When I have better access to a hardware store, will be reinforcing shelves.  Only strength comes from shelf to let connection. Anchors in shelves are plastic. Not a great combo. Tremendous amount of flex when pulled out. At least 15-20 degrees off vertical.  Not heavily loaded. As it stands, using as stationary unit. If reinforcing doesn't work, removing wheels.  Is useful storage given Location in kitchen. On the knees to get to lower shelf.