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Solubilization and partial isolation of human melanoma tumor-associated antigens
Abstract:
Human melanoma cell membrane tumor-associated antigens (TAA's) were solubilized in an active form by pronase digestion of either a fresh melanoma or cells from a melanoma cell line maintained in tissue culture. Upon elution from Sephadex G-200 column, TAA's solubilized from the melanoma cell line were found in four distinct peaks that had apparent molecular weights of approximately 48,000 (partition coefficient Kd, 0.426), 25,000 (Kd, 0.567)8 17,000 (Kd, 0.699), and 13,000 (Kd, 0.831) daltons, respectively. Fetal antigen activity was found in all but the 13,000-dalton peak. HLA antigen activity was detected in the 17,000-dalton material. TAA's prepared from the fresh tumor source eluted from Sephadex G-200 column with an apparent molecular weight of 14,000-25,000 (Kd, 0.786-0.572) daltons, as did HLA antigens. A partial resolution of the TAA's from the HLA antigens was achieved with the use of DEAE-cellulose chromatography. Results of antigenic stability assays suggested that the TAA structure is stable to prolonged exposure to low pH. Recovery of TAA activity from the strong denaturing agents 5 m urea, 0.5% (wt/vol) sodium dodecyl sulfate, and 4 m guanidine hydrochloride was partially successful. These properties of the TAA's may be useful for further isolation of the TAA's.
Insights
Researchers isolated active human melanoma tumor-associated antigens (TAAs) using pronase digestion. These TAAs, with varying molecular weights, showed stability and partial recovery from denaturing agents, aiding further isolation.
Area of Science:
- Immunology
- Biochemistry
- Oncology
Background:
- Melanoma cell membranes contain tumor-associated antigens (TAAs) that are potential targets for cancer therapy.
- Solubilizing TAAs in an active form is crucial for their characterization and therapeutic development.
Purpose of the Study:
- To solubilize and characterize active human melanoma tumor-associated antigens (TAAs).
- To investigate the molecular properties, stability, and potential for isolation of these TAAs.
Main Methods:
- Pronase digestion of melanoma cells (fresh and cell line) to solubilize TAAs.
- Sephadex G-200 gel filtration chromatography to determine molecular weights.
- DEAE-cellulose chromatography for partial antigen resolution.
- Antigenic stability assays and recovery tests using denaturing agents.
Main Results:
- TAAs from a melanoma cell line eluted in four peaks with molecular weights of approximately 48,000, 25,000, 17,000, and 13,000 daltons.
- Fetal antigen activity was present in all peaks except the 13,000-dalton one; HLA antigen activity was detected in the 17,000-dalton material.
- TAAs from fresh tumors and HLA antigens showed similar elution profiles (14,000-25,000 daltons) on Sephadex G-200.
- Partial separation of TAAs from HLA antigens was achieved using DEAE-cellulose chromatography.
- Melanoma TAAs demonstrated stability to low pH and partial recovery from urea, SDS, and guanidine hydrochloride.
Conclusions:
- Pronase digestion effectively solubilizes active human melanoma TAAs.
- Melanoma TAAs exhibit diverse molecular weights and partial separation from HLA antigens is possible.
- The observed stability and partial recovery suggest these TAAs can be further purified for potential therapeutic applications.