These updates are almost certainly from the official repositories. The packages were probably installed as dependencies of other applications. They might be removable without affecting those other packages, or they might not. Either way, you can find out what would be removed by uninstalling them by simulating the deinstallation:
apt-get -s remove packagename
packagename with the name of the package. You can list more than one, separated by spaces, but I recommend listing just one per run, so you can see specifically what each package is installed for.
If additional packages are listed to be removed, then you know that if you remove
packagename, you lose those packages, too. It's possible that there are other packages that can benefit from some of
packagename's functionality, but they will at least not be automatically removed if you remove
packagename for real.
If you want more information specific to your situation, or want to know about specific packages, then you'll have to edit your question to add that information. In particular, you might consider adding the complete text from the Terminal, so we see exactly what KDE-related packages are installed and being updated on your system. While you've provided some very general information in comments to your question, really the specific and exact name of each package would be needed to give you finely tuned advice. (But you might be able to get all the information you need, just with the general advice in this answer.)