One of the things to understand about the News module is that it is a consumer of newfeeds not the generator of news feeds. A newsfeed provider publishes their feed according to the specs of one of many formats used, RSS, Atom, or OPML. The specs are not always followed. The News module will take published date information, and 'convert' it to pubDate acording to RSS v2.0 specifications. This process assumes that the information passed is in a format that can be converted. Note hat pubDate is not part of the Atom or OPML spec exactly. So, in this processing, it works best if the module when used in aggregating feeds contain feeds of the same type. It's not mandatory, but it helps.
Now, more to the point. Yes, you can change the pubDate to display in whatever format you need, but you need to provide an RSS v2.0 XSL to do it. This part, also, assumes that the feeds you are using conform to RSSv2.0 specs with regards to how they pass the pubDate. The effort requires some knowledge of XSL to program for the formatting change.
From having worked with XSL and newsfeeds, I can say that such manipulation is not worth my trouble, as newsfeed providers are notorious for not providing any consistency in publishing feeds that conform to RSS v2.0 specs, or any other for that matter. While, I'd like to trust those providers, I've not seen much to alter my view. My approach is to take what's given to lessen my constantly updating and providing new XSL's to deal with the issues.
Not saying it can't be done for some feeds, but generally, it's going to cause a lot of extra work to keep up. Also, if you are using syndication from DNN modules, the HH:MM is not always captured by the parent module itself, so the time always reverts to the same time. The Announcements module works that way. It does not capture HH:MM, and the hour is appended according to how your SQL server is configured. Many other modules are the same. So, with DNN that type of change would be pointless.