A novel approach for identification of tumor-associated antigens expressed on the surface of tumor cells

TM9SF1 promotes bladder cancer cell growth and infiltration

BACKGROUND

Bladder cancer (BC) is the most common urological tumor. It has a high recurrence rate, displays tutor heterogeneity, and resists chemotherapy. Furthermore, the long-term survival rate of BC patients has remained unchanged for decades, which seriously affects the quality of patient survival. To improve the survival rate and prognosis of BC patients, it is necessary to explore the molecular mechanisms of BC development and progression and identify targets for treatment and intervention. Transmembrane 9 superfamily member 1 (TM9SF1), also known as MP70 and HMP70, is a member of a family of nine transmembrane superfamily proteins, which was first identified in 1997. TM9SF1 can be expressed in BC, but its biological function and mechanism in BC are not clear.

AIM

To investigate the biological function and mechanism of TM9SF1 in BC.

METHODS

Cells at 60%-80% confluence were transfected with lentiviral vectors for 48-72 h to achieve stable TM9SF1 overexpression or silencing in three BC cell lines (5637, T24, and UM-UC-3). The effect of TM9SF1 on the biological behavior of BC cells was then investigated through CCK8, wound-healing assay, transwell assay, and flow cytometry.

RESULTS

Overexpression of TM9SF1 increased the in vitro proliferation, migration, and invasion of BC cells by promoting the entry of BC cells into the G2/M phase. Silencing of TM9SF1 inhibited in vitro proliferation, migration, and invasion of BC cells and blocked BC cells in the G1 phase.

CONCLUSION

TM9SF1 may be an oncogene in BC.

m6Am methyltransferase PCIF1 is essential for aggressiveness of gastric cancer cells by inhibiting TM9SF1 mRNA translation

PCIF1 (phosphorylated CTD interacting factor 1) is the first reported RNA N6,2′-O-dimethyladenosine (m⁶Am) methyltransferase. However, the pathological significance of PCIF1 and m⁶Am modification remains unknown. Here we find that both PCIF1 expression and m⁶Am modification are significantly elevated in gastric cancer tissues. Increased PCIF1 is associated with gastric cancer progression, and predicts poor prognosis. Silence of PCIF1 inhibits the proliferation and invasion of gastric cancer cells, and suppresses tumor growth and metastasis in mouse model. m⁶Am-seq analysis reveals TM9SF1 (transmembrane 9 superfamily member 1) as a target of PCIF1. PCIF1 modifies TM9SF1 mRNA with m⁶Am leading to decreased TM9SF1 translation. TM9SF1 reverses the effects of PCIF1 on gastric cancer cell aggressiveness. Collectively, our work uncovers an oncogenic function of PCIF1, providing insights into the critical role of m⁶Am modification in cancer progression.

Extracellular vesicle-mediated EBAG9 transfer from cancer cells to tumor microenvironment promotes immune escape and tumor progression

The antitumor immune response is a critical defense system that eliminates malignant cells. The failure of the system results in immune escape and proceeds to tumor growth. We have previously showed that estrogen receptor-binding fragment-associated antigen 9 (EBAG9) is a relevant cancer biomarker and facilities immune escape of cancers from the immune surveillance. EBAG9 in cancer cells suppresses T-cell infiltration into tumor in vivo, whereas that in host immune cells functions as a limiter for T-cell cytotoxicity. Considering that EBAG9 plays immune suppressive roles in both tumor and microenvironment, we here questioned whether EBAG9 is a transferable protein from cancer to surrounding T cells and affects antitumor immune response. In this study, we showed that spontaneous development of prostate cancer was repressed in a model of Ebag9 knockout mice crossed with transgenic adenocarcinoma of the mouse prostate (TRAMP) mice. We identified TM9SF1 as a collaborative EBAG9 interactor, which regulates epithelial-mesenchymal transition (EMT) in cancer cells. Notably, extracellular vesicles (EVs) from EBAG9-overexpressing prostate cancer cells have a potential to facilitate immune escape of tumors by inhibiting T-cell cytotoxicity and modulating immune-related gene expression in T cells. Furthermore, we showed that a neutralizing antibody for EBAG9 could rescue the EV-mediated immune suppression by recovering T-cell cytotoxicity. In addition to its autocrine functions in cancer cells, EBAG9 could behave as a new class of immune checkpoint that suppresses tumor immunity in a secretory manner. We propose that EBAG9-targeting cancer treatment could be alternative therapeutic options for advanced diseases, particularly for those with EBAG9 overexpression.

