Matrix metalloproteinases 2 and 9 (MMP2 and MMP9) are proteolytic enzymes involved with extracellular matrix degradation. They play a role in tumor invasion and metastases. Be- cause of their ability to degrade signaling molecules presented in extracellular matrix, MMPs contribute to tumor proliferation and apoptosis. The aim of this study was to evaluate expression of MMP2 (latent and both active and latent forms) and MMP9 (active, latent, active and latent forms) in different subtypes of canine lymphomas and their relationship with proliferative (mi- totic index and percentage of Ki67-positive cells) and apoptotic (apoptotic index) markers. Ex- pression of MMPs was assessed immunohistochemically using an immunoreactive score system. Expression of both MMPs was found in all 20 examined lymphomas belonging to six subtypes. Most cases showed a moderate level of all analyzed forms of MMP2 and MMP9. High expres- sion of MMPs was found in single cases. Except for a positive correlation between the active form of MMP9 and the mitotic index for all lymphoma cases, no other correlations between any remaining forms of MMPs and neither proliferative nor apoptotic markers were found, irrespec- tive of whether the analysis encompassed all cases or the most numerous lymphoma subtypes i.e. centroblastic and Burkitt-like. Our results were not able to clearly confirm the influence of MMPs on the proliferation and apoptotic activity of canine lymphoma cells. However, further studies examining MMPs activity by zymography, expression of their inhibitors and other factors in- volved in activation of cell proliferation and apoptosis inhibition are needed to clarify the role of MMPs, especially the active form of MMP9, in the behavior of canine lymphoma cells.

This study aimed to determine the effects of dexamethasone and minocycline alone and combined treatment with N-acetylcysteine (NAC) and vitamin E on serum coenzyme Q10 (CoQ10) and matrix metalloproteinase-9 (MMP-9) levels in rats administered aflatoxin B1 (AFB1). The study was carried out on 66 male Wistar rats. Following the intraperitoneal (IP) administration of AFB1 at dose of 2 mg/kg, minocycline (45 and 90 mg/kg, IP) and dexamethasone (5 and 20 mg/kg, IP) were administered alone and combined with NAC (200 mg/kg, IP) and vitamin E (600 mg/kg, IP). CoQ10 and MMP-9 levels were analyzed using the HPLC-UV method and a commercial kit by ELISA, respectively. AFB1 increased MMP-9 level and decreased CoQ10 level compared to the control group. After dexamethasone and minocycline administration, there is no increase in CoQ10 level, which is caused by AFB1. However, dexamethasone and minocycline combined with NAC+vitamin E caused significant increases in CoQ10 levels. Dexamethasone and minocycline alone and combined with NAC+vitamin E decreased MMP-9 levels compared to the single AFB1 treated group. The use of MMPs inhibitors and oxidative stress-reducing agents is anticipated to be beneficial in the poisoning with AFB1.