Epidermal growth factor receptor (EGFR) is commonly over-expressed in metastatic breast cancer yet metastatic breast cancer is generally resistant to anti-EGFR therapies, and the mechanism for resistance to EGFR inhibitors in this setting is not fully understood. Hormonally up-regulated neu-associated kinase (HUNK) kinase is up-regulated in aggressive breast cancers and is thought to play a role in breast cancer metastasis. However, no studies have been conducted to examine a relationship between EGFR and HUNK in breast cancer metastasis. We performed a kinase substrate screen and identified that EGFR is phosphorylated by HUNK. Our studies show that HUNK phosphorylates EGFR at T654, enhancing receptor stability and downstream signaling. We found that increased phosphorylation of T654 EGFR correlates with increased epithelial to mesenchymal, migration and invasion, and metastasis. In addition, we found that HUNK expression correlates with overall survival and distant metastasis free survival. This study shows that HUNK directly phosphorylates EGFR at T654 to promote metastasis and is the first study to show that the phosphorylation of this site in EGFR regulates metastasis.

Strategies for successful primary treatment of HER2-positive breast cancer include use of the HER2 inhibitors trastuzumab or lapatinib in combination with standard chemotherapy. While successful, many patients develop resistance to these HER2 inhibitors indicating an unmet need. Consequently, current research efforts are geared toward understanding mechanisms of resistance and the signaling modalities that regulate these mechanisms. We have undertaken a study to examine whether signaling molecules downstream of epidermal growth factor receptor, which often act as compensatory signaling outlets to circumvent HER2 inhibition, can be co-targeted to overcome resistance. We identified JNK signaling as a potential area of intervention and now show that inhibiting JNK using the pan-JNK inhibitor, SP600125, is effective in the HER2-positive, resistant JIMT-1 xenograft mammary tumor model. We also investigate potential combination strategies to bolster the effects of JNK inhibition and find that co-targeting of JNK and the protein kinase HUNK can prohibit tumor growth of resistant HER2-positive mammary tumors in vivo.

Atopic dermatitis is a condition characterized by xerotic and pruritic skin. While the onset of the disease is usually in childhood, it may persist into adulthood. First-line treatments include adequate moisturization, avoidance of irritants, and the application of topical corticosteroids. Dupilumab is a biologic therapy, approved for moderate-to-severe atopic dermatitis, that dampens the pruritus sensation by inhibiting the downstream effects of the T helper cell type 2 pathway by binding to the interleukin-4 receptor α subunit. The monoclonal antibody is typically well-tolerated.We present a novel case of the development of generalized granuloma annulare after treatment with dupilumab. A 71-year-old male with a history of hypertension, hyperlipidemia, chronic kidney disease, gout, and bipolar disorder presented to clinic with biopsy-proven severe atopic dermatitis. First-line treatments had been exhausted, and the patient was not an ideal candidate for traditional systemic options secondary to his poor renal function. Therapy with dupilumab was initiated and continued for two years until the patient developed biopsy-proven generalized granuloma annulare. At this time, dupilumab was discontinued and the pharmaceutical company was made aware of this side effect.

No abstract

Despite the initial success of common HER2 inhibitors used in the clinic, including trastuzumab and lapatinib, HER2 positive (HER2+) breast cancer cells often acquire resistance through mechanisms that continue to remain poorly understood. A number of signaling molecules, which act downstream of HER2, including PI3K, Akt, JNK, and Hormonally-Upregulated Neu-associated Kinase (Hunk), are thought to contribute to resistance. Our recent studies indicate that targeting Hunk via shRNA in HER2+breast cancer cells that are sensitive to HER2 inhibitors (BT474) and cells that are resistant (JIMT) leads to increased caspase-3 activity in vitro and impaired tumor growth in vivo. In addition, we find that targeting Hunk not only sensitizes HER2+ cells to apoptosis, but also impairs autophagy, as indicated by decreased LC3BII expression, the lipidated form of LC3B which signifies active autophagy. Because elevated Hunk protein expression correlates with poorer prognosis, and since Hunk knockdown impairs autophagy, it is possible that Hunk acts to upregulate autophagy thereby contributing to the development of resistance. We have also found that the kinase JNK plays a role in resistance in HER2+ breast cancer cells, and demonstrate that JNK inhibition via a pan-JNK inhibitor impairs tumor growth of JIMT cells. We further show that co-targeting of JNK and HUNK results in greater cell death and significantly reduced tumor growth than either individual treatment in the JIMT-1, HER2+ resistant cell line, as well as a HER2+ line that was engineered to be lapatinib resistant, BT474-LR. Overall, our results indicate that targeting Hunk in HER2+ breast cancer not only alters autophagy and impairs tumor growth, but that co-targeting Hunk and JNK shows greater therapeutic effects on reducing tumor growth and inducing cell death. Citation Format: Joelle Zambrano, Kendall Phelps-Polirer, Melissa Abt, Elizabeth Yeh. Targeting the protein kinase Hunk in HER2+ resistant breast cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 192.