Background Pancreatic cancer (PC) is one of the most aggressive types of malignant tumors due to the fact, that early stages of the disease are asymptomatic and difficult to diagnose. Matrix metalloproteinases (MMP) play a key role in progression of early PC stages through proteolysis of collagen and a range of regulators that promotes tumor invasion and angiogenesis. MMPs are considered as promising therapeutic targets, but MMP inhibitors exhibit significant efficacy exclusively in a narrow time window, that makes it difficult to use them for prevention of local relapses. That is why MMP inhibitors and blocking antibodies demonstrated moderate results in clinical trials – progressive tumor stages could not be effectively treated with these agents, while their use in the early stages still looks very promising. The aim of the present work was to study the effects of long­term and preventive suppression of the activity of MT1­MMP (a key initiator of tumor proliferation and invasion) in pancreatic cancer using the approach of active immunization.

Methods We performed active immunization of SPF C57BL/6 mice using different variants of the vaccine: peptide fragments of MT1-MMP protein or DNA expression vectors coding these peptide fragments. 2-fold vaccine administration and serums collection were performed according to the previously published protocol.¹ The serums were collected on the 21 day of the experiment. We applied ELISA to estimate the levels of anti-MT1-MMP antibodies. The functional activity of the serums was tested using enzymatic assay and in vitro metastatic assay according to previously described protocols.²

Results We selected the serum containing high titers of anti-MT1-MMP antibodies which effectively suppressed MT1-­MMP activity in the absence of the effect on MMP­9. This feature of the serum is fundamental due to the fact, that MMP­9 is currently regarded as an undesirable target of anticancer therapy. The functional activity of selected serum and its ability to inhibit pancreatic cancer cell invasion was shown in an in vitro metastatic assay using the PC mouse cell line. In addition, we demonstrated the ability of this serum to inhibit the activity of MMP2 and TGF­β in conditioned mediums and lysates of PC cells, that suggests its additional anti­cancer properties associated with the suppression of the ability of MT1-­MMP to proteolytic activation of a number of tumor modulators.

Conclusions The selected mode could be used for effective immunization against MT1-MMP.

Acknowledgements This project is supported by grant 19-74-00096 from Russian Science Foundation.

References

1. Pavshintsev VV, Mitkin NA, Frolova OY, Kushnir EA, Averina OA, Lovat ML. Individual roles of brain and serum alcohol dehydrogenase isoforms in regulation of alcohol consumption in SPF Wistar rats. Physiology & behavior 2017;179:458–466.

2. Korneev KV, Sviriaeva EN, Mitkin NA, Gorbacheva AM, Uvarova AN, Ustiugova AS, Polanovsky OL, Kulakovskiy IV, Afanasyeva MA, Schwartz AM, Kuprash DV. Minor C allele of the SNP rs7873784 associated with rheumatoid arthritis and type-2 diabetes mellitus binds PU. 1 and enhances TLR4 expression. Biochimica et Biophysica Acta (BBA)-Molecular Basis of Disease 2020;1866(3):165626.