Kristiina Joensuu

University of Helsinki, Helsinki, Province of Southern Finland, Finland

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Publications (7)26.41 Total impact

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    ABSTRACT: IntroductionLuminal, estrogen receptor-positive (ER+) breast cancers can metastasize but lie dormant for years before recurrences prove lethal. Understanding the roles of estrogens (E) or progestins (P) in development of luminal metastases or in arousal from dormancy is hindered by few preclinical models. We have developed such models.Methods Immunocompromised, ovariectomized (ovx¿d) mice were intracardiac-injected with luminal or basal human breast cancer cells. Four lines were tested: luminal ER+PR+ cytokeratin 5 (CK5¿)-negative E3 and MCF-7 cells; basal ER¿PR¿CK5+ EWD8 cells, and basal ER¿PR¿CK5¿ MDA-MB-231 cells. Development of micrometastases or macrometastases was quantified in ovx¿d mice, and in mice supplemented with E and/or P. Metastatic deposits were analyzed by immunohistochemistry for luminal, basal and proliferation markers.ResultsER¿PR¿ cells generated macrometastases in multiple organs in the absence or presence of hormones. By contrast, ovx¿d mice injected with ER+PR+ cells appeared to be metastases-free until they were supplemented with E or E+P. Further, unlike parental ER+PR+CK5¿ cells, luminal metastases were heterogeneous, containing a significant (6 to 30%) proportion of non-proliferative ER¿PR¿CK5+ cells that would be chemotherapy resistant. Additionally, because these cells lack receptors they would also be endocrine-therapy resistant. With regard to ovx¿d control mice injected with ER+PR+ cells that appeared to be metastases-free, systematic pathologic analysis of organs showed that some harbor a reservoir of dormant micrometastases that are ER+ but PR¿. Such cells may also be endocrine- and chemotherapy resistant. Their emergence as macrometastases can be triggered by E or E+P restoration.Conclusions We conclude that hormones promote development of multi-organ macrometastases in luminal disease. The metastases display a disturbing heterogeneity, containing newly emergent ER¿PR¿ subpopulations that would be resistant to endocrine- and chemotherapies. Similar cells are found in luminal metastases of patients. Furthermore, lack of hormones is not protective. While no overt metastases form in ovx¿d mice, luminal tumor cells can seed distant organs, where they remain dormant as micrometastases and sheltered from therapies, but arousable by hormone repletion. This has implications for breast cancer survivors or women with occult disease prescribed hormones for contraception or replacement purposes.
    Breast cancer research: BCR 12/2014; 16(6):489. · 5.87 Impact Factor
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    ABSTRACT: Breast cancer can recur even decades after the primary therapy. Markers are needed to predict cancer progression and the risk of late recurrence. The estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2 (HER2), proliferation marker Ki-67, and cytokeratin CK5 were studied to find out whether their expression or occurrence in subgroups of breast cancers correlated with the time of recurrence. The expression of HER2, ER, PR, Ki-67, and CK5 was studied by IHC in 72 primary breast cancers and their corresponding recurrent/metastatic lesions. The patients were divided into three groups according to the time of the recurrence/metastasis: before two years, after 5 years, and after 10 years. Based on their IHC profiles, the tumors were divided into surrogates of the genetically defined subgroups of breast cancers and the subtype definitions were as follows: luminal A (ER or PR+HER2-), luminal B (ER or PR+HER2+), HER2 overexpressing (ER-PR-HER2+), triple-negative (ER-PR-HER2-), basal-like (ER-PR-HER2-CK5+), non-classified (ER-PR-HER2-CK5-) and luminobasal (ER or PR+CK5+). In multivariate analysis, tumor size and HER2 positivity were a significant risk of early cancer relapse. The metastases showed a significantly lower CK5 expression. CK5 positivity distinguished triple negative tumors into rapidly and slowly recurring cancers. The IHC subtype ER or PR+HER2- luminal A presented a significantly lower risk of early tumor recurrence. Ki-67 expression denoted early-relapsing tumors and correlated linearly with tumor progression, since Ki-67 positivity declined gradually from early-relapsing toward late-recurring cancers.
    Breast cancer 01/2013; 7:23-34.
  • Leena Strien, Kristiina Joensuu, Päivi Heikkilä
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    ABSTRACT: Whereas tumor dormancy occurs in melanomas, renal carcinomas and non-Hodgkin lymphomas, late recurrence is characteristic of breast cancer in particular. In the early stage, cancer cells break away from the primary tumor into the circulation, some of which are able to attach themselves to a new target tissue and avoid apoptosis. This condition represents dormancy of tumor cells, in which the cell cycle has either stopped or cell division and cell death are in mutual balance. Cessation of the dormancy state and the growth spurt that follows may result from the initiation of angiogenesis (angiogenic switch).
    Duodecim; lääketieteellinen aikakauskirja 01/2013; 129(21):2245-52.
