Proteomic identification of tumor- and metastasis-associated galectin-1 in claudin-low breast cancer.

BACKGROUND: Metastasis and mortality remain high among breast cancer patients with the claudin-low subtype because these tumors are aggressive, chemoresistant, and lack targeted therapies. Our objective was to utilize discovery-based proteomics to identify proteins associated with claudin-low primary and metastatic tumors to gain insight into pathways and mechanisms of tumor progression. METHODS: We used nano-LC-MS/MS proteomics to analyze orthotopic and metastatic tumors from the syngeneic murine T11 tumor model, which displays gene expression profiles mirroring human claudin-low tumors. Galectin-1 identity, expression and spatial distribution were investigated by biochemical and immunochemical methods and MALDI/IMS. RNA seq data from mouse and human tumors in our study and publicly available microarray data were analyzed for differential galectin-1 expression across breast cancer subtypes. RESULTS: Galectin-1, an N-acetyllactosamine-binding protein, exhibited the highest sequence coverage and high abundance rank order among nano-LC-MS/MS-identified proteins shared by T11 claudin-low tumors but not normal tissue. Label-free quantitation, Western immunoblot and ELISA confirmed galectin-1 identity and significant differential expression. MALDI/IMS spatial mapping and immunohistochemistry detected galectin-1 in T11 metastatic lung foci. Immunohistochemistry of human claudin-low tumors demonstrated intermediate-to-high intensity galectin-1 staining of tumor and stroma. Gene expression analysis of mouse and human tumors found the highest galectin-1 levels in the claudin-low breast cancer subtype. CONCLUSIONS: Proteomics and genomics reveal high expression of galectin-1 protein and RNA in primary and metastatic claudin-low breast cancer. GENERAL SIGNIFICANCE: This work endorses proteomic approaches in cancer research and supports further investigations of the function and significance of galectin-1 overexpression in claudin-low tumor progression.

American Society of Clinical Oncology-recommended surveillance and physician specialty among long-term breast cancer survivors.

BACKGROUND: It is unclear whether it is appropriate to transfer the follow-up care of breast cancer (BrCa) survivors from cancer specialists to primary care physicians (PCPs). This contemporary study compared physician specialty and documented the long-term surveillance of survivors who underwent surgery at an American academic center. METHODS: Women in this institutional review board-approved study underwent breast surgery between 1996 and 2006. Data were collected for 270 patients with stage I to III BrCa (mean follow-up, 6 years). Charts were reviewed based on American Society of Clinical Oncology (ASCO) guidelines for recommended surveillance frequency and care. RESULTS: The majority of patients (90%; n = 242) were followed by specialists with 10% (n = 28) followed by PCPs. Patients with advanced disease and a greater risk of disease recurrence more often received specialist care. Patients followed by specialists were more often seen at ASCO-recommended intervals (eg, 89% vs 69% of patients followed by a PCP at follow-up Year 6; P < .01); however, many patients were followed inconsistently. Breast disease was often not the focus of PCP visits or mentioned in clinic notes (18% patients). Women seen by specialists were more likely to have documented clinical examinations of the breast (93% vs 44% at Year 6), axilla (94% vs 52%), or annual mammograms (74% vs 48%; P = .001-.02). CONCLUSIONS: Consistent compliance with surveillance guidelines and chart documentation needs improvement among all providers; however, specialists more consistently met ASCO guidelines. If transfer of care to a PCP occurs, it should be formalized and include follow-up recommendations and defined physician responsibilities. Providers and patients should be educated regarding surveillance care and current guidelines incorporated into standard clinical practice.

Characterization of Lewis lung clonal variants in a model of syngeneic pulmonary murine metastases.

Lung cancer is the leading cause of cancer-related mortality world-wide. Since the majority of cancer deaths result from metastatic complications, understanding cellular alterations contributing to organ specific metastases is a continuing cancer research goal. Desirable models involve easy, efficient methodologies for development of pulmonary metastases utilizing genetically related syngeneic tumor cell lines varying in clonogenic frequency and growth rate for comparative studies. This work focused on development and characterization of primary and metastatic Lewis lung subclones (LLCC3, LLC1, LLCab) in a histocompatible C57B1/6 model. Surgical resection of primary tumors utilizing these cell lines resulted in reliable development of pulmonary metastases (> 90% of injected mice), while tail-vein injection proved sporadic (20% of injected mice). The preliminary analysis of selected cell-surface molecules indicates potential genetic differences that may underlie phenotypic variations. The combination of subcutaneous resection methodology and variant cell lines results in robust metastatic lung cancer for testing potential therapeutic interventions.

