Mammary epithelial cells are embedded in a unique extracellular environment to which adipocytes and other stromal cells contribute. Mammary epithelial cells are critically dependent on this milieu for survival. However, it remains unknown which adipocyte-secreted factors are required for the survival of the mammary epithelia and what role these adipokines play in the process of ductal carcinoma tumorigenesis. Here, we take a systematic molecular approach to investigate the multiple ways adipocytes and adipokines can uniquely influence the characteristics and phenotypic behavior of malignant breast ductal epithelial cells. Microarray analysis and luciferase reporter assays indicate that adipokines specifically induce several transcriptional programs involved in promoting tumorigenesis, including increased cell proliferation (IGF2, FOS, JUN, cyclin D1), invasive potential (MMP1, ATF3), survival (A20, NFkappaB), and angiogenesis. One of the key changes in the transformed ductal epithelial cells associated with the cell cycle involves the induction of NFkappaB (five-fold) and cyclin D1 (three-fold). We show that by regulating the transcription of these molecules, the synergistic activity of adipocyte-derived factors can potentiate MCF-7 cell proliferation. Furthermore, compared to other stromal cell-secreted factors, the full complement of adipokines shows an unparalleled ability to promote increased cell motility, migration, and the capacity for angiogenesis. Adipocyte-secreted factors can affect tumorigenesis by increasing the stabilization of pro-oncogenic factors such as beta-catenin and CDK6 as a result of a reduction in the gene expression of their inhibitors (i.e. p18). An in vivo coinjection system using 3T3-L1 adipocytes and SUM159PT cells effectively recapitulates the host-tumor interactions in primary tumors. Type VI collagen, a soluble extracellular matrix protein abundantly expressed in adipocytes, is further upregulated in adipocytes during tumorigenesis. It promotes GSK3beta phosphorylation, beta-catenin stabilization, and increased beta-catenin activity in breast cancer cells and may critically contribute towards tumorigenesis when not counterbalanced by other factors.

Adipocyte-secreted factors synergistically promote mammary tumorigenesis through induction of anti-apoptotic transcriptional programs and proto-oncogene stabilization

Autoantibodies against autologous tumor-associated antigens have been detected in the asymptomatic stage of cancer and can thus serve as biomarkers for early cancer diagnosis. Moreover, because autoantibodies are found in sera, they can be screened easily using a noninvasive approach. Consequently, many studies have been initiated to identify novel autoantibodies relevant to various cancer types. To facilitate autoantibody discovery, approaches that allow the simultaneous identification of multiple autoantibodies are preferred. Five such techniques--SEREX, phage display, protein microarray, SERPA and MAPPing--are discussed here. In the second part of this review, we discussed autoantibodies found in the five most common cancers (lung, breast, colorectal, stomach and liver). The discovery of panels of tumor-associated antigens and autoantibody signatures with high sensitivity and specificity would aid in the development of diagnostics, prognostics and therapeutics for cancer patients.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1742-4658.2009.07396.x

Serum autoantibodies as biomarkers for early cancer detection.

Cancer sera contain antibodies which react with a unique group of autologous cellular antigens called tumor-associated antigens (TAAs) This study determines whether a mini-array of multiple TAAs would enhance antibody detection and be a useful approach to cancer detection and diagnosis The mini-array of TAAs comprised full-length recombinant proteins expressed from cDNAs encoding c-myc, p53, cyclin B1, p62, Koc, IMP1, and survivin Enzyme immunoassay was used to detect antibodies in 527 sera from six different types of cancer Antibody frequency to any individual TAA was variable but rarely exceeded 15-20% With the successive addition of TAAs to a final total of seven antigens, there was a stepwise increase of positive antibody reactions up to a range of 44-68% Breast, lung, and prostate cancer patients showed separate and distinct profiles of reactivity, suggesting that uniquely constituted antigen mini-arrays might be developed to distinguish between some types of cancer Distinct antibody profiles were not observed in gastric, colorectal, and hepatocellular carcinomas with this set of seven TAAs Detection of autoantibodies in cancer can be enhanced by using a mini-array of several TAAs as target antigens Additional studies in early cancer patients and high-risk individuals and the design of unique antigen panels for different cancers would help to determine whether multiple antigen mini-arrays for the detection of autoantibodies might contribute a clinically useful noninvasive approach to cancer detection and diagnosis

https://cebp.aacrjournals.org/content/cebp/12/2/136.full.pdf

Enhancement of antibody detection in cancer using panel of recombinant tumor-associated antigens.

