Immunization with heat shock protein 105-pulsed dendritic cells leads to tumor rejection in mice

HSP105 expression in cutaneous malignant melanoma: Correlation with clinicopathological characteristics

BACKGROUND

Heat shock proteins can protect against stress-associated cellular challenges, but they can also protect some tumors from human immune system monitoring. Heat shock protein 105 (HSP105/110) is a high molecular weight protein whose expression has been reported in many cancers, but few studies on its role in cutaneous malignant melanoma have been published. In this study, we analyzed the relationship between HSP105 expression and the clinicopathological characteristics of CMM.

METHODS

This retrospective study included 91 patients with CMM. The clinicopathological characteristics of CMM patients, including age, lesion duration, location, pathological classification, Clark's level, Breslow thickness, metastasis and recurrence, were collected. Immunohistochemical staining and Western blot analysis for HSP105 were performed. Pigmented nevi (n = 20) served as a control. The staining intensity and percentage of stained cells were expressed as a histochemical score (HSCORE).

RESULTS

HSP105 was overexpressed in melanoma compared with nevi. Differences in the HSCORE between nevi (HSCORE = 1.05(0.15,1.50)) and CMM (HSCORE = 2.68(1.80,3.60)) were remarkable (P<0.001). Exposed site lesions, recurrent and metastatic lesions, nodular melanoma and lentigo maligna melanoma were closely associated with higher HSP105 expression (P = 0.011, P = 0.001 and P = 0.001, respectively). Moreover, no significant difference was observed in Clark's level, Breslow thickness, or lesion duration (P>0.05).

CONCLUSION

HSP105 is overexpressed in CMM. Higher HSP105 expression in lesions is associated with different clinicopathological variables. HSP105 may be a potential target for the diagnosis, treatment and prognostic prediction of CMM.

Molecular Pathway Analysis Indicates a Distinct Metabolic Phenotype in Women With Right-Sided Colon Cancer

Colon cancer is the third most commonly diagnosed cancer in the United States. Recent reports have shown that the location of the primary tumor is of clinical importance. Patients with right-sided colon cancers (RCCs) (tumors arising between the cecum and proximal transverse colon) have poorer clinical outcomes than those with left-sided colon cancers (LCCs) (tumors arising between the distal transverse colon and sigmoid colon, excluding the rectum). Interestingly, women have a lower incidence of colon cancer than men, but have a higher propensity for RCC. The reason for this difference is not known; however, identification of sex-specific differences in gene expression by tumor anatomical location in the colon could provide further insight. Moreover, it could reveal important predictive markers for response to various treatments. This study provides a comprehensive bioinformatic analysis of various genes and molecular pathways that correlated with sex and anatomical location of colon cancers using four publicly available annotated data sets housed in the National Center for Biotechnology Information's Gene Expression Omnibus. We identified differentially expressed genes in tumor tissues from women with RCC, which showed attenuated energy and nutrient metabolism when compared with women with LCC. Specifically, we showed the downregulation of 5′ AMP-activated protein kinase alpha subunit (AMPKα) and anti-tumor immune responses in women with RCC. This difference was not seen when comparing tumor tissues from men with RCC to men with LCC. Therefore, women with RCC may have a specific metabolic and immune phenotype which accounts for differences in prognosis and treatment response.

Heat shock protein 105 peptide vaccine could induce antitumor immune reactions in a phase I clinical trial

