Protective antitumor immunity induced by tumor cell lysates conjugated with diphtheria toxin and adjuvant epitope in mouse breast tumor models

Abstract

Cancer cell vaccine-based immunotherapy has received increasing interest in many clinical trials involving patients with breast cancer. Combining with appropriate adjuvants can enhance the weak immunogenic properties of tumor cell lysates (TCL). In this study, diphtheria toxin (DT) and two tandem repeats of mycobacterial heat shock protein 70 (mHSP70) fragment 407-426 (M2) were conjugated to TCL with glutaraldehyde, and the constructed cancer cell vaccine was named DT-TCL-M2. Subcutaneous injection of DT-TCL-M2 in mice effectively elicited tumor-specific polyclonal immune responses, including humoral and cellular immune responses. High levels of antibodies against TCL were detected in the serum of immunized mice with ELISA and verified with Western blot analyses. The splenocytes from immunized mice showed potent cytotoxicity on Ehrlich ascites carcinoma cells. Moreover, the protective antitumor immunity induced by DT-TCL-M2 inhibited tumor growth in a mouse breast tumor model. DT-TCL-M2 also attenuated tumor-induced angiogenesis and slowed tumor growth in a mouse intradermal tumor model. These findings demonstrate that TCL conjugated with appropriate adjuvants induced effective antitumor immunity in vivo. Improvements in potency could further make cancer cell vaccines a useful and safe method for preventing cancer recurrence after resection.

Diversity of extracellular HSP70 in cancer: advancing from a molecular biomarker to a novel therapeutic target

“…Therefore, using them as vaccines can generate robust anti-tumor immune responses in a wide range of cancers (223). Fusion diphtheria toxin (DT) and two tandem repeats of HSP70 407-426 with TCLs elicit strong humoral and cellular immune responses, leading to the growth inhibition of breast cancer (178). In addition, a tumor-derived autophagosome (Dribble) vaccine conjugated with HSP70 407-426 significantly induced a higher expression of antigen-specific cytotoxic T lymphocytes (CTLs) (179).…”

HSP70 Family in Cancer: Signaling Mechanisms and Therapeutic Advances

“…Other TAAs and TSAs, such as alpha-fetoprotein (AFP), which is over-expressed in the majority of hepatocellular carcinoma, and prostate stem cell antigen (PSCA), which is associated with the development of prostate cancer, also showed great synergistic effect with HSP70 in multiple cancers [ 203 , 204 , 205 , 206 , 207 , 208 , 209 , 210 , 211 ]. A tumor cell lysate vaccine that was conjugated to diphtheria toxin (DT) and two tandem repeats of M2 peptide had protective anti-tumor immunity in a mouse breast tumor model [ 212 ]. Additionally, research regarding vaccine delivery approaches is ongoing [ 198 , 199 , 200 , 201 ].…”

In�vivo antitumor activity evaluation of cancer vaccines prepared by various antigen forms in a murine hepatocellular carcinoma model

“…In particular, along with the development of tumor adjuvant, the efficiency of whole tumor cell vaccines has been markedly improved. In a previous study, a whole hepatocellular carcinoma cell lysate-based vaccine with diphtheria toxin and two tandem repeats of mycobacterial HSP70 fragment 407–426 (M 2 ) as adjuvant exhibited modest antitumor effects in the preventive procedure ( 10 , 11 ).…”