The Pacific Resource Partnership, in addition to apologizing to former Gov. Ben Caye­tano for a negative advertising campaign during the mayor’s race in 2012, will donate $100,000 to the University of Hawaii’s John A. Burns School of Medicine and $25,000 to the Hawaiian Humane Society in Caye­tano’s name.

The agreement settles a defamation lawsuit that Caye­tano filed against PRP shortly before his election defeat. Caye­tano lost to Kirk Caldwell for Hono­lulu mayor.

The former governor had argued that PRP’s negative ads unfairly tarnished his reputation.

PRP is a consortium of union carpenters and private contractors. The group favored the city’s rail proj­ect, which Caye­tano had vowed to block if he was elected mayor.

PRP spent more than $3.6 million in its campaign against Caye­tano and an undisclosed but substantial amount of money on a pro-rail ad blitz.

A letter from John White, PRP’s executive director, to Caye­tano that includes the apology and the donation pledge will appear in a half-page ad in Sunday’s Hono­lulu Star-Advertiser.

PRP, through a public relations firm, declined to comment on the donation pledge Friday. White said in a statement Thursday that both parties are satisfied with the settlement.