saquinavir and Prostatic-Neoplasms

Saquinavir (SQV) is a US-FDA approved HIV protease inhibitor (HPI) for HIV cure. The purpose of the present investigation was to develop and characterize the anticancer potential of the SQV-loaded folic acid (FA) conjugated PEGylated and non-PEGylated poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles (NPs) (SQV-Fol-PEG-PLGA and SQV-Fol-PLGA) employing PC-3 (human prostate) and MCF-7 (human breast) cancer cell lines.. Developed NPs were characterized by IR, NMR, DSC, XRD, size, charge and further tested for drug loading and cellular uptake properties.. The entrapment efficiency was found to be 56 ± 0.60 and 58 ± 0.80 w/v for SQV-Fol-PEG-PLGA and SQV-PLGA NPs, respectively. The obtained results of SQV-Fol-PEG-PLGA showed enhanced cytotoxicity and cellular uptake and were most preferentially taken up by the cancerous cells via folate receptor-mediated endocytosis (RME) mechanism. At 260 µM concentration, SQV-PLGA NPs and SQV-Fol-PEG-PLGA NPs showed 20%, 20% and 23% cell growth inhibition in PC-3 cells, respectively whereas in MCF-7 cells it was 12%, 15% and 14% cell growth inhibition, respectively.. Developed targeted SQV-Fol-PEG-PLGA NPs were superior anticancer potential as compared to non-targeted SQV-PLGA NPs. Thus, these targeted NPs provide another option for anticancer drug delivery scientists.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Drug Carriers; Drug Compounding; Drug Delivery Systems; Endocytosis; Female; Folic Acid; Humans; Lactic Acid; Male; MCF-7 Cells; Nanoparticles; Particle Size; Polyesters; Polyethylene Glycols; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Prostatic Neoplasms; Saquinavir

We previously reported that the NO-modified form of HIV protease inhibitor Saquinavir (Saq) is a potent antitumoral agent efficient against numerous tumor cell lines in vitro and in vivo. In acute toxicity studies, doses of Saq-NO equivalent to DL100 of the parental drug were completely nontoxic. Beside direct effect on malignant cell growth, Saq-NO sensitizes certain type of cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-mediated cell death. In this study, we evaluated the effects of Saq-NO on androgen-dependent prostate cancer LNCaP. Saq-NO inhibited both the growth of LNCaP cells in vitro and in xenograft models. Suppression of tumor growth was accompanied with cell cycle arrest in G 0/G 1 phase and established a persistent inhibition of proliferation. Furthermore, Saq-NO reverted sensitivity of LNCaP cells to TRAIL but not to TNF. Treatment of cells with Saq-NO induced transient upregulation of Akt and ERK1/2. This, however, did not represent the primary mode of action of Saq-NO, as elimination with specific inhibitors did not compromise the chemotherapic efficacy of the drug. However, permanent abrogation of phosphorylation of the S6 protein, which is the downstream target of both signaling pathways, was observed. Diminished S6 phosphorylation was associated with re-established sensitivity to TRAIL and reduction of X-linked inhibitor of apoptosis protein (XIAP). In summary, NO modification of Saq led to a new chemical entity with stronger and more pleiotropic antitumor activity than the parental drug.

Topics: Animals; Cell Death; Cell Line, Tumor; Cell Proliferation; Cell Survival; G1 Phase Cell Cycle Checkpoints; Humans; Male; MAP Kinase Signaling System; Mice; Mice, Inbred BALB C; Mice, Nude; Phosphorylation; Prostatic Neoplasms; Recombinant Proteins; Ribosomal Protein S6 Kinases; Saquinavir; TNF-Related Apoptosis-Inducing Ligand; TOR Serine-Threonine Kinases; X-Linked Inhibitor of Apoptosis Protein; Xenograft Model Antitumor Assays

