Timothy Yeatman - Academia.edu (original) (raw)

Papers by Timothy Yeatman

Cancer Res, 2010

ABSTRACT ERBB2/neu and Notch signaling are known to be deregulated in many human cancers. However... more ABSTRACT ERBB2/neu and Notch signaling are known to be deregulated in many human cancers. However, pathway cross-talk and dependencies are not well understood. In this study, we use an ERBB2-transgenic mouse model of breast cancer (neuT) to show that Notch signaling plays a critical role in tumor maintenance. Inhibition of the Notch pathway with a gamma-secretase inhibitor (GSI) decreased both the Notch and the mammalian target of rapamycin/AKT pathways. Antitumor activity resulting from GSI treatment was associated with decreased cell proliferation as measured by Ki67 and decreased expression of glucose transporter Glut1. Positron emission tomography (PET) imaging showed that the functional consequences of decreased Glut1 translated to reduced glucose uptake and correlated with antitumor effects as measured by micro-computed tomography imaging. The decrease of Glut1 in neuT tumors was also observed in several human breast cancer cell lines following GSI treatment. We provide evidence that approximately 27% of ERBB2-positive human breast cancer specimens display high expression of HES1, phospho-S6RP, and GLUT1. Together, these results suggest that pathways downstream of Notch signaling are, at least in part, responsible for promoting tumor growth in neuT and also active in both neuT and a subset of human breast cancers. These findings suggest that GSI may provide therapeutic benefit to a subset of ERBB2-positive breast cancers and that [(18)F]FDG-PET imaging may be useful in monitoring clinical response.

Annals of Surgical Oncology, Feb 1, 2007

Cytoreductive therapy for metastatic carcinoid provides symptomatic relief and improvement in ove... more Cytoreductive therapy for metastatic carcinoid provides symptomatic relief and improvement in overall survival. We evaluated whether CgA and 5HIAA could predict symptomatic relief and control of disease progression after cytoreductive surgery. We retrospectively reviewed 70 patients who underwent cytoreductive surgery for neuroendocrine hepatic metastases between 1996 and 2005. Twenty-two patients had pre and post-operative CgA and/or 5HIAA levels measured. Reduction of biomarkers following cytoreduction was correlated with patient symptoms and progression of disease following surgery. Our study consisted of 14 males and 8 females with a mean age of 55 (+/-12 years). Median follow-up was 18 months (range 5-64 months). Six patients (26.1%) had complete (R0) cytoreduction, while 4 (17.4%) and 13 (56.5%) had microscopic (R1) and gross (R2) disease remaining. All patients reported improvements in their symptoms, with 12 (54.5%) reporting complete resolution (CR) and 10 (45.5%) reporting partial resolution (PR). Reduction of CgA of >or= 80% was highly predictive of complete resolution of symptoms (P = 0.007) and stabilization of disease (P = 0.034). Reduction of 5HIAA levels of >or= 80% (or normalization) was predictive of symptomatic relief, but not progression of disease (P = 0.026 and P = 0.725). Five of six patients who had R0 resections had CR and were free of disease at last follow-up (median 24.5 months, range: 11-48, P = 0.002). We conclude that >or= 80% reduction in CgA level following cytoreductive surgery for carcinoid tumors is predictive of subsequent symptom relief and disease control. Substantial reduction in CgA is associated with improved patient outcomes, even after incomplete cytoreduction.

