Terpene conjugates of diaminedichloridoplatinum(II) complexes: antiproliferative effects in HL-60 leukemia, 518A2 melanoma, and HT-29 colon cancer cells

Twenty-eight [6-(aminomethyl)nicotinate]dichloridoplatinum(II) complexes 1 esterified with various terpene alcohols either directly or via alkyl spacers were tested for antiproliferative activity in human 518A2 melanoma and HL-60 leukemia cells. Generally, conjugates with menthanes and polycyclic sesquiterpenes attached via propane-1,2-diyl spacers were most active. In the melanoma cells, the propane-1,2-diyl-spacered conjugates of (-)-menthol (1a(2')), (+)-neomenthol (1b(2')), (-)-carvomenthol (1h(2')), and (-)-isolongifolol (1n(2')) displayed growth inhibition at IC(50)<4 microM which is ten times smaller than that of cisplatin. The stationary diamino ligand was also crucial. The (-)-menthyl ester complexes with 2,3-diaminopropanoate (9a) and 2,4-diaminobutanoate (10a) ligands caused a greater and persistent growth inhibition in HT-29 colon cancer cells upon long-term exposure when compared to the 6-(aminomethyl)nicotinate analogue 1a. The cedrenyl ester 1l and the menthoxyisopropyl ester 1a(2') proved most efficacious in all three tumor cell lines. The DNA binding of complexes 1 was assessed by electrophoretic band-shift experiments and found correlated to the terpene structure but not to the observed antiproliferative activities.     

Evaluation of cytotoxic properties of organometallic ferrocifens on melanocytes, primary and metastatic melanoma cell lines

Malignant melanoma is one of the most severe forms of skin cancer, and chemotherapeutic agents currently in use are poorly effective in curing the disease. Here we describe the properties of two organometallic ferrocenyl derivatives, ferrocifen (Fc-OH-Tam) and ferrociphenol (Fc-diOH) that show a specific antiproliferative effect on melanoma cells. After a short incubation period, Fc-OH-Tam is highly cytotoxic on melanoma cells but less toxic on melanocytes. Fc-diOH is slightly toxic at a high concentration but no discrepancy is observed between malignant and normal cells. After a long incubation time the latter is highly toxic for malignant cells but not for normal cells while the former was very highly toxic for primary malignant cells and significantly less toxic for normal cells. We also found that oxidative stress is not implicated in the mechanism of cytotoxicity, since both derivatives neither induce reactive oxygen species (ROS) level in melanocytes nor in melanoma cells. Finally, investigation on hair follicle growth revealed that the two organometallic derivatives induced an irreversible ejection of the hair shaft, thus predicting a potential hair loss side effect if used as a chemotherapeutic treatment.     

Growth of cancer cell lines under stem cell-like conditions has the potential to unveil therapeutic targets

Malignant tumors comprise a small proportion of cancer-initiating cells (CIC), capable of sustaining tumor formation and growth. CIC are the main potential target for anticancer therapy. However, the identification of molecular therapeutic targets in CIC isolated from primary tumors is an extremely difficult task. Here, we show that after years of passaging under differentiating conditions, glioblastoma, mammary carcinoma, and melanoma cell lines contained a fraction of cells capable of forming spheroids upon in vitro growth under stem cell-like conditions. We found an increased expression of surface markers associated with the stem cell phenotype and of oncogenes in cell lines and clones cultured as spheroids vs. adherent cultures. Also, spheroid-forming cells displayed increased tumorigenicity and an altered pattern of chemosensitivity. Interestingly, also from single retrovirally marked clones, it was possible to isolate cells able to grow as spheroids and associated with increased tumorigenicity. Our findings indicate that short-term selection and propagation of CIC as spheroid cultures from established cancer cell lines, coupled with gene expression profiling, represents a suitable tool to study and therapeutically target CIC: the notion of which genes have been down-regulated during growth under differentiating conditions will help find CIC-associated therapeutic targets.     

Subtypes of melanocytes and melanoma cells distinguished by their intercellular contacts: heterotypic adherens junctions,adhesive associations,and dispersed desmoglein 2 glycoproteins

In the tissue integration of melanocytes and melanoma cells, an important role is attributed to cell adhesion molecules, notably the cadherins. In cultured melanoma cells, we have previously described a more heterogeneous repertoire of cadherins than normal, including some melanoma subtypes synthesizing the desmosomal cadherin, desmoglein 2, out of the desmosomal context. Using biochemical and immunological characterization of junctional molecules, confocal laser scanning, and electron and immunoelectron microscopy, we now demonstrate homo- and heterotypic cell-cell adhesions of normal epidermal melanocytes. In human epidermis, both in situ and in cell culture, melanocytes and keratinocytes are connected by closely aligned membranes that are interspersed by small puncta adhaerentia containing heterotypic complexes of E- and P-cadherin. Moreover, melanocytes growing in culture often begin to synthesize desmoglein 2, which is dispersed over extended areas of intimate adhesive cell-cell associations. As desmoglein 2 is not found in melanocytes in situ, we hypothesize that its synthesis is correlated with cell proliferation. Indeed, in tissue microarrays, desmoglein 2 has been demonstrated in a sizable subset of nevi and primary melanomas. The biological meanings of these cell-cell adhesion molecule arrangements, the possible diagnostic and prognostic significance of these findings, and the implications of the heterogeneity types of melanomas are discussed. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. This work was supported in parts by grants from the Deutsche Forschungsgemeinschaft to W. K. Peitsch (project PE 896/1) and the Deutsche Krebshilfe to W. W. Franke (project 10-2049).     

