The Wolfpack (5-2), who had lost two of three, have dropped 19 spots in the AP poll over the last four weeks after being ranked No. 6 in the preseason Top 25.
Howell, a 6-foot-8, 257-pound senior, led North Carolina State's second-half rush to the boards. The Wolfpack had 20 rebounds in the second half, 11 on the offensive end - and Howell grabbed seven of those. The Huskies had 13 rebounds in the second half, six offensive.
Shabazz Napier led the Huskies (6-2) with 19 points and Ryan Boatright added 18.
Napier scored Connecticut's first 10 points of the game and led the Huskies to an 11-point lead. The Wolfpack later used an 11-2 run that brought them within one and they led 32-31 at halftime.
There were three ties from 8:19 to 5:14, when Leslie made two free throws for a 55-53 lead the Wolfpack never relinquished.
Lorenzo Brown had 16 points for North Carolina State and Scott Wood had 13.
Enosch Wolf added 12 points and nine rebounds for the Huskies.
Both programs had a connection to the doubleheader that is part of ESPN's week of raising money for the V Foundation as it continues to help in the fight against cancer.
Jim Valvano's signature moment came in 1983 when the Wolfpack won the national championship on a dunk by Lorenzo Charles at the buzzer and Valvano ran around the court looking for someone to hug.
Valvano's widow, Pam, flew up with the team from Raleigh.
North Carolina State coach Mark Gottfried asked adidas to help him design a uniform for this special occasion.
"They came up with kind of the design which I thought was really good when I first saw it. I thought it was really cool," he said. "I like the net somewhat around the neck, it's kind of lightly seen but it's there. Then I really love the back of the jerseys. I even like the old-style lettering, `State' in the old-fashioned block lettering for one night."
On the back, instead of the player's name, each jersey had Valvano's trademark phrase, "Don't Ever Give Up."
Sitting a few rows behind the Connecticut bench was Hall of Fame coach Jim Calhoun, who retired this year after leading the Huskies to three national championships. He is a three-time cancer survivor, overcoming prostate cancer in 2003 and skin cancer twice, most recently in 2008.
No. 15 Georgetown beat Texas 68-41 in the first game.