Erectile dysfunction (ED) is commonly experienced in men with diabetes mellitus. Vascular endothelial growth factor (VEGF) has been extensively documented for its pathogenic significance in different complications of diabetes. We hypothesized that expressions of VEGF, its receptors and its signaling pathway Akt may be drastically altered in diabetic penile tissues and their alterations may modulate penile expression of the molecules that are believed to play a role in diabetic ED. Otsuka Long-Evans Fatty (OLETF) rats, a type II (non-insulin-dependent) diabetes mellitus, were used at the insulin-resistant stage of type II diabetes (20 weeks of age). We determined protein and mRNA expressions of VEGF, its receptors, Akt, nitric oxide synthase isoforms, and apoptosis-related molecules in the penis using immunohistochemistry, Western blotting, in situ hybridization, and real-time quantitative PCR analyses. The penile sections were also submitted to the Tdt-mediated dUTP nick end labeling assay for apoptosis. OLETF rats showed marked reductions in penile expression of VEGF, its two receptors and Akt. In OLETF rat penises, endothelial and neuronal nitric oxide synthase isoforms were expressed less abundantly. Furthermore, while anti-apoptotic markers, Bcl-2 and phosphorylated Bad, were down-regulated, pro-apoptotic markers, active caspase-3 and Bax, were up-regulated, resulting in the appearance of apoptotic cells in the penile tissues of OLETF rats. The VEGF signaling system would work less well in diabetic penile tissues as a result of the reduced expression, leading to diminished endothelial production of nitric oxide and apoptosis-related erectile tissue damage. We propose that the abnormalities of the VEGF signaling system in the penis may play a role in the pathophysiology of diabetic ED.

Body tissues are traditionally classified as estrogen targets based on both the response to the hormone and the presence of estrogen receptors (ERs). We undertook the study on expression of ERalpha and ERbeta in the penis to identify compartments/cells responsive to estrogen, using immunohistochemistry, Western blotting, in situ hybridization, and RT-PCR analyses. Expressions of ERalpha and ERbeta in the rat penis were age dependent at both mRNA and protein levels, with the most intense signals being observed during the perinatal period and declining thereafter with age. Initial signals (fetal d 17) of ERalpha were localized to the mesenchyme and subepithelial stroma and later (postnatal d 2) to the corpus spongiosus, corpus cavernosus, and urethral epithelia. ERbeta was initially detected by postnatal d 2 and was localized diffusely in corpus spongiosus and cavernosus in immature rats. In the adult, both ERs were concentrated largely to the urethral epithelia and vascular and neuronal structures. The present study provides the first evidence for ER expression in the penis. Thus, our data add the penis to the list of estrogen-responsive tissues in males and provide a base and insight for future studies aimed at investigating a functional role of estrogen in the penis, especially in development.

Apoptosis is induced by many kinds of therapy-related inducers, such as hyperthermia and chemotherapeutic agents. However, differences in apoptotic pathways between these inducers remain unclear, although knowing the differences is important to map out a therapeutic strategy. Therefore, we focused on the localization and phosphorylation of Bcl-2 and Bax, key mediators of the apoptotic pathway, after hyperthermia and paclitaxel treatment of PC-10 squamous cell carcinoma cells that excessively expressed Bcl-2 and Bax in the cytoplasm. Paclitaxel treatment markedly induced qualitative changes in Bcl-2, whereas hyperthermia did only quantitative changes in Bax. The levels of Bax increased gradually with the duration of hyperthermia, whereas Bcl-2 levels slightly decreased. On the other hand, paclitaxel treatment induced dose-and time-dependent phosphorylation of Bcl-2. Interestingly, phosphorylated Bcl-2 was observed in the specific subcellular sites, mitochondria-and lysosomerich fractions. Both treatments disturbed the heterodimerization of Bax with Bcl-2. Hyperthermia, but not paclitaxel treatment, induced a gradual Bax translocation from the cytoplasm to the nucleus. Although both treatments induced a prominent cell cycle disturbance in the G2M phase, paclitaxel treatment induced typical apoptosis, and hyperthermia hardly induced apoptosis. Our results suggest that the subcellular redistribution of Bax and the phosphorylation of Bcl-2 depend on the type of apoptosis inducers, such as hyperthermia and paclitaxel, and Bcl-2 has a central role in the decision of apoptotic outcome. Our data may afford new insights in apoptosis from the aspect of an association of Bcl-2 phosphorylation with intracellular Bax localization. © 2002 Wiley-Liss, Inc. Key words: Bcl-2; Bax; hyperthermia; paclitaxel; lung cancer cellsPaclitaxel, microtubule-stabilizing agents, demonstrates a marked activity against several kinds of tumors 1 by arresting cell-cycle progression and inducing apoptosis. 2-4 Mild hyperthermia disturbs functions of the microtubule system and triggers apoptosis as well. 5 In addition, local or systemical hyperthermia is used in conjunction with paclitaxel in cancer tretment, 6 but whether a combined thermo-chemotherapy enhanced 5,7,8 or inhibited 9,10 the susceptibility of cells to apoptotic stimuli is still controversial. Therefore, understanding how paclitaxel and hyperthermia modalities induce apoptosis is critical to map out a better anticancer strategy that may offer synergistic benefits when used concurrently.Cellular apoptotic potential is mainly regulated by the relative levels of Bcl-2 and Bax, Bcl-2 family members with opposite functions and their interactions. 11 These proteins mainly act on mitochondria at a critical decision point to irreversible cellular damage. 12-15 The antiapoptotic Bcl-2 suppresses apoptosis, whereas the proapoptotic Bax counteracts the Bcl-2 function to accelerate apoptosis. These proteins exert their activity via protein/ protein interactions, such as homodimerization and heter...

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