Haploinsufficiency of NFKBIA reshapes the epigenome antipodal to the IDH mutation and imparts disease fate in diffuse gliomas

Genetic alterations help predict the clinical behavior of diffuse gliomas, but some variability remains uncorrelated. Here, we demonstrate that haploinsufficient deletions of chromatin-bound tumor suppressor NFKB inhibitor alpha (NFKBIA) display distinct patterns of occurrence in relation to other genetic markers and are disproportionately present at recurrence. NFKBIA haploinsufficiency is associated with unfavorable patient outcomes, independent of genetic and clinicopathologic predictors. NFKBIA deletions reshape the DNA and histone methylome antipodal to the IDH mutation and induce a transcriptome landscape partly reminiscent of H3K27M mutant pediatric gliomas. In IDH mutant gliomas, NFKBIA deletions are common in tumors with a clinical course similar to that of IDH wild-type tumors. An externally validated nomogram model for estimating individual patient survival in IDH mutant gliomas confirms that NFKBIA deletions predict comparatively brief survival. Thus, NFKBIA haploinsufficiency aligns with distinct epigenome changes, portends a poor prognosis, and should be incorporated into models predicting the disease fate of diffuse gliomas.

Differential escape mechanisms in cetuximab-resistant head and neck cancer cells

Acquired cetuximab resistance is a challenge for oncologists treating advanced head and neck carcinoma (HNC). While intrinsic cetuximab resistance mechanism in colorectal cancer is known, resistance in HNC is unclear. We established two different cetuximab resistant HNC cell lines by culturing epidermal growth factor (EGFR) expressing UM-SCC-1 and UM-SCC-6 cell lines in the presence of 5 μg/ml cetuximab. We then explored potential mechanisms of resistance. We found that the 2 cell lines developed resistance by different mechanisms. Specifically, we found that UM-SCC-1 resistant cells (UM-SCC-1R) showed enhanced EGF-induced downstream signals while UM-SCC-6 resistant cells (UM-SCC-6R) demonstrated EGF-independent signaling. Global kinase activity (kinomic) profiling revealed unique signaling differences in the two resistant cell lines. However, both of the resistant lines demonstrated increased phospho-serine 727 and total STAT3 expression compared to the parental lines. STAT3 knockdown promoted increased cytotoxicity both in the presence and absence of cetuximab in the resistant lines suggesting that STAT3 may be a common target in cetuximab resistance.

Tumor microenvironment regulates metastasis and metastasis genes of mouse MMTV-PymT mammary cancer cells in vivo

Metastasis is the primary cause of death in breast cancer patients, yet there are challenges to modeling this process in vivo. The goal of this study was to analyze the effects of injection site on tumor growth and metastasis and gene expression of breast cancer cells in vivo using the MMTV-PymT breast cancer model (Met-1 cells). Met-1 cells were injected into 5 sites (subcutaneous, mammary fat pad, tail vein, intracardiac, and intratibial), and tumors and metastases were monitored using bioluminescent imaging and confirmed with gross necropsy and histopathology. Met-1 tumors were analyzed based on morphology and changes in gene expression in each tissue microenvironment. There were 6 permissible sites of Met-1 tumor growth (mammary gland, subcutis, lung, adrenal gland, ovary, bone). Met-1 cells grew faster in the subcutis compared to mammary fat pad tumors (highest Ki-67 index). Morphologic differences were evident in each tumor microenvironment. Finally, 7 genes were differentially expressed in the Met-1 tumors in the 6 sites of growth or metastasis. This investigation demonstrates that breast cancer progression and metastasis are regulated by not only the tumor cells but also the experimental model and unique molecular signals from the tumor microenvironment.

