Physico-chemistry and Cytotoxicity of Tenofovir-Loaded Acid Phosphatase-Responsive Chitosan Nanoparticles

This study assesses the in vitro release of tenofovir (TFV)-loaded triphosphate (TPP) cross-linked chitosan nanoparticles (NPs) catalyzed by human prostatic acid phosphatase (hPAP) for 24 h. The physico-chemical characterization of the NPs included particle mean diameter (PMD), zeta potential (ζ), percent drug encapsulation efficiency (% EE), Fourier transform infra-red (FTIR) spectroscopy, powder X-ray diffractometry analysis (PXRD), and drug release kinetics. The first-order rate constant (k) and activation energy (Ea) of the cross-link (TPP) are determined by the integrated rate law and Arrhenius's equations. The hPAP Michaelis-Menten constant (Km) is determined by the Lineweaver-Burk's equation. The NP's safety profile is evaluated on vaginal epithelial cells (VK2/E6E7). The lyophilized drug-loaded NPs' PMD, ζ, and PDI are 149.97 nm, 4.4 mV, and 0.3, respectively. The % EE after lyophilization is 93.7 ± 4.4%. These NPs released drug at faster rate (63% of TFV within 6 h) under the enzyme's influence. The similarity and difference factors of drug release profiles (absence vs presence of hPAP) are 56.5 and 40.3, respectively. The hPAP's Km value of 0.019 mM suggests it has a good affinity for TPP at physiological pH ~ 7.4. The enhanced hydrolysis of TPP or degradation of chitosan NPs is fundamentally due to a decrease of TPP's activation energy by hPAP. In fact, the Ea value is 22.50 ± 3.06 kJ/mol or 16.33 ± 0.62 kJ/mol in the absence or presence of hPAP, respectively. The NPs are non-cytotoxic to the treated vaginal cell line. These hPAP-responsive NPs are promising topical nanomicrobicides for HIV/AIDS prevention.

Multifunctionality of prostatic acid phosphatase in prostate cancer pathogenesis

The role of human prostatic acid phosphatase (PAcP, P15309|PPAP_HUMAN) in prostate cancer was investigated using a new proteomics tool termed signal sequence swapping (replacement of domains from the native cleaved amino terminal signal sequence of secretory/membrane proteins with corresponding regions of functionally distinct signal sequence subtypes). This manipulation preferentially redirects proteins to different pathways of biogenesis at the endoplasmic reticulum (ER), magnifying normally difficult to detect subsets of the protein of interest. For PAcP, this technique reveals three forms identical in amino acid sequence but profoundly different in physiological functions, subcellular location, and biochemical properties. These three forms of PAcP can also occur with the wildtype PAcP signal sequence. Clinical specimens from patients with prostate cancer demonstrate that one form, termed ^PLPAcP, correlates with early prostate cancer. These findings confirm the analytical power of this method, implicate ^PLPAcP in prostate cancer pathogenesis, and suggest novel anticancer therapeutic strategies.

Multifunctionality of Prostatic Acid Phosphatase in Prostate Cancer Pathogenesis

The role of human prostatic acid phosphatase (PAcP, P15309|PPAP_HUMAN) in prostate cancer was investigated using a new proteomic tool termed signal sequence swapping (replacement of domains from the native cleaved amino terminal signal sequence of secretory/membrane proteins with corresponding regions of functionally distinct signal sequence subtypes). This manipulation preferentially redirects proteins to different pathways of biogenesis at the endoplasmic reticulum, magnifying normally difficult to detect subsets of the protein of interest. For PAcP this technique reveals three forms identical in amino acid sequence but profoundly different in physiological functions, subcellular location, and biochemical properties. These three forms of PAcP can also occur with the wild-type PAcP signal sequence. Clinical specimens from patients with prostate cancer demonstrate that one form, termed PLPAcP, correlates with early prostate cancer. These findings confirm the analytical power of this method, implicate PLPAcP in prostate cancer pathogenesis, and suggest novel anticancer therapeutic strategies.