DNA cleavage function of seryl-histidine dipeptide and its application

Summary. Previously published evidences highlighted the effect of transglutaminase (TG, EC 2.3.2.13) activation on the reduction of the in vitro adhesive and invasive behaviour of murine B16-F10 melanoma cells, as well as in vivo. Here, we investigated the influence of spermidine (SPD) incorporation by TG into basement membrane components i.e. laminin (LN) or Matrigel (MG), on the adhesion and invasion of B16-F10 melanoma cells by these TG/SPD-modified substrates. The adhesion assays showed that cell binding to the TG/SPD-modified LN was reduced by 30%, when compared to untreated LN, whereas the reduction obtained using TG/SPD-modified MG was 35%. Similarly, tumor cell invasion by the Boyden chamber system through TG/SPD modified LN or MG was respectively reduced by 45%, and by 69%. Evaluation of matrix metalloproteinase (gelatinases MMP-2 and MMP-9) activities by gel-zymography showed that MMP-2 activity was unaffected, while MMP-9 activity was reduced by about 32% using TG/SPD-modified substrate. These results strongly suggest that the observed antiinvasive effect of TG activation in the host may be ascribed to the covalent incorporation of polyamines, which led to the post-translational modification of some components of the cell basement membrane. This modification may interfere with the metastatic property of melanoma cells, affecting the proteolytic activity necessary for their migration and invasion activities. Authors’ address: Simone Beninati, Department of Biology, University of Rome “Tor Vergata”, Via della Ricerca Scientifica, I-00133 Rome, Italy     

PBMC are as good a source of tumor-reactive T lymphocytes as TIL after selection by Melan-A/A2 multimer immunomagnetic sorting

Choosing a reliable source of tumor-specific T lymphocytes and an efficient method to isolate these cells still remains a critical issue in adoptive cellular therapy (ACT). In this study, we assessed the capacity of MHC/peptide based immunomagnetic sorting followed by polyclonal T cell expansion to derive pure polyclonal and tumor-reactive Melan-A specific T cell populations from melanoma patient’s PBMC and TIL. We first demonstrated that this approach was extremely efficient and reproducible. We then used this procedure to compare PBMC and TIL-derived cells from three melanoma patients in terms of avidity for Melan-A A27L analog, Melan-A_26–35 and Melan-A_27–35, tumor reactivity (lysis and cytokine production) and repertoire. Regardless of their origin, i.e., fresh PBMC, peptide stimulated PBMC or TIL, all sorted populations (from the three patients) were cytotoxic against HLA-A2+ melanoma cell lines expressing Melan-A. Although some variability in peptide avidity, lytic activity and cytokine production was observed between populations of different origins in a given patient, it differed from one patient to another and thus no correlation could be drawn between T cell source and reactivity. Analysis of Vβ usage within the sorted populations showed the recurrence of Vβ3 and Vβ14 subfamilies in the three patients but differences in the rest of the Melan-A repertoire. In addition, in two patients, we observed major repertoire differences between populations sorted from the three sources. We especially documented that in vitro peptide stimulation of PBMC, used to facilitate the sort by enriching in specific T lymphocytes, could significantly alter their repertoire and reactivity towards tumor cells. We conclude that PBMC which are easily obtained from all melanoma patients, can be as good a source as TIL to derive high amounts of tumor-reactive Melan-A specific T cells, with this selection/amplification procedure. However, the conditions of peptide stimulation should be improved to prevent a possible loss of reactive clonotypes. Nathalie Labarrière and Nadine Gervois have equally contributed to this work.     