NFKBIA deletion in triple-negative breast cancer

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Background: While effective, target-directed therapies are available for ER-positive and HER2-amplified breast cancer, adjuvant therapeutic options for triple-negative breast cancer (TNBC) are limited in the absence of well-defined molecular targets. Constitutive activation of oncogenic nuclear factor kB (NFkB) has been associated with ER-negative or basal-like (BL) breast cancers, but the underlying mechanism of this activation remains undefined. We previously showed that deletion of the endogenous NFkB repressor gene NFKBIA associates with EGFR non-amplified glioblastoma multiforme and portends unfavorable clinical outcome (Bredel et al. NEJM 2011). Methods: We analyzed >5,000 human breast cancers for deletions, mutations and/or expression of NFKBIA. We studied tumor suppressor activity of NFKBIA and the effect of targeted NFkB inhibition in cell culture with various NFKBIA genotypes. We compared molecular results with outcomes of affected persons. Results: NFKBIA is often (10.8%) deleted but not mutated in breast cancer. NFKBIA deletions are significantly associated with TNBC (32.8%) and particularly frequent in the BL subtype (36.7%). Loss of NFKBIA exerts a haploinsufficient effect on NFKBIA expression and the transactivation of several NF-kB target genes with important roles in breast carcinogenesis. Restoration of NFKBIA expression or pharmacologic NFkB inhibition attenuates the malignant phenotype of cells cultured from TNBC with NFKBIA deletion. Deletion and low expression of NFKBIA are highly associated with unfavorable overall survival, independent of patient age, tumor stage, nodal status, and tumor subtype. Loss of NFKBIA expression portends significantly poorer disease-specific survival, recurrence-free survival, and distant metastasis-free survival. Moreover, NFKBIA expression is significantly associated with duration of metastasis-free survival in subgroups of patients with brain or lung metastases from breast cancer. Conclusions: NFKBIA is a new, prognostically relevant, molecular target in TNBC, which remains a clinically challenging subtype of breast cancer with limited treatment options.

AU-rich elements in the 3'-UTR regulate the stability of the 141 amino acid isoform of parathyroid hormone-related protein mRNA

We demonstrated previously that parathyroid hormone-related protein (PTHrP) 1-141 mRNA is the least stable of three isoforms and is the only isoform that is stabilized by TGF-β. In order to understand how PTHrP mRNA is stabilized by TGF-β, we first sought to elucidate the mechanism(s) that are responsible for the instability of PTHrP isoform 1-141 mRNA. The 3'-UTR of isoform 1-141 contains four AU-rich elements (AREs), which are known to mediate mRNA degradation. We utilized a luciferase reporter system to test whether these four AREs are responsible for the short half-life of PTHrP 1-141 mRNA. Our results demonstrated that ARE elements in the 3'-UTR of PTHrP 1-141 mRNA play a significant role in regulation of the stability of the mRNA. It is known that AREs mediate their effects on mRNA stability through a number of ARE-binding proteins that recruit the exosome, a complex of exonucleases that degrades the mRNA. We identified tristetraproline (TTP) as an RNA-binding protein that may be involved in ARE-mediated degradation of PTHrP 1-141 mRNA.

Characterization of bone resorption in novel in vitro and in vivo models of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most commonly diagnosed oral malignancy in humans and cats and frequently invades bone. The objective of this study was to determine if feline OSCC serves as a relevant model of human OSCC in terms of osteolytic behavior and expression of bone resorption agonists. Novel feline OSCC cell lines (SCCF2 and SCCF3) were derived from spontaneous carcinomas. Gene expression and osteolytic behavior were compared to an established feline OSCC cell line (SCCF1) and three human OSCC cell lines (UMSCC-12, A253 and SCC25). Interaction of OSCC with bone and murine pre-osteoblasts (MC3T3) was investigated using in vitro co-culture techniques. In vivo bioluminescent imaging, Faxitron radiography and microscopy were used to measure xenograft growth and bone invasion in nude mice. Human and feline OSCC expressing the highest levels of parathyroid hormone-related protein (PTHrP) were associated with in vitro and in vivo bone resorption and osteoclastogenesis. MC3T3 cells had increased receptor activator of nuclear factor κB ligand (RANKL) expression and reduced osteoprotegerin (OPG) expression in conditioned medium from bone-invasive SCCF2 cells compared to minimally bone invasive SCCF3 cells, which was partially reversed with a neutralizing anti-PTHrP antibody. Human and feline OSCC cells cultured in bone-conditioned medium had increased PTHrP secretion and proliferation. Feline OSCC-induced bone resorption was associated with tumor cell secretion of PTHrP and with increased RANKL:OPG expression ratio in mouse preosteoblasts. Bone-CM increased OSCC proliferation and secretion of PTHrP. The preclinical models of feline OSCC recapitulated the bone-invasive phenotype characteristic of spontaneous OSCC and will be useful to future preclinical and mechanistic studies of bone invasive behavior.

