Matrix metalloproteinases 2 and 9 in situ mRNA expression in colorectal tumors from Iraqi patients

Matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9) preferentially degrade the basement membrane, a key step in tumor invasion, metastases, and induction of vascularization of tumor tissue.

To determine MMP-2 and MMP-9 in situ mRNA expressions in colorectal adenocarcinomas from Iraqi patients.

Forty archived paraffin-embedded colorectal adenocarcinoma samples and their resection margins were enrolled in our study. Thin paraffin embedded sections (3-5 μm thick) of both tumor and resection margins were prepared for each respective biopsy and were used to detect MMP-2 and MMP-9 in situ mRNA expressions based on in situ hybridization technique.

Statistical analyses were conducted to describe different variables and parameters in this research, and to describe relationships with each other as well. For the comparisons, the t test of significance was used. The associations were found by chi-square (χ2 ) and analysis of variance (ANOVA) tests, or as appropriate, as well as 95% confidence interval. The correlations were calculated using correlation coefficient (r). Statistical significance was defined as P < 0.05.

Based on the current outcome, there were significant differences in MMP-2 and MMP-9 in situ mRNA expressions when each tumor sample were compared to its respective resection margin (P < 0.001 and P < 0.001, respectively). When tumor samples were analyzed based on their depth of invasion, means of in situ mRNA expressions of both MMP-2 and MMP-9 were significantly increased in the group in which tumor invaded submucosa into muscularis properia (SMP) compared to that of tumor in serosa (SE) group and tumor invading other organs (OR) group (P < 0.05 and P < 0.05, respectively). Furthermore, when tumor lymph node metastases were questioned, exclusively, MMP-2 in situ mRNA expression was significantly differentiated among N0, N1, and N2 groups (P < 0.05). Regarding the possible correlation between the two investigated parameters with respect to various histopathological variables, both MMP-2 and MMP-9 in situ mRNA expressions have significant positive correlation in tumor samples (r = 0.88), whereas in resection margins, this correlation was absent. Interestingly, MMP-2 and MMP-9 in situ mRNA expressions were found to correlate positively as well as significantly within tumor differentiation [well-differentiated (WD) adenocarcinoma: r = 0.78; moderately differentiated (MD) adenocarcinoma: r = 0.90; and poorly differentiated (PD) adenocarcinoma: r = 0.91], tumor stage (A-B: r = 0.70 and C-D: r = 0.95), depth of invasion (SMP: r = 0.77; SE: r = 0.87; and OR: r = 0.97), lymph node metastasis (N0: r = 0.82; N1: r = 0.92; and N2: r = 0.96), and tumor size (<3 mm 3 : r = 0.76 versus ≥3 mm3: r = 0.94).

Overexpression of MMP-2 and MMP-9 are often associated with increased invasive metastatic potential of colorectal adenocarcinoma. However, their activities are essential during the early stages of tumor progression.