Suppression of Lewis lung tumor development in alpha 1,3 galactosyltransferase knock-out mice.

BACKGROUND: Humans lack the gene alpha 1,3 galactosyltransferase (GalT) and instead produce abundant cytolytic antibodies against cells bearing the antigen [gal alpha1,3 gal] (alphaGal). We have previously studied humoral anti-alphaGal responses in GalT knock-out (GalT KO) mice and shown that murine anti-alphaGal IgM, like human anti-alphaGal IgM, causes extensive complement-mediated cytolysis of GalT+ murine Lewis Lung carcinoma cells (LLCa) in vitro. Here we test the hypothesis that anti-alphaGal immune responses can inhibit the in vivo development of GalT+ tumors. MATERIALS AND METHODS: GalT KO mice orally immunized to produce anti-alphaGal antibodies (n =52) and naïve non-immunized KO mice (n=37) were challenged s.c. with 10(5) LLCa tumor cells. Anti-alphaGal antibody titers were measured before and after LLCa challenge. RESULTS: Anti-alphaGal IgM titers present at challenge correlated with protection from tumor development (p<0.04). Seventy-five percent of mice with titers > or = 1:1280 remained tumor-free versus 43% of naïve mice. Tumor onset was delayed in mice with circulating anti-alphaGal IgM versus naïve animals (p=0.02). LLCa challenge itself induced and augmented anti-alphaGal IgM and post-challenge titers correlated highly with protection from tumor development (p<0.001). No mice with post-challenge anti-alphaGal IgM titers > or = 1:1280 developed tumors, compared to 83% of mice lacking antibody. Inhibition studies showed that 30% of post-challenge IgM recognized LLCa antigens distinct from alphaGal. Anti-alphaGal IgG was low or undetectable both pre- and post challenge and did not affect tumor formation. CONCLUSION: The finding that anti-alphaGal IgM suppresses GaIT+ tumor development in vivo supports the premise that immunotherapy using GalT expression can utilize human anti-alphaGal responses and induce significant anti-tumor effects.

Induction of cytolytic anti-Gal antibodies in alpha-1,3-galactosyltransferase gene knockout mice by oral inoculation with Escherichia coli O86:B7 bacteria.

Naturally occurring antibodies against [Gal alpha-1,3-Gal] structures (anti-Gal antibodies) are the primary effectors of human hyperacute rejection (HAR) of nonhuman tissue. Unlike most mammals, humans lack a functional alpha-1,3-galactosyltransferase (GalT) gene and produce abundant anti-Gal antibodies, putatively in response to GalT(+) enteric bacteria. GalT knockout (KO) mice have been generated as a small animal model of HAR but inconsistently express anti-Gal antibodies. We hypothesized that enteric exposure of GalT KO mice to live GalT(+) bacteria would produce cytolytic anti-Gal antibodies. Naive mice lacking anti-Gal antibodies were orally immunized with 10(10) live GalT(+) Escherichia coli O86:B7 bacteria and assayed for anti-Gal antibody titer, isotype, and cytolytic activity. Fecal samples were tested for E. coli O86:B7 prior to and after inoculation. In two separate experiments, 77 to 100% (n = 31) of mice developed serum anti-Gal immunoglobulin G (IgG; titer, 1:5 to 1:80) and/or anti-Gal IgM antibodies (titer, 1:5 to 1:1,280) 14 days postinoculation. Induced anti-Gal antibodies caused complement-mediated cytolysis of GalT(+) target cells, with extensive cytolysis observed consistently at serum IgM titers of >/=1:320. Absorption with synthetic [Gal alpha-1,3-Gal] inhibited both antibody binding and cytolysis. E. coli O86:B7 was recovered from stool samples from 83 to 94% of inoculated mice but not from naive mice, thus confirming enteric exposure. These findings demonstrate that oral inoculation with E. coli O86:B7 is a novel and effective method to induce cytolytic anti-Gal antibodies in GalT KO mice and support the premise that enteric exposure to GalT(+) bacteria induces anti-Gal antibodies in humans. These studies also suggest a role for GalT KO mice in elucidating anti-Gal responses in microbial immunity.