Lilach Abramovitz

Malignant melanoma is the deadliest of skin cancers. Melanoma frequently metastasizes to the brain, resulting in dismal survival. Nevertheless, mechanisms that govern early metastatic growth and the interactions of disseminated metastatic cells with the brain microenvironment are largely unknown. To study the hallmarks of brain metastatic niche formation, we established a transplantable model of spontaneous melanoma brain metastasis in immunocompetent mice and developed molecular tools for quantitative detection of brain micrometastases. Here we demonstrate that micrometastases are associated with instigation of astrogliosis, neuroinflammation, and hyperpermeability of the blood–brain barrier. Furthermore, we show a functional role for astrocytes in facilitating initial growth of melanoma cells. Our findings suggest that astrogliosis, physiologically instigated as a brain tissue damage response, is hijacked by tumor cells to support metastatic growth. Studying spontaneous melanoma b...

Purpose: Klotho is a transmembrane protein which can be shed, act as a circulating hormone and modulate the insulin-like growth factor (IGF)-I and the fibroblast growth factor (FGF) pathways. We have recently identified klotho as a tumor suppressor in breast cancer. Klotho is expressed in the normal pancreas and both the IGF-I and FGF pathways are involved in pancreatic cancer development. We, therefore, undertook to study the expression and activity of klotho in pancreatic cancer.Experimental Design: Klotho expression was studied using immunohistochemistry and quantitative RT-PCR. Effects of klotho on cell growth were assessed in the pancreatic cancer cells Panc1, MiaPaCa2, and Colo357, using colony and MTT assays and xenograft models. Signaling pathway activity was measured by Western blotting.Results: Klotho expression is downregulated in pancreatic adenocarcinoma. Overexpression of klotho, or treatment with soluble klotho, reduced growth of pancreatic cancer cells in vitro and i...

Adrenergic signaling plays a central role in physiological regulation, including modulation of processes in the immune system. However, the effects of adrenergic activation on antibody-mediated immune response remain unknown. Here, we investigate the effects of stress - induced β-adrenergic receptor activation on the B cell response at molecular and the systemic levels. We find that β-adrenergic agonist treatment of B cells from three convalescent SARS coronavirus-2 donors, reduced both membrane IgG expression and clonal expansion when the cells were stimulated ex vivo with spike receptor binding domain (RBD). Interestingly, monoclonal anti-RBD antibodies cloned from B cells cultured in the presence of β-adrenergic agonist, exhibited higher affinity for RBD compared to antibodies cloned from control cultures, suggesting that clones under stress exhibit higher antigen affinity. As a corollary, following ovalbumin immunization in mice, physiological stress during germinal center react...

Klotho is a transmembranal protein, which can be cleaved, shed and act as a circulating hormone. Klotho deficient mice present a syndrome of early aging, while overexpression of klotho extends lifespan. Klotho is a potent inhibitor of the insulin growth factor (IGF)-1 and the basic fibroblast growth factor (FGF) pathways. Klotho is also an essential co-factor for the activity of FGF23 and thus serves as a major regulator of phosphate homeostasis. We have recently identified klotho as a tumor suppressor in breast cancer. As klotho is expressed in the normal pancreas and as the IGF-1 and FGF pathways are involved in pancreatic cancer development, we undertook to study the expression and activity of klotho in pancreatic cancer. Immunohistochemistry analysis revealed significantly reduced expression of klotho in pancreatic cancer compared to normal pancreas, and low levels of klotho mRNA were noted in the pancreatic cancer cells Panc1, Colo357 and MiaPaCa2 compared to normal pancreas cells. Further studies revealed that klotho silencing is mediated by epigenetic mechanisms. Overexpression of klotho or treatment with soluble klotho (8pM) reduced clonal growth of pancreatic cancer cell lines, and a synergistic effect was observed in combination with chemotherapeutic drugs. Daily injections of klotho (10μg/kg) inhibited tumor formation of Panc1 cells in athymic mice. Klotho inhibited activation of the IGF-1 pathway in pancreatic cancer cells. As klotho further enhanced growth inhibition by the IGF-1R inhibitor AG1024, modulation of additional signaling pathways by klotho was suspected. Indeed, klotho overexpression inhibited the bFGF pathway in these cells. The extracellular region of klotho is composed of two internal repeats, KL1 and KL2, and each of them can be cleaved and act separately. While both domains share homology to glycosidase, a structural model suggested that only KL1 retains enzymatic activity. While the KL2 domain did not show growth inhibitory activities, KL1 effectively slowed growth of pancreatic cancer cells, both in vitro and in vivo and was found to be a potent inhibitor of the IGF-1 and bFGF pathways. Importantly, KL1 did not promote FGF23 signaling and therefore, in contrary to the full-length protein, its administration to mice did not affect phosphate homeostasis. In conclusion, these studies indicate klotho as a potent tumor suppressor in pancreatic cancer and suggest, for the first time, that klotho growth inhibitory activities are mediated by the KL1 domain, possibly due to its putative enzymatic activities. As the KL1 domain is not involved in regulation of phosphate homeostasis, its administration may serve as a potential safe and effective novel strategy for the treatment of pancreatic cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2192. doi:10.1158/1538-7445.AM2011-2192