EWS/FLI-l peptide-pulsed dendritic cells induces the antitumor immunity in a murine Ewing's sarcoma cell model

An increasing number of T-cell epitopes derived from various tumor-associated antigens have been reported, and they proved to play significant roles for tumor rejection both in vivo and in vitro. Over 85% of Ewing's sarcoma family of tumors (ESFTs) express tumor-specific chimeric protein EWS/FLI-1, making it an attractive target for therapeutic cytotoxic T-lymphocyte responses. Here, we identified a novel peptide epitope derived from the EWS/FLI-1 protein and demonstrated that effectors induced by the peptide could specifically secrete IFN-γ and lyse the tumor cell line of EWS/FLI-1-positive and HLA-matched cells. In addition, mice treated with dendritic cells pulsed with the EWS/FLI-1 epitope were able to reject a lethal tumor inoculation of the Ewing's sarcoma A673 cells. Therefore, these data provide evidence for the use of the EWS/FLI-l peptide epitope in T cell-based immunotherapeutic concepts against Ewing's sarcoma cell in vitro and in vivo.

Comprehensive description of the N-glycoproteome of mouse pancreatic β-cells and human islets

Cell surface N-glycoproteins provide a key interface of cells to their environment and therapeutic entry points for drug and biomarker discovery. Their comprehensive description denotes therefore a formidable challenge. The β-cells of the pancreas play a crucial role in blood glucose homeostasis, and disruption of their function contributes to diabetes. By combining cell surface and whole cell capturing technologies with high-throughput quantitative proteomic analysis, we report on the identification of a total of 956 unique N-glycoproteins from mouse MIN6 β-cells and human islets. Three-hundred-forty-nine of these proteins encompass potential surface N-glycoproteins and include orphan G-protein-coupled receptors, novel proteases, receptor protein kinases, and phosphatases. Interestingly, stimulation of MIN6 β-cells with glucose and the hormone GLP1, known stimulators of insulin secretion, causes significant changes in surface N-glycoproteome expression. Taken together, this β-cell N-glycoproteome resource provides a comprehensive view on the composition of β-cell surface proteins and expands the scope of signaling systems potentially involved in mediating responses of β-cells to various forms of (patho)physiologic stress and the extent of dynamic remodeling of surface N-glycoprotein expression associated with metabolic and hormonal stimulation. Moreover, it provides a foundation for the development of diabetes medicines that target or are derived from the β-cell surface N-glycoproteome.

Monoclonal antibodies in the treatment of pancreatic cancer

Human pancreatic cancer is a malignant disease with almost equal incidence and mortality. Effective diagnostic and therapeutic strategies are still urgently needed to improve its survival rate. With advances in structural and functional genomics, recent work has focused on targeted molecular therapy using monoclonal antibodies. This review summarizes the target molecules on the tumor cell surface and normal tissue stroma, which are related to pancreatic cancer oncogenesis, tumor growth or resistance to chemotherapy, as well as molecules involved in regulating inflammation and host immunoresponses. Targeted molecules include cell-surface receptors, such as the EGF receptor, HER2, death receptor 5 and IGF-1 receptor. Effects of monoclonal antibodies against these target molecules alone or in combination with chemotherapy, small-molecule signal transduction inhibitors, or radiation therapy are also discussed. Also discussed are the use of toxin or radioisotope conjugates, and information relating to the use of these targeting agents in pancreatic cancer clinical trials. Although targeted molecular therapy with monoclonal antibodies has made some progress in pancreatic cancer treatment, especially in preclinical studies, its clinical application to improve the survival rate of pancreatic cancer patients requires further investigation.

The ERBB3 receptor in cancer and cancer gene therapy

ERBB3, a member of the epidermal growth factor receptor (EGFR) family, is unique in that its tyrosine kinase domain is functionally defective. It is activated by neuregulins, by other ERBB and nonERBB receptors as well as by other kinases, and by novel mechanisms. Downstream it interacts prominently with the phosphoinositol 3-kinase/AKT survival/mitogenic pathway, but also with GRB, SHC, SRC, ABL, rasGAP, SYK and the transcription regulator EBP1. There are likely important but poorly understood roles for nuclear localization and for secreted isoforms. Studies of ERBB3 expression in primary cancers and of its mechanistic contributions in cultured cells have implicated it, with varying degrees of certainty, with causation or sustenance of cancers of the breast, ovary, prostate, certain brain cells, retina, melanocytes, colon, pancreas, stomach, oral cavity and lung. Recent results link high ERBB3 activity with escape from therapy targeting other ERBBs in lung and breast cancers. Thus a wide and centrally important role for ERBB3 in cancer is becoming increasingly apparent. Several approaches for targeting ERBB3 in cancers have been tested or proposed. Small inhibitory RNA (siRNA) to ERBB3 or AKT is showing promise as a therapeutic approach to treatment of lung adenocarcinoma.