Jane E. Armes

STAT3 and STAT1 mediate IL-11–dependent and inflammation-associated gastric tumorigenesis in gp130 receptor mutant mice

Deregulated activation of STAT3 is frequently associated with many human hematological and epithelial malignancies, including gastric cancer. While exaggerated STAT3 signaling facilitates an antiapoptotic, proangiogenic, and proproliferative environment for neoplastic cells, the molecular mechanisms leading to STAT3 hyperactivation remain poorly understood. Using the gp130(Y757F/Y757F) mouse model of gastric cancer, which carries a mutated gp130 cytokine receptor signaling subunit that cannot bind the negative regulator of cytokine signaling SOCS3 and is characterized by hyperactivation of the signaling molecules STAT1 and STAT3, we have provided genetic evidence that IL-11 promotes chronic gastric inflammation and associated tumorigenesis. Expression of IL-11 was increased in gastric tumors in gp130(Y757F/Y757F) mice, when compared with unaffected gastric tissue in wild-type mice, while gp130(Y757F/Y757F) mice lacking the IL-11 ligand-binding receptor subunit (IL-11Ralpha) showed normal gastric STAT3 activation and IL-11 expression and failed to develop gastric tumors. Furthermore, reducing STAT3 activity in gp130(Y757F/Y757F) mice, either genetically or by therapeutic administration of STAT3 antisense oligonucleotides, normalized gastric IL-11 expression and alleviated gastric tumor burden. Surprisingly, the genetic reduction of STAT1 expression also reduced gastric tumorigenesis in gp130(Y757F/Y757F) mice and coincided with reduced gastric inflammation and IL-11 expression. Collectively, our data have identified IL-11 as a crucial cytokine promoting chronic gastric inflammation and associated tumorigenesis mediated by excessive activation of STAT3 and STAT1.

The natural history of ductal carcinoma in situ of the breast : a review

BackgroundDuctal carcinoma in situ represents about 20% of all tumours diagnosed within mammographic screening programs. The natural history of DCIS is poorly understood, as it cannot be observed directly. Estimates of the proportion of DCIS that progress to invasive cancer, as well as factors that may influence progression, are important for clinical management. Here we review various sources of evidence regarding the natural history of DCIS.MethodsWe identified relevant publications of studies on: follow-up studies of DCIS initially misdiagnosed as benign, studies of recurrence of DCIS as invasive cancer, autopsy studies, studies of risk factors for DCIS, animal studies and studies that used mathematical models to study growth of DCIS and invasive cancer. Data sources included the MEDLINE data base, searches of articles cited in key reviews and editorials.ResultsThe most direct evidence regarding the progression of DCIS to invasive cancer comes from studies where DCIS was initially misdiagnosed as benign and treated by biopsy alone. These studies suggest that between 14–53% of DCIS may progress to invasive cancer over a period of 10 or more years. The reported prevalence of undiagnosed DCIS in autopsy studies, of approximately 9%, has been used to suggest a larger reservoir of DCIS may exist in the population. All types of study designs reviewed had limitations that may bias the estimate of progression in either direction.ConclusionThe available evidence suggests not all DCIS will progress to invasive cancer in the medium term but precise estimates of progression are not possible given the limitations of the data. Mathematical modelling of various scenarios of progression and studies of genetic factors involved in progression may shed further light on the natural history of DCIS.

Gain- and Loss-of-Function Lyn Mutant Mice Define a Critical Inhibitory Role for Lyn in the Myeloid Lineage

To investigate the role of the Lyn kinase in establishing signaling thresholds in hematopoietic cells, a gain-of-function mutation analogous to the Src Y527F-activating mutation was introduced into the Lyn gene. Intriguingly, although Lyn is widely expressed within the hematopoietic system, these mice displayed no propensity toward hematological malignancy. By contrast, analysis of aging cohorts of both loss- and gain-of-function Lyn mutant mice revealed that Lyn(-/-) mice develop splenomegaly, increased numbers of myeloid progenitors, and monocyte/macrophage (M phi) tumors. Biochemical analysis of cells from these mutants revealed that Lyn is essential in establishing ITIM-dependent inhibitory signaling and for activation of specific protein tyrosine phosphatases within myeloid cells. Loss of such inhibitory signaling may predispose mice lacking this putative protooncogene to tumorigenesis.

