Anti-E-Cadherin Apoptosis of Inflammatory Breast Carcinoma

Institution: University of California, Los Angeles
Investigator(s): Mary Alpaugh, Ph.D. -
Award Cycle: 2000 (Cycle VI) Grant #: 6FB-0007 Award: $80,000
Award Type: Postdoctoral Fellowship
Research Priorities
Biology of the Breast Cell>Pathogenesis: understanding the disease

Initial Award Abstract (2000)
Inflammatory breast cancer is an unusual type of the disease that is characterized by a very high degree of invasion into the blood and lymphatic vessels. We have established the first human model of this form of the disease, a transplantable inflammatory carcinoma xenograft model called MARY-X. This is a human tumor obtained from a patient with inflammatory breast carcinoma, which grows in mice similar to humans. This allows us to study the detailed molecular mechanisms that regulate inflammatory carcinoma. Our specific interest is the invasion of cancer cells into the blood and lymphatic vessels. MARY-X is extremely aggressive in this invasion process, and it even turns the skin of the mouse bright red just like inflammatory cancer does in humans.

We have been comparing MARY- X with non-inflammatory breast carcinoma cell lines and xenografts for a number of different molecules. A key difference appears to be in a cell adhesion receptor called E-cadherin. MARY-X cells have increased amounts of cell surface E-cadherin. This was surprising because E-cadherin functions in normal breast epithelial cells in the formation of cell-cell junctional complexes. In most breast cancers the amount of E-cadherin decreases, such that is a ‘marker’ for cancer. MARY-X cells usually grow in the form of cell balls or spheroids. We find that treating these cells with E-cadherin antibodies will cause cell disaggregation and cell death (i.e., apoptosis).

Thus, the focus of the present study is to explore the role of the E-cadherin cell surface receptor in the biology of inflammatory breast carcinoma by studying key processes in our mouse model, MARY-X. We plan to study, first, how E-cadherin attaches to the cell cytoskeleton in these cells. Secondly, we plan to detail the relationship between E-cadherin and apoptotic cell death pathways.

Inflammatory breast cancer spreads locally via micrometastasis. Our goal is to answer key questions on the cell adhesion properties in this form of breast cancer with the aim of developing approaches to treat this form of the disease.

Final Report (2002)
Introduction: Lymphovascular tumor emboli are a marker of breast carcinoma aggressiveness, recurrence, metastasis and chemotherapy/radiotherapy failures.

Topic Addressed: Using an both in vivo and in vitro models of lymphovascular emboli formation, we have gained insights into the mechanisms of both their formation as well as their resistance to therapy. We use a model system for inflammatory breast carcinoma, called MARY-X. Using this model we can study the facotors that maintain tumor cell structure, and how this structure is associated with cell growth, sensiticvity to drugs, and the underlying genetic changes.

Progress toward Specific Aims: Lymphovascular emboli form on the basis of an intact and overexpressed E-cadherin/ α, β-catenin/actin axis and decreased degree of sialylation of MUC1. This resulting tight ball of tumor cells resists radiation and chemotherapy-induced apoptosis for a number of reasons. First, the center of the emboliare hypoxic as evidenced by pimonidazole uptake studies. Secondly, the periphery of the emboli do not exhibit a Rb, p21 or p27 mediated growth arrest. Thus, while cells are susceptible to the damaging effects of radiation and chemotherapy from the standpoint of the cell cycle, the affected cells will exert protective “bystander effects” on neighboring tumor cells. Disadherence of the lymphovascular embolus by differing immunological (anti-E-cadherin antibodies), proteolysis (trypsin), cation removal (Ca++) and gene transfer (dominant negative E-cadherin mutant; fucosyl transferase) strategies all induce apoptosis measured by TUNEL and flow cytometry by a common, yet seemingly novel, apoptotic pathway determined by gene microarray analysis. This novel apoptotic pathway differs from classical anoikis (i.e., cell death resulting from loss of adherence). These same disadherence strategies also potentiate the apoptosis-inducing effects of both chemotherapy and radiation therapy which previously were ineffective at inducing apoptosis of intact emboli. The mechanism of this apoptosis potentiation suggested by gene chip analysis is different from the mechanism of apoptosis induction. Further details on our results can be referenced in the publications below.

Future Directions and Impact: Lymphovascular emboli, in the final analysis, are the major cause of morbidity and mortality from breast cancer. New strategies targeting both their formation and neutralizing their resistance to therapy would be highly desired in future rational drug design approaches.

Relationship of sialyl-Lewis(x/a) underexpression and E-cadherin overexpression in the lymphovascular embolus of inflammatory breast carcinoma
Periodical:American Journal of Pathology
Index Medicus: Am J Pathol
Authors: Alpaugh ML, Tomlinson JS, Ye Y, Barsky SH
Yr: 2002 Vol: 161 Nbr: 2 Abs: Pg:619-28

Cooperative role of E-cadherin and sialyl-Lewis X/A-deficient MUC1 in the passive dissemination of tumor emboli in inflammatory breast carcinoma
Index Medicus: Oncogene
Authors: Alpaugh ML, Tomlinson JS, Kasraeian S, Barsky SH
Yr: 2002 Vol: 21 Nbr: 22 Abs: Pg:3631-43

The molecular basis of inflammatory breast carconoma
Periodical:Proceedings of the American Association for Cancer Research
Index Medicus: Proc Am Assoc Cancer Res
Authors: Barsky SH and Alpaugh ML
Yr: 2002 Vol: Nbr: Abs: Pg:

An intact overexpressed E-cadherin/alph, beta-catenin axis characterizes the lymphovascular emboli of inflammatory breast carcinoma
Periodical:Cancer Research
Index Medicus: Cancer Res
Authors: Tomlinson JS, Alpaugh ML, and Barsky SH
Yr: 2001 Vol: 61 Nbr: 13 Abs: Pg:5231-5241