The invention provides compositions and methods for reducing one or more symptoms of disease by administering compositions comprising SipA. The invention's compositions and methods are particularly advantageous in reducing symptoms of diseases that are associated with overexpression of P-gp and/or p53. The invention's compositions and methods are useful in reducing cancer symptom and/or cancer multidrug resistance (MDR). The invention provides a method for reducing one or more symptoms of cancer in a mammalian subject in need thereof, comprising administering to said subject a composition comprising purified SipA. In one embodiment, said SipA is operably conjugated to a nanoparticle. In another embodiment, said cancer comprises cancer cells resistant to at least one cytotoxin.