Proffered Paper: Cell density, Her2 and progesterone signaling regulate dissemination of breast cancer cells

Hosseini, Hedayatollah; Harper, Kathryn; Obradović, M.; Sosa, María Soledad; Nanduri, Lahiri Kanth; Hoffmann, Markus; Werno, Christian; Aguirre‐Ghiso, Julio A.

doi:10.1016/s0959-8049(16)61014-6

Cited by 1 publication

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“…There are substantial differences in the biology of DTCs and primary tumors related to cell cycle status and microenvironmental signaling [50,11,51]. In humans, this extends to intrinsic properties of the cells themselves, since DTCs have less genomic aberrations than matched primary tumors [52][53][54][55]. There is also a substantive difference in treatment paradigm-daily application of a kinase inhibitor to keep a tumor at bay, versus intermittent treatment and release in order to prevent eventual recurrence.…”

Section: Accepted Articlementioning

confidence: 99%

The PI3K/mTOR inhibitor Gedatolisib eliminates dormant breast cancer cells in organotypic culture, but fails to prevent metastasis in preclinical settings

et al. 2021

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Dormant, disseminated tumor cells (DTCs) are thought to be the source of breast cancer metastases several years or even decades after initial treatment. To date, a selective therapy that leads to their elimination has not been discovered. While dormant DTCs resist chemotherapy, evidence suggests that this resistance is driven not by their lack of proliferation, but by their engagement of the surrounding microenvironment, via integrin‐β1‐mediated interactions. Because integrin‐β1‐targeted agents have not been translated readily to the clinic, signaling nodes downstream of integrin‐β1 could serve as attractive therapeutic targets in order to sensitize dormant DTCs to therapy. By probing a number of kinases downstream of integrin‐β1, we determined that PI3K inhibition with either a tool compounds or a compound (PF‐05212384; aka Gedatolisib) in clinical trials robustly sensitizes quiescent breast tumor cells seeded in organotypic bone marrow cultures to chemotherapy. These results motivated the preclinical study of whether Gedatolisib—with or without genotoxic therapy—would reduce DTC burden and prevent metastases. Despite promising results in organotypic culture, Gedatolisib failed to reduce DTC burden or delay, reduce or prevent metastasis in murine models of either triple‐negative or estrogen receptor‐positive breast cancer dissemination and metastasis. This result held true whether analyzing Gedatolisib on its own (vs. vehicle‐treated animals) or in combination with dose‐dense doxorubicin and cyclophosphamide (vs. animals treated only with dose‐dense chemotherapies). These data suggest that PI3K is not the node downstream of integrin‐β1 that confers chemotherapeutic resistance to DTCs. More broadly, they cast doubt on the strategy to target PI3K in order to eliminate DTCs and prevent breast cancer metastasis.

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