Remove all exclusive Latin characters using regex

I'm developing a Portuguese software, so many of my entities have names like 'maça' or 'lição' and I want to use the entity as a resource key. So I want keep every character except the 'ç,ã,õ....'

There is some optimum solution using regex? My actual regex is (as Remove characters using Regex suggest):

Regex regex = new Regex(@"[\W_]+");
string cleanText = regex.Replace(messyText, "").ToUpper();

only to emphasize, I'm worried just with Latin characters.