Effects of parathyroid hormone-related protein and macrophage inflammatory protein-1α in Jurkat T-cells on tumor formation in vivo and expression of apoptosis regulatory genes in vitro

Parathyroid hormone-related protein (PTHrP) and macrophage inflammatory protein-1α (MIP-1α) have been implicated in the pathogenesis of adult T-cell leukemia/lymphoma, but their effects on T-cells have not been well studied. Here we analyzed the functions of PTHrP and MIP-1α on T-cell growth and death both in vitro and in vivo by overexpressing either factor in human Jurkat T-cells. PTHrP or MIP-1α did not affect Jurkat cell growth in vitro, but PTHrP increased their sensitivity to apoptosis. Importantly, PTHrP and MIP-1α decreased both tumor incidence and growth in vivo. To investigate possible mechanisms, polymerase chain reaction (PCR) arrays and real-time reverse transcription (RT)-PCR assays were performed. Both PTHrP and MIP-1α increased the expression of several factors including signal transducer and activator of transcription 4, tumor necrosis factor α, receptor activator of nuclear factor κB ligand and death-associated protein kinase 1, and decreased the expression of inhibitor of DNA binding 1, interferon γ and CD40 ligand in Jurkat cells. In addition, MIP-1α also increased the expression of transcription factor AP-2α and PTHrP increased expression of the vitamin D3 receptor. These data demonstrate that PTHrP and MIP-1α exert a profound antitumor effect presumably by increasing the sensitivity to apoptotic signals through modulation of transcription and apoptosis factors in T-cells.

Development of a brain metastatic canine prostate cancer cell line

BACKGROUND

Prostate cancer in men has a high mortality and morbidity due to metastatic disease. The pathobiology of prostate cancer metastasis is not well understood and cell lines and animal models that recapitulate the complex nature of the disease are needed. Therefore, the goal of the study was to establish and characterize a new prostate cancer line derived from a dog with spontaneous prostate cancer.

METHODS

A new cell line (Leo) was derived from a dog with spontaneous prostate cancer. Immunohistochemistry and PCR were used to characterize the primary prostate cancer and xenografts in nude mice. Subcutaneous tumor growth and metastases in nude mice were evaluated by bioluminescent imaging, radiography and histopathology. In vitro chemosensitivity of Leo cells to therapeutic agents was measured.

RESULTS

Leo cells expressed the secretory epithelial cytokeratins (CK)8, 18, and ductal cell marker, CK7. The cell line grew in vitro (over 75 passages) and was tumorigenic in the subcutis of nude mice. Following intracardiac injection, Leo cells metastasized to the brain, spinal cord, bone, and adrenal gland. The incidence of metastases was greatest to the central nervous system (80%) with a lower incidence to bone (20%) and the adrenal glands (16%). In vitro chemosensitivity assays demonstrated that Leo cells were sensitive to Velcade and an HDAC-42 inhibitor with IC(50) concentrations of 1.9 nm and 0.95 µm, respectively.

CONCLUSION

The new prostate cancer cell line (Leo) will be a valuable model to investigate the mechanisms of the brain and bone metastases.

Dickkopf-1 (DKK-1) stimulated prostate cancer growth and metastasis and inhibited bone formation in osteoblastic bone metastases

BACKGROUND

Osteoblastic bone metastasis is the predominant phenotype observed in prostate cancer patients and is associated with high patient mortality and morbidity. However, the mechanisms determining the development of this phenotype are not well understood. Prostate cancer cells secrete several osteogenic factors including Wnt proteins, which are not only osteoinductive but also oncogenic. Therefore, the purpose of the study was to investigate the contribution of the Wnt signaling pathway in prostate cancer growth, incidence of bone metastases, and osteoblastic phenotype of bone metastases. The strategy involved overexpressing the Wnt antagonist, DKK-1, in the mixed osteoblastic and osteolytic Ace-1 prostate cancer cells.

