Hailiang Ge

The immunologic aspects in advanced ovarian cancer patients treated with paclitaxel and carboplatin chemotherapy.

Till now, little is known about the effects of chemotherapy on the immunity of cancer patients and the ideal timing (“window” period) for immunotherapy combined with chemotherapy. In this study, we addressed the immunogenicity of apoptotic ovarian cancer cells induced by paclitaxel and carboplatin, the immunologic aspects in ovarian cancer patients under chemotherapy, and the CTL response when CD8+ T cells were stimulated with tumor antigen in the “window” period. The immunogenicity of apoptotic ovarian cancer cells was detected first. Then, blood samples from each ovarian cancer patient were obtained before (S0) and at days 5–7 (S1), days 12–14 (S2) and days 25–28 (S3) after chemotherapy. The proportions of immunocyte subsets and the function of NK cells were studied. We found that apoptotic ovarian cancer cells elicited a powerful CTL response with antitumor activity in vitro. The proportions of CD3+ T cells, CD4+ T cells and the ratio of CD4+ to CD8+ cells did not change significantly on S1, S2 and S3, compared to S0, whereas the percentage of Treg cells decreased remarkably on S2. The proportions of Th1, Tc1, CD45RO memory T, NKT cells and the ratio of Tc1 to Tc2 cells increased significantly on S2. IFN-γ secreting CD8+ T cells also increased remarkably on S2, especially when CD8+ T cells were stimulated with autologous tumor antigen. From our point of view, chemotherapy induces temporary immune reconstitution and augments anti-tumor immune response. It is probable that the “window” period of days 12–14 after chemotherapy provides the best opportunity for immunotherapy.

RNA interference targeting CML66, a novel tumor antigen, inhibits proliferation, invasion and metastasis of HeLa cells

CML66 is a novel, promising tumor antigen; however, its biological roles remain unclear. In present study, we applied a short hairpin RNA triggered RNA interfering to suppress CML66 expression in HeLa cervical carcinoma cells. Knockdown of CML66 inhibited proliferation, migration and invasion activities of HeLa cells in vitro. Meanwhile, in nude mice, CML66 silencing suppressed tumor growth and pulmonary metastasis with HeLa cells injected subcutaneously. Furthermore, using metastasis-related genes cDNA microarrays, we found 9 genes were significantly down-regulated after CML66 silencing, including cathepsin L, MMP15, uPAR, VEGF, COX-2, S100A4, MUC1, MDM2 and RAC1. These results imply that CML66 may play an oncogenic role in ways of favoring tumor cells proliferation, invasion and metastasis-associated with multiple pathways. Thus, CML66 might be a potential target for development of cancer therapy.

dCTP pyrophosphohydrase exhibits nucleic accumulation in multiple carcinomas

Nucleoside triphosphate pyrophosphohydrolase (NTP-PPase) functions as one of the mechanisms to guarantee the fidelity of DNA replication through the cleavage of non-canonical nucleotides into di- or monophosphates. Human NTP-PPase is poorly understood and investigated. In the present study, by using tissue microarrays with the paired cancer and adjacent regions, we found that with the prevalent expression of dCTP pyrophosphohydrase (DCTPP1) in the cytosol and nucleus in tumors investigated, DCTPP1 was inclined to accumulate in the nucleus of cancer cells compared to the paired adjacent tissue cells in multiple carcinomas including lung, breast, liver, cervical, gastric and esophagus cancer. More significantly, the higher DCTPP1 expression in the nucleus of lung, gastric and esophagus cancer cells was associated with histological subtypes. The nucleic accumulation of DCTPP1 was apparently observed as well when tumor cell line MCF-7 was treated with H2O2 in vitro. Considering the roles of DCTPP1 on restricting the concentration of non-canonical nucleotides in the nucleotide pool, accumulation of DCTPP1 in the nucleus of tumor cells might suffice for maintaining the proper DNA replication in order to fulfill the requirement for the survival and proliferation of tumor cells.

Humoral immune responses against tumor-associated antigen OVA66 originally defined by serological analysis of recombinant cDNA expression libraries and its potentiality in cellular immunity.

Immunotherapy for cancer relies on the identification of tumor antigens and efficacy of antitumor immune responses. Serological analysis of recombinant cDNA libraries (SEREX), which is based on the spontaneous humoral responses against potential tumor antigens, has provided a novel strategy for searching novel tumor‐associated candidates. Through SEREX analysis, we have identified 24 distinct gene clones by immunoscreening of a cDNA library derived from an ovarian cancer patient. Among these genes, a novel gene, OVA66, was found to be expressed significantly higher in carcinoma samples from cancer patients than in normal controls. Comparing humoral responses to OVA66 between tumor patients and healthy donors, it has been shown that the IgG level against OVA66 was significantly elevated in the serum of cancer patients from different histological types of cancer. To determine whether SEREX‐defined OVA66 can trigger promising cytotoxic T lymphocyte (CTL) responses, human leukocyte antigen (HLA)‐A*0201‐restricted T‐cell epitopes were predicted through a computational algorithm. Of four predicted peptides, p306–314 (L235) possesses the ability to induce efficient peripheral blood lymphocyte (PBL)‐derived CTL responses capable of specifically recognizing peptide‐pulsed T2 cells and lysing carcinoma cell lines expressing both HLA‐A2 and OVA66 as determined by cytotoxicity and enzyme‐linked immunospot assay (ELISPOT). Taken together, our results demonstrate that the SEREX‐defined tumor‐associated antigen OVA66 can elicit humoral immunity and may also serve as a potential candidate for T‐cell‐based immunotherapy for cancer. (Cancer Sci 2008; 99: 1670–1678)

