Bisphosphonates inactivate human EGFRs to exert antitumor actions

Abstract

Bisphosphonates are the most commonly prescribed medicines for osteoporosis and skeletal metastases. The drugs have also been shown to reduce cancer progression, but only in certain patient subgroups, suggesting that there is a molecular entity that mediates bisphosphonate action on tumor cells. Using connectivity mapping, we identified human epidermal growth factor receptors (human EGFR or HER) as a potential new molecular entity for bisphosphonate action. Protein thermal shift and cell-free kinase assays, together with computational modeling, demonstrated that N-containing bisphosphonates directly bind to the kinase domain of HER1/2 to cause a global reduction in downstream signaling. By doing so, the drugs kill lung, breast, and colon cancer cells that are driven by activating mutations or overexpression of HER1. Knocking down HER isoforms thus abrogates cell killing by bisphosphonates, establishing complete HER dependence and ruling out a significant role for other receptor tyrosine kinases or the enzyme farnesyl pyrophosphate synthase. Consistent with this finding, colon cancer cells expressing low levels of HER do not respond to bisphosphonates. The results suggest that bisphosphonates can potentially be repurposed for the prevention and therapy of HER family-driven cancers.tyrosine kinase inhibitor | drug repurposing | Her2/neu | receptor tyrosine kinase | osteoporosis B isphosphonates are the mainstay of therapy worldwide for osteoporosis and skeletal metastasis (1, 2). However, the drugs have also been shown to kill cancer cells in people independently of their action on osteoclasts (3). Most compelling is evidence that breast cancer patients treated with the potent bisphosphonate zoledronic acid display a profound reduction in disseminated tumor cell burden and increased disease-free survival (4-7). More intriguing, however, is that patients on oral bisphosphonates for osteoporosis have a lower incidence of colon and breast cancer (8-10). Nonetheless, the mechanism underscoring these anticancer actions is not well understood.Whereas newer N-containing bisphosphonates inhibit farnesyl pyrophosphate synthase (FPPS) (1), they have also been shown to block tumor growth independently of FPPS, namely through ɤδ T-cell receptor activation (11-13), NF-κB inhibition (14), and VEGF and hypoxia inducible factor-1α suppression (15-17). However, the rank orders of the antitumor and anti-FPPS potencies of bisphosphonates do not match, suggesting that yet undiscovered mechanisms mediate their action on cancer cells. Here we report the human EGFR (HER) family of receptor tyrosine kinases (RTKs) as a potential molecular entity for bisphosphonate action.A large number of malignancies, including lung, breast, colorectal, stomach, head and neck, and pancreatic cancers, are driven by members of the human EGFR family, which are either overexpressed or mutated to constitutively active forms. About 30% of nonsmall-cell lung cancers, which cause the highest number of cancer-related deaths worldwide, are driven by activating mu...

FSIP1 binds HER2 directly to regulate breast cancer growth and invasiveness

“…Two-tailed Student's t test, *P ≤ 0.05, **P ≤ 0.01. (Table S1) osteoporosis and skeletal metastasis, has the potential for adjunctive use in EGFR-driven lung, breast, and other cancers (12,14). Two antihelminthic agents and a β-blocker similarly track on CMAP with a Gaucher disease gene signature (13).…”

“…CMAP provides a unique strategy for unraveling new actions of drugs currently used for other medical conditions (13)(14)(15). The approach uses a gene signature to query the CMAP for gene expression profiles (https://portals.broadinstitute.org/cmap/).…”

“…Nonparametric, rank-based pattern matching using the Kolmogorov-Smirnov statistic is used to examine shared mechanisms of action to reveal both mimics and antimimics of any biological intervention (15). We have previously used this strategy to unravel an action of the commonly used class of drugs for osteoporosis and skeletal metastasis-the bisphosphonates-on the EGFR family of tyrosine kinase receptors (14).…”

Physiologic Activity of Bisphosphonates – Recent Advances

“…This is because the physiologic mechanism of bisphosphonate action is complex, and they have been shown to block tumor growth independently of FPPS inhibition, namely through γ,δ T-cell receptor activation, [132,133] NF-κB inhibition, [134]. VEGF and hypoxia inducible factor-α suppression [135] as well as inactivation of epidermal growth factor receptors [136]. There is also a report showing that bisphosphonates target the three most epigenetic cell levels, namely DNA methylation, histone deacetylation and microRNAs [137].…”

Repurposing of bisphosphonates for the prevention and therapy of nonsmall cell lung and breast cancer

“…We recently showed that aminobisphosphonates can inactivate human epidermal growth factor receptor (HER) family of receptor tyrosine kinases (RTKs) (4). We found that the drugs directly bind the HER1/2 kinase domain and, by inhibiting downstream signaling, reduce the cell viability in HER-driven lung, breast, and colon cancers (4). Knocking down the four HER isoforms abrogate bisphosphonate action, proving a selective action through this pathway (4).…”