In my talk I will give a brief overview of our recent results on polarization independent optical response of oligomer-like structures for linearly polarized light. Based on the discrete-dipole approximation we have analytically proved that systems with discrete rotational symmetry will exhibit polarization independent extinction, scattering and absorption cross-sections, making then optically isotropic. It is becoming extremely important in the vicinity of the Fano resonances, which makes common description and understanding of this effect in terms of interference of "bright" and "dark" modes questionable. I will also cover some of our results on circular dihroism for oligomer-like structure