Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2014;13(8):1256-64.
doi: 10.4161/cc.28156. Epub 2014 Feb 17.

CAPER, a novel regulator of human breast cancer progression

Isabelle Mercier  1 , Donna M Gonzales  2 , Kevin Quann  2 , Timothy G Pestell  2 , Alexander Molchansky  2 , Federica Sotgia  3 , James Hulit  4 , Ricardo Gandara  4 , Chenguang Wang  2 , Richard G Pestell  5 , Michael P Lisanti  3 , Jean-François Jasmin  1
Affiliations

CAPER, a novel regulator of human breast cancer progression

Isabelle Mercier et al. Cell Cycle. 2014.

Abstract

CAPER is an estrogen receptor (ER) co-activator that was recently shown to be involved in human breast cancer pathogenesis. Indeed, we reported increased expression of CAPER in human breast cancer specimens. We demonstrated that CAPER was undetectable or expressed at relatively low levels in normal breast tissue and assumed a cytoplasmic distribution. In contrast, CAPER was expressed at higher levels in ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC) specimens, where it assumed a predominantly nuclear distribution. However, the functional role of CAPER in human breast cancer initiation and progression remained unknown. Here, we used a lentiviral-mediated gene silencing approach to reduce the expression of CAPER in the ER-positive human breast cancer cell line MCF-7. The proliferation and tumorigenicity of MCF-7 cells stably expressing control or human CAPER shRNAs was then determined via both in vitro and in vivo experiments. Knockdown of CAPER expression significantly reduced the proliferation of MCF-7 cells in vitro. Importantly, nude mice injected with MCF-7 cells harboring CAPER shRNAs developed smaller tumors than mice injected with MCF-7 cells harboring control shRNAs. Mechanistically, tumors derived from mice injected with MCF-7 cells harboring CAPER shRNAs displayed reduced expression of the cell cycle regulators PCNA, MCM7, and cyclin D1, and the protein synthesis marker 4EBP1. In conclusion, knockdown of CAPER expression markedly reduced human breast cancer cell proliferation in both in vitro and in vivo settings. Mechanistically, knockdown of CAPER abrogated the activity of proliferative and protein synthesis pathways.

Keywords: CAPER; breast cancer; estrogen receptor; proliferation; tumor growth.

PubMed Disclaimer

Figures

None
Figure 1. Knockdown of CAPER expression reduces the proliferation of MCF-7 cells in vitro. (A) Western blot analysis shows reduced CAPER protein levels in MCF-7 cells stably expressing CAPER shRNAs. Immunoblot analysis with GAPDH is shown as a control for equal loading. (B) Knockdown of CAPER expression markedly reduced the proliferation (~4-fold) of MCF-7 cells in vitro (*P < 0.001 vs control shRNA, n = 4).
None
Figure 2. Knockdown of CAPER expression markedly reduces tumor growth in vivo. (A) Mice injected with MCF-7 cells harboring CAPER shRNAs developed smaller tumors (indicated by arrows) than mice injected with MCF-7 cells harboring control shRNAs. Quantitative analyses demonstrated a ~2-fold reduction in tumor weight (B, *P < 0.001 vs. control shRNA) and ~3-fold reduction in tumor volume (C, *P < 0.001 vs control shRNA) in mice injected with MCF-7 cells harboring CAPER shRNAs (n = 14–20 for each group). (D) When tumors were stratified as either small (≤0.1 g) or large (>0.1 g), 21.4% of mice injected with human breast cancer cells harboring CAPER shRNAs displayed large tumors as compared with 88.0% of mice injected with cells harboring control shRNAs.
None
Figure 3. The expression of CAPER positively correlates with tumor size. Pearson correlation analyses demonstrate that endogenous CAPER expression positively correlates with both the (A) tumor weight (P = 0.0002, n = 31) and (B) tumor volume (P = 0.0042, n = 31). Tumors derived from mice injected with MCF-7 cells harboring control shRNAs are represented as black squares (n = 20), while tumors derived from mice injected with MCF-7 cells harboring CAPER shRNAs are represented as red squares (n = 11).
None
Figure 4. Knockdown of CAPER expression modulates the expression of cell cycle regulators. (A) Immunoblot analyses demonstrate that tumors collected from mice injected with MCF-7 cells harboring CAPER shRNAs display reduced expression of the cell cycle regulators PCNA, MCM7, and Cyclin D1. Immunoblot analysis with GAPDH is shown as a control for equal loading. (B) Immunohistochemical analyses confirm the reduced expression of PCNA, MCM7, and Cyclin D1 in tumors derived from mice injected with MCF-7 cells stably expressing CAPER shRNAs.
None
Figure 5. Knockdown of CAPER expression reduces the levels of protein synthesis markers. (A) Immunoblot analyses demonstrate that tumors collected from mice injected with MCF-7 cells harboring CAPER shRNAs display reduced levels of the protein synthesis marker phospho-4EBP1. Immunoblot analysis with GAPDH is shown as a control for equal loading. (B) Immunohistochemical analysis confirms the reduced levels of phospho-4EBP1 in tumors derived from mice injected with MCF-7 cells stably expressing CAPER shRNAs.
None
Figure 6. Knockdown of CAPER expression reduces the phosphorylation of c-Jun. (A) Immunoblot analyses demonstrate that tumors collected from mice injected with MCF-7 cells harboring CAPER shRNAs display reduced levels of phospho(ser63)-c-Jun and phospho(ser73)-c-Jun. Immunoblot analysis with GAPDH is shown as a control for equal loading. (B) Immunohistochemical analyses confirm the reduced levels of phospho(ser63)-c-Jun and phospho(ser73)-c-Jun in tumors derived from mice injected with MCF-7 cells stably expressing CAPER shRNAs.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Pike MC, Spicer DV, Dahmoush L, Press MF. Estrogens, progestogens, normal breast cell proliferation, and breast cancer risk. Epidemiol Rev. 1993;15:17–35. - PubMed
    1. Gustafsson JA. Therapeutic potential of selective estrogen receptor modulators. Curr Opin Chem Biol. 1998;2:508–11. doi: 10.1016/S1367-5931(98)80127-0. - DOI - PubMed
    1. Heldring N, Pike A, Andersson S, Matthews J, Cheng G, Hartman J, Tujague M, Ström A, Treuter E, Warner M, et al. Estrogen receptors: how do they signal and what are their targets. Physiol Rev. 2007;87:905–31. doi: 10.1152/physrev.00026.2006. - DOI - PubMed
    1. Clemons M, Goss P. Estrogen and the risk of breast cancer. N Engl J Med. 2001;344:276–85. doi: 10.1056/NEJM200101253440407. - DOI - PubMed
    1. Kelsey JL, Bernstein L. Epidemiology and prevention of breast cancer. Annu Rev Public Health. 1996;17:47–67. doi: 10.1146/annurev.pu.17.050196.000403. - DOI - PubMed

Publication types

MeSH terms