The Urban Dictionary provides the following definitions of a “presstitute” (noun): http://www.urbandictionary.com/define.php?term=presstitute .
1. A member of the media who will alter their story and reporting based on financial interests or other ties with usually partisan individuals or groups.
2. A term coined by Gerald Celente and often used by independent journalists and writers in the alternative media in reference to journalists and talking heads in the mainstream media who give biased and predetermined views in favor of the government and corporations, thus neglecting their fundamental duty of reporting news impartially. It is a portmanteau of press and prostitute.
3. One who "screws" the general public by intentionally submitting false or mis-leading information to the Press. Esp. for politicians and news folks.
(e.g. “Our congressperson really presstituted themselves with that interview”. or “That politician is a known presstitute” ).
4. Either an individual reporter or news broadcaster, or a media news group, who reports to be unbiased, but is in fact tailoring their news to suite someone's goal (usually corporations or big business political affiliates).