1. Used alone to mean you wish a situation hadn't happened because it is bad luck or brings pain, suffering or embarrassment to someone. English = 'It's a shame!', 'What a shame!', 'What bad luck!', and so on.
2. Used alone to mean you find that something said or done is so bad or obscene that you dislike it intensely and feel that the person responsible ought to be ashamed. English = 'Shame on you!', 'How disgusting!', 'You ought to be ashamed of yourself!'