Spray 5- to 6-quart slow cooker with cooking spray. Add broth, tomatoes, corn, enchilada sauce, onions, green chiles, cumin and chili powder to slow cooker; stir to combine. In 10-inch nonstick skillet, heat oil over medium-high heat. Add chicken to skillet; sprinkle with pepper. Cook 4 to 6 minutes, turning once, until browned on both sides. Place chicken in slow cooker.