Sperm protein 17 (Sp17) is a suitable target for immunotherapy of multiple myeloma

Sperm protein 17 (Sp17) is a protein recently identified as a novel cancer-testis (CT) antigen in multiple myeloma (MM). Because this tumor antigen demonstrates a very restricted normal tissue expression, Sp17 may be an excellent target for tumor vaccine of MM. In this study, we determined the ability to generate Sp17-specific HLA class I-restricted cytotoxic T lymphocytes (CTLs) from the peripheral blood of 4 patients with MM, 3 consecutive Sp17(+) patients, and 1 Sp17(-) patient. Dendritic cells were generated from monocytes of 4 patients with MM and used to present a recombinant Sp17 protein to autologous T cells. Following 4 rounds of antigen stimulation, the CTLs were tested for their ability to kill autologous targets in an Sp17-dependent and HLA-class I- restricted manner in standard cytotoxicity assays. Despite previous chemotherapy and the immunosuppression so often associated with MM, CTL generation was successful in all 4 patients, irrespective of the Sp17 status of their tumors. Most importantly, the CTLs were able to lyse autologous tumor cells that expressed Sp17. Tumor cell lysis in all cases appeared to be mainly mediated by perforin and could be blocked by concanamycin A. We conclude that Sp17 is a suitable target for immunotherapy of MM. Our findings provide the basis for a clinical study aimed at inducing a cellular immune response directed at Sp17(+) MM.     

The cancer-testis antigens CT7 (MAGE-C1) and MAGE-A3/6 are commonly expressed in multiple myeloma and correlate with plasma-cell proliferation

Multiple myeloma is a malignancy of plasma cells. Vaccine immunotherapy is among the novel therapeutic strategies under investigation for this disease. To identify myeloma-associated antigens as potential targets for vaccine immunotherapy, we surveyed a comprehensive panel of bone marrow specimens from patients with monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma for expression of cancer-testis (CT) antigens. Immunohistochemistry (IHC) demonstrated that 82% of stage-III myeloma specimens expressed the CT antigen CT7 (also known as melanoma antigen C1 [MAGE-C1]) and 70% expressed MAGE-A3/6. Messenger RNA for CT7 and MAGE-A family members was detected in 87% and 100% of stage-III samples, respectively. CT7 protein expression increased with advanced stage of disease. Higher levels of CT7 and MAGE-A3/6 proteins also correlated with elevated plasma-cell proliferation. These results show that CT7 and MAGE-A3/6 are promising myeloma-associated antigens for application in vaccine immunotherapy. Furthermore, the common expression and correlation with proliferation suggest a possible pathogenic role for these proteins in myeloma.     

Cancer immunotherapy targeting Sp17: When should the laboratory findings be translated to the clinics?

Despite advances in chemotherapeutic agents, the prognosis for some cancers remains extremely poor, suggesting the need for other treatment modalities. Immunotherapy appears an ideal approach because the mechanisms of tumor cell killing induced by tumor vaccines are different from those from chemotherapy. Various investigations are ongoing to identify suitable targets for this purpose. Sperm protein 17 (Sp17) was originally identified by our group as a novel cancer-testis antigen in various malignancies, including multiple myeloma. Sp17 is a highly immunogenic protein and the observation that more than 90% of vasectomized males develop immunity against Sp17 suggests the opportunity and safety of Sp17 for tumor vaccines. Recent works by other workers suggest a low level of expression of Sp17 in some normal tissues, and investigators have questioned whether Sp17 is in fact a suitable target for immunotherapy. In this paper, we review the general principles of immunotherapy and provide evidence supporting the highly immunogenic nature of Sp17. We also address the discrepancies between the objectives of oncologists involved in treating cancer patients and their familiarity with acceptable levels of toxicity of any effective therapy and those of pure laboratory-based investigators. Finally, we present some early clinical data supporting the rationale for further investigations of Sp17 for tumor vaccines.     

Sperm protein 17 is expressed on normal and malignant lymphocytes and promotes heparan sulfate-mediated cell-cell adhesion

Sperm protein 17 (Sp17) is a highly conserved mammalian protein present on acrosome-reacted sperm that is thought to promote fertilization by binding sulfated carbohydrates of the oocyte zona pellucida. Although Sp17 was originally described as a testis-specific antigen, emerging evidence indicates that it may be more ubiquitously expressed than was previously thought. With the use of a specific antiserum, Sp17 was found to be present on the surface of malignant lymphoid cells, including B- and T-lymphoid cell lines, and on the surface of primary cells isolated from 2 patients having B-lymphoid tumors. Surprisingly, circulating B lymphocytes isolated from healthy volunteers also expressed Sp17, while circulating T lymphocytes exhibited only very weak expression. The role of Sp17 in promoting lymphoid cell adhesion was addressed with the use of recombinant Sp17 (rSp17). The rSp17 binds to the surface of myeloma cells but not to cells pretreated with heparitinase, an enzyme that removes heparan sulfate from the cell surface. Moreover, rSp17 promotes extensive aggregation of cells that express the syndecan-1 heparan sulfate proteoglycan, but in contrast, cells lacking syndecan-1 expression fail to aggregate in the presence of rSp17. These findings suggest that Sp17 promotes heparan sulfate-mediated cell aggregation and thereby plays a role in regulating adhesion and migration of normal and malignant lymphocytes.     