METHODS

Ace-1 prostate cancer cells stably expressing human DKK-1 or empty vector were established and transduced with lentiviral yellow fluorescent protein (YFP)-luciferase (Luc). The Ace-1/vector(YFP-LUC) and Ace-1/DKK-1(YFP-LUC) cells were injected subcutaneously, intratibially, or in the left cardiac ventricle in athymic mice.

RESULTS

Unexpectedly, DKK-1 significantly increased Ace-1 subcutaneous tumor mass and the incidence of bone metastases after intracardiac injection of Ace-1 cells. DKK-1 increased Ace-1 tumor growth associated with increased phospho46 c-Jun amino-terminal kinase by the Wnt noncanonical pathway. As expected, DKK-1 decreased the Ace-1 osteoblastic phenotype of bone metastases, as confirmed by radiographic, histopathologic, and microcomputed tomographic analysis. DKK-1 decreased osteoblastic activity via the Wnt canonical pathway evidenced by an inhibition of T-cell factor activity in murine osteoblast precursor ST2 cells.

CONCLUSION

The present study showed that DKK-1 is a potent inhibitor of bone growth in prostate cancer-induced osteoblastic metastases.

Zoledronic acid reduces bone loss and tumor growth in an orthotopic xenograft model of osteolytic oral squamous cell carcinoma

Squamous cell carcinoma (SCC) is the most common form of oral cancer. Destruction and invasion of mandibular and maxillary bone frequently occurs and contributes to morbidity and mortality. We hypothesized that the bisphosphonate drug zoledronic acid (ZOL) would inhibit tumor-induced osteolysis and reduce tumor growth and invasion in a murine xenograft model of bone-invasive oral SCC (OSCC) derived from an osteolytic feline OSCC. Luciferase-expressing OSCC cells (SCCF2Luc) were injected into the perimaxillary subgingiva of nude mice, which were then treated with 100 μg/kg ZOL or vehicle. ZOL treatment reduced tumor growth and prevented loss of bone volume and surface area but had no effect on tumor invasion. Effects on bone were associated with reduced osteolysis and increased periosteal new bone formation. ZOL-mediated inhibition of tumor-induced osteolysis was characterized by reduced numbers of tartrate-resistant acid phosphatase-positive osteoclasts at the tumor-bone interface, where it was associated with osteoclast vacuolar degeneration. The ratio of eroded to total bone surface was not affected by treatment, arguing that ZOL-mediated inhibition of osteolysis was independent of effects on osteoclast activation or initiation of bone resorption. In summary, our results establish that ZOL can reduce OSCC-induced osteolysis and may be valuable as an adjuvant therapy in OSCC to preserve mandibular and maxillary bone volume and function.

Osteolytic bone resorption in adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is caused by human T lymphotropic virus type 1 (HTLV-1). Patients with ATLL frequently develop humoral hypercalcemia of malignancy (HHM) resulting from increased osteoclastic bone resorption. Our goal was to investigate the mechanisms of ATLL-induced osteoclastic bone resorption. Murine calvaria co-cultured with HTLV-1-infected cells directly or conditioned media from cell cultures had increased osteoclast activity that was dependent on RANKL, indicating that factors secreted from ATLL cells had a stimulatory effect on bone resorption. Factors released from resorbing bone stimulated proliferation of HTLV-1-infected T-cells. Parathyroid hormone-related protein (PTHrP) and macrophage inflammatory protein-1alpha (MIP-1alpha), both osteoclast stimulators, were expressed in HTLV-1-infected T-cell lines. Interestingly, when HTLV-1-infected T-cells were co-cultured with pre-osteoblasts, the expression of osteoprotegerin (OPG), an osteoclast inhibitory factor, was significantly down-regulated in the pre-osteoblasts. When OPG was added into the ex vivo osteoclastogenesis assay induced by HTLV-1-infected T-cells, osteoclastogenesis was strongly inhibited. In addition, HTLV-1-infected T-cells inhibited expression of early osteoblast genes and induced late genes. These regulators will serve as future therapeutic targets for the treatments of HHM in ATLL.