Human Pathology, Aug 31, 2003

The insulin-like growth factor-1 receptor (IGF1-R) is a cellular receptor overexpressed in many t... more The insulin-like growth factor-1 receptor (IGF1-R) is a cellular receptor overexpressed in many tumor cell lines and in some human tumors that seems to play a critical role in transformation, tumorigenicity, and metastasis. To date, a comprehensive evaluation of tissue distribution of IGF1-R in human carcinomas from different anatomical sites has been lacking. Using stage-oriented human cancer tissue microarrays, we studied IGF1-R expression and distribution in a group of 152 human carcinomas from a variety of anatomical sites and from 63 normal tissues through immunohistochemistry. The tumors included carcinomas from breast (8), ovary (9), endometrium (7), esophagus (5), stomach (7), pancreas (7), liver (4), colon (10), kidney (14), bladder (17), prostate (11), head and neck (31), salivary glands (8), lung (13), and skin (1). Formalin-fixed, paraffin embedded tissues of each case were immuno-stained using the avidin-biotin peroxidase method and an anti-IGF1-R rabbit polyclonal antibody. High-membranous IGF1-R staining was observed in 7 of 8 (87.5%) breast carcinomas, in 9 of 9 (100%) ovarian carcinomas, in 7 of 7 (100%) endometrial carcinomas, in 5 of 7 (71.1%) gastric carcinomas, in 4 of 7 (57.1%) pancreatic carcinomas, in 9 of 10 (90%) colon adenocarcinomas, in 11 of 13 (84.6%) lung carcinomas, in 6 of 11 (54.5%) prostatic adenocarcinomas, and in 17 of 17 (100%) transitional cell carcinomas of the bladder. Only a minority of squamous cell carcinomas of the head and neck and esophagus (34), salivary gland tumors (5), and renal cell carcinomas (14) were IGF1-R positive. This study demonstrates the overexpression of IGF1-R across a wide variety of human carcinomas of glandular or transitional cell origin.

MDMX is an important regulator of p53 transcriptional activity and stress response. MDMX overexpr... more MDMX is an important regulator of p53 transcriptional activity and stress response. MDMX overexpression and gene amplification are implicated in p53 inactivation and tumor development. Unlike MDM2, MDMX is not inducible by p53, and little is known about its regulation at the transcriptional level. We found that MDMX levels in tumor cell lines closely correlate with promoter activity and mRNA

Diagnostic Immunology, Feb 1, 1983

Detection of cell surface antigens through the use of specific antisera has been possible using v... more Detection of cell surface antigens through the use of specific antisera has been possible using vital dye exclusion and radionuclide labeling. Viability determination by these and other more sophisticated methods, however, is often inconvenient. We have developed a method for analysis of cell death due to immune cytolysis that employs the Coulter counter, an electronic particle analyzer. Cell viability after treatment with antisera plus complement was determined and the values correlate well with those of Trypan blue dye exclusion tests. Future applications of this methodology are also discussed.

Clinical and Experimental Gastroenterology, 2008

Background and aims:OATP1B3 is an organic anion transporting polypeptide (OATP) that functions as... more Background and aims:OATP1B3 is an organic anion transporting polypeptide (OATP) that functions as a multispecific transporter in the normal liver. We examined the expression and clinical significance of OATP1B3 in colon cancers in tissue microarrays.Methods:Immunohistochemistry was used to assess OATP1B3 protein expression in paraffinized colon tumor tissue microarrays. OATP1B3 immunostaining was evaluated by location and intensity. Relationships between OATP1B3 expression, known prognostic variables and clinical outcomes were examined.Results:278 colon tumor samples of all stages were evaluated for OATP1B3 expression. OATP1B3 immunostaining was detectable in the majority (56%) of the tumor samples. Higher OATP1B3 expression was seen in lower stage tumors (p = 0.003) and lower grade (p = 0.004) tumors, but was not predictive of 5-year survival or tumor recurrence as an independent variable. Within individual tumor grades, OATP1B3 expression was associated with improved 5-year survival, but not recurrence in patients with poorly differentiated tumors.Conclusion:OATP1B3 expression was seen in the majority of colon tumors and may be a marker of lower grade and lower stage tumors and may predict for improved outcome in certain tumors.