hTERT、Sp1、c-myc在良恶性胰岛β细胞瘤中的表达差异

目的检测人端粒酶逆转录酶(hTERT)、刺激蛋白1(Sp1)和原癌基因转录因子(c-myc)在良、恶性胰岛β细胞瘤和正常胰岛β细胞组织中的表达,探讨三者与胰岛β细胞瘤的关系,为临床鉴别良、恶性胰岛β细胞瘤和判断预后提供理论依据。方法用免疫组化方法检测hTERT、Sp1、c-myc在27例良性、16例恶性胰岛β细胞瘤和20例正常胰岛β细胞组织中的表达,并行相关性分析。结果 hTERT、Sp1、c-myc在恶性胰岛β细胞瘤中的阳性表达率分别为81.2%、75.0%、87.5%,在良性胰岛β细胞瘤中的阳性表达率分别为25.9%、29.6%、14.8%,在正常胰岛β细胞组织中没有表达。hTERT、Sp1和c-myc在良、恶性胰岛β细胞瘤的表达差异均有统计学意义(P均<0.05),且在恶性胰岛β细胞瘤的表达明显高于良性胰岛β细胞瘤和正常胰岛β细胞组织;hTERT与Sp1、c-myc的表达呈明显正相关(r分别为0.992、0.893,P均<0.01)。结论端粒酶的激活在良、恶性胰岛β细胞瘤的发生发展中起重要作用。联合检测hTERT、Sp1和c-myc的表达可作为鉴别良、恶性胰岛β细胞瘤的手段。     

Role of nucleostemin in growth regulation of gastric cancer, liver cancer and other malignancies

AIM: To examine the role of nucleostemin in the growth regulation of gastric cancer, liver cancer and other cancers. METHODS: RT-PCR was used to clone the fragment of nucleostemin cDNA from HEK 293 cells. Eighteen kinds of malignant tumor tissues including gastric adenocarcinoma and liver cancer tissues, 3 kinds of benign tumor tissues, 3 kinds of benign hyperplastic tissues and normal tissues were employed to examine nucleostemin gene expression by RT-PCR, Slot blot, Northern blot and in situ hybridization. RESULTS: We successfully cloned a 570 bp fragment of nucleostemin-cDNA from HEK-293 cells. All detected malignant tumor tissues, benign tumor tissues, and benign hyperplastic tissues had high levels of nucleostemin expression. Nucleostemin was also expressed in human placenta tissue at a high level. In terminally differentiated normal human adult kidney and mammary gland tissues, no nucleostemin expression could be detected. CONCLUSION: Nucleostemin can help regulate the proliferation of both cancer cells and stem cells. It might play an important role in the growth regulation of gastric cancer, liver cancer and other cancers.     

Transcription factor Sp1 expression in gastric cancer and its relationship to long-term prognosis

AIM: To explore the expression of Spl in gastric carcinoma as well as its association with other clinicopathologic features, and to evaluate the role of Spl as a prognostic indicator of gastric carcinoma.METHODS: By using immunohistochemistry, we examined the Sp1 expression patterns in 65 cases of human gastric cancer, and 40 normal gastric mucosa specimens. Simultaneously, the correlation between Sp1 expression and clinical outcome or clinicopathologic features was investigated.RESULTS: The percentage of Spl expression was 12.5% (5/40) in normal gastric mucosa, and the Sp1 protein was mainly expressed in the nuclei of cells located in the mucous neck region. In sharp contrast, strong Sp1 expression was detected in tumor cells, whereas no or faint Sp1 staining was detected in stromal cells and normal glandular cells surrounding the tumors. The expression rate of Sp1 in gastric cancer lesions was 53.85% (35/65). The medium survival duration in patients who had a tumor with negative, weak and strong Sp1 expressions was 1700, 1560 and 1026d, respectively (P&lt;0.05). Sp1 protein expression was closely related to the depth of tumor infiltration (x^2=13.223, P&lt;0.01) and TNM stage (x^2=11.009, P&lt;0.05), but had no relationship with the number of lymph nodes and Lauren‘s classification (P&gt;0.05). Cox regression model for multivariate analysis revealed that high Spl expression (P&lt;0.05) and advanced stage (P&lt;0.01) were independent predictors of poor survival.CONCLUSION: Normal and malignant gastric tissues have unique Sp1 expression patterns. Spl might serve as an independent prognostic factor, by influencing the tumor infiltration and progression.     

