Biomedical subjects

Adrian L Harris

Publications and source records attributed to Adrian L Harris.

136 records · Page 8Linked to original sources

PubMed2002

HIF activation identifies early lesions in VHL kidneys: evidence for site-specific tumor suppressor function in the nephron.

Mutations in the von Hippel-Lindau (VHL) gene are associated with hereditary and sporadic clear cell renal carcinoma. VHL acts in a ubiquitin ligase complex regulating hypoxia-inducible factor-1 (HIF-1), but the link between this function and cancer development is unclear. Here we show that in the kidneys of patients with VHL disease, HIF activation is an early event occurring in morphologically normal single cells within the renal tubules. In comparison, dysplastic lesions, cystic lesions, and tumors showed evidence of additional mechanisms that amplify HIF activation. Detection of cells with constitutive HIF activation identified a large number of previously unrecognized foci of VHL inactivation. In proximal tubules these were almost entirely unicellular, whereas multicellular foci were almost exclusively seen in the distal nephron.

Adenocarcinoma, Clear Cell↗

PubMed2002

Tumor-associated macrophages in breast cancer.

Neoplastic cells form only one part of a complex network of cell types that make up a breast tumor. The normal cell types that make up the nonneoplastic components of tumors include fibroblasts, endothelium, and inflammatory cells, such as tumor associated macrophages (TAMs). TAMs have the potential to carry out both anti- and protumor activities In their antitumor role TAMs can present tumor antigens to cytotoxic T-cells and are capable of being directly cytotoxic to neoplastic cells. Conversely, TAMs are also able to promote tumor growth directly by secreting breast tumor mitogens, such as epidermal growth factor, and indirectly by stimulating tumor angiogenesis and metastasis. Recent studies have indicated that in breast cancers the protumor role of TAMs is dominant, and that TAMs may be executing a "wound healing" type of process in response to stimuli found in the tumor microenvironment, such as hypoxia. As such, TAMs may provide opportunities for future therapeutic interventions.

Animals↗

PubMed2002

Differential assessment of angiogenic activity and of vascular survival ability (VSA) in breast cancer.

Recent reports provide evidence that some growth factors behave as inhibitors of the apoptosis of the endothelial cells, bringing forward the concept of vascular survival as a post-angiogenesis process. At least two different vasculature development processes occur within a tumor: the angiogenic (formation of new vessels) and the vascular survival pathway, which is devoted to the preservation of the newly-formed vessels in layers that lose contact with the adjacent normal tissue. We developed a method to assess these processes in tissue samples. We noted that differences among tumors may exist not only in the tumor angiogenic activity (TAA) but also in the vascular survival ability (VSA). One third of the highly angiogenic breast cancer cases examined had a poor ability to maintain high vessel density in inner tumor areas. Both parameters are independently related to prognosis, while VSA was directly related to tumor dimensions and node involvement. Patients with high TAA and VSA had a particularly poor prognosis. It is suggested that although cancer angiogenic activity is important for the local invasion and dissemination into vessels and lymphatics, the VSA may be important for the effective formation of viable tumor foci in lymph nodes or distant organs. Recognition and quantification of the vascular survival ability in human tumors may significantly improve the prognostic value of the assessment of tumor vasculature, and may help to stratify patients for clinical trials with novel anti-angiogenic or angiotoxic drugs. Elucidation of the pathways may provide additional targets for antiangiogenic therapy.

Breast Neoplasms↗

PubMed2002

Hypoxia--a key regulatory factor in tumour growth.

Cells undergo a variety of biological responses when placed in hypoxic conditions, including activation of signalling pathways that regulate proliferation, angiogenesis and death. Cancer cells have adapted these pathways, allowing tumours to survive and even grow under hypoxic conditions, and tumour hypoxia is associated with poor prognosis and resistance to radiation therapy. Many elements of the hypoxia-response pathway are therefore good candidates for therapeutic targeting.

Animals↗

PubMed2002

Thymidine phosphorylase expression in gallbladder adenocarcinomas.

The expression of thymidine phosphorylase (TP), a potent chemotactic factor for endothelial cells, was studied in 60 adenocarcinomas of the gallbladder, by use of immunohistochemical techniques. Results on patterns of TP expression were correlated with angiogenesis (anti-CD31), histopathological variables, and patient survival. TP was frequently expressed in tumor cells, stromal cells, tumor-associated macrophages, and lymphocytes of gallbladder adenocarcinomas. The expression was mixed nuclear/cytoplasmic. However, only nuclear TP (TPnuc) expression by tumor cells was correlated with increased angiogenic activity. High angiogenesis, assessed as microvessel density (MVD), was the most significant prognostic factor. The subgroup of patients with TPnuc and medium/high MVD had the worst prognosis as evaluated by the survival curves. Furthermore, CD31+ lymphocytes, frequently seen in carcinomas with high-fibroblastic TP reactivity, were connected with an improved survival. It is concluded that angiogenesis, as verified by multivariate analysis, is the most important prognostic factor in gallbladder carcinomas. In these tumors, high histologic grade and low CD31+ lymphocytic infiltration are also independent predictors of poor prognosis. TP is associated with an aggressive phenotype apparently because of its anglogenic activity. Therapeutic strategies targeting TP may be of value in patients overexpressing this enzyme.

