How to access an entity loaded out of the cache
Although the questions is not so clear I will try to give you some directions. I think it is time to dive into the new Cache API (I haven't done it so far!)

First of all, to get the "information" for a cached page you need to deal with the contexts and the cache tags.

To invalidate the tags you may need to use function invalidateTags(array $tags) (here is an example of using this class).

On the other hand if you want to invalidate cache of each node while loading the node you can set this option to the node_load($nid = NULL, $reset = FALSE) function by using $reset = TRUE.