no denying in LoL but lanes tend to be far more aggressive in LoL compared to dota/hon.

yeah, you can't deny in the same sense as DotA/HoN. However, you can positionally control the creep wave and keep the other player out of GP/XP range by forcing them back. Best way is to harass them down low enough that they can't fight you then sit between them and their own creeps. If they move up to get XP or last hits, you attack them, otherwise you just sit there and last hit your way to early game dominance.

How did you deny in DotA?

Gangplank is the only character with a true "deny" skill (Raise Morale).

I think Raise Morale still gives experience to the enemies in XP range, though.

Defense of the Ancients did not have any restrictions against attacking your own team, Speusippus. This allowed you to attack your own creeps or minions in order to kill them; if you killed a creep, your opponents did not get experience or gold for it. If you click the "For DOTA players" button on the LoL home page, there's a little blurb about it on that page (which for the most part talks about the differences between LoL and DOTA).