Plasma MMP-2 and MMP-7 levels are elevated first month after surgery and may promote growth of residual metastases

ARTICLE HIGHLIGHTS

Research background

Major abdominal surgery is known to results a brief period of immunosuppression and short lived plasma protein alterations. In past decade it has been shown that minimally invasive colorectal cancer resection (MICR) is associated with elevated levels of at least 8 plasma proteins after surgery that play major role in angiogenesis. Angiogenic proteins included on this list are vascular endothelial-derived growth factor (VEGF), angiopoeitin-2, placental growth factor, soluble vascular adhesion molecule-1 (sVCAM-1), monocyte chemotactic protein-1 (MCP-1), interleukin 8 (IL-8) and matrix metalloproteinase-3 (MMP-3). The plasma from the second and third postoperative weeks stimulates in vitro endothelial cell proliferation, migration and invasions which are critical for angiogenesis suggests that post colorectal surgery plasma bears proangiogenic property. The impact of MICR for colorectal cancer (CRC) on plasma levels of MMP-2 and MMP-7 is unknown.

Research motivation

MMP-2 and MMP-7 are two proteins that play a key role in angiogenesis whose postoperative blood levels have not been thoroughly studied investigated. Both proteins are members of the large zinc dependent MMP family that breaks down extracellular matrix (ECM) proteins. Based on their substrate specificities MMP-2 and MMP-7 are grouped in the gelatinase and matrilysin sub families, respectively. MMP-2 degrades gelatin and the following ECM components; collagen (types IV, V, VII and X), decorin, elastin, and fibronectin. MMP-2 ECM degradation releases increase bioavailability of angiogenic VEGF and transforming growth factor β. MMP-2 promotes tumor cell invasion and metastasis because of its high specificity for type IV collagen. MMP-7 is produced in normal large bowel epithelium as well as in cancer cells and is associated with tumor invasion and metastasis by virtue of the damage it incurs to the basement membrane. MMP-7, like MMP-2, has a high affinity for numerous ECM proteins. MMP-7 related vascular basement membrane degradation has been shown to facilitate hematogenous metastasis. Overexpression of MMP-2 and MMP-7 activity has been linked to a poor prognosis in many cancers including CRC has been associated with tumor progression. The impact of MICR for CRC on plasma levels of MMP-2 and MMP-7 is unknown. Motivation of this study was to assess plasma MMP-2 and MMP-7 levels during first month after MICR for CRC.

Research objectives

The objective of this study was to determine plasma MMP-2 and MMP-7 levels during first month after minimally invasive colorectal resection at various postoperative time points, which include the first blood draw on the day of operation before surgery, the second on post-operative day 1 (POD 1), the third on POD 3, and additional four time points between POD 7 and POD 34. The hypothesis was that if blood levels of proangiogenic MMP-2 and MMP-7, which play major roles in wound healing, remain elevated for month after surgery would confirm that surgery has long lasting systemic manifestations that have the potential to influence growth in residual cancer after surgery and metastasis.

Research methods

This study analyzed colorectal patients who underwent elective surgery for cancer pathology. Plasma was obtained from IRB approved perioperative tissue and data bank. The clinical, demographic and pathologic data was prospectively gathered. Blood samples were obtained preoperative (Preop) and at varying postop time points and were stored at -80 °C. Blood samples were obtained from consented patients Preop and at varying postop time points. Late post op samples were collected during follow-up visits. Because of the fewer specimens taken after POD 3, the 7 d blocks were bundled and considered as single time points (POD 7-13, POD 14-20, POD21-27, and POD 28-34). Plasma MMP2 and MMP7 protein levels were determined in duplicate via highly specific commercially available Enzyme-linked Immunosorbent Assays. Demographic and clinical data are expressed as the mean ± SD for continuous variables. The Wilcoxon signed rank test was used for MMP-2 and MMP-7 data preop vs postop comparisons. Other comparisons (males vs females, surgical methods, etc.) were carried out using the Mann Whitney test. Correlation between plasma MMP-2/MMP-7 levels and age, incision size and length of surgery were assessed by the Spearman's rank correlation coefficient (rs).

