Figure 3.

Abnormal laminin γ2 expression by premalignant keratinocytes. A: Lamγ2 immunofluorescence-stained confluent cultures of normal oral keratinocyte line OKF6, premalignant dysplastic oral keratinocyte lines POE9n and D17, normal epidermal keratinocyte line strain N, and strain N transduced to express the HPV16 E6 and E7 oncoproteins (N/E6E7). Note continued Lamγ2 expression at confluence by POE9n, D17, and N/E6E7 in contrast to repression of Lamγ2 under this condition by normal keratinocytes. Scale bar = 200 μm. B: Left: Lamγ2 Western blots of low-density (L) and high-density (H) cultures of the same cell lines, confirming lack of γ2 repression at confluence by POE9n, D17, and N/E6E7. Right: Lamγ2 Western blots of N/E7, N/E6, N/E6JH26, and of strain N transduced to express a dominant-negative mutant p53 and a p16^INK4A-resistant mutant cdk4 (N/p/c), showing that E6 alone can dysregulate Lamγ2, and that functional loss of p53 is not involved in this dysregulation. Densitometric quantification of each band is shown below the blots. The Lamγ2 level (normalized to its actin band) of the preconfluent culture of each cell line is set as 1 (gray bars), with the relative Lamγ2 level of the confluent culture shown for each cell line (black bars). Error bars indicate the results of quantifying scans of two exposures of each gel. The error bars show the results of the scans of two different exposure times of the same Western blot. The gray and black bars show the average of these two scans.