In vivo evaluation of a novel albumin-binding prodrug of doxorubicin in an orthotopic mouse model of prostate cancer (LNCaP)

Abstract

PSA, which is overexpressed in prostate carcinoma, represents a molecular target for selectively releasing an anticancer agent from a prodrug formulation. In this study, we report on the in vivo antitumor efficacy of an efficacious albumin-binding prodrug of doxorubicin (PSA9) that incorporates p-aminobenzyloxycarbonyl (PABC) as a self-immolative spacer in addition to the heptapeptide, Arg-Ser-Ser-Tyr-Tyr-Ser-Leu, which serves as a substrate for PSA. The prodrug is cleaved very efficiently by PSA releasing H-Ser-Leu-PABC-doxorubicin and subsequently doxorubicin in PSA-positive cell lysates and prostate tumor homogenates as the final cleavage product. PSA9 at 3 Â 6 mg kg À1 doxorubicin equivalents (intravenous) was compared with conventional doxorubicin at equitoxic doses (at 3 Â 3 mg kg À1 ; intravenous) in an orthotopic mouse model of prostate cancer using LNCaP lentiviral luciferase-neomycin cells transduced with luciferase. Whereas doxorubicin did not show any efficacy against the primary tumor or metastases, the prodrug reduced the primary tumor by 30-50% and circulating PSA levels, and in addition, showed a pronounced reduction in lung and bone metastases by B77% and B96%, respectively, and a positive trend regarding the activity against liver and lymph-node metastases compared with control and doxorubicin-treated animals. The incorporation of PABC as a self-immolative spacer together with a PSA substrate demonstrates superior antitumor effects over doxorubicin attributed to an efficient cleavage by PSA releasing doxorubicin as the final active agent in prostate tumor homogenates. Using this approach for developing effective prodrugs against prostate cancer, is worthy of further preclinical optimization.

TRIM24 Is an Oncogenic Transcriptional Activator in Prostate Cancer

“…The orthotopic intraprostatic injection of modified LNCaP cells was performed as previously published (Elsadek et al, 2011) and was carried out at the DFCI Lurie Family Imaging Center. The animal experiments were carried out under the Lurie Center IACUC protocol and were in accordance with the IACUC standards for the welfare of animals.…”

Combination effect of PectaSol and Doxorubicin on viability, cell cycle arrest and apoptosis in DU‐145 and LNCaP prostate cancer cell lines

“…PectaSol MCP (modified citrus pectin), a complex water‐soluble indigestible polysaccharide obtained from the peel and pulp of citrus fruits and modified by means of high pH treatment, which was invented by Isaac Eliaz and uses as a dietary supplement has emerged as one of the most promising anti‐metastatic drugs (Glinsky and Raz, 2009) that decreases PSA ( Pisum sativum agglutinin) in prostatic cancer patients (Guess et al, 2003; Elsadek et al, 2011). PCa (prostate cancer) is the world's most common malignancy and the second leading cause of death from cancer (Sanches et al, 2009).…”

Enhanced anti-tumor activity of the Multi-Leu peptide PACE4 inhibitor transformed into an albumin-bound tumor-targeting prodrug

“…However, even with the extended incubation time (up to 24 h) no release product was detected. We hypothesized that the lack of the PSA cleavage (not observed in the case of doxorubicin prodrugs 26,32 ) might be due to the steric hindrance imposed by the ML peptide and/or reduced substrate specificity for this enzyme due to the presence of a mulit-Leu core. To address this problem, we decided to separate both peptides, i.e.…”

“…The conjugation to albumin should increase the bioavailability of the ML-peptide by reducing its rate of clearance and its proteolytic degradation through the shielding effect of the nearby protein. As a release mechanism, we incorporated at the N -terminal position of the ML-peptide a 7-mer peptide sequence (Arg-Ser-Ser-Tyr-Tyr ↓ Ser-Leu, where ↓ indicates the cleavage site) that can be specifically recognized by prostate-specific antigen (PSA) 32 . PSA is an enzyme belonging to the kallikrein-related peptidase family of serine proteases and is secreted at low levels by normal prostatic glandular cells but is highly upregulated in prostate cancer cells 33 .…”