Abstract 653: Stat3 as a molecular signature and therapeutic target for inflammatory breast cancer

Inflammatory breast cancer (IBC) is the most aggressive and lethal of all breast cancers. There is little known about the molecular signatures of IBC with the exception that these breast cancers commonly over-express E-cadherin and Rho C GTPase and exist as tumor emboli within dermal lymphatics. In addition, IBC tumor emboli exhibit characteristics of tumor initiating cells, i.e., cancer stem cells. Another interesting characteristic of IBC tumors is their ability to undergo vasculogenic mimicry, forming tube-like structures that abrogate the need of this very aggressive tumor type to induce the development of angiogenic endothelium. In vitro under low adherence culture conditions, IBC cells readily form tumor spheroids that contain ”label retaining” cells and exhibit self-renewal. In addition, when cultured as tumor spheroids in 3 dimensions, they express high levels of the phosphorylated form of the signal transducer and activator of transcription 3 (phospho-stat3), recently shown to regulate survival of embryonic stem cells. From a panel of newly developed novel stat3-targeted peptidomimetics, we found that the lead compound, designated as PM-73G, inhibited phospho-stat3, which was associated with blockade of the robust invasion, anchorage independent growth in soft agar and vasculogenic mimicry exhibited by IBC tumor cells without a significant anti-proliferative effect. Using array-based PCR and protein analysis, we found a specific pattern of inhibition of genes/proteins within the Jak/Stat pathway by PM-73G. Results of comparative studies using both PM-73G and stat3 shRNA demonstrate a role for stat3 in maintenance of the cancer stem cell phenotype exhibited by IBC tumor spheroids. Taken together, these studies suggest that stat3 may serve both as a molecular signature of IBC and as a target for development of effective therapeutics for this lethal form of breast cancer that contain tumor cells exhibiting a cancer stem cell phenotype. (Funded by The Susan G. Komen For The Cure Promise Grant KGO 81287 (FMR), The State of Texas Rare and Aggressive Breast Cancer Fund (FMR), NIH NCI CA096652 (JSM) and Center for Targeted Therapy at The University of Texas M.D. Anderson Cancer Center and the Texas Institute for Drug and Diagnostic Development at The University of Texas, Austin. (FMR & JSM).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 653.

NOD/SCID mouse model of canine T-cell lymphoma with humoral hypercalcaemia of malignancy: cytokine gene expression profiling and in vivo bioluminescent imaging

Lymphoma is a malignant neoplasm arising from B or T lymphocytes. In dogs, one-third of lymphomas are highly aggressive multicentric T-cell lymphomas that are often associated with humoral hypercalcaemia of malignancy (HHM). There are no cell lines or animal models to investigate the pathogenesis of T-cell lymphoma and HHM in dogs. We developed the first xenograft model by injecting lymphoma cells from an Irish Wolfhound intraperitoneally into NOD/SCID mice. The mice developed multicentric lymphoma along with HHM and increased parathyroid hormone-related protein (PTHrP) as occurs in dogs with T-cell lymphoma. Using cytokine complementary DNA arrays, we identified genes that have potential implications in the pathogenesis of T-cell lymphoma. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) of T-cell lymphoma samples from hypercalcaemic canine patients showed that PTHrP likely plays a central role in the pathogenesis of HHM and that hypercalcaemia is the result of a combinatorial effect of different hypercalcaemic factors. Finally, we monitored in vivo tumour progression and metastases in the mouse model by transducing the lymphoma cells with a lentiviral vector that encodes a luciferase-yellow fluorescent protein reporter and showed that in vivo trafficking patterns in this model were similar to those seen in dogs. This unique mouse model will be useful for translational research in lymphoma and for investigating the pathogenesis of T-cell lymphoma and HHM in the dog.

Zoledronic acid decreased osteolysis but not bone metastasis in a nude mouse model of canine prostate cancer with mixed bone lesions

BACKGROUND

Bone metastasis is the most common cause of morbidity and mortality in patients with advanced prostate cancer and is manifested primarily as mixed osteoblastic and osteolytic lesions. However, the mechanisms responsible for bone metastases in prostate cancer are not clearly understood, in part due to the lack of relevant in vivo models that mimic the clinical presentation of the disease in humans. We previously established a nude mouse model with mixed bone metastases using intracardiac injection of canine prostate cancer cells (Ace-1). In this study, we hypothesized that tumor-induced osteolysis promoted the incidence of bone metastases and osteoblastic activity.

