Neuromedin U: A Candidate Biomarker and Therapeutic Target to Predict and Overcome Resistance to HER-Tyrosine Kinase Inhibitors

Abstract

Intrinsic and acquired resistance to HER-targeting drugs occurs in a significant proportion of HER2-overexpressing breast cancers. Thus, there remains a need to identify predictive biomarkers that could improve patient selection and circumvent these types of drug resistance. Here, we report the identification of neuromedin U (NmU) as an extracellular biomarker in cells resistant to HER-targeted drugs. NmU overexpression occurred in cells with acquired or innate resistance to lapatinib, trastuzumab, neratinib, and afatinib, all of which displayed a similar trend upon short-term exposure, suggesting NmU induction may be an early response. An analysis of 3,489 cases of breast cancer showed NmU to be associated with poor patient outcome, particularly those with HER2-overexpressing tumors independent of established prognostic indicators. Ectopic overexpression of NmU in drug-sensitive cells conferred resistance to all HER-targeting drugs, whereas RNAi-mediated attenuation sensitized cells exhibiting acquired or innate drug resistance. Mechanistic investigations suggested that NmU acted through HSP27 as partner protein to stabilize HER2 protein levels. We also obtained evidence of functional NmU receptors on HER2-overexpressing cells, with the addition of exogenous NmU eliciting an elevation in HER2 and EGFR expression along with drug resistance. Finally, we found that NmU seemed to function in cell motility, invasion, and anoikis resistance. In vivo studies revealed that NmU attenuation impaired tumor growth and metastasis. Taken together, our results defined NmU as a candidate drug response biomarker for HER2-overexpressing cancers and as a candidate therapeutic target to limit metastatic progression and improve the efficacy of HER-targeted drugs. Cancer Res; 74(14); 3821-33. Ó2014 AACR.

Profile of neratinib and its potential in the treatment of breast cancer

“…Recently, expression of the neuropeptide neuromedin U was associated with a poor prognosis in HER2-overexpressing breast cancer and has been shown to correspond with resistance to HER-targeting agents, including neratinib in vitro. It was suggested that neuromedin U acts through the chaperone heat shock protein 27 to aid HER2 stability 77. As with lapatinib,46 we observed a reactivation of HER3 and AKT phosphorylation after 24 hours of neratinib treatment in HER2-positive breast cancer cells, although we did not assess whether this was NRG1-dependent 26.…”

Neuromedin U: A Multifunctional Neuropeptide with Pleiotropic Roles

“…Several functional assays have revealed that overexpression or treatment of cancer cells with exogenous NmU increases cell proliferation, migration, invasion, and resistance to loss of anchorage-induced apoptosis, while knockdown of NmU expression has the opposite effects (128,(131)(132)(133). These results were confirmed in in vivo assays, where NmU overexpression was shown to enhance tumor formation and metastasis, as well as possibly inducing cachexia (130 ).…”

“…Moreover, overexpression of NmU was associated with worse prognosis (45,133 ). NMUR2 has been detected in human pancreatic cancer samples and canine peripheral nerve sheath tumors, suggesting that the autocrine/paracrine NmU-NMUR2 axis might be important for the development and/or progression of these tumors (131,134 ).…”

Small lipidated anti-obesity compounds derived from neuromedin U

“…Since NmU has cardiovascular effects [70,71] as well as being indicated in cancer [72–74], it is of great interest whether prolonged exposure to our analogs may have related side effects. To assess such possible effects we measured levels of lysophosphatidic acid (LPA, (20:4)-1-arachidonoyl-2-hydroxy-sn-glycero-3-phosphatidic acid; (18:2)-1-linoleoyl-2-hydroxy-sn-glycero-3-phosphatidic acid; and (18:1)-1-oleoyl-2-hydroxy-sn-glycero-3-phosphatidic acid) in the plasma of animals treated frequently (1603 nmoles/kg; every 2 or 4 or 7 days for 21 days) with NM4A or NM4-C 16 using a previously described LC-ESI-MS/MS-based method [75–78].…”

“…As shown in Figure 6C, prolonged treatment of DIO mice with NM4A does not increase plasma levels of LPA suggesting that therapy should have no negative effects on obese patients that are prone to atherosclerosis and diabetes development. Since LPA is also indicated in cancer, these results also suggest that use in obese cancer patients or people who are not aware they have cancer, should be relatively safe, which may be of concern due to the connection of NmU with breast and pancreatic cancers [72–74]. In the case of NM4-C 16 slightly elevated levels of (20:4) were observed which may be of concern since this particular lipid was shown to enhance progression of atherosclerosis in animal model [82].…”