Cancer Research, Oct 15, 2004

Clusterin is a widely expressed glycoprotein that has been paradoxically observed to have both pr... more Clusterin is a widely expressed glycoprotein that has been paradoxically observed to have both pro-and antiapoptotic functions. Recent reports suggest this apparent dichotomy of function may be related to two different isoforms, one secreted and cytoplasmic, the other nuclear. To clarify the functional role of clusterin in regulating apoptosis, we examined its expression in human colon cancer tissues and in human colon cancer cell lines. We additionally explored its expression and activity using models of adenomatous polyposis coli (APC)-and chemotherapy-induced apoptosis. Clusterin RNA and protein levels were decreased in colon cancer tissues largely devoid of wild-type APC when compared with matched normal tissue controls, suggesting a means for invasive cancers to avoid apoptosis. Conversely, induction of apoptosis by expression of wildtype APC or by treatment with chemotherapy led to increased clusterin RNA and protein levels localizing to apoptotic nuclei. We found that transient transfection of clusterin to colon cancer cell lines directly enhanced basal and chemotherapy-induced apoptosis. Clusterin-induced apoptosis was inhibited by antisense clusterin and was found to be highly dependent on p21 but not p53 expression, yet a deficit in p21 can be subverted by clusterin transfection. Collectively, these data support the hypothesis that nuclear clusterin function is proapoptotic when induced by APC or chemotherapy in the context of p21 expression. Absent of p21, clusterin in not induced, and apoptosis is significantly inhibited. These data support a potential therapeutic role for clusterin in enhancing chemotherapy-induced apoptosis and in promoting apoptosis in cells deficient in p21.

Cancer Research, Nov 1, 2001

Metastasis represents a crucial transition in disease development and progression and has a profo... more Metastasis represents a crucial transition in disease development and progression and has a profound impact on survival for a wide variety of cancers. Cell line models of metastasis have played an important role in developing our understanding of the metastatic process. We used a 19,200element human cDNA microarray to profile transcription in three paired cell-line models of colorectal tumor metastasis. By correlating expression patterns across these cell lines, we have identified 176 genes that appear to be differentially expressed (greater than 2-fold) in all highly metastatic cell lines relative to their reference. An analysis of these genes reiterates much of our understanding of the metastatic process and suggests additional genes, many of previously uncharacterized function, that may be causatively involved in, or at least prognostic of, metastasis. Northern analysis of a limited number of these genes validates the observed pattern of expression and suggests that further investigation and functional characterization of the identified genes is warranted.

Surgical Oncology Clinics of North America, Aug 1, 1999

The significance of breast cancer lymph node micrometastasis has been addressed by numerous studi... more The significance of breast cancer lymph node micrometastasis has been addressed by numerous studies. Although the results of these studies are mixed, most of the larger trials strongly suggest that the presence of a lymph node micrometastasis, in the absence of other nodal disease, will have a negative impact on disease free survival and on overall survival. The focus of this article is to analyze the biologic and therapeutic significance of micrometastatic disease in the axillary lymph nodes of patients with breast cancer.

Clinical cancer research : an official journal of the American Association for Cancer Research, Jan 7, 2015

We previously found that an epithelial-to-mesenchymal transition (EMT)-based gene expression sign... more We previously found that an epithelial-to-mesenchymal transition (EMT)-based gene expression signature was highly correlated to the first principal component (PC1) of 326 colorectal cancer (CRC) tumors and was prognostic. This study was designed to improve these signatures for better prediction of metastasis and outcome. 468 CRC tumors including all stages (I-IV) and metastatic lesions were used to develop a new prognostic score (ΔPC1.EMT) by subtracting the EMT signature score from its correlated PC1 signature score. The score was validated on six other independent datasets with total 3697 tumors. ΔPC1.EMT was found to be far more predictive of metastasis and outcome than its parent scores. It performed well in Stages I-III, amongst MSI subtypes, and across multiple mutation-based subclasses, demonstrating a refined capacity to predict distant metastatic potential in tumors even with a "good" prognosis. For example, in the PETACC-3 clinical trial dataset it predicted wors...