Therapeutic effect of MIP-1α-recruited dendritic cells on preestablished solid and metastatic tumors

We previously found that dendritic cell (DC) precursors could be recruited into the peripheral blood of B6 mice by administration of macrophage inflammatory protein (MIP)-1alpha. These MIP-1alpha-recruited DCs could induce anti-tumor protective immunity when pulsed with tumor cell lysate. In this study, MIP-1alpha-recruited DCs could not effectively suppress preestablished tumor when pulsed with B16 tumor cell lysate. However, inoculation with these DCs expressing MAGE-1 induced an anti-tumor immunity against preestablished solid and metastatic tumor from B16-MAGE-1 cells. These MIP-1alpha-recruited DCs expressed higher level of CCR7 and displayed a more significant chemotactic response toward secondary lymphoid tissue. Therefore, they are superior in the induction of cytotoxic T lymphocytes and the inhibition of tumor development and metastasis than bone marrow-derived DCs. This study established a novel approach to the treatment of preestablished solid and metastatic tumors using MIP-1alpha-recruited DCs transduced with tumor antigen gene.

OVA66 increases cell growth, invasion and survival via regulation of IGF-1R–MAPK signaling in human cancer cells

Ovarian cancer-associated antigen 66 (OVA66), also known as CML66 (GenBank Accession No. AF283301), was first identified in an ovarian carcinoma complementary DNA (cDNA) expression library and was shown to play a role in tumorigenesis. Here, we find that OVA66 influences tumorigenesis by regulating the type I insulin-like growth factor receptor (IGF-1R) signaling pathway. Stable knockdown of OVA66 in cancer cells attenuated phosphorylation of IGF-1R and extracellular signal-regulated kinase 1/2 (ERK1/2)-Hsp27; similarly, a higher level of p-IGF-1R and ERK1/2-Hsp27 signaling was also detected after OVA66 overexpression in HO8910 cells. In vivo knockdown of OVA66 both reduced tumor burden in nude mice and decreased phosphorylation of IGF-1R, ERK1/2 and hsp27. We blocked IGF-1R function both by small interfering RNA (siRNA) and with the chemical inhibitor Linsitinib (OSI-906). By either method, tumorigenesis was inhibited regardless of OVA66 expression; thus, mechanistically, IGF-1R, probably, lies downstream of OVA66 in cancer cells. We also found that OVA66 regulates expression of murine double minute 2 (MDM2); this attenuates ubiquitination of IGF-1R in response to IGF-1 stimulation and promotes active ERK1/2 signaling. Thus, we propose that combined overexpression of OVA66 and MDM2 promotes oncogenesis by enhancing activation of the IGF-1R-ERK1/2 signaling pathway.

Fas Ligand gene transfer enhances the survival of tissue-engineered chondrocyte allografts in mini-pigs ☆

BACKGROUND AND PURPOSE Since the Fas/Fas Ligand (FasL) interaction has been recognized as an apoptotic pathway, it eliminates the activated T cells and promotes the survival of grafts. In this study, the effect of FasL transfection of pig chondrocytes on allogeneic transplantation was examined in vitro and in vivo. METHODS Chondrocytes were isolated from articular and aural cartilages of anesthetized Guizhou Xiang (Gz) pig. The cells were transfected with G418 selected virus, packed from PA317 cells with a constructed plasmid using pig FasL (pGCEN-FasL). The apoptotic effect of FasL transfection was examined on Jurkat cells and activated recipient Gz T cells. The FasL expression was assessed by Western blot and flow cytometry. FasL+chondrocytes-Pluronic F-127 complex was injected into the right abdomen of recipient Gz pig. Histology and morphology of the engineered tissue were examined after 2 and 5 weeks of transplantation. RESULTS The FasL expression was confirmed in pGCEN-FasL transfected chondrocytes. The expression of FasL of chondrocytes from Gz pig was analyzed by FACS. The apoptosis of Jurkat cells and activated recipient Gz T cells was increased by co-culture with FasL(+) chondrocytes (53.41% and 30.38% (E/T=10:1), in contrast of 32.27% and 13.16% with the control chondrocytes, respectively, P<0.01). FasL(+) chondrocytes-Pluronic F-127 implant expressed FasL and Type II collagen at the 5th week and survived until the 8th week. INTERPRETATION The result indicates that the expression of FasL by chondrocytes is capable of inducing apoptosis of activated T cells. This suggests a potential role for allogeneic transplantation with chondrocytes.

