Total loss of HLA class I expression on a melanoma cell line after growth in nude mice in absence of autologous antitumor immune response

Abstract

Loss of HLA class I expression on tumor cells is a frequent event as an immune escape mechanism. Seven different altered HLA phenotypes have been defined in tumors. Various molecular mechanisms have been described as responsible for HLA class I loss. HLA class I expression alterations occur successively and unpredictably during tumor progression in vivo and immunoselection has been implicated in this process. We present an experimental xenograft model in which melanoma cell line Ando-2 injected into athymic nude mice lost total surface HLA class I expression and exhibited HLA class II cell surface expression. A strong down-regulation of HLA class I expression and de novo HLA class II expression were also found when Ando-2 melanoma cells were injected into SCID-Beige mice. These phenomena were reproducible and were only observed in local growth in nude or SCID-Beige mice and not in vitro after multiple passages. HLA class I surface expression was recovered after IFN-c treatment, indicating regulatory defects. The mechanism implicated in loss of HLA class I molecule expression were a down-regulation of different components of antigen processing machinery and HLA class I heavy chains. These data suggest that HLA class I alterations can also occur in absence of autologous adaptive immune response. This is a good experimental in vivo model to study the relationship between tumor progression and HLA class I alterations. ' 2007 Wiley-Liss, Inc.

Differential down-modulation of HLA class I and II molecule expression on human tumor cell lines upon in vivo transfer

“…On the other hand, trichostatin A counteracted HLA down-modulation in IGROV-1 cells, a finding suggesting that histone acetylation may represent an additional relevant mechanism, as previously reported in a different setting [3]. These data are also in line with a previous study reporting an epigenetic effect of the microenvironment, where bystander stromal cells may have a major influence on the growth and progression of tumors [14].…”

“…To evaluate this possibility, we cultured tumor cells explanted ex vivo with different epigenetic drugs (namely, trichostatin A and decitabine) that had already proven to be effective in vitro [3, 4] or in vivo [1], respectively. Surprisingly, we observed that the simple placement of tumor cells in complete medium, without the addition of any drug, led to reversion of the down-modulated phenotype (when present) within a few hours (data not shown).…”

“…Tumor cells explanted ex vivo were cultured in vitro with different epigenetic drugs (trichostatin A and decitabine, also known as 2′-deoxy-5-azacytidine) that had already proven to be effective in vitro [3, 4] or in vivo [1]. Cells were plated at 5 × 10 5 cells/well in 24-well plate in complete medium (control) or medium added with trichostatin A (50, 250, and 500 nM, Sigma) or decitabine (1 μM, Pharmachemie B.V., Haarlem, Holland), for up to 72 h. For in vivo experiments, mice were treated with trichostatin A (1 mg/kg once a day, days 0–3, Sigma [5]), decitabine (0.25 mg/kg once at day 0, then twice a day, days 1–3 [1]), suberoylanilide hydroxamic acid (SAHA, 1.25 mg/mouse, once a day, days 1–3, Alexis Biochemicals, Lausen, Switzerland [6]), valproic acid (5 mg/mouse, once a day, days 1–3, modified from [7], Sigma), and Interferon-γ (50,000 IU/mouse, once, 6 h before cells recovery, modified from [1], PeproTech, Rocky Hill, NJ).…”

Recovery HLA-A2 and Beta2-microglobulin Expression in Tumor Cells Using Viral Vectors

“…We constructed both vectors carrying HLA-A2 gene and compared their efficacy to induce HLA-A2 transgene expression in different tumor cell lines. Using these viral vectors, we successfully recovered HLA-A2 expression in melanoma cell line Ando-2 which has been characterized to lack endogenous HLA-A2 due to a haplotype loss caused by loss of heterozygosity at chromosome 6 (Table 1) [26]. (Table 1).…”

“…All melanoma cell lines, except for Ando-2, were obtained from the European Searchable Tumour Cell Line Data Base (ESTDAB) [24] and have been previously genotyped for HLA-I and characterized for HLA phenotype [25]. Ando-2 was kindly provided by Dr P. Coulie (Université Catholique de Louvain (UCL), Brussels, Belgium) and is characterized by the loss of HLA-A2 expression due to HLA-I haplotype loss [26]. Prostate cancer cell lines DU145 and PC3, as well as bladder cancer cell lines T24, WIL and RT112, were obtained from American Type Culture Collection (ATCC).…”