Heat shock protein 105 (HSP105) is overexpressed in many cancers, including colorectal cancer (CRC) and esophageal cancer (EC). We carried out a phase I clinical trial of HLA-A24- and HLA-A2-restricted HSP105 peptide vaccines in patients with CRC or EC. In this additional study of the trial, we examined the immunological efficacy of the novel vaccine. Thirty patients with advanced CRC or EC underwent HSP105 peptide vaccination. Immunological responses were evaluated by ex vivo and in vitro γ-interferon enzyme-linked immunospot assays and their correlation with patients' prognosis was analyzed. The HSP105 peptide vaccines induced peptide-specific CTLs in 15 of 30 patients. Among HLA-A24 patients (n = 15), 7 showed induction of CTLs only ex vivo, whereas among HLA-A2 patients (n = 15), 4 showed the induction ex vivo and 6 in vitro. Heat shock protein 105-specific CTL induction correlated with suppression of cancer progression and was revealed as a potential predictive biomarker for progression-free survival (P = .008; hazard ratio = 3.03; 95% confidence interval, 1.34-6.85) and overall survival (P = .025; hazard ratio = 2.72; 95% confidence interval, 1.13-6.52). Production of cytokines by HSP105 peptide-specific CTLs was observed at the injection sites (skin) and tumor tissues, suggesting that HSP105-specific CTLs not only accumulated at vaccination sites but also infiltrated tumors. Furthermore, we established 2 HSP105 peptide-specific CTL clones, which showed HSP105-specific cytokine secretion and cytotoxicity. Our results suggest that the HSP105 peptide vaccine could induce immunological effects in cancer patients and improve their prognosis.

Identification of HLA-A2 or HLA-A24-restricted CTL epitopes for potential HSP105-targeted immunotherapy in colorectal cancer

We previously reported that heat shock protein 105 (HSP105) is overexpressed in a variety of human cancers, including colorectal, pancreatic and esophageal cancer and has proven to be a novel biomarker for the immunohistochemical detection of these cancers. In the present study, we used HLA-transgenic mice (Tgm) and the peripheral blood mononuclear cells (PBMCs) of colorectal cancer patients to identify HLA-A2 and HLA-A24-restricted HSP105 epitopes, as a means of expanding the application of HSP105-based immunotherapy to HLA-A2- or HLA-A24-positive cancer patients. In addition, we investigated by ex vivo IFN-γ ELISPOT assay whether the HSP105-derived peptide of cytotoxic T cells (CTLs) exists in PBMCs of pre-surgical colorectal cancer patients. We found that four peptides, HSP105 A2-7 (RLMNDMTAV), HSP105 A2-12 (KLMSSNSTDL), HSP105 A24-1 (NYGIYKQDL) and HSP105 A24-7 (EYVYEFRDKL), are potential HLA-A2 or HLA-A24-restricted CTL HSP105-derived epitopes. HSP105-specific IFN-γ-secreting T cells were detected in 14 of 21 pre-surgical patients with colorectal cancer in response to stimulation with these four peptides. Our study raises the possibility that these HSP105 peptides are applicable to cancer immunotherapy in patients with HSP105-expressing cancer, particularly colorectal cancer.

Identification of tumor antigens that elicit a humoral immune response in the sera of Chinese esophageal squamous cell carcinoma patients by modified serological proteome analysis

Our aim was to identify novel tumor-associated antigens from the esophageal squamous cell carcinoma (ESCC) cell line EC0156, and related autoantibodies in sera from patients with ESCC. We used modified serological proteome analysis, involving one- and two-dimensional electrophoresis, Western blot, and MALDI-TOF/TOF-MS to identify 6 ESCC-associated antigens. From these, 105 kDa heat shock protein (HSP105) and triosephosphate isomerase (TIM) were further evaluated and we determined they could induce autoantibody responses in ESCC sera and are highly expressed in ESCC tissues. Anti-HSP105 and anti-TIM autoantibodies were found in 39.1% (18/46) and 34.8% (16/46) of patients with ESCC, respectively, but only in two controls. A receiver operating characteristic curve constructed with HSP105 and TIM gave a sensitivity of 54.3% and 95% (38/40) specificity in discriminating ESCC from matched controls. Interestingly, we found that autoantibodies against TIM in ESCC serum mainly reacted with glycosylated but not deglycosylated TIM. The preliminary results suggest the potential utility of screening autoantibodies in sera for use as biomarkers for cancer diagnosis.