OVA66, a tumor associated protein, induces oncogenic transformation of NIH3T3 cells.

The tumor associated antigen OVA66 has been demonstrated to be highly expressed in malignant tumors and implicated in various cellular processes. To further elucidate its oncogenic character, we established an OVA66 stably overexpressed NIH3T3 cell line and a vector transfected control, named NIH3T3-flagOVA66 and NIH3T3-mock, respectively. NIH3T3-flagOVA66 cells showed faster cell cycling, proliferation, cell migration and more resistance to 5-fluorouracil-induced apoptosis. When NIH3T3-flagOVA66 and NIH3T3-mock cells were injected into nude mice for xenograft tumorigenicity assays, the NIH3T3-flagOVA66 cells formed tumors whereas no tumors were observed in mice inoculated with NIH3T3-mock cells. Analysis of PI3K/AKT and ERK1/2 MAPK signaling pathways by serum stimulation indicated hyperactivation of AKT and ERK1/2 in NIH3T3-flagOVA66 cells compared with NIH3T3-mock cells, while a decreased level of p-AKT and p-ERK1/2 were observed in OVA66 knocked down HeLa cells. To further validate if the p-AKT or p-ERK1/2 is essential for OVA66 induced oncogenic transformation, we treated the cells with the PI3K/AKT specific inhibitor LY294002 and the ERK1/2 MAPK specific inhibitor PD98059 and found either inhibitor can attenuate the cell colony forming ability in soft agar and the cell viability of NIH3T3-flagOVA66 cells, suggesting aberrantly activated AKT and ERK1/2 signaling be indispensible of the tumorigenic role of OVA66. Our results indicate that OVA66 is important in oncogenic transformation, promoting proliferation, cell migration and reducing apoptosis via hyperactivating PI3K/AKT and ERK1/2 MAPK signaling pathway. Thus, OVA66 might be a novel target for early detection, prevention and treatment of tumors in the future.

OVA12, a novel tumor antigen, promotes cancer cell growth and inhibits 5-fluorouracil-induced apoptosis

To achieve a better understanding of mechanisms that underlie carcinogenesis and to identify novel target molecules for diagnosis and therapy of carcinoma, we previously identified 24 distinct gene clones by immunoscreening of a cDNA library derived from an ovarian cancer patient through SEREX analysis. Among these genes we focused on a novel gene termed OVA12 and which putatively encodes a 114-amino-acid protein. In the present study, we found that OVA12 was ubiquitously overexpressed in diverse human tumor cell lines. Interestingly, we noticed that overexpression of OVA12 promoted proliferation of cancer cells in vitro and accelerated tumor growth in nude mice as compared to controls. Conversely, specific downregulation of OVA12 inhibited tumor cell proliferation and tumor growth both in vitro and in vivo. Furthermore, OVA12 inhibited 5-FU-induced apoptosis through specific upregulation of Mcl-1 and survivin. These results demonstrate that OVA12 is able to promote tumor growth, suggesting that this antigen might be a new potential target for development of cancer therapy.

OVA12 promotes tumor growth by regulating p53 expression in human cancer cells

Ovarian cancer-associated antigen 12 (OVA12) was first identified in an ovarian carcinoma complementary DNA (cDNA) expression library and has been shown to play an important role in tumor growth. Here, we found that overexpression of OVA12 accelerated tumor growth in different tumor cells, whereas OVA12 depletion was associated with the opposite effect. Moreover, knocking down OVA12 led to a significant increase in the protein levels of p53, and the overexpression of OVA12 significantly decreased endogenous p53 levels. In addition, OVA12 stimulated p53 polyubiquitination and degradation by the proteasome and promoted tumor growth at least partially through the p53 pathway. Taken together, these results indicate that OVA12 is a negative regulator of p53 and that inhibition of OVA12 expression might serve as a therapeutic target to restore tumor suppression.Ovarian cancer-associated antigen 12 (OVA12) was first identified in an ovarian carcinoma complementary DNA (cDNA) expression library and has been shown to play an important role in tumor growth. Here, we found that overexpression of OVA12 accelerated tumor growth in different tumor cells, whereas OVA12 depletion was associated with the opposite effect. Moreover, knocking down OVA12 led to a significant increase in the protein levels of p53, and the overexpression of OVA12 significantly decreased endogenous p53 levels. In addition, OVA12 stimulated p53 polyubiquitination and degradation by the proteasome and promoted tumor growth at least partially through the p53 pathway. Taken together, these results indicate that OVA12 is a negative regulator of p53 and that inhibition of OVA12 expression might serve as a therapeutic target to restore tumor suppression.