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Characterization of a Gene Expression Signature in Normal Rat Prostate Tissue Induced by the Presence of a Tumor Elsewhere in the Organ
Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
Umeå University, Faculty of Medicine, Department of Medical Biosciences, Pathology.
2015 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 6, e0130076Article in journal (Refereed) Published
Abstract [en]

Implantation of rat prostate cancer cells into the normal rat prostate results in tumor-stimulating changes in the tumor-bearing organ, for example growth of the vasculature, an altered extracellular matrix, and influx of inflammatory cells. To investigate this response further, we compared prostate morphology and the gene expression profile of tumor-bearing normal rat prostate tissue (termed tumor-instructed/indicating normal tissue (TINT)) with that of prostate tissue from controls. Dunning rat AT-1 prostate cancer cells were injected into rat prostate and tumors were established after 10 days. As controls we used intact animals, animals injected with heat-killed AT-1 cells or cell culture medium. None of the controls showed morphological TINT-changes. A rat Illumina whole-genome expression array was used to analyze gene expression in AT-1 tumors, TINT, and in medium injected prostate tissue. We identified 423 upregulated genes and 38 downregulated genes (p<0.05, >= 2-fold change) in TINT relative to controls. Quantitative RT-PCR analysis verified key TINT-changes, and they were not detected in controls. Expression of some genes was changed in a manner similar to that in the tumor, whereas other changes were exclusive to TINT. Ontological analysis using GeneGo software showed that the TINT gene expression profile was coupled to processes such as inflammation, immune response, and wounding. Many of the genes whose expression is altered in TINT have well-established roles in tumor biology, and the present findings indicate that they may also function by adapting the surrounding tumor-bearing organ to the needs of the tumor. Even though a minor tumor cell contamination in TINT samples cannot be ruled out, our data suggest that there are tumor-induced changes in gene expression in the normal tumor-bearing organ which can probably not be explained by tumor cell contamination. It is important to validate these changes further, as they could hypothetically serve as novel diagnostic and prognostic markers of prostate cancer.

Place, publisher, year, edition, pages
2015. Vol. 10, no 6, e0130076
National Category
Cancer and Oncology
URN: urn:nbn:se:umu:diva-106329DOI: 10.1371/journal.pone.0130076ISI: 000356329900133PubMedID: 26076453OAI: diva2:842004
Available from: 2015-07-16 Created: 2015-07-10 Last updated: 2016-04-27Bibliographically approved
In thesis
1. TINT Tumor Indicating Normal Tissue: new field of diagnostic biomarkers for prostate cancer
Open this publication in new window or tab >>TINT Tumor Indicating Normal Tissue: new field of diagnostic biomarkers for prostate cancer
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Prostate cancer is the most common cancer in Sweden. Due its highly variable behavior, multifocal nature, and insufficient diagnostic methods, prostate cancer is difficult to diagnose and prognosticate. Some patients have an aggressive lethal disease, but the majority of prostate cancer patients have slow-growing, non-lethal disease with long expected survival without treatment. Current diagnostic methods―serum levels of prostate-specific antigen (PSA) and histological grading of biopsied prostate tissue―often do not give the information required to be able to safely differentiate indolent tumors from potentially lethal ones. Many prostate cancers are difficult to detect by imaging, so tissue biopsy cannot be safely guided towards the tumor, and particularly not towards the most aggressive forms. To overcome this problem, multiple needle biopsies are taken from the organ, but biopsies are small and they sample less than 1% of the whole prostate. In this thesis, we explore the non-malignant prostate tissue adjacent to tumors, which is always sampled in biopsies, and we study adaptive changes in this tissue, which may provide new diagnostic and prognostic markers for prostate cancer. We have therefore proposed that this type of tissue should be termed TINT (Tumor Instructed/indicating Normal Tissue).

 Methods: In our studies, we used orthotopic rat prostate cancer models with tumors of different aggressiveness. We also used clinical materials from patients diagnosed with prostate cancer at transurethral resection (1975‒1990); the majority of these men were followed with watchful waiting. Analyses were performed with whole-genome expression array, quantitative real-time PCR, immunohistochemistry, and western blotting.

 Results: Using the animal model, we found that the presence of a tumor induces changes in gene expression in the surrounding tumor-bearing organ (TINT). The gene signature of TINT was linked to processes such as extracellular matrix organization, immune responses, and inflammation. We also showed that some of these adaptive TINT changes appear to be related to the aggressiveness and metastatic potential of the growing tumor, such as increases in macrophages, in mast cells, in vascular densities, and in vascular cell-proliferation. Some of these findings were confirmed by our observations in patient samples. We found that high staining of the extracellular matrix component hyaluronan in the stroma of the non-malignant prostate tissue was prognostic for short cancer-specific survival. We also found that an elevated proportion of C/EBP-beta positive epithelial cells in non-malignant (TINT) prostate tissue was associated with a good prognosis.

 Conclusions: Using animal experiments and patient samples, we showed that the presence of prostate cancer induces changes in the tumor-bearing organ, alterations associated with tumor aggressiveness, and that grading of these changes in TINT can be used to predict outcome in prostate cancer patients. 

Place, publisher, year, edition, pages
Umeå University, 2016. 52 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1809
prostate cancer, biomarkers, TINT
National Category
Clinical Medicine
Research subject
urn:nbn:se:umu:diva-119706 (URN)978-91-7601-470-7 (ISBN)
Public defence
2016-05-20, Hörsal B Unod T 9, Umeå, 13:00 (Swedish)
Available from: 2016-04-28 Created: 2016-04-25 Last updated: 2016-04-27Bibliographically approved

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