Allogeneic mRNA-based electrotransfection of autologous dendritic cells and specific antitumor effects against osteosarcoma in rats

Vaccination with dendritic cells (DCs) transfected with tumor-derived mRNA antigen has emerged as a promising strategy for generating protective immunity in mammals. However, the integration of allogeneic osteosarcoma mRNA and autologous DCs has not been fully examined. This study was designed to investigate the antitumor effects of tumor vaccine produced by autologous DCs transfected of allogeneic osteosarcoma mRNA through electroporation in tumor-bearing rats model. In the present study, extraction of Wistar rat tumor mRNA was performed as a two-step procedure. First, total RNA was extracted by use of Trizol; then, mRNA purification was performed by use of polyT-coated magnetic beads. Then, we transfected the allogeneic-derived tumor mRNA to Sprague-Dawley (SD) rat bone marrow-derived DCs through electroporation. The tumor vaccine was applied to tumor-bearing rats model, and the specific antitumor effects of the tumor vaccine were observed. The immunization using autologous DCs electrotransfected with allogeneic osteosarcoma total RNA induced specific CTL responses, which were statistically significant (P < 0.05), and the cytotoxic activity was confirmed in cold target inhibition assays and using mAbs blocking MHC class I molecules. In in vivo experiments, 70 % of the rats immunized with allogeneic osteosarcoma RNA transfected to DCs were typically able to reject tumor challenge and remained tumor-free. Vaccinated survivors developed long immunological memory and were able to reject a subsequent rechallenge with the same tumor cells but not a syngeneic unrelated tumor line. In the present study, we demonstrated that allogeneic tumor mRNA isolated from rat osteosarcoma cell line could be applied to produce tumor vaccine inducing specific antitumor effects, especially in DC-based immunotherapy strategy. This study also provides the foundations for an effective and broadly applicable treatment to a wide range of cancer indications for which tumor-associated antigens have not been identified.

The forkhead box M1 transcription factor as a candidate of target for anti-cancer immunotherapy

The present study attempted to identify a target antigen for immunotherapy for cholangiocarcinoma. Forkhead box M1 (FOXM1) was selected as a candidate antigen based on the data of previous cDNA microarray analysis of clinical samples of cholangiocarcinoma. The level of FOXM1 mRNA was more than 4 times higher in cancer cells in comparison to adjacent normal epithelial cells, in all of 24 samples of cholangiocarcinoma tissues. An immunohistochemical analysis also detected FOXM1 protein in the cancer cells but not in the normal cells. Twenty‐three human FOXM1‐derived peptides predicted to bind to HLA‐A2 were analyzed to determine their ability to induce HLA‐A2‐restricted T cells in HLA‐A2 transgenic mice. FOXM1_362‐370 (YLVPIQFPV), FOXM1_373‐382 (SLVLQPSVKV), and FOXM1_640‐649 (GLMDLSTTPL) peptides primed HLA‐A2‐restricted cytotoxic T lymphocytes (CTLs) in the HLA‐A2 transgenic mice. Human CTL lines reactive to these 3 peptides could also be established from HLA‐A2‐positive healthy donors and cancer patients. Natural processing of the 3 epitopes from FOXM1 protein was confirmed by specific killing of HLA‐A2‐positive FOXM1‐transfectants by peptide‐induced CTLs. FOXM1 is expressed in various types of cancers and it is also functionally involved in oncogenic transformation and the survival of cancer cells. Therefore, FOXM1 may be a suitable target for immunotherapy against various cancers including cholangiocarcinoma.

