Terufumi Kubo

Preferential expression of cancer/testis genes in cancer stem‐like cells: proposal of a novel sub‐category, cancer/testis/stem gene

Cancer/testis (CT) antigens encoded by CT genes are immunogenic antigens, and the expression of CT gene is strictly restricted to only the testis among mature organs. Therefore, CT antigens are promising candidates for cancer immunotherapy. In a previous study, we identified a novel CT antigen, DNAJB8. DNAJB8 was found to be preferentially expressed in cancer stem-like cells (CSCs)/cancer-initiating cells (CICs), and it is thus a novel CSC antigen. In this study, we hypothesized that CT genes are preferentially expressed in CSCs/CICs rather than in non-CSCs/-CICs and we examined the expression of CT genes in CSCs/CICs. The expression of 74 CT genes was evaluated in side population (SP) cells (=CSC) and main population (MP) cells (=non-CSC) derived from LHK2 lung adenocarcinoma cells, SW480 colon adenocarcinoma cells and MCF7 breast adenocarcinoma cells by RT-PCR and real-time PCR. Eighteen genes (MAGEA2, MAGEA3, MAGEA4, MAGEA6, MAGEA12, MAGEB2, GAGE1, GAGE8, SPANXA1, SPANXB1, SPANXC, XAGE2, SPA17, BORIS, PLU-1, SGY-1, TEX15 and CT45A1) showed higher expression levels in SP cells than in MP cells, whereas 10 genes (BAGE1, BAGE2, BAGE4, BAGE5, XAGE1, LIP1, D40, HCA661, TDRD1 and TPTE) showed similar expression levels in SP cells and MP cells. Thus, considerable numbers of CT genes showed preferential expression in CSCs/CICs. We therefore propose a novel sub-category of CT genes in this report: cancer/testis/stem (CTS) genes.

High expression of CD109 antigen regulates the phenotype of cancer stem-like cells/cancer-initiating cells in the novel epithelioid sarcoma cell line ESX and is related to poor prognosis of soft tissue sarcoma.

Epithelioid sarcoma (ES) is a relatively rare, highly malignant soft tissue sarcoma. The mainstay of treatment is resection or amputation. Currently other therapeutic options available for this disease are limited. Therefore, a novel therapeutic option needs to be developed. In the present study, we established a new human ES cell line (ESX) and analyzed the characteristics of its cancer stem-like cells/cancer-initiating cells (CSCs/CICs) based on ALDH1 activity. We demonstrated that a subpopulation of ESX cells with high ALDH1 activity (ALDHhigh cells) correlated with enhanced clonogenic ability, sphere-formation ability, and invasiveness in vitro and showed higher tumorigenicity in vivo. Next, using gene expression profiling, we identified CD109, a GPI-anchored protein upregulated in the ALDHhigh cells. CD109 mRNA was highly expressed in various sarcoma cell lines, but weakly expressed in normal adult tissues. CD109-positive cells in ESX predominantly formed spheres in culture, whereas siCD109 reduced ALDH1 expression and inhibited the cell proliferation in vitro. Subsequently, we evaluated the expression of CD109 protein in 80 clinical specimens of soft tissue sarcoma. We found a strong correlation between CD109 protein expression and the prognosis (P = 0.009). In conclusion, CD109 might be a CSC/CIC marker in epithelioid sarcoma. Moreover, CD109 is a promising prognostic biomarker and a molecular target of cancer therapy for sarcomas including ES.

Olfactory Receptor Family 7 Subfamily C Member 1 Is a Novel Marker of Colon Cancer-Initiating Cells and Is a Potent Target of Immunotherapy.

Purpose: Cancer-initiating cells (CICs) are thought to be essential for tumor maintenance, recurrence, and distant metastasis, and they are therefore reasonable targets for cancer therapy. Cancer immunotherapy is a novel approach to target cancer. In this study, we aimed to establish novel CIC-targeting immunotherapy. Experimental Design: Colorectal cancer (CRC) CICs were isolated as side population (SP) cells. The gene expression profile of CRC CICs was analyzed by cDNA microarray and RT-PCR. Protein expression of olfactory receptor family 7 subfamily C member 1 (OR7C1) were analyzed by Western blot and immunohistochemical staining. The functions of OR7C1 were analyzed by gene overexpression and gene knockdown using siRNAs. OR7C1-positive cells were isolated by a flow cytometer and analyzed. CTLs specific for OR7C1 peptide were generated, and the antitumor effect was addressed by mice adoptive transfer model. Results: OR7C1 has essential roles in the maintenance of colon CICs, and the OR7C1-positive population showed higher tumorigenicity than that of the OR7C1-negative population, indicating that OR7C1 is a novel functional marker for colon CIC. Immunohistochemical staining revealed that OR7C1 high expression was correlated with poorer prognosis in CRC patients. OR7C1-derived antigenic peptide-specific CTLs showed specific cytotoxicity for CICs, and an OR7C1-specific CTL clone showed a greater antitumor effect than did a CTL clone targeting all cancer cells in a CTL adoptive transfer mouse model. Conclusions: OR7C1 is a novel marker for colon CICs and can be a target of potent CIC-targeting immunotherapy. Clin Cancer Res; 22(13); 3298–309. ©2016 AACR.

