First of all, I think people tend to use "the DNC" when what they really mean is "the Democratic Establishment". The DNC itself is basically just a fundraising operation; those guys couldn't engineer a birthday party, much less a conspiracy to rig a nomination. The Establishment isn't a specific organization or group of people, but I think we all intuitively know what it is.
So semantics aside, could the Establishment stop Bernie with a plurality of delegates from getting the nomination? I could easily be wrong about this, but I don't see it happening. First, the fact that the Establishment is so amorphous works against it. We'll see a lot more carping anonymously to the Times than we will organizing in secret to install a nominee. Second, they're going to face the same problem the Republican Establishment faced in 2016: no plausible alternative. Yes, maybe if the race plays out the way Obama/Hillary did in '08, with a single challenger doing very well in the closing races, it could possibly happen. But that's unlikely to happen here. We'll probably get Bernie with a plurality lead and a few flawed challengers bunched up behind him, none with a solid claim to why they should be the nominee.
Two more reasons why it won't happen: The Establishment pretty clearly hates Bernie (or, more accurately, they don't particularly like him on a personal level and fear that he would be a disastrous candidate). But I don't think that's true of rank-and-file Democrats. Bernie has, I believe, some of the highest favorability ratings of any of the major candidates. Second, there's going to be so much pressure to unify against Trump, and if Bernie has a plurality, even the most hidebound member of the Establishment is going to realize that getting behind him gives the party the best chance of victory, certainly relative to tearing it apart with a contested convention that ends up with a minority choice and pisses off a lot of people.