SUMMARY The ovarian steroids estrogen and progesterone are important in directing the normal grow... more SUMMARY The ovarian steroids estrogen and progesterone are important in directing the normal growth and development of the mouse mammary gland. Previously, we have demonstrated that the majority of proliferating mammary epithelial cells do not express estrogen receptor- a (ER a ). In this study we examined the relationship between progester- one receptor (PR) expression and proliferation in mammary epithelial
The purpose of this study was to evaluate the expression of Notch-induced transcription factors (... more The purpose of this study was to evaluate the expression of Notch-induced transcription factors (NTFs) HEY1, HES1 and SOX9 in colorectal cancer (CRC) patients to determine their clinicopathologic and prognostic significance. Levels of HEY1, HES1 and SOX9 protein were measured by immunohistochemistry in a nonmalignant and malignant tissue microarray of 441 CRC patients, and the findings correlated with pathologic, molecular and clinical variables. The NTFs HEY1, HES1 and SOX9 were overexpressed in tumours relative to colonic mucosa (OR=3.44, P<0.0001; OR=7.40, P<0.0001; OR=4.08 P<0.0001, respectively). HEY1 overexpression was a negative prognostic factor for all CRC patients (HR=1.29, P=0.023) and strongly correlated with perineural and vascular invasion and lymph node (LN) metastasis. In 5-fluorouracil (5-FU)-treated patients, the tumour overexpression of SOX9 correlated with markedly poorer survival (HR=8.72, P=0.034), but had no predictive effect in untreated patients (HR...
Post-lactational involution of the mammary gland is initiated within days of weaning. Clearing of... more Post-lactational involution of the mammary gland is initiated within days of weaning. Clearing of cells occurs by apoptosis of the milk-secreting luminal cells in the alveoli and through stromal tissue remodeling to return the gland almost completely to its pre-pregnant state. The pathways that specifically target involution of the luminal cells in the alveoli but not the basal and ductal cells are poorly understood. In this study we show in cultured human mammary alveolar structures that the involution process is initiated by fresh media withdrawal, and is characterized by cellular oxidative stress, expression of activated macrophage marker CD68 and finally complete clearing of the luminal but not basal epithelial layer. This process can be simulated by ectopic addition of reactive oxygen species (ROS) in cultures without media withdrawal. Cells isolated from post-involution alveoli were enriched for the CD49f(+) mammary stem cell (MaSC) phenotype and were able to reproduce a compl...
Background: SPARC is a matricellular protein involved in tissue remodelling, cell migration and a... more Background: SPARC is a matricellular protein involved in tissue remodelling, cell migration and angiogenesis, while forkhead box P3 (FOXP3) protein functions as a transcription factor involved in immune cell regulation. Both SPARC and FOXP3 can play an anti-tumorigenic role in cancer progression. The aim was to determine if SPARC, FOXP3, CD8 and CD45RO expression levels are associated with colorectal cancer (CRC) stage, disease outcome and long-term cancer-specific survival (CSS) in stage II and III CRC.
RUNX3 is believed to have tumour suppressor properties in several cancer types. Inactivation of R... more RUNX3 is believed to have tumour suppressor properties in several cancer types. Inactivation of RUNX3 has been shown to occur by methylation-induced transcriptional silencing and by mislocalization of the protein to the cytoplasm. The aim of this study was to examine the clinical significance of RUNX3 expression in a large series of colorectal cancers using immunohistochemistry and tissue arrays. With advancing tumour stage, expression of RUNX3 in the nucleus decreased, whereas expression restricted to the cytoplasmic compartment increased. Nuclear RUNX3 expression was associated with significantly better patient survival compared to tumours in which the expression of RUNX3 was restricted to the cytoplasm (P ¼ 0.025). These results support a role for RUNX3 as a tumour suppressor in colorectal cancer.