The NO-derivative of the HIV protease inhibitor saquinavir (Saq-NO) is a nontoxic variant of the parental drug with enhanced anticancer activity on several cell lines. However, it is still unclear whether the p53 status of the target cell might influence the sensitivity to Saq-NO. In this study we evaluated the in vitro and in vivo activity of Saq-NO on the p53-deficient hormone resistant prostate cancer PC-3 cells. We demonstrate that the absence of functional p53 is not essential for the capacity of Saq-NO to reduce prostate cancer cell growth. In contrast to its previously described cytostatic action in B16 and C6 cell lines, Saq-NO exerted cytotoxic effects in PC-3 cells leading to dominant induction of apoptosis and enhanced production of proapoptotic Bim. In addition, differently from saquinavir, Saq-NO restored TRAIL sensitivity that was correlated with increased expression of DR5 independent from ROS/RNS production and YY1 repression. NF-κB activation may be responsible of the Saq-NO induced DR5 expression. Moreover, Saq-NO but not saquinavir, exerted synergistic activity with conventional cytostatic therapy. In agreement with these in vitro studies, Saq-NO inhibited the in vivo growth of PC-3 cells xenotransplants to a greater extent than the parental compound. Taken together, these data indicate that Saq-NO possesses powerful and suitable in vitro and in vivo chemotherapeutic potential to be further studied as a novel drug for the treatment of prostate cancer in the clinical setting.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cisplatin; Doxorubicin; Drug Resistance, Neoplasm; Drug Synergism; Humans; Male; Mice; Mice, Nude; Paclitaxel; Prostatic Neoplasms; Protease Inhibitors; Saquinavir; Transplantation, Heterologous; Tumor Suppressor Protein p53

Cancer cells frequently show high constitutive activity of the antiapoptotic transcription factor nuclear factor kappaB (NF-kappaB), which results in their enhanced survival. Activation of NF-kappaB classically depends on degradation of its inhibitor IkappaBalpha by the 26s proteasome. Specific proteasome inhibitors induce apoptosis in cancer cells and, at nonlethal concentrations, sensitize cells to the cytotoxic effects of ionizing radiation and chemotherapeutic drugs. Recently, the protease coded by the HIV-I virus has been shown to share cleavage activities with the proteasome. For this reason, we investigated whether the HIV-I protease inhibitor saquinavir can inhibit NF-kappaB activation, block 26s proteasome activity in prostate cancer cells, and promote their apoptosis. The effect of saquinavir on LPS/IFN-gamma-induced activation of NF-kappaB was assessed by gel-shift assays and by Western analysis of corresponding IkappaBalpha-levels. Its effect on 20s and 26s proteasome activity was analyzed with a fluorogenic peptide assay using whole cell lysates from LnCaP, DU-145, and PC-3 prostate cancer cells pretreated with saquinavir for 9 h. Proteasome inhibition in living cells was assessed using ECV 304 cells stably transfected with an expression plasmid for an ubiquitin/green fluorescence protein fusion protein (ECV 304/10). Apoptosis was monitored morphologically and by flow cytometry. Saquinavir treatment prevented LPS/IFN-gamma-induced activation of NF-kappaB in RAW cells and stabilized expression of IkappaBalpha. It inhibited 20s and 26s proteasome activity in lysates from LnCaP, DU-145, and PC-3 prostate cancer cells with an IC(50) of 10 micro M and caused the accumulation of an ubiquitin/green fluorescence protein fusion protein in living ECV 304/10 cells. Incubation of PC-3 and DU-145 prostate cancer, U373 glioblastoma, and K562 and Jurkat leukemia cells with saquinavir caused a concentration-dependent induction of apoptosis. In the case of PC-3 and DU-145, saquinavir sensitized the surviving cells to ionizing radiation. We conclude that saquinavir inhibits proteasome activity in mammalian cells as well as acting on the HIV-I protease. Because saquinavir induced apoptosis in human cancer cells, HIV-I protease inhibitors might become a new class of cytotoxic drugs, alone or in combination with radiation or chemotherapy.

Topics: Animals; Apoptosis; HIV Protease Inhibitors; Humans; Macrophages; Male; Mice; NF-kappa B; Peptide Hydrolases; Prostatic Neoplasms; Protease Inhibitors; Proteasome Endopeptidase Complex; Radiation Tolerance; Radiation-Sensitizing Agents; Saquinavir; Tumor Cells, Cultured