Visceral pain is characterized by spontaneous pain and referred hyperalgesia. After inducing visceral pain in mice using intracolonic mustard oil administration, we examined the effects of various nonsteroidal antiinflammatory drugs (NSAIDs) on pain-related behavior and on Evans blue dye extravasation. Animals were given one of the following: saline, ethanol, dimethylsulfoxide (DMSO), morphine, ketoprofen, ketorolac, or DFU (a cyclooxygenase-2 inhibitor). After drug treatment, mice underwent intracolonic administration of 50 microL 1.5% mustard oil. Spontaneous pain-related responses were assessed for the next 20 min. The frequency of withdrawal responses to the application of von Frey hairs to the abdomen, foot, and tail was determined. After completion of the behavioral tests, Evans blue was injected into the animals via the tail vein. Two hours later, the colon was removed postmortem and Evans blue content was measured. Spontaneous pain behaviors were significantly less in animals administered 3 and 10 mg/kg morphine, 50 mg/kg ketorolac, 100 mg/kg ketoprofen, and 20 mg/kg DFU (P < 0.05). Response frequencies to the application of von Frey hairs were lower in mice administered 3 and 10 mg/kg morphine (P < 0.05) but were not affected by ketorolac, ketoprofen, or DFU treatment. Colonic Evans blue content was smaller in mice given 100 mg/kg ketoprofen and 20 mg/kg DFU (P < 0.05). We concluded that NSAIDs reduced pain behavior and inflammation but had little effect on referred hyperalgesia.

With the worldwide increase of the human lifespan, the frequency and prevalence of neurodegenerative diseases (NDs) is on the rise. “Neurodegenerative diseases” is an umbrella term for a range of conditions, all of which result in a progressive degeneration and destruction of nerve cells. The destruction of nerve cells can produce either ataxia (impairment of movement) or dementia (impairment of memory and cognitive capabilities) and sometimes both. Such symptoms have a debilitating effect on the patient's quality of life and usually end with a lingering death. The most common ND is Alzheimer's disease (AD), which accounts for more then 50% of dementia cases in the U.S. Among the most widespread are also Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS). Despite intensive research, there is currently no effective treatment for NDs, with patients expecting a slow progression toward a debilitated state. Present therapies for N...

Purpose: Klotho is a transmembrane protein which can be shed, act as a circulating hormone and modulate the insulin-like growth factor (IGF)-I and the fibroblast growth factor (FGF) pathways. We have recently identified klotho as a tumor suppressor in breast cancer. Klotho is expressed in the normal pancreas and both the IGF-I and FGF pathways are involved in pancreatic cancer development. We, therefore, undertook to study the expression and activity of klotho in pancreatic cancer. Experimental Design: Klotho expression was studied using immunohistochemistry and quantitative RT-PCR. Effects of klotho on cell growth were assessed in the pancreatic cancer cells Panc1, MiaPaCa2, and Colo357, using colony and MTT assays and xenograft models. Signaling pathway activity was measured by Western blotting. Results: Klotho expression is downregulated in pancreatic adenocarcinoma. Overexpression of klotho, or treatment with soluble klotho, reduced growth of pancreatic cancer cells in vitro and...

