Nope. PLS and M3U are different formats.
PLS needs some structural information that MUST not be there in M3U.
Here's an example of the PLS structure:
Title1=My Favorite Online Radio
[playlist] must be the first line and Version=2 must be the last line. The File#= lines are mandatory, Length# and Title# are optional. The NumberOfEntries=# must have the same number as the last File#,Title#,Length# entries (i.e. for 3 entries you start numbering with 1 and the NumberOfEntries must also be 1)
You see, PLS is way more complicated than the simple M3U format.