Tumor destruction using electrochemotherapy followed by CpG oligodeoxynucleotide injection induces distant tumor responses

PURPOSE: Electrochemotherapy (ECT) is an effective local therapy of human cutaneous cancers but has no effect on distant untreated tumors. We addressed whether tumor-associated antigens released after ECT could induce an efficient systemic immunity when associated with an appropriate immunoadjuvant. METHODS AND RESULTS: We first studied the nature of the cellular recruitment and the expression of various toll-like receptors (TLRs) in tumors treated by ECT. We found that ECT induced a massive recruitment of CD11c and CD11b positive cells in the tumors and a strong increase of TLR9 expression. We then tested antitumor effects of the combination: ECT followed by TLR-9 ligands, CpG oligodeoxynucleotides (CpG ODN), in three murine tumor models. We found that this combination triggered both potent local synergistic antitumor effects, on the ipsi-lateral ECT-treated tumor, and more interestingly, a systemic antitumor response on the contra-lateral untreated tumor, in the three models. The systemic protection was T-cell dependent as it was not observed in nude littermates. The combination induced tumor-specific T cell effectors in the tumor-draining lymph nodes and in the spleen which secreted significantly more gamma-interferon upon activation than with ECT or CpG ODN alone. CONCLUSIONS: Our data show that ECT and CpG ODN synergize and induce a significant increase of the local effect and a systemic T-dependent antitumor response. Such combination constitutes a potential innovative vaccination strategy using in situ tumor-associated antigens that could eventually be translated into the clinic.     

Impact of the CCR5 gene polymorphism on the survival of metastatic melanoma patients receiving immunotherapy

Purpose Chemokines influence both tumor progression and anti-tumor immune response. A 32-bp-deletion polymorphism in the chemokine receptor 5 gene (CCR5Δ32) has been shown to result in a non-functional protein. This study was aimed at evaluating the potential impact of this gene polymorphism on disease progression and treatment outcome in patients with melanoma. Patients and methods CCR5 genotyping was performed by PCR on DNA extracted from serum samples of 782 cutaneous melanoma patients with known disease history and long-term clinical follow-up. Genotypes were correlated with patient survival and types of treatment. Results Of 782 melanoma patients, 90 (11.5%) were heterozygous and 12 (1.5%) were homozygous for CCR5Δ32. Analyzing the complete cohort, the disease-specific survival from date of primary diagnosis was not influenced by CCR5 status. Similarly, no significant impact could be detected on the treatment outcome of stage III patients. In 139 stage IV patients receiving immunotherapy, CCR5Δ32 was associated with a decreased survival compared to patients not carrying the deletion (median 12.5 vs. 20.3 months, P = 0.029). Multivariate analysis revealed the CCR5 genotype as an independent factor impacting disease-specific survival in this patient population (P = 0.002), followed by gender (P = 0.019) and pathological classification of the primary (pT; P = 0.022). Conclusion The presence of the CCR5Δ32 polymorphism in patients with stage IV melanoma results in a decreased survival following immunotherapy and may help to select patients less likely to benefit from this type of treatment. Selma Ugurel and David Schrama have contributed equally to this work.     

Induction of immune response against NY-ESO-1 by CHP-NY-ESO-1 vaccination and immune regulation in a melanoma patient

BACKGROUND: NY-ESO-1 is a cancer/testis antigen highly immunogenic in cancer patients. Cholesterol-bearing hydrophobized pullulan (CHP) is a nanoparticle-forming antigen-delivery vehicle and CHP complexed with NY-ESO-1 protein (CHP-NY-ESO-1) efficiently activates CD4 and CD8 T cells in vitro. AIM: In this study we report on a 50-year-old male melanoma patient with multiple skin and organ metastases (T4N3M1c) who was vaccinated with CHP-NY-ESO-1 at biweekly intervals and who had an unusual disease course. We characterized in this patient humoral and cellular immune responses, immune regulatory cells, and cytokine profiles in the peripheral blood and at local tumor sites. RESULTS: Ten days after the second CHP-NY-ESO-1 vaccination (day 25), blisters appeared on the skin at the metastatic lesions associated with inflammatory changes. A skin biopsy showed the presence of many NY-ESO-1-expressing apoptotic melanoma cells as determined by a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) test. However, the tumors continued to grow, and the patient died of pulmonary failure due to multiple metastases on day 48. Serum antibody responses were detected after the second CHP-NY-ESO-1 vaccination and antibody titer increased with subsequent vaccinations. Th1 dependent IgG1 was the predominant immunoglobulin subtype. Both, NY-ESO-1-specific CD4 and CD8 T cell responses were detected in PBMC by IFN-gamma secretion assays. After CHP-NY-ESO-1 vaccination a slight decrease in CD4(+)CD25(+)Foxp3(+) Tregs was observed in PBMC but significantly increased numbers of CD4(+)CD25(+)Foxp3(+) Tregs and CD68(+) immunoregulatory macrophages were detected at the local tumor sites. CD4(+)CD25(+)Foxp3(+) Tregs were also increased in the blister fluid. Cytokines in the serum suggested a polarization towards a Th1 pattern in the PBMC and those in the blister fluid suggested a Th2-type response at the tumor site. CONCLUSIONS: Our observations indicate induction of specific humoral and cellular immune responses against NY-ESO-1 after CHP-NY-ESO-1 vaccination in a melanoma patient. The concomitant appearance of regulatory T cells and of immune regulatory macrophages and cytokines at the local tumor sites in this patient may explain immune escape.