Research results

A total of 88 CRC patients were studied. Majority of patients (62%) underwent laparoscopic assisted resection whereas 38% had a hand-assisted MIS procedure. The most common resection performed was right colectomy (37%) followed by sigmoid (24%) and rectal resection (18%). The cancer stage breakdown was: Stage 1, 31%; Stage 2, 30%; stage 3, 34%; and stage 4, 5%. The mean Preop MMP-2 level (ng/mL) was 179.3 ± 40.9. Significantly elevated mean plasma levels were noted on POD 1 (214.3 ± 51.2, P < 0.001), POD 3 (258.0 ± 63.9, P < 0.001), POD 7-13 (229.9 ± 62.3, P < 0.001), POD 14-20 (234.9 ± 47.5, P < 0.001), POD 21-27 (237.0 ± 63.5, P < 0.001) and on POD 28-34 time point (255.4 ± 59.7, P < 0.001). The mean Preop MMP-7 level (ng/mL) was 3.9 ± 1.9. When compared to Preop levels, no significant differences were noted on POD 1 or 3, however, significantly elevated mean plasma levels were noted on POD 7-13 (5.7 ± 2.5, P < 0.001), POD 14-20 (5.9 ± 2.5, P < 0.001), POD 21-27 (6.1 ± 3.6, P = 0.002) and on POD 28-34 (6.8 ± 3.3, P < 0.001) when compared to Preop levels. Furthermore, when the postop results of the rectal and colon cancer subgroups were compared, no significant differences were noted for either protein. Likewise, the choice of surgical method (laparoscopic vs hand-assisted laparoscopic) did not significantly influence the postoperative plasma levels of these 2 proteins.

Research conclusions

This study reports plasma MMP-2 levels are elevated for 5 wk and MMP-7 levels elevated for weeks 2-6 after minimally invasive CRC for cancer pathology. Mean MMP-2 levels were found to be significantly elevated during weeks 1 through 5 after surgery (change from mean baseline varied from 22% to 43%). This study revealed that MMP-2, therefore, fits the pattern noted for almost all of the other blood proteins (such as VEGF, PlGF, ANG2, sVCAM-1, MCP1, CHI3L1, MMP-3, IL-8) noted to have long duration elevations, namely both early and late postop increases. MMP-7 is unique because although its levels are significantly increased during weeks 2-5 (change from mean baseline varied from 41%-46%), during the first 3 d after surgery plasma levels were not significantly altered. The MMP-7 results support the concept that, perhaps, that the etiology of the early and late protein elevations are different. The etiology of these short lived blood protein elevations is likely to include anesthesia, surgical trauma, and the acute inflammatory response. The etiology of the later postop plasma changes is unclear, however, there is evidence that at least 1 source of the added proteins are the healing wounds. It is postulated that the notably increased levels of these proteins in the wounds are the result of healing related angiogenesis; as a result of diffusion along concentration gradients, blood levels of these proteins subsequently increase. The persistent wound fluid elevations of these proteins also confirms that angiogenesis plays a prominent role in wound healing. It is the authors’ position that the first month after MICR (or any major operation) may be a dangerous period for cancer patients with residual disease due to elevated levels blood levels of MMP-2 and MMP-7, which play roles in both wound healing and tumor growth.

Research perspectives

Plasma MMP-2 and MMP-7, which play important roles in both wound healing and tumor growth, are elevated after surgery for over 1 mo. The findings of this study will add 2 more angiogenic proteins to the growing list of proangiogenic proteins which includes VEGF, PlGF, ANG2, sVCAM-1, MCP1, CHI3L1, MMP-3 and IL-8 that shown to be elevated post MICR for up to 5 wk. The results of this study add further evidence and support for the concept that the first month after MICR (or any major operation) may be a dangerous period for cancer patients with residual disease. All of these proteins have proangiogenic effects and plasma from the 2^nd and 3^rd postop weeks has been shown to stimulate Endothelial Cell invasion, migration, and proliferation which are critical steps in neovascularization. Additionally, previous study showed that simultaneously measured perioperative levels of 8 proangiogenic proteins in both the blood and fluid from surgical wounds for up to 3 wk after MICR, it was noted that wound fluid protein levels were 3-40 times higher than plasma levels which, in turn, were significantly elevated from preop plasma baseline levels. It is postulated that the notably increased levels of these proteins in the wounds are the result of healing related angiogenesis; as a result of diffusion along concentration gradients, blood levels of these proteins subsequently increase. The persistent wound fluid elevations of these proteins also confirms that angiogenesis plays a prominent role in wound healing. These findings raise the possibility that the elevated proangiogenic postop plasma might stimulate tumor angiogenesis in residual metastases, thus stimulating tumor growth early postoperatively. This study further supports the idea of administration of anti-cancer agents during the first month after surgery. Adjuvant chemotherapy is usually started 4-8 wk after surgery. The use of standard chemotherapeutic agents is problematic since these agents may interfere with wound and anastomotic healing. Immunotherapies (vaccines, select monoclonal antibodies, immunomodulators) and other anti-cancer agents that do not interfere with wound healing, however, might be given during the first month after surgery.