Klotho is an anti-aging transmembrane protein, which is expressed in the brain and kidney, and also in various endocrine-related tissues including the pancreas. We have recently identified klotho as a tumor suppressor and a modulator of the insulin-like growth factor (IGF)-1 and the fibroblast growth factor (FGF) pathways in breast cancer. Pancreatic adenocarcinoma is one of the most lethal of human cancers, with less than 5% 5-year survival. The IGF-1 pathway plays an important role in the pathogenesis of pancreatic cancer. IGF-I and IGF-I receptor (IGF-IR) are overexpressed in human pancreatic tumors and cell lines. Inhibition of the IGF-1R suppresses tumorigenicity in vitro and in vivo and increases sensitivity of pancreatic tumors to radiation and chemotherapy-induced apoptosis. Thus, the IGF pathway may serve as an attractive target for novel therapies against pancreatic cancer. As klotho inhibits the IGF-I pathway and is expressed in normal pancreas, we aimed to study its expr...

Evidence has emerged that some healthy individuals with a history of exposure to Mycobacterium tuberculosis (Mtb) can develop protective antibody responses. However, it is not known whether patients with active tuberculosis elicit protective antibodies, and if they do, which bacterial antigens are targeted. To investigate the B cell responses during active infection, we generated a panel of monoclonal antibodies isolated from memory B cells of one patient. The antibodies, members of four distinct B cell clones, were directed against the Mtb phosphate transporter subunit PstS1. Antibodies p4-36 and p4-163 from two different B cell clones showed protective efficacy against Mtb and Mycobacterium bovis-BCG in an ex vivo human whole blood growth inhibition assay. Germline versions of p4-36 and p4-163 could no longer bind Mtb, implying that affinity maturation was vital for their activity. Crystal structures of p4-36 and a closely related clonal variant of p4-163, p4-170, complexed to Pst...

Cancer-associated fibroblasts (CAFs) are highly prominent in breast tumors, but their functional heterogeneity and origin are still largely unresolved. We report that bone marrow (BM)–derived mesenchymal stromal cells (MSCs) are recruited to primary breast tumors and to lung metastases and differentiate to a distinct subpopulation of CAFs. We show that BM-derived CAFs are functionally important for tumor growth and enhance angiogenesis via up-regulation of Clusterin. Using newly generated transgenic mice and adoptive BM transplantations, we demonstrate that BM-derived fibroblasts are a substantial source of CAFs in the tumor microenvironment. Unlike resident CAFs, BM-derived CAFs do not express PDGFRα, and their recruitment resulted in a decrease in the percentage of PDGFRα-expressing CAFs. Strikingly, decrease in PDGFRα in breast cancer patients was associated with worse prognosis, suggesting that BM-derived CAFs may have deleterious effects on survival. Therefore, PDGFRα expressio...

Mycobacterium tuberculosis (Mtb) exposure drives antibody responses, but whether patients with active tuberculosis elicit protective antibodies, and against which antigens, is still unclear. Here we generate monoclonal antibodies from memory B cells of one patient to investigate the B cell responses during active infection. The antibodies, members of four distinct B cell clones, are directed against the Mtb phosphate transporter subunit PstS1. Antibodies p4-36 and p4-163 reduce Mycobacterium bovis-BCG and Mtb levels in an ex vivo human whole blood growth inhibition assay in an FcR-dependent manner; meanwhile, germline versions of p4-36 and p4-163 do not bind Mtb. Crystal structures of p4-36 and p4-170, complexed to PstS1, are determined at 2.1 Å and 2.4 Å resolution, respectively, to reveal two distinctive PstS1 epitopes. Lastly, a prophylactic p4-36 and p4-163 treatment in Mtb-infected Balb/c mice reduces bacterial lung burden by 50%. Our study shows that inhibitory anti-PstS1 B ce...