Sustained Activation of Lyn Tyrosine Kinase In Vivo Leads to Autoimmunity

Genetic ablation of the Lyn tyrosine kinase has revealed unique inhibitory roles in B lymphocyte signaling. We now report the consequences of sustained activation of Lyn in vivo using a targeted gain-of-function mutation (Lynup/up mice). Lynup/up mice have reduced numbers of conventional B lymphocytes, down-regulated surface immunoglobulin M and costimulatory molecules, and elevated numbers of B1a B cells. Lynup/up B cells are characterized by the constitutive phosphorylation of negative regulators of B cell antigen receptor (BCR) signaling including CD22, SHP-1, and SHIP-1, and display attributes of lymphocytes rendered tolerant by constitutive engagement of the antigen receptor. However, exaggerated positive signaling is also apparent as evidenced by the constitutive phosphorylation of Syk and phospholipase Cγ2 in resting Lynup/up B cells. Similarly, Lynup/up B cells show a heightened calcium flux in response to BCR stimulation. Surprisingly, Lynup/up mice develop circulating autoreactive antibodies and lethal autoimmune glomerulonephritis, suggesting that enhanced positive signaling eventually overrides constitutive negative signaling. These studies highlight the difficulty in maintaining tolerance in the face of chronic stimulation and emphasize the pivotal role of Lyn in B cell signaling.

The LIM domain gene LMO4 inhibits differentiation of mammary epithelial cells in vitro and is overexpressed in breast cancer

LMO4 belongs to a family of LIM-only transcriptional regulators, the first two members of which are oncoproteins in acute T cell leukemia. We have explored a role for LMO4, initially described as a human breast tumor autoantigen, in developing mammary epithelium and breast oncogenesis. Lmo4 was expressed predominantly in the lobuloalveoli of the mammary gland during pregnancy. Consistent with a role in proliferation, forced expression of this gene inhibited differentiation of mammary epithelial cells. Overexpression of LMO4 mRNA was observed in 5 of 10 human breast cancer cell lines. Moreover, in situ hybridization analysis of 177 primary invasive breast carcinomas revealed overexpression of LMO4 in 56% of specimens. Immunohistochemistry confirmed overexpression in a high percentage (62%) of tumors. These studies imply a role for LMO4 in maintaining proliferation of mammary epithelium and suggest that deregulation of this gene may contribute to breast tumorigenesis.

Biological markers that predict clinical recurrence in ductal carcinoma in situ of the breast.

The optimal management of ductal carcinoma in situ (DCIS) is controversial, due in part to our poor understanding of its natural history. We undertook to identify subgroups of DCIS based on the expression of biomarkers, which were related to the likelihood of clinical recurrence. Biomarker expression of a total of 95 DCIS lesions in a nested case-control study within a population-based cohort with up to 135 months follow-up data (median 101 months) was analysed using immunohistochemistry. ERBB2-positivity and bcl-2-, oestrogen receptor (ER)- and progesterone receptor (PR)-negativity were individually associated with the risk of clinical recurrence. The predictive value of these biomarkers was independent of cytonuclear grade. ERBB2, bcl-2, ER and PR expression were conserved in the recurrent lesions, including subsequent invasive cancers. p21-positive DCIS was also associated with clinical recurrence, independently of the associations with ERBB2/bcl-2/ER/PR expression. These data identify clinically and biologically relevant subcategories of DCIS lesions, an essential basis for improving management.

Candidate tumor-suppressor genes on chromosome arm 8p in early-onset and high-grade breast cancers

Loss of genetic material from chromosome arm 8p occurs commonly in breast carcinomas, suggesting that this region is the site of one or more tumor-suppressor genes (TSGs). Comparative genomic hybridization analysis showed that 8p loss is more common in breast cancers from pre-menopausal compared with post-menopausal patients, as well as in high-grade breast cancers, regardless of the menopausal status. Subsequent high-resolution gene expression profiling of genes mapped to chromosome arm 8p, on an extended cohort of clinical tumor samples, indicated a similar dichotomy of breast cancer clinicopathologic types. Some of these genes showed differential downregulation in early-onset and later-onset, high-grade cancers compared with lower-grade, later-onset cancers. Three such genes were analysed further by in situ technologies, performed on tissue microarrays representing breast tumor and normal tissue samples. PCM1, which encodes a centrosomal protein, and DUSP4/MKP-2, which encodes a MAP kinase phosphatase, both showed frequent gene and protein loss in carcinomas. In contrast, there was an excess of cases showing loss of expression in the absence of reduced gene copy number of SFRP1, which encodes a dominant-negative receptor for Wnt-family ligands. These candidate TSGs may constitute some of the molecular drivers of chromosome arm 8p loss in breast carcinogenesis.

