1. Identification of a novel immunogenic HLA-A*0201-binding epitope of HER-2/neu with potent antitumor properties
Angelos D Gritzapis, et al. J Immunol. 2008 Jul 1;181(1):146-54. doi: 10.4049/jimmunol.181.1.146.
HER-2/neu oncoprotein is overexpressed in a variety of human tumors and is associated with aggressive disease. Immunogenic HER-2/neu CTL epitopes have been used as vaccines for the treatment of HER-2/neu positive malignancies with limited success. By applying prediction algorithms for MHC class I ligands and proteosomal cleavages, in this study, we describe the identification of HER-2/neu decamer LIAHNQVRQV spanning residues 85-94 (HER-2(10(85))). HER-2(10(85)) proved to bind with high affinity to HLA-A2.1 and was stable for 4 h in an off-kinetics assay. This peptide was immunogenic in HLA-A2.1 transgenic (HHD) mice inducing peptide-specific CTL, which responded to tumor cell lines of various origin coexpressing human HER-2/neu and HLA-A2.1. This demonstrates that HER-2(10(85)) is naturally processed from endogenous HER-2/neu. Five of sixteen HER-2/neu+ HLA-A2.1+ breast cancer patients analyzed had HER-2(10(85))-reactive T cells ranging from 0.35-0.70% of CD8+ T cells. Depletion of T regulatory cells from PBMC enabled the rapid expansion of HLA-A2.1/HER-2(10(85))pentamer+/CD8+ cells (PENT+/CD8+), whereas significantly lower numbers of CTL could be generated from unfractionated PBMC. HER-2(10(85))-specific human CTL recognized the HER-2/neu+ HLA-A2.1+ tumor cell line SKBR3.A2, as determined by IFN-gamma intracellular staining and in the high sensitivity CD107alpha degranulation assay. Finally, HER-2(10(85)) significantly prolonged the survival of HHD mice inoculated with the transplantable ALC.A2.1.HER tumor both in prophylactic and therapeutic settings. These data demonstrate that HER-2(10(85)) is an immunogenic peptide, capable of eliciting CD8-mediated responses in vitro and in vivo, providing the platform for further exploitation of HER-2(10(85)) as a possible target for anticancer immunotherapy.
2. Breast cancer sphingosine-1-phosphate is associated with phospho-sphingosine kinase 1 and lymphatic metastasis
Junko Tsuchida, Masayuki Nagahashi, Masato Nakajima, Kazuki Moro, Kumiko Tatsuda, Rajesh Ramanathan, Kazuaki Takabe, Toshifumi Wakai J Surg Res. 2016 Sep;205(1):85-94. doi: 10.1016/j.jss.2016.06.022. Epub 2016 Jun 16.
Background: Sphingosine-1-phosphate (S1P), a pleiotropic bioactive lipid mediator, has been implicated as a key regulatory molecule in cancer through its ability to promote cell proliferation, migration, angiogenesis, and lymphangiogenesis. Previous studies suggested that S1P produced by sphingosine kinase 1 (SphK1) in breast cancer plays important roles in progression of disease and metastasis. However, the associations between S1P and clinical parameters in human breast cancer have not been well investigated to date. Materials and methods: We determined levels of S1P and other sphingolipids in breast cancer tissue by electrospray ionization-tandem mass spectrometry. Associations between S1P levels and clinicopathologic features of the tumors were analyzed. Expression of phospho-SphK1 (pSphK1) in breast cancer tissues was determined by immunohistochemical scoring. Results: Levels of S1P in breast cancer tissues were significantly higher in patients with high white blood cell count in the blood than those patients without. S1P levels were lower in patients with human epidermal growth factor receptor 2 overexpression and/or amplification than those patients without. Furthermore, cancer tissues with high pSphK1 expression showed significantly higher levels of S1P than cancer tissues without. Finally, patients with lymph node metastasis showed significantly higher levels of S1P in tumor tissues than the patients with negative nodes. Conclusions: To our knowledge, this is the first study to demonstrate that high expression of pSphK1 is associated with higher levels of S1P, which in turn is associated with lymphatic metastasis in breast cancer.
3. Ontak reduces the immunosuppressive tumor environment and enhances successful therapeutic vaccination in HER-2/neu-tolerant mice
Angelos D Gritzapis, Ioannis F Voutsas, Constantin N Baxevanis Cancer Immunol Immunother. 2012 Mar;61(3):397-407. doi: 10.1007/s00262-011-1113-4. Epub 2011 Sep 18.
Disrupting tumor-mediated mechanisms suppressing host immunity represents a novel approach to tumor immunotherapy. Depletion of regulatory T cells (Tregs) increases endogenous anti-tumor immunity and the efficacy of active immunotherapy in experimental tumor models. HLA-A2.1/HLA-DR1 (A2.1/DR1) × BALB- neuT+ (neuT+) triple transgenic mice represent an improvement over neuT+ mice for evaluating vaccination regimens to overcome tolerance against HER-2/neu. We questioned whether depletion of Tregs with Denileukin diftitox (Ontak) enhances the efficacy of a therapeutic vaccine consisting of HER-2(85-94) (p85) CTL and HER-2(776-790) (p776) Th peptides against the growth of TUBO.A2 transplantable tumor in male A2.1/DR1 × neuT+ Tg mice. While the therapeutic vaccine primed the tumor-reactive CD8+ CTLs and CD4+ effector T lymphocytes (Teffs) compartment, inducing activation, tumor infiltration, and tumor rejection or delay in tumor growth, treatment with Ontak 1 day prior to vaccination resulted in enhanced CD4+ and CD8+ T-cell-mediated vaccine-specific immune responses in the periphery. This was closely associated with greater infiltration and a striking change in the intratumor balance of Tregs and vaccine-specific CTLs/Teffs that directly correlated with markedly enhanced antitumor activity. The data suggest that Tregs control both CD4+ and CD8+ T-cell activity within the tumor, emphasize the importance of the intratumor ratio of vaccine-specific lymphocytes to Tregs, and demonstrate significant inversion of this ratio and correlation with tumor rejection during Ontak/vaccine immunotherapy.
