No, it can't (although that'd be an interesting concept).
If it went below 0, I'm guessing that it means that the attack heals right?
I'd say it's a no for 2 reasons:
One, I think that'd make this card less balanced (too strong). It's powerful enough and you get to heal yourself by bringing down opponent's attack? Sounds a bit too good to be true deal.
Second, it doesn't go with the fire theme. If you exhaust someone with heat, it makes sense to take away their energy, but no matter how much you heat him/her up, they are not going to have negative attack values that heal you.
That's my thought. But, I'll say it again, I think that sounds interesting and maybe you should make a card with that concept (maybe in Entropy?)