Bcl-xL is overexpressed in hormone-resistant prostate cancer and promotes survival of LNCaP cells via interaction with proapoptotic Bak.

Androgen-sensitive prostate cancer cells turn androgen resistant through complex mechanisms that involve dysregulation of apoptosis. We investigated the role of antiapoptotic Bcl-xL in the progression of prostate cancer as well as the interactions of Bcl-xL with proapoptotic Bax and Bak in androgen-dependent and -independent prostate cancer cells. Immunohistochemical analysis was used to study the expression of Bcl-xL in a series of 139 prostate carcinomas and its association with Gleason grade and time to hormone resistance. Expression of Bcl-xL was more abundant in prostate carcinomas of higher Gleason grades and significantly associated with the onset of hormone-refractory disease. In vivo interactions of Bcl-xL with Bax or Bak in untreated and camptothecin-treated LNCaP and PC3 cells were investigated by means of coimmunoprecipitation. In the absence of any stimuli, Bcl-xL interacts with Bax and Bak in androgen-independent PC3 cells but only with Bak in androgen-dependent LNCaP cells. Interactions of Bcl-xL with Bax and Bak were also evidenced in lysates from high-grade prostate cancer tissues. In LNCaP cells treated with camptothecin, an inhibitor of topoisomerase I, the interaction between Bcl-xL and Bak was absent after 36 h, Bcl-xL decreased gradually and Bak increased coincidentally with the progress of apoptosis. These results support a model in which Bcl-xL would exert an inhibitory effect over Bak via heterodimerization. We propose that these interactions may provide mechanisms for suppressing the activity of proapoptotic Bax and Bak in prostate cancer cells and that Bcl-xL expression contributes to androgen resistance and progression of prostate cancer.

Endocarditis por Trichoderma longibrachiatum en paciente con nutrición parenteral domiciliaria.

Home parenteral nutrition (HPN) improves the quality of life of the patients although it has complications. Catheter-related infections and mechanical complications are the most frequent ones. We report the case of endocarditis over catheter in a man suffering from short bowel and receiving HPN. The special features of the case are firstly the catheter was a remaining fragment on the right atrial and secondly the infection was caused by Trichoderma longibrachiatum, an isolated fact regarding this pathology so far. Conventional surgery was applied to take the catheter out. Staphylococcus epidermidis, Ochrobactrum anthropi and Trichoderma longibrachiatum were isolated from the surgical specimen. The extraction of the infected catheter along with antibiotic therapy led to the complete recovery of the subject. Ochrobactrum anthropi and Trichoderma longibrachiatum are unusual microorganisms but they are acquiring more relevance. Although there is no agreement about intravascular retained catheter management, the most recommended approach consists on monitoring them and removing the device in case of complications.