Adenocarcinoma↗

PubMed2002

Role of thymidine phosphorylase in an in vitro model of human bladder cancer invasion.

PURPOSE: It has been previously demonstrated that the angiogenic factor thymidine phosphorylase is elevated significantly in invasive bladder cancer. We report that it is not merely an incidental finding. Thymidine phosphorylase has a functional role in bladder cancer invasion. MATERIALS AND METHODS: The superficial bladder cancer cell line RT112 was transfected by retroviral techniques to generate the RT112-TP clone that expressed significantly elevated levels of thymidine phosphorylase, comparable to those of invasive human bladder cancers. The empty vector control RT112-EV was generated for comparison. Growth of these transfectants was examined using a new in vitro model of bladder cancer invasion based on de-epithelialized rat bladder and by assessing growth as xenografts in nude mice. The effect of 5-deoxy-5-fluorouridine, a prodrug activated by TP to produce 5-fluorouracil, was also examined. RESULTS: RT112-TP high thymidine phosphorylase expressing cells invaded into the stroma of the in vitro model but wild-type RT112 and RT112-EV cells did not. This invasion was abolished by 5-deoxy-5-fluorouridine. Invasion correlated with thymidine phosphorylase expression on immunohistochemical testing. There was also a significantly greater xenograft growth rate for RT112-TP than for RT112-EV, confirming the malignant growth advantage conferred by thymidine phosphorylase. CONCLUSIONS: We demonstrated that thymidine phosphorylase may have a functional role in bladder cancer invasion and the apparent advantage of thymidine phosphorylase expression to tumor cells can be exploited by therapies that utilize prodrugs such as 5-deoxy-5-fluorouridine, which is activated by thymidine phosphorylase and inhibited invasion in our model.

Animals↗

PubMed2002

Prognostic significance of soluble urokinase plasminogen activator receptor in serum and cytosol of tumor tissue from patients with primary breast cancer.

PURPOSE: The aim of the study was to evaluate the prognostic value of soluble urokinase plasminogen activator receptor (suPAR) in preoperatively obtained sera samples (s-suPAR) from breast cancer patients. EXPERIMENTAL DESIGN: suPAR levels were determined by the use of a kinetic ELISA in sera from 274 breast cancer patients and in tumor cytosols (c-suPAR) from 188 of these patients. In addition, s-suPAR levels were analyzed in 174 female blood donors. RESULTS: The mean s-suPAR level was 3.8 ng/ml (range, 1.6-9.2 ng/ml) in the patients and 3 ng/ml (range, 1.3-6.4 ng/ml) in the donors. The mean c-suPAR level was 0.55 ng/mg protein (range, 0.07-2.83 ng/mg protein). A weak but significant linear association was found between s-suPAR and age in the donors; thus, all of the s-suPAR levels were adjusted for this age dependency (aa-s-suPAR). The aa-s-suPAR levels were significantly increased in the patients as compared with the donors (P < 0.0001). No difference was found in aa-s-suPAR levels between the lymph node-positive and -negative patients (P = 0.27), and no correlation was seen between aa-s-suPAR and c-suPAR (sigma = 0.08; P = 0.71). During the follow-up period (5.9 years) 77 patients experienced a relapse and 69 died. aa-s-suPAR as a continuous variable was significantly associated with relapse-free survival [hazard ratio (HR), 1.4; 95% confidence interval (CI), 1.1-1.8; P = 0.003] and overall survival (HR, 1.6; 95% CI, 1.2-2.0; P < 0.0001). In multivariate Cox analysis including the classical prognostic parameters in breast cancer, continuous aa-s-suPAR was significantly associated with both relapse-free survival (HR, 1.4; 95% CI, 1.1-1.7; P = 0.001) and overall survival (HR, 1.4; 95% CI, 1.1-1.8; P = 0.002). In these analyses positive lymph nodes, tumor size >2 cm, and negative estrogen receptor content were also significantly associated with patient outcome. CONCLUSION: This study shows that high preoperative aa-s-suPAR levels are significantly associated with poor outcome for breast cancer patients independent of lymph node status, tumor size, and estrogen receptor status.