O ne of the major challenges for modern biorepositories is gaining visibility and recognition as ... more O ne of the major challenges for modern biorepositories is gaining visibility and recognition as professional infrastructures and service providers, in front of national regulatory bodies, institutional review boards (IRB), data protection authorities, research funding organizations, and the diagnostic and pharmaceutical industries. This recognition is necessary to ensure biorepository-specific law texts and IRB and data protection guidelines are drawn up, and to attract public and private funding. All the above elements and especially the last are necessary for long term biorepository sustainability. There are two ways to ensure this:
In mice, CD49f hi mammary stem cells (MaSCs) asymmetrically divide to generate CD49f 1 committed ... more In mice, CD49f hi mammary stem cells (MaSCs) asymmetrically divide to generate CD49f 1 committed progenitor cells that differentiate into CD49f 2 phenotypes of the milk-secreting tissue at the onset of pregnancy. We show CD49f 1 primary mammary epithelial cells (PMECs) isolated from lactating tissue uniquely respond to pregnancyassociated hormones (PAH) compared with CD49f 1 cells from nonlactating tissue. Differentiation of CD49f 1 PMEC in extracellular matrix produces CD49f 2 luminal cells to form differentiated alveoli. The PAH prolactin and placental lactogen specifically stimulate division of CD49f 2 lumi-nal cells, while receptor activator of nuclear factor (NF)-jB ligand (RANKL) specifically stimulates division of basal CD49f 1 cells. In nondifferentiating conditions, we observed a greater proportion of multipotent self-renewing cells, and RANKL treatment activated the RANK pathway in these cultures. Furthermore, we observed the deposition of calcium nodules in a proportion of these cells. These data imply that a MaSC unique to the lactating breast exists in humans, which generates progeny with discrete lineages and distinct response to PAH.
Inter-ethnic differences in drug handling and frequencies of pharmacogenetic variants are increas... more Inter-ethnic differences in drug handling and frequencies of pharmacogenetic variants are increasingly being characterized. In this study, we systematically assessed the feasibility of inferring ethnic trends in chemotherapy outcomes from inter-ethnic differences in pharmacogenetic variant frequencies. Frequencies of 51 variants and chemotherapy outcomes of East Asian and Caucasian colorectal cancer patients on standard chemotherapy regimens were summarized by meta-analyses, and variant frequencies were validated by MassARRAY analysis. Inferences of relative chemotherapy outcomes were made by considering minor allele function and population differences in their frequency. Significant population differences in genotype distributions were observed for 13/23 (60%) and 27/35 (77%) variants in the meta-analyses and validation series, respectively. Across chemotherapy regimens, East Asians had lower rates of grade 3/4 toxicity for diarrhea and stomatitis/mucositis than Caucasians, which was correctly inferred from 13/18 (72%, P=0.018) informative genetic variants. With appropriate variant selection, inferring relative population toxicity rates from population genotype differences may be relevant.
WWP1 is a ubiquitin ligase, associated with the post-translational regulation of several tumour-p... more WWP1 is a ubiquitin ligase, associated with the post-translational regulation of several tumour-promoting and tumour suppressor proteins. Here we show that WWP1 expression is up-regulated in a subset of breast tumour cell lines and primary breast tumours. We overexpressed WWP1 in MCF10A breast epithelial cells and demonstrated increased cell growth and anchorage-independent colony formation. RNAi knockdown of WWP1 expression in T47D and MCF7 breast tumour cell lines reduced anchorage-independent colony formation. We used WWP1 protein expression levels, in combination with its subcellular localization, to classify breast tumours into four categories. Surprisingly, a category with low/absent WWP1 expression displayed a consistently worse prognosis compared with WWP1-expressing tumours. Importantly, the association with disease-free survival was independent of the status of other commonly used prognostic indicators. Thus, WWP1 is a prognostic marker and may be a potential therapeutic target for a subset of breast tumours. Figure 5. Prognostic value of WWP1 expresssion in breast tumours. (A, B)
The ovarian steroids estrogen and progesterone are important in directing the normal growth and d... more The ovarian steroids estrogen and progesterone are important in directing the normal growth and development of the mouse mammary gland. Previously, we have demonstrated that the majority of proliferating mammary epithelial cells do not express estrogen receptor-␣ (ER ␣). In this study we examined the relationship between progesterone receptor (PR) expression and proliferation in mammary epithelial cells using simultaneous immunohistochemistry for progesterone receptor (PR) and tritiated thymidine [ 3 H]-Tdr) autoradiography. Results showed that the majority ( Ͼ80%) of mammary epithelial cells labeled with [ 3 H]-Tdr were PR-positive in the terminal end buds (TEBs) of pubertal mice and the ducts of pubertal and adult mice. Whereas the majority of mammary epithelial cells were also PR-positive, the basal cell population, which comprises the minority of mammary epithelial cells in the mammary ducts, was predominantly PR-negative. Nevertheless, the PR-positive phenotype remained the major proliferating cell type in the basal population. These findings suggest that the progesterone signaling pathway is involved in the proliferation of basal cell populations, potentially directing formation of tertiary side branching during pubertal development and alveolar bud formation in adult glands. A proportion of the basal cells exhibited weak expression of ER , suggesting that the role of ER  in mediating normal estrogen-induced responses should be further studied.
