You can use the coinwarz DOGE mining calculator. Just subsitutute 400 for the block reward and 140 for the diff.

http://www.coinwarz.com/calculators/dogecoin-mining-calculator/?h=1200.00&p=500.00&pc=0.10&pf=3.00&d=143.00000000&r=400.00000000&er=0.00003000&btcer=570.94700000&hc=200.00

It's no longer profitable to mine at the current diff of 140+ at anything less than 4000 sat. Probably wont even pay for your power consumption. IMO the coin was an insta-mine pump and dump. The insta-mine has been dumped and you're all left holding the bag.