Tracking human multiple myeloma xenografts in NOD-Rag-1/IL-2 receptor gamma chain-null mice with the novel biomarker AKAP-4

Identification of CD8+ T-cell epitope from multiple myeloma-specific antigen AKAP4

Multiple myeloma (MM) is a malignant plasma cell disorder affecting mainly the elderly population. Revolutionary progress in immunotherapy has been made recently, including monoclonal antibodies and chimeric antigen receptor T cell (CAR-T) therapies; however, the high relapse rate remains problematic. Therefore, combination therapies against different targets would be a reasonable strategy. In this study, we present a new X-chromosome encoded testis-cancer antigen (CTA) AKAP4 as a potential target for MM. AKAP4 is expressed in MM cell lines and MM primary malignant plasma cells. HLA-A*0201-restricted cytotoxic T lymphocytes (CTLs) induced by dendritic cells (DCs) transduced with an adenovirus vector encoding the full-length AKAP4 gene were demonstrated to lyse AKAP4⁺ myeloma cells. Seven of the 12 candidate epitopes predicated by the BIMAS and SYFPEITH algorithms were able to bind HLA-A*0201 in the T2 binding assay, of which only two peptides were able to induce CTL cytotoxicity in the co-culture of peptide-loaded human mature dendritic cells and the autologous peripheral blood mononuclear cells (PBMCs) from the same HLA-A*0201 donor. The AKAP4 630–638 VLMLIQKLL was identified as the strongest CTL epitope by the human IFN-γ ELISPOT assay. Finally, the VLMLIQKLL-specific CTLs can lyse the HLA-A*0201⁺AKAP4⁺ myeloma cell line U266 in vitro, and inhibit tumor growth in the mice bearing U266 tumors in vivo. These results suggest that the VLMLIQKLL epitope could be used to develop cancer vaccine or T-cell receptor transgenic T cells (TCR-T) to kill myeloma cells.

Patient-derived tumor models are attractive tools to repurpose drugs for ovarian cancer treatment: Pre-clinical updates

Despite advances in understanding of ovarian cancer biology, the progress in translation of research findings into new therapies is still slow. It is associated in part with limitations of commonly used cancer models such as cell lines and genetically engineered mouse models that lack proper representation of diversity and complexity of actual human tumors. In addition, the development of de novo anticancer drugs is a lengthy and expensive process. A promising alternative to new drug development is repurposing existing FDA-approved drugs without primary oncological purpose. These approved agents have known pharmacokinetics, pharmacodynamics, and toxicology and could be approved as anticancer drugs quicker and at lower cost. To successfully translate repurposed drugs to clinical application, an intermediate step of pre-clinical animal studies is required. To address challenges associated with reliability of tumor models for pre-clinical studies, there has been an increase in development of patient-derived xenografts (PDXs), which retain key characteristics of the original patient’s tumor, including histologic, biologic, and genetic features. The expansion and utilization of clinically and molecularly annotated PDX models derived from different ovarian cancer subtypes could substantially aid development of new therapies or rapid approval of repurposed drugs to improve treatment options for ovarian cancer patients.

Silencing of A-kinase anchor protein 4 inhibits the metastasis and growth of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is one of the most malignant tumors. The treatment of advanced NSCLC can be challenging due to drug resistance. The discovery of novel cancer-testis antigens to develop new strategies for advanced metastatic NSCLC is required. AKAP4 is an oncogene discovered in some malignant tumors, and its molecular function of AKAP4 in NSCLC is unknown. This study aimed to explore the potential function of AKAP4 in the development and progression of NSCLC. AKAP-4 was found to be significantly upregulated in both clinical NSCLC tissues and NSCLC cell lines. Cell viability and migration were suppressed, apoptosis was induced, and tube formation was inhibited by the knockdown of AKAP-4, accompanied by the downregulation of VEGF, N-cadherin, EphA2, and MMP-2, and upregulation of c-AMP, PKA, and E-cadherin. In vivo xenograft experiments revealed that tumor growth was inhibited by the knockdown of AKAP4, accompanied by the activation of c-AMP/PKA signaling and inhibition of epithelial-mesenchymal transition progression. Our results show that AKAP4 might be an important target for treating NSCLC because of its function in promoting the migration and proliferation of NSCLC cells.