Identification of the H2-Kd-restricted cytotoxic T lymphocyte epitopes of a tumor-associated antigen, SPARC, which can stimulate antitumor immunity without causing autoimmune disease in mice

We previously reported that the secreted protein acidic and rich in cystein (SPARC) was overexpressed in melanoma in humans, and the serum SPARC level was useful as a novel tumor marker for melanoma. SPARC was also reported to be overexpressed in various human cancers. In this study, we asked whether SPARC-specific cytotoxic T lymphocytes (CTL) could induce antitumor immunity to SPARC-expressing tumor in mice or not as a preclinical study of SPARC-directed anticancer immunotherapy. Because of similarities in the structural motifs of major histocompatibility complex-binding peptides between H2-Kd and HLA-A24 (A*2402), the most common human leukocyte antigen class I allele in the Japanese population, we attempted to identify the H2-Kd-restricted SPARC epitope for CTL in BALB/c mice and we found that the mouse SPARC143-151 (DYIGPCKYI) and SPARC225-234 (MYIFPVHWQF) peptides could induce peptide-reactive CTL in BALB/c mice without causing autoimmune diseases. The immunization of mice with SPARC225-234 peptide-pulsed bone marrow-derived dendritic cells (BMDC) inhibited the growth of s.c. inoculated mouse mammary cancer cell line, N2C, expressing SPARC and these mice lived longer than the mice immunized with peptide-unpulsed BMDC. In conclusion, our study indicated that SPARC peptide-based cancer immunotherapy was effective and safe at least in a mouse tumor prevention model.

Regression of intestinal adenomas by vaccination with heat shock protein 105-pulsed bone marrow-derived dendritic cells in Apc(Min/+) mice

Heat shock protein (HSP) 105 is overexpressed in various cancers, but is expressed at low levels in many normal tissues, except for the testis. A vaccination with HSP105-pulsed bone marrow-derived dendritic cells (BM-DC) induced antitumor immunity without causing an autoimmune reaction in a mouse model. Because Apc(Min/+) mice develop multiple adenomas throughout the intestinal tract by 4 months of age, the mice provide a clinically relevant model of human intestinal tumor. In the present study, we investigated the efficacy of the HSP105-pulsed BM-DC vaccine on tumor regression in the Apc(Min/+) mouse. Western blot and immunohistochemical analyses revealed that the tumors of the Apc(Min/+) mice endogenously overexpressed HSP105. Immunization of the Apc(Min/+) mice with a HSP105-pulsed BM-DC vaccine at 6, 8, and 10 weeks of age significantly reduced the number of small-intestinal polyps accompanied by infiltration of both CD4(+) and CD8(+) T cells in the tumors. Cell depletion experiments proved that both CD4(+) and CD8(+) T cells play a critical role in the activation of antitumor immunity induced by these vaccinations. These findings indicate that the HSP105-pulsed BM-DC vaccine can provide potent immunotherapy for tumors that appear spontaneously as a result of the inactivation of a tumor suppressor gene, such as in the Apc(Min/+) mouse model.

Calreticulin requires an ancillary adjuvant for the induction of efficient cytotoxic T cell responses

Molecular chaperones stimulate the immune system to induce both protective immune responses and therapeutic tumor rejection. However, the underlying basis for this immunogenic activity is not well understood. A variety of chaperones, including calreticulin, hsp70 and grp94, function as vehicles to efficiently traffic associated peptides into professional antigen presenting cells. Importantly, these chaperones have also been proposed to function as adjuvants by stimulating the dendritic cell activation and co-stimulatory responses required to elicit peptide-specific CD8(+) T cell cytolytic activity. The efficacy of chaperone-mediated tumor rejection has been attributed to the ability of chaperones to function in both of these capacities. However, purified calreticulin has not previously been assessed for its ability to elicit DC maturation and, moreover, recent data indicates that it is not efficient at inducing Nf-kappaB activity which often accompanies or stimulates DC maturation. Here we use two complementary methods to produce endotoxin-free calreticulin and demonstrate that it does not measurably mature or activate dendritic cells both in vitro and in vivo. Additionally, a calreticulin/peptide complex required the addition of an exogenous adjuvant to elicit in vivo cytotoxic CD8(+) T cell responses. These data are discussed with respect to current models for chaperone-derived immune responses and in regard to rational vaccine design.