Howard is right on where the lease is concerned. Just because there is a lease does NOT mean a new one can't be negotiated, especially if the responsible tenant is going to change.
If a Landlord is truly unwilling to talk new lease and put the new tenant on the hook, this is something you want to check into further.
As a landlord, I'm always willing to discuss the lease if there is a change of ownership. I usually end up with a stronger lease. It might be money, it might be terms, it just might be a better tenent.