An Improved Animal Model of Multiple Myeloma Bone Disease

Multiple myeloma (MM) is a plasma cell malignancy that causes an accumulation of terminally differentiated monoclonal plasma cells in the bone marrow, accompanied by multiple myeloma bone disease (MMBD). MM animal models have been developed and enable to interrogate the mechanism of MM tumorigenesis. However, these models demonstrate little or no evidence of MMBD. We try to establish the MMBD model with severe bone lesions and easily accessible MM progression. 1 × 106 luciferase-expressing 5TGM1 cells were injected into 8-12 week-old NOD SCID gamma mouse (NSG) and C57BL/KaLwRij mouse via the tail vein. Myeloma progression was assessed weekly via in vivo bioluminescence (BL) imaging using IVIS-200. The spine and femur/tibia were extracted and scanned by the micro-computer tomography for bone histo-morphometric analyses at the postmortem. The median survivals were 56 days in NSG while 44.5 days in C57BL/KaLwRij agreed with the BL imaging results. Histomorphic and DEXA analyses demonstrated that NSG mice have severe bone resorption that occurred at the lumbar spine but no significance at the femur compared to C57BL/KaLwRij mice. Based on these, we conclude that the systemic 5TGM1 injected NSG mouse slowly progresses myeloma and develops more severe MMBD than the C57BL/KaLwRij model.

Low intensity vibration mitigates tumor progression and protects bone quantity and quality in a murine model of myeloma

Myeloma facilitates destruction of bone and marrow. Since physical activity encourages musculoskeletal preservation we evaluated whether low-intensity vibration (LIV), a means to deliver mechanical signals, could protect bone and marrow during myeloma progression. Immunocompromised-mice (n=25) were injected with human-myeloma cells, while 8 (AC) were saline-injected. Myeloma-injected mice (LIV; n=13) were subjected to daily-mechanical loading (15min/d; 0.3g @ 90Hz) while 12 (MM) were sham-handled. At 8w, femurs had 86% less trabecular bone volume fraction (BV/TV) in MM than in AC, yet only a 21% decrease in LIV was observed in comparison to AC, reflecting a 76% increase versus MM. Cortical BV was 21% and 15% lower in MM and LIV, respectively, than in AC; LIV showing 30% improvement over MM. Similar outcomes were observed in the axial skeleton, showing a 35% loss in MM with a 27% improved retention of bone in the L5 of LIV-treated mice as compared to MM. Transcortical-perforations in the femur from myeloma-induced osteolysis were 9× higher in MM versus AC, reduced by 57% in LIV. Serum-TRACP5b, 61% greater in MM versus AC, rose by 33% in LIV compared to AC, a 45% reduction in activity when compared to MM. Histomorphometric analyses of femoral trabecular bone demonstrated a 70% elevation in eroded surfaces of MM versus AC, while measures in LIV were 58% below those in MM. 72% of marrow in the femur of MM mice contained tumor, contrasted by a 31% lower burden in LIV. MM mice (42%) presented advanced-stage necrosis of tibial marrow while present in just 8% of LIV. Myeloma infiltration inversely correlated to measures of bone quality, while LIV slowed the systemic, myeloma-associated decline in bone quality and inhibited tumor progression through the hindlimbs.

