Loss of MMP-8 accelerates tumor onset; promotes progression, tumor size and lung macrometastases in the MMTV-PyMT model.

A) Detection of first palpable tumors of MMTV-PyMT; Mmp8 wild-type (WT, n = 17), MMTV-PyMT; Mmp8 heterozygote (HET, n = 30) and MMTV-PyMT; Mmp8 null (KO, n = 10) mice. Mean ± sem, 2-tailed unpaired t-test; * p < 0.05; ** p < 0.01. B) Tumor progression determined by palpation of all 10 mammary glands from day 21 to day 98 for MMTV-PyMT; Mmp8 wild-type (WT, n = 26), heterozygote (HET, n = 34) and null (KO, n = 21) mice. C) Tumor size distribution (0, < 0.5, 0.5-1, >1 cm) at 10 weeks of age for MMTV-PyMT; Mmp8 wild-type (WT, n = 26), MMTV-PyMT; Mmp8 heterozygote (HET, n = 34) and MMTV-PyMT; Mmp8 null (KO, n = 21) mice; and at 14 weeks of age for MMTV-PyMT; Mmp8 wild-type (WT, n = 22), MMTV-PyMT; Mmp8 heterozygote (HET, n = 30) and MMTV-PyMT; Mmp8 null (KO, n = 16) mice. Chi-square test, * p < 0.01. D) Number of lung macrometastases assessed at 14 weeks of age for MMTVPyMT; Mmp8 wild-type (WT, n = 4), MMTV-PyMT; Mmp8 heterozygote (HET, n = 4) and MMTV-PyMT; Mmp8 null (KO, n = 2) mice. Left panel of representative pictures depicts the top and bottom of all lung lobes (1 lobe of the left lung, 4 lobes of the right lung). Black solid arrows = smaller macrometastases, white solid arrows = larger macrometastases. Mean ± sem, 2-tailed unpaired t-test; ** p < 0.01.