Src has been implicated in the development and progression of human colon cancer. Because the cap... more Src has been implicated in the development and progression of human colon cancer. Because the capacity for tumor cells to dissociate from the primary tumor is a critical step in the development of metastases, the effect of a naturally occurring, activated Src-531 on intercellular adhesion was examined. Homotypic adhesion was assessed using dissociation assays on Src-transformed rat fibroblasts and human

Intelligent Engineering Systems through Artificial Neural Networks Volume 18, 2008

Cancer Res, 2010

ABSTRACT ERBB2/neu and Notch signaling are known to be deregulated in many human cancers. However... more ABSTRACT ERBB2/neu and Notch signaling are known to be deregulated in many human cancers. However, pathway cross-talk and dependencies are not well understood. In this study, we use an ERBB2-transgenic mouse model of breast cancer (neuT) to show that Notch signaling plays a critical role in tumor maintenance. Inhibition of the Notch pathway with a gamma-secretase inhibitor (GSI) decreased both the Notch and the mammalian target of rapamycin/AKT pathways. Antitumor activity resulting from GSI treatment was associated with decreased cell proliferation as measured by Ki67 and decreased expression of glucose transporter Glut1. Positron emission tomography (PET) imaging showed that the functional consequences of decreased Glut1 translated to reduced glucose uptake and correlated with antitumor effects as measured by micro-computed tomography imaging. The decrease of Glut1 in neuT tumors was also observed in several human breast cancer cell lines following GSI treatment. We provide evidence that approximately 27% of ERBB2-positive human breast cancer specimens display high expression of HES1, phospho-S6RP, and GLUT1. Together, these results suggest that pathways downstream of Notch signaling are, at least in part, responsible for promoting tumor growth in neuT and also active in both neuT and a subset of human breast cancers. These findings suggest that GSI may provide therapeutic benefit to a subset of ERBB2-positive breast cancers and that [(18)F]FDG-PET imaging may be useful in monitoring clinical response.

Annals of Surgical Oncology, Feb 1, 2007

Cytoreductive therapy for metastatic carcinoid provides symptomatic relief and improvement in ove... more Cytoreductive therapy for metastatic carcinoid provides symptomatic relief and improvement in overall survival. We evaluated whether CgA and 5HIAA could predict symptomatic relief and control of disease progression after cytoreductive surgery. We retrospectively reviewed 70 patients who underwent cytoreductive surgery for neuroendocrine hepatic metastases between 1996 and 2005. Twenty-two patients had pre and post-operative CgA and/or 5HIAA levels measured. Reduction of biomarkers following cytoreduction was correlated with patient symptoms and progression of disease following surgery. Our study consisted of 14 males and 8 females with a mean age of 55 (+/-12 years). Median follow-up was 18 months (range 5-64 months). Six patients (26.1%) had complete (R0) cytoreduction, while 4 (17.4%) and 13 (56.5%) had microscopic (R1) and gross (R2) disease remaining. All patients reported improvements in their symptoms, with 12 (54.5%) reporting complete resolution (CR) and 10 (45.5%) reporting partial resolution (PR). Reduction of CgA of >or= 80% was highly predictive of complete resolution of symptoms (P = 0.007) and stabilization of disease (P = 0.034). Reduction of 5HIAA levels of >or= 80% (or normalization) was predictive of symptomatic relief, but not progression of disease (P = 0.026 and P = 0.725). Five of six patients who had R0 resections had CR and were free of disease at last follow-up (median 24.5 months, range: 11-48, P = 0.002). We conclude that >or= 80% reduction in CgA level following cytoreductive surgery for carcinoid tumors is predictive of subsequent symptom relief and disease control. Substantial reduction in CgA is associated with improved patient outcomes, even after incomplete cytoreduction.