AKAP4 is a circulating biomarker for non-small cell lung cancer

Cancer testis antigens (CTAs) are widely expressed in tumor tissues, circulating tumor cells (CTCs) and in cancer derived exosomes that are frequently engulfed by lymphoid cells. To determine whether tumor derived CTA mRNAs could be detected in RNA from purified peripheral blood mononuclear cells (PBMC) of non-small cell lung cancer (NSCLC) patients, we assayed for the expression of 116 CTAs in PBMC RNA in a discovery set and identified AKAP4 as a potential NSCLC biomarker. We validated AKAP4 as a highly accurate biomarker in a cohort of 264 NSCLCs and 135 controls from 2 different sites including a subset of controls with high risk lung nodules. When all (264) lung cancers were compared with all (135) controls the area under the ROC curve (AUC) was 0.9714. When 136 stage I NSCLC lung cancers are compared with all controls the AUC is 0.9795 and when all lung cancer patients were compared to 27 controls with histologically confirmed benign lung nodules, a comparison of significant clinical importance, the AUC was 0.9825. AKAP4 expression increases significantly with tumor stage, but independent of age, gender, smoking history or cancer subtype. Follow-up studies in a small number of resected NSCLC patients revealed a decrease of AKAP4 expression post-surgical resection that remained low in patients in remission and increased with tumor recurrence. AKAP4 is a highly accurate biomarker for the detection of early stage lung cancer.

Myeloma Cell Dynamics in Response to Treatment Supports a Model of Hierarchical Differentiation and Clonal Evolution

PURPOSE

Since the pioneering work of Salmon and Durie, quantitative measures of tumor burden in multiple myeloma have been used to make clinical predictions and model tumor growth. However, such quantitative analyses have not yet been performed on large datasets from trials using modern chemotherapy regimens.

EXPERIMENTAL DESIGN

We analyzed a large set of tumor response data from three randomized controlled trials of bortezomib-based chemotherapy regimens (total sample size n = 1,469 patients) to establish and validate a novel mathematical model of multiple myeloma cell dynamics.

RESULTS

Treatment dynamics in newly diagnosed patients were most consistent with a model postulating two tumor cell subpopulations, "progenitor cells" and "differentiated cells." Differential treatment responses were observed with significant tumoricidal effects on differentiated cells and less clear effects on progenitor cells. We validated this model using a second trial of newly diagnosed patients and a third trial of refractory patients. When applying our model to data of relapsed patients, we found that a hybrid model incorporating both a differentiation hierarchy and clonal evolution best explains the response patterns.

CONCLUSIONS

The clinical data, together with mathematical modeling, suggest that bortezomib-based therapy exerts a selection pressure on myeloma cells that can shape the disease phenotype, thereby generating further inter-patient variability. This model may be a useful tool for improving our understanding of disease biology and the response to chemotherapy regimens. Clin Cancer Res; 22(16); 4206-14. ©2016 AACR.

AKAP4 mediated tumor malignancy in esophageal cancer

AKAP4 as a new Cancer/Testis (CT) antigen is expressed not only in human germ cells, but also expressed in various tumor cells. AKAP4 is correlated with tumor malignancy; however, the role of AKAP4 in esophageal cancer remains unknown. Here we explored the function of AKAP4 in esophageal cancer. We found that AKAP4 mRNA and protein levels were up-regulated in the esophageal cancer tissues compared to normal control. In KYSE150 cell line, inhibition of AKAP4 suppressed cell growth and invasiveness. Overexpression of AKAP4 promoted cell growth and invasiveness. In addition, expression of epithelial markers (E-cadherin and ZO-1) was up-regulated or down-regulated and expression of mesenchymal markers (vimentin and N-cadherin) was down-regulated or up-regulated after knockdown or overexpression of AKAP4 in vitro. In vivo in a xenograft model silencing AKAP4 suppressed tumor growth. We also found that NF-κB p65 bound to AKAP4 promoter and regulated expression of AKAP4. In conclusion, overexpression of AKAP4 is associated with esophageal cancer progression. Inhibition of AKAP4 leads to suppressed growth and invasion of esophageal cancer.

Targeting Tumor Initiating Cells through Inhibition of Cancer Testis Antigens and Notch Signaling: A Hypothesis

Tumor initiating cells (TICs) differ from normal stem cells (SCs) in their ability to initiate tumorigenesis, invasive growth, metastasis and the acquisition of chemo and/or radio-resistance. Over the past years, several studies have indicated the potential role of the Notch system as a key regulator of cellular stemness and tumor development. Furthermore, the expression of cancer testis antigens (CTA) in TICs, and their role in SC differentiation and biology, has become an important area of investigation. Here, we propose a model in which CTA expression and Notch signaling interacts to maintain the sustainability of self-replicating tumor populations, ultimately leading to the development of metastasis, drug resistance and cancer progression. We hypothesize that Notch-CTA interactions in TICs offer a novel opportunity for meaningful therapeutic interventions in cancer.

