The use of dipeptide derivatives of 5-aminolaevulinic acid promotes their entry to tumor cells and improves tumor selectivity of photodynamic therapy

The use of endogenous protoporphyrin IX generated after administration of 5-aminolaevulinic acid (ALA) has led to many applications in photodynamic therapy (PDT). However, the bioavailability of ALA is limited by its hydrophilic properties and limited cell uptake. A promising approach to optimize the efficacy of ALA-PDT is to deliver ALA in the form of prodrugs to mask its hydrophilic nature. The aim of this work was to evaluate the potential of two ALA dipeptide derivatives, N-acetyl terminated leucinyl-ALA methyl ester (Ac-Leu-ALA-Me) and phenylalanyl-ALA methyl ester (Ac-Phe-ALA-Me), for their use in PDT of cancer, by investigating the generation of protoporphyrin IX in an oncogenic cell line (PAM212-Ras), and in a subcutaneous tumor model. In our in vitro studies, both derivatives were more effective than ALA in PDT treatment, at inducing the same protoporphyrin IX levels but at 50- to 100-fold lower concentrations, with the phenylalanyl derivative being the most effective. The efficient release of ALA from Ac-Phe-ALA-Me appears to be consistent with the reported substrate and inhibitor preferences of acylpeptide hydrolase. In vivo studies revealed that topical application of the peptide prodrug Ac-Phe-ALA-Me gave greater selectivity than with ALA itself, and induced tumor photodamage, whereas systemic administration improved ALA-induced porphyrin generation in terms of equivalent doses administered, without induction of toxic effects. Our data support the possibility of using particularly Ac-Phe-ALA-Me both for topical treatment of basal cell carcinomas and for systemic administration. Further chemical fine-tuning of this prodrug template should yield additional compounds for enhanced ALA-PDT with potential for translation to the clinic

Characterization of a fibroblastoid mammary carcinoma cell line (LM2) originated from a mouse adenocarcinoma

We established and characterized a new mammary tumor cell line, LM2, derived from M2 mammary adenocarcinoma which spontaneously appeared in a BALB/c female mouse. The LM2 cell line has been maintained in culture for more than 40 passages and grows as poorly differentiated elongated cells. Ultrastructural and immunocytochemistry analysis revealed characteristic features of adenocarcinoma. Cytogenetic studies showed that LM2 cells are fundamentally hypotetraploid. They express metalloproteinases (MMP) and show high levels of plasminogen activator type urokinase (uPA). They were sensitive to nitric oxide (NO)-mediated cytotoxicity when NO derived from an exogenous donor. In vivo, although LM2 cells were able to grow in the lungs, they could not metastasize to the same target organ from s.c. primary tumors. The LM2 mouse mammary adenocarcinoma cell line is a suitable model to examine different aspects of tumor biology, in particular those related to the different pathways involved in the metastatic cascade and in the cytotoxicity mediated by NO.Fil: Galli, S.. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; ArgentinaFil: Colombo, Lucas Luis. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vanzuli, Silvia. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; ArgentinaFil: Daroqui, Maria Cecilia. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vidal, María del Carmen C.. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; ArgentinaFil: Jasnis, Maria Adela. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; ArgentinaFil: Sacerdote de Lustig, Eugenia. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Eijan, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Ángel H. Roffo"; ArgentinaUnidad documental simpl