METHODS

We studied the effect of inhibition of osteolysis with zoledronic acid (ZA) on the prevention and progression of Ace-1 bone metastases in nude mice using prophylactic and delayed treatment protocols. Bioluminescent imaging, radiography, and histopathological evaluation were performed to monitor the effect of ZA on the incidence, progression and nature of bone metastases.

RESULTS

Unexpectedly, there was no significant difference in tumor burden and the incidence of metastasis between control and treatment groups as detected by bioluminescent imaging and bone histomorphometry. However, radiographic and histopathological analysis showed a significant treatment-related decrease in osteolysis, but no effect on tumor-induced trabecular bone thickness in both treatment groups compared to controls.

CONCLUSION

Our results demonstrated that the incidence of prostate cancer bone metastases in vivo was not reduced by zoledronic acid even though zoledronic acid inhibited bone resorption and bone loss associated with the mixed osteoblastic/osteolytic bone metastases in the Ace-1 model.

A novel bioluminescent mouse model and effective therapy for adult T-cell leukemia/lymphoma

Adult T-cell /lymphomaleukemia (ATLL) is caused by human T-cell lymphotropic virus type 1 (HTLV-1). Approximately 80% of ATLL patients develop humoral hypercalcemia of malignancy (HHM), a life-threatening complication leading to a poor prognosis. Parathyroid hormone-related protein (PTHrP) and macrophage inflammatory protein-1 alpha (MIP-1 alpha) are important factors in the pathogenesis of HHM in ATLL and the expression of PTHrP can be activated by nuclear factor kappaB (NF-kappaB). NF-kappaB is constitutively activated in ATLL cells and is essential for leukemogenesis including transformation of lymphocytes infected by HTLV-1. Our goal was to evaluate the effects of NF-kappaB disruption by a proteasomal inhibitor (PS-341) and osteoclastic inhibition by zoledronic acid (Zol) on the development of ATLL and HHM using a novel bioluminescent mouse model. We found that PS-341 decreased cell viability, increased apoptosis, and down-regulated PTHrP expression in ATLL cells in vitro. To investigate the in vivo efficacy, nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice were xenografted with ATLL cells and treated with vehicle control, PS-341, Zol, or a combination of PS-341 and Zol. Bioluminescent imaging and tumor cell count showed a significant reduction in tumor burden in mice from all treatment groups. All treatments also significantly reduced the plasma calcium concentrations. Zol treatment increased trabecular bone volume and decreased osteoclast parameters. PS-341 reduced PTHrP and MIP-1 alpha expression in tumor cells in vivo. Our results indicate that both PS-341 and Zol are effective treatments for ATLL and HHM, which are refractory to conventional therapy.

New bone formation and osteolysis by a metastatic, highly invasive canine prostate carcinoma xenograft

BACKGROUND

Osteoblastic metastases are commonly induced by prostate cancer. A canine prostate carcinoma xenograft (Ace-1) was developed and used to evaluate neoplastic prostate cell growth, metastasis, and effects on bone formation in nude mice.

METHODS

Characteristics of the Ace-1 cells were evaluated with histopathology, radiography, and bioluminescent imaging (BLI). Immunohistochemistry and quantitative RT-PCR were used to evaluate the expression of factors important in the development of osteoblastic metastases.

RESULTS

The Ace-1 cells were invasive and induced bone formation and destruction. Radiographs demonstrated a mixed osteoblastic/osteolytic reaction. Lung and lymph node metastases occurred in 30% of mice. The tumor cells expressed parathyroid hormone-related protein (PTHrP-141 isoform), cathepsin K, keratins 8/18, and vimentin, but not keratins 5/14, and were androgen receptor negative. Intracardiac (IC) injections resulted in metastases in vertebrae and long bones.

CONCLUSIONS

The Ace-1 xenograft is a useful model for investigating the pathogenesis of prostate cancer invasion and mixed osteoblastic/osteolytic bone metastases.