Arachidonate 5-Lipoxygenase Establishes Adaptive Humoral Immunity by Controlling Primary B Cells and Their Cognate T-Cell Help

In this study, we report the unique role of arachidonate 5-lipoxygenase (Alox5) in the regulation of specific humoral immune responses. We previously reported an L22 monoclonal antibody with which human primary resting B cells in the mantle zones of lymphoid follicles are well-defined. Proteomics analyses enabled identification of an L22 antigen as Alox5, which was highly expressed by naive and memory B cells surrounding germinal centers. Cellular growth of mantle cell lymphoma cells also seemed to depend on Alox5. Alox5(-/-) mice exhibited weak antibody responses specific to foreign antigens at the initial and recall phases. This was probably attributable to the low number of follicular and memory B cells and the functional loss of interleukin-21-mediated responses of follicular B cells. Moreover, Alox5(-/-) mice could not fully foster the development of follicular B helper T (Tfh) cells even after immunization with foreign antigens. Further experiments indicated that Alox5 affected mortality in experimentally induced enterocolitis in germ-prone circumstances, indicating that Alox5 would endow immunologic milieu. Our results illustrate the novel role of Alox5 in adaptive humoral immunity by managing primary B cells and Tfh cells in vivo.

Tonsillar crypt epithelium of palmoplantar pustulosis secretes interleukin-6 to support B-cell development via p63/p73 transcription factors†

Palmoplantar pustulosis (PPP) is an autoimmune disease characterized by psoriasis‐like erythematous lesions on palms and/or soles due to an abnormal humoral immune response. Tonsillectomy is effectively employed for the treatment of PPP; however, how tonsils are involved in the aetiology of PPP remains unclear. Here we analysed surgically resected palatine tonsils from 36 cases of PPP as well as usual recurrent tonsillitis (RT) as a control. Histological examination revealed that a unique lesion, with lymphoid follicles surrounded by reticular crypt epithelial cells, was more frequently observed in tonsils of patients with PPP than in those with RT (p < 0.0001; PPP vs RT). Interestingly, crypt epithelial cells in primary cultures derived from PPP tonsils showed marked production of interleukin‐6 (IL‐6). Moreover, these epithelial cells from PPP tonsils expressed p53‐related transcription factors in their nuclei that were found to contribute to the up‐regulation of IL‐6 gene expression. These findings suggest that, at least in part, the specialized lymphoepithelial symbiosis of PPP tonsils, under the control of p53‐related factors, may be relevant to the generation of the impaired micro‐environment underlying the aberrant production of autoantibodies. Copyright

ΔNp63 Controls a TLR3-Mediated Mechanism That Abundantly Provides Thymic Stromal Lymphopoietin in Atopic Dermatitis

In the skin lesions of atopic dermatitis (AD), keratinocytes release large quantities of thymic stromal lymphopoietin (TSLP), causing unfavorable inflammation along with skin damage. Nevertheless, how TSLP influences keratinocytes themselves is still unknown. In this study, we showed that ΔNp63, a p53-homologue, predominantly expressed in keratinocytes regulated the receptor complex of TSLP, which determines susceptibility to self-derived TSLP. Expression of TSLP receptors in skin tissues and keratinocytes was assessed by immunohistochemistry and quantitative RT-PCR, and in vitro studies were also performed to examine the functional relevance of ΔNp63 in the expression of TSLP receptors and the constituting autocrine and/or paracrine pathway of TSLP under the condition of stimuli to innate receptors sensing cell damage. The results showed that normal keratinocytes in the upper epidermis preferentially expressed TSLP receptors and conversely lacked ΔNp63, which has an inhibitory effect on the expression of TSLP receptors. Interestingly, the epidermis of AD lesions was found to abundantly contain keratinocytes with low or undetectable levels of ΔNp63 (ΔNp63lo/-). Moreover, in the absence of ΔNp63, keratinocytes readily presented TSLP and other cytokines by stimuli through Toll-like receptor 3 (TLR3). Together with the evidence that extrinsic TSLP itself augments TSLP production by keratinocytes without ΔNp63, the results indicate that ΔNp63lo/- keratinocytes generate TSLP through a putative autocrine and/or paracrine pathway upon TLR3 stimulation within AD lesions, since moieties of damaged cells and pathogens stimulate TLR3.

ECRG4 is a negative regulator of caspase-8-mediated apoptosis in human T-leukemia cells.

