In environments where local network policy or firewalls require use of an upstream http proxy/cache, Sakai needs to be configured accordingly. Otherwise components or services which use http requests, such as the BasicNewsService for RSS feeds in the News tool, cannot retrieve data from the target URLs. This can be fixed with the following JAVA_OPTS arguments:
export JAVA_OPTS="-Dhttp.proxyHost=cache.some.domain -Dhttp.proxyPort=8080"