting that Etheridge is a cancer survivor.

Singer-songwriter Jason Mraz, whose hit “The Remedy” was inspired by a friend’s battle with bone cancer, also was slated to join the star-studded finale performance.

Rehearsing with Etheridge and others “actually gave me chills,” Mraz said. “Their star power is stripped away and they’re just human beings today.”

Casey Affleck, who was set to help answer donation calls, said he had a secret way to command more contributions.

“I’ll probably tell them I’m ... someone more famous and exciting so I can get a bigger donation,” he said.

America Ferrera left the “Ugly Betty” cast in New York so she could participate in the fundraiser. The Emmy nominee said she lost a beloved college professor to cancer, and that she hoped the evening would be a “hopeful” one that will inspire those facing the disease.

Hollywood producer Laura Ziskin, one of the telethon’s organizers, has fought cancer since 2004. After seeing what “An Inconvenient Truth” did for environmental awareness, Ziskin wanted to make a documentary about cancer, a disease she has fought since 2004.

But, teaming up with two other prominent women, she found another approach.

Former Paramount Pictures chief Sherry Lansing, who established a namesake foundation dedicated to cancer research and awareness, was working with television networks to put on a cancer-awareness TV special. So was Katie Couric, who has been an advocate for early cancer screenings—and even televised her own colonoscopy—since losing her husband to colon cancer 10 years ago.

So the women got together—along with other entertainment-industry execs and more than 60 of their famous friends—to create Stand Up to Cancer.

“I jokingly say I have to make cancer awareness entertaining,” said Ziskin, who is producing the show at Hollywood’s Kodak Theatre. “The good news is that the entertainment community gets it. We’re touched. Look at Patrick Swayze. Look at Christina Applegate. Look at Robin Roberts.