Antiviral Therapy 10:215–223 The HIV protease inhibitors nelfinavir and saquinavir, but not a variety of HIV reverse transcriptase inhibitors, adversely affect human proteasome function Marco Piccinini1, Maria T Rinaudo1*, Annalisa Anselmino1, Barbara Buccinnà1, Cristina Ramondetti1, Antonio Dematteis1, Emanuela Ricotti 2, Lucia Palmisano3, Michael Mostert2 and Pier-Angelo Tovo2 1Department of Medicine and Experimental Oncology and 2Department of Paediatric Sciences, University of Turin, Turin, Italy 3Istituto Superiore di Sanità, Rome, Italy *Corresponding author: Tel: +39 011 670 5303 Fax: +39 011 670 5311; E-mail:
[email protected] Background: In HIV-infected patients some clinical and drugs at different concentrations. Intracellular protea- immunological benefits of antiretroviral therapy, which some proteolytic activity was evaluated by searching for frequently include a combination of HIV protease inhibitors ubiquitin-tagged proteins in HL60 cells incubated with (PIs) and reverse transcriptase inhibitors (RTIs), cannot be and without the drugs. solely explained by the drugs’ action on viral enzymes. Results: At therapeutic dosages, nelfinavir and saquinavir Proteasomes constitute the central protease of the ubiq- inhibited proteasome peptidase activity and caused uitin ATP-dependent pathway involved in many cellular intracellular accumulation of polyubiquitinated proteins, processes, as well as in HIV maturation and aggressiveness. a hallmark of proteasome proteolytic inhibition in vivo; Objective: To explore whether the PIs nelfinavir and the RTIs failed to evoke either effect. saquinavir and the RTIs abacavir, nevirapine, delavirdine, Conclusion: Proteasomes are targeted by the two PIs but stavudine and didanosine affect proteasome function in not the RTIs. Therefore, in HIV-infected patients the vitro and in vivo. beneficial effect of a therapy including one of the two Methods: Peptidase activity of purified human 26S and PIs should partly rely on inhibition of host proteasome 20S proteasomes was assayed with and without the function.