Spray large nonstick skillet with nonstick cooking spray. Heat over medium-high heat until hot. Add onions; cook and stir until tender.
Stir in beans, tomatoes and corn. Bring to a boil. Reduce heat to low; simmer 5 to 8 minutes or until thoroughly heated.
Sprinkle with cheese; cover and cook an additional 1 to 2 minutes or until cheese is melted.