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Catalogue No.


Cell Line Name


Cell Line Description

The MCF7/ExeR-3 cell line was developed as a model of resistance to anti-cancer treatment with aromatase inhibitors. Exemestane-resistant cell lines were established from MCF7 cells grown in medium with 10% NCS and 10⁻⁷ M testosterone. A culture of MCF7 cells were treated with 10⁻⁷ M exemetane for one week, trypsinized and seeded in serial dilutions in 24-well plates. Single colonies were transferred to new wells and gradually expanded in medium with exemestane. After ~2-3 months, the isolated colonies gave rise to exemestane-resistant cell lines, which could be grown in medium containing exemestane with a weekly split ratio of ~1:25.

General Info



Unique to ECACC


Also Known As

MCF-7/ExeR-3, MCF-7/ExeR3, MCF7/ExeR3

Release Conditions

Restricted - commercial organisations are required to complete the 'Cell Line Release Authorisation for Research Use in Commercial Organisations' release conditions form in the supporting documents section.



Breast cancer cell line resistant to the aromatase inhibitor exemestane. Oestrogen receptor positive.


Related cell lines:MCF7/LetR-1, -LetR-2, -LetR-3 and -LetR-4 resistant to the non-steroidal Aromatase Inhibitor, letrozole.MCF7/ExeR-1, -ExeR-2, and -ExeR-4 resistant to the steroidal Aromatase Inhibitor, exemestane.MCF7/AnaR-1, -AnaR-2, -AnaR-3 and -AnaR-4 resistant to the non steroidal Aromatase Inhibitor, anastrozole.

Tissue of Origin



Polygonal epithelium

DNA profile (STR Profile)

Amelogenin: X

CSF1PO: 9, 10

D3S1358: 16

D5S818: 11,12

D7S820: 9

D8S1179: 10, 14

D13S317: 11

D16S539: 11, 12

D18S51: 14, 21

D21S11: 30

FGA: 19, 23, 25

Penta D: 12

Penta E: 7, 12

TH01: 6

TPOX: 9, 12

vWA: 14, 15


The MCF7/ExeR-3 cell line was developed as a model of resistance to anti-cancer treatment with aromatase inhibitors. Third generation aromatase inhibitors (AIs) have proven to be effective treatment for estrogen receptor positive (ER+) breast cancer and are today recommended as first line endocrine therapy for post-menopausal ER+ breast cancer patients, making up the majority of breast cancer patients. However, a major problem is development of resistance against AIs. Since molecular mechanisms of AI resistance are largely undisclosed, the development of cell lines resistant to the steroidal AI exemestane allows the study of the molecular basis for resistance to AIs to unravel new targets for treatment. Other Exemestane -resistant cell lines derived from MCF7 cells include MCF7/ExeR-1, MCF7/ExeR-2 and MCF7/ExeR-4.


Pleural Effusion of a Ductal Carcinoma

Culture Conditions

Cell Type


Subculture Routine

Split sub-confluent cultures at 70-80% confluency. Subculture cells using 0.05% trypsin/EDTA solution or TrypLE Express™ (1X), without phenol red and wash with phosphate buffered saline (PBS). Pellet cells by centrifugation (~100 x g) and re-suspend in growth medium. Initiate the culture at a dilution of approximately 1:3 to 1:6 i.e. seeding at 2-4 x 10⁴ cells/cm². Incubate cultures in 5% CO₂ at 37°C. Recommend media changes every 2-3 days.It is recommended that upon resuscitation the cells are washed in phosphate buffered saline (PBS) or serum-free medium, pelleted by centrifugation and re-suspended in growth medium prior to initiation of culture.

Culture Medium

Phenol-red-free DMEM/F12 medium supplemented with 10% newborn calf serum (NCS), 2.5 mM Glutamax, 6 ng/ml insulin, 0.1 µM testosterone and 0.1 µM exemestane. Cells are cryopreserved in Newborn calf serum (NCS) (90%) and dimethyl sulphoxide (DMSO) (10%).

Growth Mode


Additional Info


Ximbio (Formerly Cancer Research Technologies Limited)

Country of Origin


Hazard Group (ACDP)

Hazard Group (ACDP) 2



Hole et al. 2015. Breast Cancer Res Treat. 149(3):715-26. PMID: 25667100. Hole et al. 2015. Int J Oncol. 46(4):1481-90. PMID: 25625755

Available Formats

  • Frozen
  • DNA-5µg (100ng/µl)

If use of this culture results in a scientific publication, it should be cited in the publication as: MCF7/ExeR-3 (ECACC 16022522).

Unless specified otherwise, at ECACC we routinely handle all of our cell lines at containment level 2 in accordance with the ACDP guidelines (Advisory Committee on Dangerous Pathogens) (UK). All cell cultures have the potential to carry as yet unidentified adventitious agents. It is the responsibility of the end user to ensure that their facilities comply with biosafety regulations for their own country. ACDP Guidance: Biological agents: Managing the risks in laboratories and healthcare premises.

The Culture Collections represent deposits of cultures from world-wide sources. While every effort is made to ensure details distributed by Culture Collections are accurate, Culture Collections cannot be held responsible for any inaccuracies in the data supplied. References where quoted are mainly attributed to the establishment of the cell culture and not for any specific property of the cell line, therefore further references should be obtained regarding cell culture characteristics. Passage numbers where given act only as a guide and Culture Collections does not guarantee the passage number stated will be the passage number received by the customer.

Cultures supplied by Culture Collections are for research purposes only. Enquiries regarding the commercial use of a cell line are referred to the depositor of the cell line. Some cell lines have additional special release conditions such as the requirement for a material transfer agreement to be completed by the potential recipient prior to the supply of the cell line. Please view the Terms & Conditions of Supply for more information.