Collagenolytic activities of squamous cell carcinoma of the skin.

Electron microscopic and physicochemical studies on collagenolytic activities of squamous cell carcinomas of the skin were performed. Collagen and basal lamina de generation was evident in the stroma immediately sur rounding the squamous cell carcinomas. With the excep tion of fine filament aggregations with periodical crossbands at 1000-A intervals, amorphous debris, and intact elastic Tibers, the peri-squamous cell carcinoma stroma was empty. A large number of villous projections from the ad vancing border of the squamous cell carcinomas perforated the basal lamina. An amorphous coat of the elastic fibers produced hemidesmosomes with tumor cells. Electron microscopic examination of segment-long-spacing tropocollagen prepared from squamous cell carcinoma homogenate-treated calf skin collagen revealed molecules cleaved at the (822region. Squamous cell carcinoma homogenates released significantly higher radioactivity from proline14C-labeled guinea pig collagen than did the normal skin control. Caseinolytic activity of squamous cell carcinoma homogenate was higher than that of the normal skin, but soybean trypsin inhibitor inhibited collagenolysis only 12.7%. Known collagenase inhibitors such as normal human serum (10%) ethylenediaminetetraacetic acid (0.01 M), and cysteine (0.01 M), on the other hand, inhibited collagenol ysis 75, 70, and 57.2%, respectively. Disc electrophoresis of the reaction mixture showed degradation bands of a and ßchains. Specific viscosity of tropocollagen decreased by 42% after 24 hr of incubation with squamous cell carci noma homogenate. The melting temperature midpoint of tropocollagen dropped about 10°as a result of incubation