We previously established Fas-resistant variant clones from the human T-cell leukemia lines Jurkat and SUP-T13. Comparative gene expression analysis of the Fas-resistant and Fas-sensitive clones revealed several genes that were aberrantly expressed in the Fas-resistant clones. One of the genes, esophageal cancer-related gene 4 (ECRG4), contained a VDAC2-like domain that might be associated with apoptotic signals. In the present study, we examined the subcellular localization and function of ECRG4 in Fas-mediated apoptosis. By confocal fluorescence microscopy, ECRG4-EGFP fusion protein was detected in mitochondria, endoplasmic reticulum and the Golgi apparatus in gene-transfected HeLa cells. Overexpression of ECRG4 in Fas-sensitive Jurkat cells inhibited mitochondrial membrane permeability transition, leading to resistance against Fas-induced apoptosis. Tumor necrosis factor-alpha-induced apoptosis was also suppressed in ECRG4-overexpressing Jurkat cells. Immunoprecipitation assay demonstrated that ECRG4 is associated with procaspase-8. The inhibitory mechanism included the inhibition of caspase-8 activity and Bid cleavage. Since ECRG4 expression is downregulated in activated T cells, our results suggest that ECRG4 is a novel antiapoptotic gene which is involved in the negative regulation of caspase-8-mediated apoptosis in T cells.

Diagnostic utility of FOSB immunohistochemistry in pseudomyogenic hemangioendothelioma and its histological mimics

BackgroundPseudomyogenic hemangioendothelioma (PHE) is an unusual vascular tumor of intermediate malignancy that rarely metastasizes and tends to arise in the lower limbs of young adults and children. Histologically, PHE shows fascicular proliferation of eosinophilic spindle cells and/or epithelioid cells showing “pseudomyogenic” morphology. Immunohistochemically, PHE is usually positive for vimentin, cytokeratin, CD31 and ERG.MethodWe examined FOSB immunohistochemistry (IHC) in 27 cases consisting of 4 PHE and its histologic mimics including 6 epithelioid hemangioendotheliomas (EHE), 8 angiosarcomas (AS), 4 Kaposi sarcomas (KS) and 5 epithelioid sarcomas (ES). In addition, we performed IHC of CAMTA1 which has recently been established as a useful marker of EHE. We elucidated the diagnostic utility of FOSB IHC in the differential diagnosis of PHE and its histological mimics and also examined the usefulness of FOSB and CAMTA1 IHC combination in the differential diagnosis of the tumors.ResultsIHC revealed diffuse and strong FOSB expression in all PHE cases, while the other tumor types demonstrated limited, weak or no FOSB expression. All EHE cases exhibited diffuse and moderate to strong expression of CAMTA1. All tumor types except for EHE showed limited, weak or no CAMTA1 reactivity.ConclusionsDiffuse and strong FOSB expression was specific for PHE in the current series and FOSB IHC is an effective tool for differentiating between PHE and its histological mimics. Moreover, the combination of FOSB and CAMTA1 IHC is useful for distinguishing PHE from EHE.

Wild-type AIRE cooperates with p63 in HLA class II expression of medullary thymic stromal cells

During T cell development in the thymus, autoreactive T cells are deleted through a mechanism that is actively supported by medullary epithelial cells. These epithelial cells possess particular transcription factors including autoimmune regulator (AIRE), which is responsible for regulating expression of self-antigens, as well as p63, a p53-like molecule. Here we present evidence suggesting interaction of AIRE with p63 through a SAND domain and a transactivation domain, respectively. Interestingly an AIRE molecule with a mutated SAND domain of G228W, whose genetic alteration is inherited in an autosomal dominant manner, could not establish a complex with p63 as indicated by immunoprecipitation and molecular modeling analyses. Further in vitro study indicated that the G228W mutation led to downregulation of the transcription levels of CIITA and, accordingly, the cell surface expression of HLA class II molecules in thymic epithelial cells with p63. This indicates novel involvement of AIRE and p63 in the regulation of HLA class II, and suggests that defects in the AIRE-p63 interaction may lead to malfunction of HLA-based selection of self-reactive helper CD4(+) T cells in the thymus.

Ectopically Expressed Variant Form of Sperm Mitochondria-Associated Cysteine-Rich Protein Augments Tumorigenicity of the Stem Cell Population of Lung Adenocarcinoma Cells

Cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are defined as a small population of cancer cells that have self-renewal ability, differentiation ability and high tumor-initiating ability. CSCs/CICs are resistant to cancer therapies including chemotherapy and radiotherapy. Therefore, CSCs/CICs are thought to be responsible for cancer recurrence and distant metastasis after treatment. However, the molecular mechanisms of CSCs/CICs are still elusive. In this study, we isolated CSCs/CICs as side population (SP) cells from lung carcinoma, colon carcinoma and breast carcinoma cells and analyzed the molecular mechanisms of CSCs/CICs. cDNA micro-array screening and RT-PCR analysis revealed that sperm mitochondria-associated cysteine-rich protein (SMCP) is ectopically expressed in SP cells. 5′-Rapid amplification of cDNA end (RACE) analysis revealed that the SMCP transcript in SP cells was a variant form (termed vt2) which is composed from only one exon. SMCP vt2 was detected in only cancer cells, whereas the wild-type (vt1) form of SMCP was expressed in the testis. SMCP was shown to have a role in tumor initiation by SMCP overexpression and SMCP knockdown using siRNAs in lung cancer cells. Taken together, the initiation results indicate that an ectopically expressed variant form of SMCP has a role in tumor initiation of CSCs/CICs and that the variant form of SMCP might be a novel CSC/CIC marker and a potential and promising target of CSC/CIC-targeting therapy.