Human Pathology, Aug 31, 2003

The insulin-like growth factor-1 receptor (IGF1-R) is a cellular receptor overexpressed in many t... more The insulin-like growth factor-1 receptor (IGF1-R) is a cellular receptor overexpressed in many tumor cell lines and in some human tumors that seems to play a critical role in transformation, tumorigenicity, and metastasis. To date, a comprehensive evaluation of tissue distribution of IGF1-R in human carcinomas from different anatomical sites has been lacking. Using stage-oriented human cancer tissue microarrays, we studied IGF1-R expression and distribution in a group of 152 human carcinomas from a variety of anatomical sites and from 63 normal tissues through immunohistochemistry. The tumors included carcinomas from breast (8), ovary (9), endometrium (7), esophagus (5), stomach (7), pancreas (7), liver (4), colon (10), kidney (14), bladder (17), prostate (11), head and neck (31), salivary glands (8), lung (13), and skin (1). Formalin-fixed, paraffin embedded tissues of each case were immuno-stained using the avidin-biotin peroxidase method and an anti-IGF1-R rabbit polyclonal antibody. High-membranous IGF1-R staining was observed in 7 of 8 (87.5%) breast carcinomas, in 9 of 9 (100%) ovarian carcinomas, in 7 of 7 (100%) endometrial carcinomas, in 5 of 7 (71.1%) gastric carcinomas, in 4 of 7 (57.1%) pancreatic carcinomas, in 9 of 10 (90%) colon adenocarcinomas, in 11 of 13 (84.6%) lung carcinomas, in 6 of 11 (54.5%) prostatic adenocarcinomas, and in 17 of 17 (100%) transitional cell carcinomas of the bladder. Only a minority of squamous cell carcinomas of the head and neck and esophagus (34), salivary gland tumors (5), and renal cell carcinomas (14) were IGF1-R positive. This study demonstrates the overexpression of IGF1-R across a wide variety of human carcinomas of glandular or transitional cell origin.

MDMX is an important regulator of p53 transcriptional activity and stress response. MDMX overexpr... more MDMX is an important regulator of p53 transcriptional activity and stress response. MDMX overexpression and gene amplification are implicated in p53 inactivation and tumor development. Unlike MDM2, MDMX is not inducible by p53, and little is known about its regulation at the transcriptional level. We found that MDMX levels in tumor cell lines closely correlate with promoter activity and mRNA

Diagnostic Immunology, Feb 1, 1983

Detection of cell surface antigens through the use of specific antisera has been possible using v... more Detection of cell surface antigens through the use of specific antisera has been possible using vital dye exclusion and radionuclide labeling. Viability determination by these and other more sophisticated methods, however, is often inconvenient. We have developed a method for analysis of cell death due to immune cytolysis that employs the Coulter counter, an electronic particle analyzer. Cell viability after treatment with antisera plus complement was determined and the values correlate well with those of Trypan blue dye exclusion tests. Future applications of this methodology are also discussed.

Clinical and Experimental Gastroenterology, 2008

Background and aims:OATP1B3 is an organic anion transporting polypeptide (OATP) that functions as... more Background and aims:OATP1B3 is an organic anion transporting polypeptide (OATP) that functions as a multispecific transporter in the normal liver. We examined the expression and clinical significance of OATP1B3 in colon cancers in tissue microarrays.Methods:Immunohistochemistry was used to assess OATP1B3 protein expression in paraffinized colon tumor tissue microarrays. OATP1B3 immunostaining was evaluated by location and intensity. Relationships between OATP1B3 expression, known prognostic variables and clinical outcomes were examined.Results:278 colon tumor samples of all stages were evaluated for OATP1B3 expression. OATP1B3 immunostaining was detectable in the majority (56%) of the tumor samples. Higher OATP1B3 expression was seen in lower stage tumors (p = 0.003) and lower grade (p = 0.004) tumors, but was not predictive of 5-year survival or tumor recurrence as an independent variable. Within individual tumor grades, OATP1B3 expression was associated with improved 5-year survival, but not recurrence in patients with poorly differentiated tumors.Conclusion:OATP1B3 expression was seen in the majority of colon tumors and may be a marker of lower grade and lower stage tumors and may predict for improved outcome in certain tumors.

