Of course you can... Take the Hiwatt Custom 100 for example, it's used for guitar and bass in equal measure. The amp will be fine, the speaker may suffer if it's not good and heavy duty, but if your ohmages match on the speaker and the amp, and the speaker is rated a few watts (like double) higher than the amp, which is common sense even for guitar then you shouldn't have any problems.
A proper nice thick bass cab, 4x10 or similar, will sound better as it will reproduce the bass frequencies better than a cab built for guitar, but you really shouldn't experience too many problems...
Likewise you can play a guitar through a bass amp...