SUMMARY The ovarian steroids estrogen and progesterone are important in directing the normal grow... more SUMMARY The ovarian steroids estrogen and progesterone are important in directing the normal growth and development of the mouse mammary gland. Previously, we have demonstrated that the majority of proliferating mammary epithelial cells do not express estrogen receptor- a (ER a ). In this study we examined the relationship between progester- one receptor (PR) expression and proliferation in mammary epithelial
The purpose of this study was to evaluate the expression of Notch-induced transcription factors (... more The purpose of this study was to evaluate the expression of Notch-induced transcription factors (NTFs) HEY1, HES1 and SOX9 in colorectal cancer (CRC) patients to determine their clinicopathologic and prognostic significance. Levels of HEY1, HES1 and SOX9 protein were measured by immunohistochemistry in a nonmalignant and malignant tissue microarray of 441 CRC patients, and the findings correlated with pathologic, molecular and clinical variables. The NTFs HEY1, HES1 and SOX9 were overexpressed in tumours relative to colonic mucosa (OR=3.44, P<0.0001; OR=7.40, P<0.0001; OR=4.08 P<0.0001, respectively). HEY1 overexpression was a negative prognostic factor for all CRC patients (HR=1.29, P=0.023) and strongly correlated with perineural and vascular invasion and lymph node (LN) metastasis. In 5-fluorouracil (5-FU)-treated patients, the tumour overexpression of SOX9 correlated with markedly poorer survival (HR=8.72, P=0.034), but had no predictive effect in untreated patients (HR...
Post-lactational involution of the mammary gland is initiated within days of weaning. Clearing of... more Post-lactational involution of the mammary gland is initiated within days of weaning. Clearing of cells occurs by apoptosis of the milk-secreting luminal cells in the alveoli and through stromal tissue remodeling to return the gland almost completely to its pre-pregnant state. The pathways that specifically target involution of the luminal cells in the alveoli but not the basal and ductal cells are poorly understood. In this study we show in cultured human mammary alveolar structures that the involution process is initiated by fresh media withdrawal, and is characterized by cellular oxidative stress, expression of activated macrophage marker CD68 and finally complete clearing of the luminal but not basal epithelial layer. This process can be simulated by ectopic addition of reactive oxygen species (ROS) in cultures without media withdrawal. Cells isolated from post-involution alveoli were enriched for the CD49f(+) mammary stem cell (MaSC) phenotype and were able to reproduce a compl...
Background: SPARC is a matricellular protein involved in tissue remodelling, cell migration and a... more Background: SPARC is a matricellular protein involved in tissue remodelling, cell migration and angiogenesis, while forkhead box P3 (FOXP3) protein functions as a transcription factor involved in immune cell regulation. Both SPARC and FOXP3 can play an anti-tumorigenic role in cancer progression. The aim was to determine if SPARC, FOXP3, CD8 and CD45RO expression levels are associated with colorectal cancer (CRC) stage, disease outcome and long-term cancer-specific survival (CSS) in stage II and III CRC.
RUNX3 is believed to have tumour suppressor properties in several cancer types. Inactivation of R... more RUNX3 is believed to have tumour suppressor properties in several cancer types. Inactivation of RUNX3 has been shown to occur by methylation-induced transcriptional silencing and by mislocalization of the protein to the cytoplasm. The aim of this study was to examine the clinical significance of RUNX3 expression in a large series of colorectal cancers using immunohistochemistry and tissue arrays. With advancing tumour stage, expression of RUNX3 in the nucleus decreased, whereas expression restricted to the cytoplasmic compartment increased. Nuclear RUNX3 expression was associated with significantly better patient survival compared to tumours in which the expression of RUNX3 was restricted to the cytoplasm (P ¼ 0.025). These results support a role for RUNX3 as a tumour suppressor in colorectal cancer.
