Figure 5. PLX4720 and JNK inhibition dramatically accelerate cSCC development in the UV-driven Hairless mouse model.

(A–E) Chronically-irradiated Hairless mice were treated with PLX4720 (n = 5), or vehicle (n = 5) starting at day 72 (arrow, E). Tumors were induced within 20 days of PLX-4720 treatment (B), whereas only erythema was seen in control animals (A). The tumors in PLX4720-treated mice progressed to well-differentiated cSCC (C, scale bar 75 μm), steadily increasing in size and number (D, day 132). (E) Even at 150 days (78 days of drug treatment), only PLX4720-treated mice had tumors and the differences in tumor number persisted throughout (‘**’, p=0.0026). (F–J) cSCC from mice were harvested and assessed for phospho-JNK and cleaved caspase 3 expression by immunohistochemistry. Tumors from PLX4720-treated animals showed significantly lower levels of phospho-JNK (G) and cleaved caspase 3 (I) as compared to control-treated animals (F and H). Differences in these parameters were significant across all comparisons (J, ‘*’, p<0.05).

DOI: http://dx.doi.org/10.7554/eLife.00969.020

Figure 5—figure supplement 1. cSCC and papillomas arising in Hairless mice treated with PLX4720 do not have Ras mutations.

(A and B) cDNA was reverse-transcribed from total RNA, PCR-amplified with the above primers (B) and analyzed by Sanger sequencing for mutations in both directions. No mutations in Hras, Kras, or Nras were detected in any of the papillomas (n = 5) or carcinomas (n = 3) isolated from PLX4720-treated mice. One of the papillomas from untreated mice had a heterozygous point mutation (A) in Hras (G35A, G12E) among 14 samples (12 papillomas, 2 cSCC).

DOI: http://dx.doi.org/10.7554/eLife.00969.021