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    ABSTRACT: Luminal breast cancers express estrogen (ER) and/or progesterone (PR) receptors and respond to hormone therapies. Basal-like "triple negative" cancers lack steroid receptors but are cytokeratin (CK) 5-positive and require chemotherapy. Here we show that more than half of primary ER(+)PR(+) breast cancers contain an ER(-)PR(-)CK5(+) "luminobasal" subpopulation exceeding 1% of cells. Starting from ER(+)PR(+) luminal cell lines, we generated lines with varying luminal to luminobasal cell ratios and studied their molecular and biological properties. In luminal disease, luminobasal cells expand in response to antiestrogen or estrogen withdrawal therapies. The phenotype and gene signature of the hormone-resistant cells matches that of clinical triple negative basal-like and claudin-low disease. Luminobasal cell expansion in response to hormone therapies is regulated by Notch1 signaling and can be blocked by γ-secretase inhibitors. Our data establish a previously unrecognized plasticity of ER(+)PR(+) luminal breast cancers that, without genetic manipulation, mobilizes outgrowth of hormone-resistant basal-like disease in response to treatment. This undesirable outcome can be prevented by combining endocrine therapies with Notch inhibition.
    Proceedings of the National Academy of Sciences 02/2012; 109(8):2742-7. · 9.81 Impact Factor
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    ABSTRACT: Breast cancer is known for its propensity to recur decades after treatment. The biology behind the phenomenon of tumor dormancy is still poorly understood. Bmi-1, c-myc, and Snail are transcription factors that have prognostic roles in several malignancies. In order to reveal whether any of these markers has impact on late relapses, we used immunohistochemistry to study the expression of Bmi-1, c-myc, Snail, and estrogen receptor in 73 primary breast cancers and in their metastatic relapses detected within 2 years, or 5 or 10 years after primary surgery. The expression of Bmi-1 was higher in the metastases than in their corresponding primary tumors in both early and late relapses. The highest expression of Bmi-1 was seen in the very late relapsing tumors (first tumor relapse after 10 years). Previously, Bmi-1 has been reported to function as a marker of tumor stem cells in breast cancer. Our results indicate that metastases, when compared to primary tumors, arise from tumor cells that have retained stem cell properties. We also analyzed the relationship between the expression of these markers and clinical parameters. A significant association between the expression of Bmi-1 and estrogen receptor was found. Nuclear expression of c-myc in primary tumors correlated with an increased risk for axillary lymph node metastasis.
    Archiv für Pathologische Anatomie und Physiologie und für Klinische Medicin 06/2011; 459(1):31-9. · 2.68 Impact Factor
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    ABSTRACT: Maspin is a serine protease inhibitor with tumor suppressor activity. Maspin can suppress tumor growth and metastasis in vivo and tumor cell motility and invasion in vitro. Maspin also modulates apoptosis of tumor cells, possibly by modulating the expression of the B-cell lymphoma-2 family member. p53 regulates the expression of the tumor suppressor gene maspin. Breast cancer is known for its propensity to recur even after decades. The biology behind this phenomenon of tumor dormancy is poorly understood. This study was conducted to clarify the role of maspin and B-cell lymphoma-2 in early and late recurring breast cancer. The expression of maspin, B-cell lymphoma-2, p53, and estrogen receptor was studied by immunohistochemistry in 73 primary breast cancers and in their metastatic relapses detected within 2 years, or 5 or 10 years after primary surgery. The cytoplasmic expression of maspin was significantly higher in the primary tumors of the early metastasizing breast cancers (first tumor relapse within 2 years) and also in their metastases compared to late metastasizing cancers. An opposite activity was observed in the expression of B-cell lymphoma-2. The level of B-cell lymphoma-2 staining was lower in the early relapsing cancers and significantly lower in their metastases, compared to tumors which metastasized 5 or 10 years after primary surgery. High cytoplasmic expression of maspin and low expression of B-cell lymphoma-2 in primary breast cancer predict early tumor relapse.
    Human pathology 06/2009; 40(8):1143-51. · 3.03 Impact Factor
  • Kristiina Joensuu, Päivi Heikkilä, Leif C Andersson
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    ABSTRACT: Breast cancer is known for its propensity to recur even after decades. The biology behind this phenomenon of tumor dormancy is poorly understood. The stanniocalcins (stanniocalcin-1, STC-1 and stanniocalcin-2, STC-2) are 56kDa homodimeric proteins. They act as pro-survival factors and contribute to the endurance of terminally differentiated cells such as neurons and adipocytes. We investigated whether elevated expression of stanniocalcins also plays a part in the tumor dormancy of breast cancer. The expression of STC-1, STC-2 and estrogen receptor (ER) was studied by immunohistochemistry in 72 primary breast cancers and in their metastatic relapses detected before two years, or after 5 or 10 years from primary surgery. When compared to primary tumors with early relapse and their metastases, the expression of STC-1 and STC-2 was significantly higher in relapses occurring after five year (STC-1 p=0.0012, STC-2 p=0.004) and even higher in very late relapses occurring 10 years after surgery (STC-1 p=0.0017, STC-2 p=0.0001). Moreover, primary tumors with a propensity of very late relapse displayed a higher initial expression of STC-2 (p=0.0001). A significantly increased frequency of ER expression was found in the very late relapses. These findings suggest that elevated expression of STC-1 or STC-2 act as survival factors also for breast cancer cells and thereby contribute to tumor dormancy.
    Cancer Letters 07/2008; 265(1):76-83. · 5.02 Impact Factor