Need help with grep command pattern

I have an input file that consists of many lines, each divided on 3 parts by colon:

test:wwwww:A
test2:nnnnnn:B
TEST3:qqqqqq:A
*test4:wwwww:C

I need to retrieve those lines that start with an alphanumeric character either upper case or lowercase and might have a digit anywhere in the middle of the string or at the end, and those that have its thord part equal to A. The line cannot start with a digit, *, # or any other character besides letters

For exaple from the sample lines above my code would need to return:

test:wwwww:A
TEST3:qqqqqq:A

Here is what I got:

grep "^[a-zA-Z]*:.*:A" foo | while read LINE
do
echo $LINE
done

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But it returns only:

test:wwwww:A

grep "^[a-zA-Z][0-9]:.*:A" foo | while read LINE
do
echo $LINE
done

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Does not return anything.

grep "^[a-zA-Z]*[0-9]:.*:A" foo | while read LINE
do
echo $LINE
done

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only returns

TEST3:qqqqqq:A

and it would ignore any line with a digit in the middle of a string:
TE3T:qqqqqq:A



Can anyone help to fix my pattern?