The Dione-Kisumu Company (or DKC) was a business that marketed products it developed through medical research.
DKC originated in Kenya. By the early 23rd century, they had moved their headquarters from the town of Kisumu to Dione, a moon of Saturn. They were the chief producer of memory RNA tablets in the solar system, which were mainly used for educational programmes.
Director Madhanagopal, part of the Brotherhood of the Immanent Flesh, was using the DKC facilites to figure out how to reliably give psychic powers to humans. At first he experimented on the artificial intelligence FLORANCE, then turned his attention to GRUMPY.
Bernice Summerfield and Roz Forrester, sent back to 2227 by the Seventh Doctor to research the origins of a virus causing colonists on Yemaya 4 to develop psychic abilities, arrived at the DKC headquarters. They were given a tour by Madhanagopal and met FLORANCE and GRUMPY. He gives them his latest experimental virus, but GRUMPY is able to substitute it with a cure for the one on Yemaya 4.
About ten years later, GRUMPY escaped from DKC. They chased him until they forced the shuttle it was occupying to crash on Yemaya 4.
When DKC decided to allow colonisation of Yemaya 4 around 2257, they took samples from the planet to develop vaccines. Unknown to them, GRUMPY had insinuated his memory RNA into the environment. This gave the colonists pieces of its memory, which it planned to use to reconsitute itself. By this point it had renamed itself SLEEPY. It also triggered the colonists' latent psychic abilities.
When DKC discovered what was happening, they sent one of their warships, Flame Warrior, to investigate. In the original timeline, they destroyed the colony and all the inhabitants to cover up the results of the illegal experiment.
However, the Doctor decided to find out what had happened on Yemaya 4. His interference created a new timeline where the colony was saved and DKC's involvement was revealed, causing it great embarrassment. (PROSE: Sleepy)