Cancer Research, Oct 15, 2004

Clusterin is a widely expressed glycoprotein that has been paradoxically observed to have both pr... more Clusterin is a widely expressed glycoprotein that has been paradoxically observed to have both pro-and antiapoptotic functions. Recent reports suggest this apparent dichotomy of function may be related to two different isoforms, one secreted and cytoplasmic, the other nuclear. To clarify the functional role of clusterin in regulating apoptosis, we examined its expression in human colon cancer tissues and in human colon cancer cell lines. We additionally explored its expression and activity using models of adenomatous polyposis coli (APC)-and chemotherapy-induced apoptosis. Clusterin RNA and protein levels were decreased in colon cancer tissues largely devoid of wild-type APC when compared with matched normal tissue controls, suggesting a means for invasive cancers to avoid apoptosis. Conversely, induction of apoptosis by expression of wildtype APC or by treatment with chemotherapy led to increased clusterin RNA and protein levels localizing to apoptotic nuclei. We found that transient transfection of clusterin to colon cancer cell lines directly enhanced basal and chemotherapy-induced apoptosis. Clusterin-induced apoptosis was inhibited by antisense clusterin and was found to be highly dependent on p21 but not p53 expression, yet a deficit in p21 can be subverted by clusterin transfection. Collectively, these data support the hypothesis that nuclear clusterin function is proapoptotic when induced by APC or chemotherapy in the context of p21 expression. Absent of p21, clusterin in not induced, and apoptosis is significantly inhibited. These data support a potential therapeutic role for clusterin in enhancing chemotherapy-induced apoptosis and in promoting apoptosis in cells deficient in p21.

Cancer Research, Nov 1, 2001

Metastasis represents a crucial transition in disease development and progression and has a profo... more Metastasis represents a crucial transition in disease development and progression and has a profound impact on survival for a wide variety of cancers. Cell line models of metastasis have played an important role in developing our understanding of the metastatic process. We used a 19,200element human cDNA microarray to profile transcription in three paired cell-line models of colorectal tumor metastasis. By correlating expression patterns across these cell lines, we have identified 176 genes that appear to be differentially expressed (greater than 2-fold) in all highly metastatic cell lines relative to their reference. An analysis of these genes reiterates much of our understanding of the metastatic process and suggests additional genes, many of previously uncharacterized function, that may be causatively involved in, or at least prognostic of, metastasis. Northern analysis of a limited number of these genes validates the observed pattern of expression and suggests that further investigation and functional characterization of the identified genes is warranted.

Surgical Oncology Clinics of North America, Aug 1, 1999

The significance of breast cancer lymph node micrometastasis has been addressed by numerous studi... more The significance of breast cancer lymph node micrometastasis has been addressed by numerous studies. Although the results of these studies are mixed, most of the larger trials strongly suggest that the presence of a lymph node micrometastasis, in the absence of other nodal disease, will have a negative impact on disease free survival and on overall survival. The focus of this article is to analyze the biologic and therapeutic significance of micrometastatic disease in the axillary lymph nodes of patients with breast cancer.

Clinical cancer research : an official journal of the American Association for Cancer Research, Jan 7, 2015

We previously found that an epithelial-to-mesenchymal transition (EMT)-based gene expression sign... more We previously found that an epithelial-to-mesenchymal transition (EMT)-based gene expression signature was highly correlated to the first principal component (PC1) of 326 colorectal cancer (CRC) tumors and was prognostic. This study was designed to improve these signatures for better prediction of metastasis and outcome. 468 CRC tumors including all stages (I-IV) and metastatic lesions were used to develop a new prognostic score (ΔPC1.EMT) by subtracting the EMT signature score from its correlated PC1 signature score. The score was validated on six other independent datasets with total 3697 tumors. ΔPC1.EMT was found to be far more predictive of metastasis and outcome than its parent scores. It performed well in Stages I-III, amongst MSI subtypes, and across multiple mutation-based subclasses, demonstrating a refined capacity to predict distant metastatic potential in tumors even with a "good" prognosis. For example, in the PETACC-3 clinical trial dataset it predicted wors...

Src has been implicated in the development and progression of human colon cancer. Because the cap... more Src has been implicated in the development and progression of human colon cancer. Because the capacity for tumor cells to dissociate from the primary tumor is a critical step in the development of metastases, the effect of a naturally occurring, activated Src-531 on intercellular adhesion was examined. Homotypic adhesion was assessed using dissociation assays on Src-transformed rat fibroblasts and human

Intelligent Engineering Systems through Artificial Neural Networks Volume 18, 2008