The DoT and CaSki human cervical carcinoma cell lines ectopically produce material immunologically similar to the β-subunit of human chorionic gonadotropin (hCGΒ). Culture fluids were analyzed by gel filtration chromatography and radioimmunoassay (RIA) using (a) antiserum directed to conformation-specific (core-directed) determinants not involving the carboxyl-terminal peptide (CTP) in hCGΒ purified from urinary hCG (i.e., standard hCG0) or (b) antiserum directed to the CTP in standard hCGΒ. CTP-directed RIA recognized a peak of hCGΒ-Iike immunoreactive material that eluted in the same position as standard hCGΒ. However, core-directed RIA recognized additional hCGΒ-like material (i.e., ectopic β-II) most of which eluted before standard hCGΒ. CaSki cells were incubated with [H]mannose, [H]proline, and [H] leucine, and the spent medium was immunoprecipitated and analyzed by gel electrophoresis. Several labeled peaks were detected in the lane from the anti-hCGΒ •Sepharose immunoprecipitate, one of which corresponded in mobility to standard hCGΒ, with two more intense components migrating at higher apparent molecular weights. Carboxypeptidase Y digestion released only 0.2 mol equivalents each of [H]proline and [H]leucine from the labeled CaSki material immunoprecipitated with anti-hCGΒ • Sepharose, compared to 1 mol equivalent each in similar analysis of standard hCGΒ. These findings were consistent with the absence of the 4-carboxy-terminal amino acids from 80% of the hCGΒ-like immunoreactive material secreted by CaSki cells. The affinity purified ectopic β-II failed to combine with standard hCGα under conditions in which combination of standard hCGΒ with standard hCGα was essentially complete. Neither aggregation nor proteolytic degradation was the cause of failure of ectopic β-II to combine with hCGα. We conclude that both the DoT and CaSki cervical carcinoma cell lines secrete a distinctive form of hCGΒ-like material, ectopic β-II. Lack of recognition by CTP-directed antisera and amino acid analysis suggest that ectopic β-II may lack the CTP, despite its apparent larger size relative to standard hCGΒ.
|Original language||English (US)|
|Number of pages||7|
|State||Published - Apr 1986|
ASJC Scopus subject areas
- Cancer Research