Biological Treatment for Liver Tumor and New Potential Biomarkers

The search for effective and efficacious therapy for liver tumor was started many years ago and is still ongoing. Despite all of the surgical advances, much work needs to be done to improve understanding of the biology of the tumor and its treatment. The rules of hepatic surgery are changing because of two recent major trends: (1) technical simplification, and (2) the endeavor to treat an increasing number of patients. T lymphocytes are potent cellular effectors of the immune system and possess a memory that responds to rechallenge by the same antigen. Being more specific and less toxic than chemotherapy, tumor infusion could be an ideal adjuvant therapy for patients with primary and secondary liver malignancies. Moreover, tumor cell vaccines have demonstrated efficacy in terms of minimal residual disease and are being investigated, but the requirement for an adequate supple of autologos tumor may limit the general applicability of these approaches. Various studies have demonstrated the aberrant expression of germ-cell proteins called cancer-testis (CT) antigens in liver neoplastic cells. Their selective normal-tissue expression makes them ideal antigens for immune targeting of malignant disease. Specific expression of CT antigens also suggests their application as tumor markers to detect circulating hepatocellular carcinoma (HCC) cells, as an adjuvant diagnostic tool, and as indicators for recurrence and prognosis. Biological therapy is now generating more clinical trials. More studies need to be performed and further experiments need to be done, although currently this seems a valid pathway for the treatment of liver cancer. Cytoreduction treatment of liver tumor and the vaccine might be the future of the treatment of primary and secondary liver tumor.     

Production of cytokines by bone marrow cells obtained from patients with multiple myeloma

Previous work with continuously cultured multiple myeloma lines suggested that cytokine production by tumor cells may mediate some of the medical complications of this disease. To further investigate this issue, we assayed freshly obtained bone marrow (BM) cells from myeloma patients for the in vitro production of cytokines and the presence of cytokine RNA. Production of cytokine protein was assessed by bioassays with the aid of specific neutralizing anticytokine antibodies. These assays detected interleukin-1 (IL-1) and tumor necrosis factor (TNF) secretion by myeloma BM cells, which was significantly greater than secretion from similarly processed BM cells of control individuals. In contrast, lymphotoxin and interleukin-2 (IL-2) production could not be detected. The levels of IL-1 and TNF produced in vitro peaked at 24 hours of culture and correlated with stage and the presence (or absence) of extensive osteolytic bone disease. Northern blot analysis demonstrated the presence of IL-1 beta and TNF RNA in uncultured myeloma BM cells but no detectable IL-1 alpha or lymphotoxin RNA. In addition, the amount of cytokine RNA correlated with protein production, being significantly greater in patients' BM cells than in control marrow. These data suggest a role for IL-1 beta and/or TNF in the pathophysiology of multiple myeloma and argue against a role for lymphotoxin or IL-2.     

Tumor-specific aneuploidy not detected in CD19+ B-lymphoid cells from myeloma patients in a multidimensional flow cytometric analysis

Aneuploidy and lg light chain restriction were used as separate, independent tumor specific markers to study 26 patients with multiple myeloma to determine whether bone marrow B cells, as defined by CD19 expression, are clonally related to myeloma plasma cells. Specimens were characterized using multidimensional flow cytometry to identify the presence of clonality in both the B lymphoid and plasma cell populations using both surface and cytoplasmic staining with antibodies specific for kappa or lambda lg light chain In none of the patients with multiple myeloma were CD19+ cells found to be clonally restricted to kappa or lambda. The monoclonal plasma cells (MPC) were found to be uniformly negative for CD10, CD19, and CD34, while the CD19+ B lymphoid cells present within the samples expressed normal intensities and relationships of these antigens, which allowed them to serve as internal positive controls. Combined analysis of call surface antigen expression and DNA content allowed plasma cell populations to be characterized for aneuploidy without interference from normal bone marrow cells. The MPC, detected on the basis of bright CD38 expression (CD38+2), demonstrated DNA aneuploidy in 65% of cases (DNA index range of 0.9 to 1.3). These aneuploid DNA distributions had typical cell cycle profiles (including G1,S and G2+M) expected of a proliferating population. In all cases, DNA aneuploidy was confined almost entirely to the CD38+2, CD19- malignant plasma cells, while cells expressing CD19 were diploid. These results support the concept that myeloma is a disease process mediated by self-replicating, late compartments of B- cell ontogeny.