This review summarizes studies on humoral immune responses against tumor-associated antigens (TAAs) with a focus on antibody frequencies and the potential diagnostic, prognostic, and etiologic relevance of antibodies against TAAs. We performed a systematic literature search in Medline and identified 3,619 articles on humoral immune responses and TAAs. In 145 studies, meeting the inclusion criteria, humoral immune responses in cancer patients have been analyzed against over 100 different TAAs. The most frequently analyzed antigens were p53, MUC1, NY-ESO-1, c-myc, survivin, p62, cyclin B1, and Her2/neu. Antibodies against these TAAs were detected in 0–69% (median 14%) of analyzed tumor patients. Antibody frequencies were generally very low in healthy individuals, with the exception of few TAAs, especially MUC1. For several TAAs, including p53, Her2/neu, and NY-ESO-1, higher antibody frequencies were reported when tumors expressed the respective TAA. Antibodies against MUC1 were associated with a favorable prognosis while antibodies against p53 were associated with poor disease outcome. These data suggest different functional roles of endogenous antibodies against TAAs. Although data on prediagnostic antibody levels are scarce and antibody frequencies for most TAAs are at levels precluding use in diagnostic assays for cancer early detection, there is some promising data on achieving higher sensitivity for cancer detection using panels of TAAs.

/pdf/a-systematic-review-of-humoral-immune-responses-against-tonnzaxu72.pdf

A systematic review of humoral immune responses against tumor antigens

A common, if not intrinsic, feature of autoimmunity is a humoral immune response manifested by the production of autoantibodies targeted against self-cellular proteins and nucleic acids (1). Although first studied comprehensively in rheumatic autoimmune disease, autoantibodies and autoimmunity have now become major areas of research in many other illnesses, including type 1 diabetes and other diseases discussed in this Perspective series (2–4); the paraneoplastic neurological disorder (PND) syndromes (5, 6); bullous skin diseases; liver disease; and many others (for review see ref. 7). Among the many known autoantigens are several ubiquitous cellular proteins involved in fundamental cellular functions such as DNA replication and transcription. The process by which these and other self-molecules become immunogenic is not yet understood (8).

The study of tumor-associated autoimmunity may offer insights not only into the pathogenesis of autoimmune diseases in general, but perhaps also into the events that drive certain classes of cancer. Thus, changes in the structure or expression of certain self proteins, occurring during tumorigenesis, suggest mechanisms by which the immune system could be primed to perceive tumor-associated epitopes as foreign. One major route to cancer autoimmunity involves genetic mutations resulting in the production of defective p53 tumor suppressor protein. Another pathway, active in individuals with liver cancer, involves the aberrant expression of specific mRNA-binding proteins that may induce cell proliferation by preventing the turnover of mRNAs for growth factors. Other classes of mRNA-binding protein are normally restricted to the immunologically privileged domain of the brain but can become expressed ectopically and represent autoantigens in the PND syndromes. Together, these findings highlight the importance of altered post-transcriptional control at different stages of tumorigenesis.

/pdf/autoantibodies-as-reporters-identifying-aberrant-cellular-teyfu1gvpd.pdf

Autoantibodies as reporters identifying aberrant cellular mechanisms in tumorigenesis.

A feature of hepatocellular carcinoma (HCC) is that antecedent liver cirrhosis and chronic hepatitis are common precursor conditions and during transition to malignancy some patients develop autoantibodies which were not present during the preceding chronic liver disease phase. Serum samples from such patients can be used to immunoscreen cDNA expression libraries to identify genes encoding the new autoantigens. We demonstrate here the de novo appearance of antibodies to p62, a cytoplasmic protein which has been shown to bind to a developmentally regulated fetal species of insulin-like growth factor II (IGF-II) mRNA. Another antibody appearing during the transition period was against CENP-F, a cell cycle-related nuclear protein with maximum expression in the G2 and M phases of the cell cycle and previously shown to have a high association with malignancy. In three additional patients in whom serial serum samples were examined, new appearance of anti-p62 was detected in two patients and anti-CENP-F in one patient. This study demonstrates that transition to malignancy can be associated with autoantibody responses to certain cellular proteins which might have some role in tumorigenesis.

W. Zhu

Papers

De-novo humoral immune responses to cancer-associated autoantigens during transition from chronic liver disease to hepatocellular carcinoma.