Targeting metastatic breast cancer with peptide epitopes derived from autocatalytic loop of Prss14/ST14 membrane serine protease and with monoclonal antibodies

Abstract

Background In order to develop a new immunotherapeutic agent targeting metastatic breast cancers, we chose to utilize autocatalytic feature of the membrane serine protease Prss14/ST14, a specific prognosis marker for ER negative breast cancer as a target molecule. Methods The study was conducted using three mouse breast cancer models, 4 T1 and E0771 mouse breast cancer cells into their syngeneic hosts, and an MMTV-PyMT transgenic mouse strain was used. Prss14/ST14 knockdown cells were used to test function in tumor growth and metastasis, peptides derived from the autocatalytic loop for activation were tested as preventive metastasis vaccine, and monoclonal and humanized antibodies to the same epitope were tested as new therapeutic candidates. ELISA, immunoprecipitation, Immunofluorescent staining, and flow cytometry were used to examine antigen binding. The functions of antibodies were tested in vitro for cell migration and in vivo for tumor growth and metastasis. Results Prss14/ST14 is critically involved in the metastasis of breast cancer and poor survival rather than primary tumor growth in two mouse models. The epitopes derived from the specific autocatalytic loop region of Prss14/ST14, based on structural modeling acted as efficient preventive metastasis vaccines in mice. A new specific monoclonal antibody mAb3F3 generated against the engineered loop structure could reduce cell migration, eliminate metastasis in PyMT mice, and can detect the Prss14/ST14 protein expressed in various human cancer cells. Humanized antibody huAb3F3 maintained the specificity and reduced the migration of human breast cancer cells in vitro. Conclusion Our study demonstrates that Prss14/ST14 is an important target for modulating metastasis. Our newly developed hybridoma mAbs and humanized antibody can be further developed as new promising candidates for the use in diagnosis and in immunotherapy of human metastatic breast cancer. Electronic supplementary material The online version of this article (10.1186/s13046-019-1373-y) contains supplementary material, which is available to authorized users.

Critical Adjuvant Influences on Preventive Anti-Metastasis Vaccine Using a Structural Epitope Derived from Membrane Type Protease PRSS14

“…Typically, adjuvants are compounds that enhance the quality, potency and longevity of antigen-specific immune responses. Freund's complete adjuvant (CFA), a water-in-oil emulsion containing inactivated mycobacteria, generally appears to induce a T H 1 type immune response ( 8 9 ). In addition, Freund's incomplete adjuvant (IFA) without mycobacteria, together with CFA can induce effective T H 1 and T H 2 type immune responses ( 8 ).…”

“…However, the method by which alum modifies the immune system has not been fully understood. It is shown to induce a strong T H 2 immune response ( 9 11 ) and is also linked to serious autoimmune outcomes and adverse effects including association with breast cancer induction ( 12 13 ).…”

“…When Prss14 hypomorphic mice, which express a minimal amount of Prss14, were crossed into spontaneous breast cancer transgenic mice, mouse mammary tumor virus (MMTV)-polyoma middle tumor-antigen (PyMT), tumor growth was significantly reduced ( 22 ). When breast cancer cell lines with Prss14 knocked down were implanted into syngeneic mouse strains, tumor growth and metastasis were reduced ( 9 23 ). In addition, the survival of patients that highly express PRSS14 (suppression of tumorigenicity 14 [ST14]) was remarkably low, especially in estrogen receptor negative (ER − ) or triple negative breast cancer patients ( 21 ).…”

“…Since Prss14 is capable of autoactivation, it can lead to activation of multiple downstream substrates ( 24 25 ). Recently, we reported that a structural epitope derived from a functionally important motif in the autoactivation loop of Prss14 can behave as an effective preventive metastasis vaccine (i.e., loop metavaccine) in 2 mouse models ( 9 ). Immunization of loop metavaccine increased the survival rate and decreased lung metastasis in tail-vein injection of E0771 or 4T1 into syngenic C57BL/6 (T H 1) or Balb/c (T H 2) hosts, respectively.…”

A JUN N-terminal kinase inhibitor induces ectodomain shedding of the cancer-associated membrane protease Prss14/epithin via protein kinase CβII

“…We have reported that knockdown of Prss14/epithin reduces cell migration (9,10) and metastatic ability of breast cancer cells such as 4T1 (9) and EO771 (11). When a specific monoclonal antibody raised against the activation loop portion of Prss14/epithin was injected into a PyMT breast cancer mouse model, metastasis was significantly reduced (11).…”