Collagenous colitis : jejunal and colorectal pathology

AIMS: To determine: (1) whether there is an association between collagenous colitis and coeliac disease or lymphocytic colitis; (2) the distribution of lymphocyte subsets and macrophages in the lamina propria and surface epithelial layer in collagenous colitis; and (3) the colorectal distribution of the disease and whether a mucosal biopsy specimen, using a flexible sigmoidoscope, is sufficient to diagnose it. METHODS: The clinical data and colorectal biopsy specimens from 38 patients with collagenous colitis were studied. In 10, small bowel biopsy specimens were also available for review. Immunostaining of the mucosal lymphoid infiltrate with a panel of relevant antibodies was carried out on formalin fixed tissue in seven cases; in three the phenotyping was performed on fresh biopsy specimens separately frozen or fixed in B5 solution. RESULTS: Coeliac disease was found in four out of the 10 patients with collagenous colitis who had had a small bowel biopsy, in contrast to the prevalence of the disease in Australia of 1 in 3000. Collagenous colitis did not respond to gluten withdrawal. Five of 29 (17%) of the patients had a mixed pattern of lymphocytic and collagenous colitis. Immunostaining of the lymphoid infiltrate showed that the striking increase in intraepithelial lymphocytes in collagenous colitis was due to an influx of CD8 positive cells. The occurrence and severity of collagenous colitis along the large bowel were independent of the anatomical site, and in more than 90% of cases biopsy specimens from the sigmoid colon or rectum were diagnostic. CONCLUSIONS: There is a very high incidence of coeliac disease among patients with collagenous colitis so that jejunal biopsy should be an essential part of their investigations, especially if symptoms persist. However, only a minority showed a mixed pattern of lymphocytic and collagenous colitis. The intraepithelial lymphocytes in collagenous colitis are CD8 positive cells. Collagenous colitis can be diagnosed from rectal or sigmoid colon biopsy specimens in more than 90% of cases.

The pathology of inherited breast cancer

Summary Familial breast cancer has been recognised for many years. In the 1990s the genetic mechanism of inheritance of a proportion of these familial cancers was found to be attributable to germline mutation in either of two newly discovered genes, namely BRCA1 and BRCA2. Since the discovery of these genes, studies have been performed in which the pathological characteristics of familial cancers arising in patients with germline BRCA1 and BRCA2 mutation have been examined. A distinct pathological phenotype of high‐grade, oestrogen receptor‐negative breast cancer, often with medullary features, has been consistently described for BRCA1 cancers. A less distinct phenotype has been described for BRCA2 cancers. The discovery of genotypephenotype correlation has significant implications for patient management and novel treatment strategies, not only for inherited cancers, but for breast cancer in general.

Abnormalities of the RB1 pathway in ovarian serous papillary carcinoma as determined by overexpression of the p16(INK4A) protein.

Summary:Dysfunction of proteins involved in the G1 to S transition of the cell cycle, such as p16(INK4A) and RB1, is common in many cancer types. A screen of p16 protein expression was performed in benign, borderline, and invasive ovarian tumors, together with endometrial cancers, aligned on a tissue microarray. We observed frequent p16 overexpression in serous papillary carcinomas of ovarian and endometrial origin. An extended cohort of ovarian serous papillary carcinomas was examined to further evaluate the frequency of p16 overexpression. Strong, uniform staining in the majority of cancer cells occurred commonly in invasive serous papillary ovarian cancers, particularly in grade 3 carcinomas. RB1 protein expression abnormalities were rare. Our data indicate that abnormalities in the retinoblastoma pathway, as determined by p16 overexpression, are common in serous papillary carcinomas and are probably an early event.