The three sister bed is a method in which squash, corn and beans are grown together. The squash covers the soil, the corn supports the climbing beans and the beans supply nitrogene.
So I guess that growing pumpkins (same famliy) and corn, or pumkins and beans should be possible as well.
A lot will depend on the space between the corn or beans and the space the pumpkins take up. Non-trailing courgettes can be very large plants and will hardly fit in between standard spaced corn. But if you spaced them further apart, then it could be okay.
Hope this helps.