[CA125 cytosolic levels in lung adenocarcinomas. New biological aspects]

CA125 is a useful serum tumor marker in patients with non-mucinous ovarian cancer, but there may be high serum levels in other malignant tumors, among them the non-small cell lung cancers. We decided to study the cytosolic levels of CA125 in lung adenocarcinomas and compare them with pS2, CD44s, CD44v5 and CD44v6, all of them with biological interest in this subtype of lung carcinomas.

The study group included 55 patients (33 males) having lung adenocarcinomas. CA125 and cytostolic pS2 were measured by both IRMAS methods (CIS. Biointernational. France). The concentrations of CD44 standard (CD44s), CD44v5 and CD44v6 on cell surfaces were dosed by EIAS (Bender Diagnostics. Austria). Clinical stage, ploidy and S-phase cellular fraction were also taken into account.

In the 55 lung adenocarcinomas, cytosolic CA125 levels ranged between 1 and 225 U/mg prot. (median 80.5) and were higher (p:0.002) than those observed in 16 normal lung tissues from the same patients (r: 1-32.5; median 6.7 U/mg prot.). When the 25th (7.2 U/mg prot.) and 75th (320 U/mg prot.) percentiles were used as clinical cut-offs, we found that the cases with high antigenic levels showed a greater positivity for CD44v6 (p:0.002) and a reduced positivity for CD44 standard (p:0.053). Likewise, they showed a tendency towards being pS2 + (p:0.09) more frequently.

Our results lead us to draw the following conclusions: 1) Cytosolic CA125 levels in lung adenocarcinomas were higher than those observed in normal tissues from the same patients. 2) Lung adenocarcinomas with high cytosolic CA125 concentrations had a greater positivity for CD44v6, a reduced positivity for CD44s and were more frequently pS2 +. These associations support the usefulness of the cytosolic CA125 levels as an indicator of poor outcome in this subtype of lung carcinomas.