AC Cable for use in DC

1.1KV obviously. the limitation will be the breakdown voltage of the insulation which is pretty much agnostic towards the direction of the current. (the exception being high frequencies where it does matter.).

Contact the cable manufacture.
The DC rating should be higher than the peak AC rating, but it could also be lower in some cases.

Though this Wiki extract refers to HVDC, it should be even more valid for 1.1kV ?

_{HVDC can carry more power per conductor because, for a given power rating, the constant voltage in a DC line is the same as the peak voltage in an AC line. The power delivered in an AC system is defined by the root mean square (RMS) of an AC voltage, but RMS is only about 71% of the peak voltage. The peak voltage of AC determines the actual insulation thickness and conductor spacing. Because DC operates at a constant maximum voltage, this allows existing transmission line corridors with equally sized conductors and insulation to carry more power into an area of high power consumption than AC, which can lower costs}

The one time I could see this causing a problem is if you used 1100V + or - to a grounded 0V. The voltage to earth may be too high.