hi, no worries.
you are staying in a great region first of all.
cimen sokak actually is the street where christians ( armenians, rums (old byzantien) people live). i have many friends living there. my girlfriend was living there. so foreigners are welcome.
but, at night, at that part of Şişli (one part is Nisantasi, where high society lives / the other part Dolaptere-Kurtuluş. they are the same place, just one street apart.), at night many hookers. :)) but it is safe. they are nice people also, really.
so nice place, dont worry.
cheers