Adolescent↗

PubMed2002

Coexpression of hypoxia-inducible factors 1alpha and 2alpha, carbonic anhydrase IX, and vascular endothelial growth factor in nasopharyngeal carcinoma and relationship to survival.

PURPOSE: Tumor hypoxia is known to be associated with resistance to chemotherapy, radiotherapy, and poorer survival. Recently, it is shown that hypoxia induces the expression of hypoxia-inducible factor-1alpha and 2alpha (HIF-1alpha and HIF-2alpha), which then up-regulates the expression of downstream genes such as carbonic anhydrase IX (CA IX) and vascular endothelial growth factor (VEGF). EXPERIMENTAL DESIGN: We examined the expression of HIF-1alpha, HIF-2alpha, CA IX, and VEGF by immunohistochemistry in nasopharyngeal carcinoma (NPC) biopsies from 90 consecutive patients recruited between 1994 and 1997 in a randomized controlled trial of chemoradiation in locally advanced NPC and investigated their relationship with survival. RESULTS: HIF-1alpha was expressed in 52 of 90 (58%), HIF-2alpha in 6 of 89 (7%), CA IX in 51 of 90 (57%), and VEGF in 54 of 90 (60%) of tumors. Tumor HIF-1alpha expression correlated significantly with that of CA IX (P = 0.008) and VEGF (P = 0.003). High tumor HIF-1alpha expression was associated with a trend for poor overall survival (P = 0.06). Tumors with a positive hypoxic profile (defined as high expression of both HIF-1alpha and CA9) were associated with worse progression-free survival (P = 0.04). Tumors with both hypoxic and angiogenic profile (defined as high VEGF expression) were associated with a worse progression-free survival (P = 0.0095). CONCLUSION: Overexpression of HIF-1alpha, CA IX, and VEGF is common in NPC, which is probably related to hypoxia up-regulated expression involving a HIF-dependent pathway, and is associated with poor prognosis. Targeting the hypoxia pathway may be useful in the treatment of NPC.

Adult↗

PubMed2002

Analysis of gene expression in ductal carcinoma in situ of the breast.

PURPOSE: The risk of recurrence and progression of ductal carcinoma in situ (DCIS) of the breast is best designated by morphological indicators, including the presence of necrosis. Our purpose was to identify molecular alterations underlying progression of DCIS. EXPERIMENTAL DESIGN: We have compared gene expression within a cohort of six cases of DCIS with necrosis (DCIS(necrosis+)) and four cases without necrosis (DCIS(necrosis-)) using microdissection and cDNA microarray. RESULTS: A set of 69 cDNAs from a group of 1,181 was identified that were consistently differentially expressed. Among this set, the mRNA for angio-associated migratory cell protein and a serine threonine protein kinase, nuclear Dbf2 related, were consistently higher in DCIS(necrosis+) and were also found to be overexpressed in the T47D breast cancer cell line subjected to hypoxia. Further study of angio-associated migratory cell protein by quantitative reverse transcriptase-PCR and in situ hybridization analysis of 37 cases of DCIS confirmed higher mRNA expression in DCIS(necrosis+) (P = 0.0095). CONCLUSIONS: This study shows that although levels of gene expression are mostly similar between morphologically different DCIS, consistent differences in expression of a subset of genes can be identified between DCIS with and without necrosis.

Adaptor Proteins, Signal Transducing↗

PubMedDate not supplied

Histological quantitation of tumour angiogenesis.

Tumours establish their blood supply via a number of processes in addition to angiogenesis. These include vasculogenesis, vascular remodelling, intussusception and possibly vascular mimicry in certain tumours. The mainstay of the assessment of tumour vascularity has been counting the number of immunohistochemically identified microvessels in vascular hot spots. Nevertheless, several other techniques are available, including Chalkley counting, vascular grade and the use of image analysis systems. Angiogenic activity can furthermore be assessed in histological samples by measuring the molecules involved in the establishment of the tumour vasculature, including angiogenic growth factors and their receptors, cell adhesion molecules, proteases and markers of activated, proliferating, cytokine stimulated or angiogenic vessels, such as CD105. Measuring the maturity of vessels may give an indication of the proportion of the tumour vasculature that is functional. Other reagents that can identify hypoxia-activated pathways are also being developed. The histological assessment of tumour vascularity is mainly used in the research setting but may also have applications in the clinic if appropriate methodology and trained observers perform the studies. Gene arrays may be able to provide an angiogenesis profile. Continued study into the processes involved in generating a tumour blood supply is likely to identify new markers that may be more accurate measures.

Animals↗