The Houston Texans' defense took a major blow Friday when defensive rookie of the year Brian Cushing learned he is being suspended four games for violating the NFL's policy on performance-enhancing substances.

Cushing, who said in a statement that he tested positive for a non-steroidal banned substance, appealed the league's decision at a hearing at the NFL scouting combine in February, but the linebacker was informed Friday his appeal had been rejected.

"I believe we presented compelling evidence during the appeal process to challenge the test results, and I disagree with and am disappointed by the suspension," Cushing said in the statement. "Bound by the decision of the league, I regret the situation it presents to the Texans' organization, my teammates, and our fans. My dedication to a championship season in 2010 continues undeterred."

Cushing will be allowed to participate in training camp with the Texans this summer, but then will serve his four-game suspension to start the 2010 regular season.

"We were disappointed to learn that Brian has been suspended for the first four games of the 2010 season," Houston general manager Rick Smith said in a statement. "Brian is a productive member of our team and this is a significant loss, but we have to be prepared to win without him."

Cushing's attorney, Harvey Steinberg, did not return telephone calls seeking comment.

The Texans' defense will suffer without Cushing, especially considering that its first game of the season is against the defending AFC South champion Indianapolis Colts. Cushing will also miss games against the Washington Redskins, Dallas Cowboys and Oakland Raiders.

Cushing, who was voted to the Pro Bowl, had 133 tackles and helped lead the Texans to a 9-7 record, their first winning season in franchise history. Cushing finished the season with four sacks, four interceptions and two forced fumbles.

Cushing was hounded by rumors of performance-enhancing drug use before he became a pro, but the Texans were undeterred. They said then they found no truth to those rumors in their draft preparations.

"I've passed every drug test out there and still have," Cushing said during his 2009 draft news conference. "I'm not that kind of guy."

Cushing had been promoting an appearance on the NFL Network show "Total Access Live" scheduled for Friday evening on his Facebook page before posting the following message Friday afternoon: "Had to cancel NFL Network and all other interviews due to a family emergency. Heading to airport to fly back to NJ to be with the fam."

Cushing did not provide any further details about an emergency. He is from New Jersey and had been in school in California this week.

Adam Schefter is an NFL Insider for ESPN.com. The Associated Press contributed to this report.