To reproduce

1. Create minimal dot-file test.dot:

graph test {
n [label=-1]
}

2. Run
   dot test.dot -Tpdf -o test.pdf
3. Open test.pdf . It contains one node with label "-1".
4. Run Gephi.
5. Open test.dot. The following diagnostic message appears:

Cannot find label in line "2" (or something like that, mine is in Russian).

Expected Behavior

Gephi should support negative numbers w/o quotation marks, as GraphViz does.