O ne of the major challenges for modern biorepositories is gaining visibility and recognition as ... more O ne of the major challenges for modern biorepositories is gaining visibility and recognition as professional infrastructures and service providers, in front of national regulatory bodies, institutional review boards (IRB), data protection authorities, research funding organizations, and the diagnostic and pharmaceutical industries. This recognition is necessary to ensure biorepository-specific law texts and IRB and data protection guidelines are drawn up, and to attract public and private funding. All the above elements and especially the last are necessary for long term biorepository sustainability. There are two ways to ensure this:
In mice, CD49f hi mammary stem cells (MaSCs) asymmetrically divide to generate CD49f 1 committed ... more In mice, CD49f hi mammary stem cells (MaSCs) asymmetrically divide to generate CD49f 1 committed progenitor cells that differentiate into CD49f 2 phenotypes of the milk-secreting tissue at the onset of pregnancy. We show CD49f 1 primary mammary epithelial cells (PMECs) isolated from lactating tissue uniquely respond to pregnancyassociated hormones (PAH) compared with CD49f 1 cells from nonlactating tissue. Differentiation of CD49f 1 PMEC in extracellular matrix produces CD49f 2 luminal cells to form differentiated alveoli. The PAH prolactin and placental lactogen specifically stimulate division of CD49f 2 lumi-nal cells, while receptor activator of nuclear factor (NF)-jB ligand (RANKL) specifically stimulates division of basal CD49f 1 cells. In nondifferentiating conditions, we observed a greater proportion of multipotent self-renewing cells, and RANKL treatment activated the RANK pathway in these cultures. Furthermore, we observed the deposition of calcium nodules in a proportion of these cells. These data imply that a MaSC unique to the lactating breast exists in humans, which generates progeny with discrete lineages and distinct response to PAH.
Inter-ethnic differences in drug handling and frequencies of pharmacogenetic variants are increas... more Inter-ethnic differences in drug handling and frequencies of pharmacogenetic variants are increasingly being characterized. In this study, we systematically assessed the feasibility of inferring ethnic trends in chemotherapy outcomes from inter-ethnic differences in pharmacogenetic variant frequencies. Frequencies of 51 variants and chemotherapy outcomes of East Asian and Caucasian colorectal cancer patients on standard chemotherapy regimens were summarized by meta-analyses, and variant frequencies were validated by MassARRAY analysis. Inferences of relative chemotherapy outcomes were made by considering minor allele function and population differences in their frequency. Significant population differences in genotype distributions were observed for 13/23 (60%) and 27/35 (77%) variants in the meta-analyses and validation series, respectively. Across chemotherapy regimens, East Asians had lower rates of grade 3/4 toxicity for diarrhea and stomatitis/mucositis than Caucasians, which was correctly inferred from 13/18 (72%, P=0.018) informative genetic variants. With appropriate variant selection, inferring relative population toxicity rates from population genotype differences may be relevant.
WWP1 is a ubiquitin ligase, associated with the post-translational regulation of several tumour-p... more WWP1 is a ubiquitin ligase, associated with the post-translational regulation of several tumour-promoting and tumour suppressor proteins. Here we show that WWP1 expression is up-regulated in a subset of breast tumour cell lines and primary breast tumours. We overexpressed WWP1 in MCF10A breast epithelial cells and demonstrated increased cell growth and anchorage-independent colony formation. RNAi knockdown of WWP1 expression in T47D and MCF7 breast tumour cell lines reduced anchorage-independent colony formation. We used WWP1 protein expression levels, in combination with its subcellular localization, to classify breast tumours into four categories. Surprisingly, a category with low/absent WWP1 expression displayed a consistently worse prognosis compared with WWP1-expressing tumours. Importantly, the association with disease-free survival was independent of the status of other commonly used prognostic indicators. Thus, WWP1 is a prognostic marker and may be a potential therapeutic target for a subset of breast tumours. Figure 5. Prognostic value of WWP1 expresssion in breast tumours. (A, B)
The ovarian steroids estrogen and progesterone are important in directing the normal growth and d... more The ovarian steroids estrogen and progesterone are important in directing the normal growth and development of the mouse mammary gland. Previously, we have demonstrated that the majority of proliferating mammary epithelial cells do not express estrogen receptor-␣ (ER ␣). In this study we examined the relationship between progesterone receptor (PR) expression and proliferation in mammary epithelial cells using simultaneous immunohistochemistry for progesterone receptor (PR) and tritiated thymidine [ 3 H]-Tdr) autoradiography. Results showed that the majority ( Ͼ80%) of mammary epithelial cells labeled with [ 3 H]-Tdr were PR-positive in the terminal end buds (TEBs) of pubertal mice and the ducts of pubertal and adult mice. Whereas the majority of mammary epithelial cells were also PR-positive, the basal cell population, which comprises the minority of mammary epithelial cells in the mammary ducts, was predominantly PR-negative. Nevertheless, the PR-positive phenotype remained the major proliferating cell type in the basal population. These findings suggest that the progesterone signaling pathway is involved in the proliferation of basal cell populations, potentially directing formation of tertiary side branching during pubertal development and alveolar bud formation in adult glands. A proportion of the basal cells exhibited weak expression of ER , suggesting that the role of ER  in mediating normal estrogen-induced responses should be further studied.
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Papers by Nikolajs Zeps