No, you can't.
Ok, you might be able to, but you shouldn't.
The thing is that while a big enough advantage in ilevel might place a piece of PvP gear ahead of the lower level PvE counterpart, it simply doesn't hold true for a tank.
A PvP piece simply comes with one useful stat only. That's stamina, and stamina isn't good enough to warrant the absence of mastery and avoidance.
Resilience, in difference from before, is an entirely dead stat for us tanks. Where it used to decrease the risk of us taking a critical hit it does absolutely nothing today. Apart from resilience that piece will come with dps-stats, and those won't keep you alive better.
So, to prove myself wrong, there are two pieces that come to mind. One would be the weapon slot and the other the helmet slot. If your currently use a piece of green ilevel 316 item in that slot, yes, then the PvP piece will be an upgrade. Reaon being weapons tending to hold rather poor tanking stats to begin with, and the helmet at least being preconfigured with mastery.
But, really, avoid PvP gear like the plague unless you plan smacking some players over the head. If that is the case, yes, you can tank other players in your PvP gear.