A 74-year-old man presents to the clinic for assessment of symptoms of fatigue, shortness of breath on exertion, and back and rib pain that is made worse with movement. Investigations reveal he is anemic, the calcium, urea, and creatinine are elevated. X-rays reveal multiple lytic lesions in the long bones and ribs, and protein electrophoresis is positive for an immunoglobulin G (IgG) paraprotein. Which of the following is the most likely mechanism for the renal injury?