On the renormalization of CPT/Lorentz violating QED in curved space
  We consider the one-loop renormalization of QED in curved space-time with additional Lorentz and/or CPT breaking terms. The renormalization group equations in the vacuum sector are derived. In the special case of Minkowski metric and with constant Lorentz and CPT breaking terms these equations reduce to the ones obtained earlier by other authors. The necessary form of the vacuum counterterms indicate possible violations of the space or time homogeneity or space isotropy in the gravitational phenomena. However, the necessity of the phenomenologically most interesting terms such as linear in the space-time curvature or torsion, is related to the non-constant nature of the dimensionless Lorentz and CPT breaking parameters. 
G. de Berredo-Peixoto and I.L. Shapiro