Human cancer growth and therapy in immunodeficient mouse models

Since the discovery of the "nude" mouse more than 40 years ago, investigators have attempted to model human tumor growth in immunodeficient mice. Here, we summarize how the field has advanced over the ensuing years owing to improvements in the murine recipients of human tumors. These improvements include the discovery of the scid mutation and development of targeted mutations in the recombination-activating genes 1 and 2 (Rag1(null), Rag2(null)) that severely cripple the adaptive immune response of the murine host. More recently, mice deficient in adaptive immunity have been crossed with mice bearing targeted mutations designed to weaken the innate immune system, ultimately leading to the development of immunodeficient mice bearing a targeted mutation in the gene encoding the interleukin 2 (IL2) receptor common γ chain (IL2rg(null), also known in humans as cytokine receptor common subunit γ). The IL2rg(null) mutation has been used to develop several immunodeficient strains of mice, including the NOD-scid IL2rg(null) (NSG) strain. Using NSG mice as human xenograft recipients, it is now possible to grow almost all types of primary human tumors in vivo, including most solid tumors and hematological malignancies that maintain characteristics of the primary tumor in the patient. Programs to optimize patient-specific therapy using patient-derived xenograft tumor growth in NSG mice have been established at several institutions, including The Jackson Laboratory. Moreover, NSG mice can be engrafted with functional human immune systems, permitting for the first time the potential to study primary human tumors in vivo in the presence of a human immune system.

Gene silencing of A-kinase anchor protein 4 inhibits cervical cancer growth in vitro and in vivo

Earlier, we reported an association of A-kinase anchor protein 4 (AKAP4) expression in cervical cancer patient specimens, indicating its implications as an immunotherapeutic target. In this study, we investigated the possible role of AKAP4 in cervical carcinogenesis. AKAP4 messenger RNA and protein expression was assessed in four cervical cancer cell line models, C-33A, CaSki, HeLa and SiHa. Gene silencing approach was employed to investigate the potential role of AKAP4 in cellular growth, proliferation, colony-forming ability, migration and invasion in aggressive squamous cell carcinoma cells (SiHa). Further, the effect of downregulation of AKAP4 on tumor growth was examined in the cervical cancer xenograft model in nude mice. Our data clearly indicated that AKAP4 was expressed in all cervical cancer cells at the gene and protein level. We also observed distinct cytoplasmic and surface localization by indirect immunofluorescence and flow cytometry, respectively. Ablation of AKAP4 protein caused significant inhibition in cellular proliferation, colony-forming ability, migration and invasion ability of SiHa cells. Further, gene silencing of AKAP4 also resulted in reduced tumor growth in nude mice in vivo. Collectively, AKAP4 surface localization and its significant association with malignant properties of cervical cancer cells imply its clinical utility as an immunotherapeutic target.

Anti-Notch treatment prevents multiple myeloma cells localization to the bone marrow via the chemokine system CXCR4/SDF-1

Multiple myeloma (MM) is a deadly hematopoietic malignancy characterized by proliferation of malignant plasma cells in the bone marrow (BM) and bone disease. Interactions between myeloma and BM cells facilitate tumor progression and resistance to therapies. CXCR4 and its ligand Stromal cell-derived factor-1 (SDF-1) have a primary role in this process and are associated with poor prognosis. The Notch pathway is active in myeloma cells, resulting in increased proliferation, resistance to apoptosis and osteolytic activity. We hypothesized that the CXCR4/SDF-1 axis mediates the effects of Notch signals in myeloma cells. Here we show that Notch positively controls CXCR4/SDF-1 expression and functions in myeloma cell lines, and that forced CXCR4 activation partially rescues tumor cells from the outcomes of Notch inhibition. Additionally, we provide evidences that Notch blocking in vivo significantly reduces BM infiltration by human myeloma cells in mouse xenografts. This is the first evidence that a Notch-targeted approach effectively prevents MM cell migration, proliferation and resistance to apoptosis by reducing CXCR4 and SDF-1 levels.