Hyperactivated mTOR and JAK2/STAT3 Pathways: Molecular Drivers and Potential Therapeutic Targets of Inflammatory and Invasive Ductal Breast Cancers After Neoadjuvant Chemotherapy

Clin Breast Cancer. 2016 Apr;16(2):113-22.e1. doi: 10.1016/j.clbc.2015.11.006. Epub 2015 Dec 1.


Introduction: Inflammatory breast cancer (IBC) is an aggressive and rare cancer with a poor prognosis and a need for novel targeted therapeutic strategies. Preclinical IBC data showed strong activation of the phosphatidylinositide-3-kinase/mammalian target of rapamycin (mTOR) and Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathways, and expression of inflammatory cytokines and tumor-associated macrophages (TAMs).

Patients and methods: Archival tumor tissue from 3 disease types (IBC treated with neoadjuvant chemotherapy [NAC], n = 45; invasive ductal carcinoma [IDC] treated with NAC [n = 24; 'treated IDC'; and untreated IDC [n = 27; 'untreated IDC']) was analyzed for the expression of biomarkers phospho-S6 (pS6) (mTOR), phospho-JAK2 (pJAK2), pSTAT3, interleukin (IL)-6, CD68 (monocytes, macrophages), and CD163 (TAMs). Surrounding nontumor tissue was also analyzed.

Results: Biomarker levels and surrogate activity according to site-specific phosphorylation were shown in the tumor tissue of all 3 disease types but were greatest in IBC and treated IDC and least in untreated IDC for pS6, pJAK2, pSTAT3, and IL-6. Of 37 IBC patients with complete biomarker data available, 100% were pS6-positive and 95% were pJAK2-positive. In nontumor tissue, biomarker levels were observed in all groups but were generally greatest in untreated IDC and least in IBC, except for JAK2.

Conclusion: IBC and treated IDC display similar levels of mTOR and JAK2 biomarker activation, which suggests a potential mechanism of resistance after NAC. Biomarker levels in surrounding nontumor tissue suggested that the stroma might be activated by chemotherapy and resembles the oncogenic tumor-promoting environment. Activation of pS6 and pJAK2 in IBC might support dual targeting of the mTOR and JAK/STAT pathways, and the need for prospective studies to investigate combined targeted therapies in IBC.

Keywords: Biomarkers; Inflammatory breast cancer; Resistance to chemotherapy; Signaling pathways; Targeted therapies.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology*
  • Biomarkers, Tumor / metabolism
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology*
  • Carcinoma, Ductal, Breast / drug therapy
  • Carcinoma, Ductal, Breast / metabolism
  • Carcinoma, Ductal, Breast / pathology*
  • Female
  • Follow-Up Studies
  • Humans
  • Immunoenzyme Techniques
  • Inflammatory Breast Neoplasms / drug therapy
  • Inflammatory Breast Neoplasms / metabolism
  • Inflammatory Breast Neoplasms / pathology*
  • Janus Kinase 2 / metabolism*
  • Middle Aged
  • Neoadjuvant Therapy*
  • Neoplasm Invasiveness
  • Neoplasm Recurrence, Local / drug therapy
  • Neoplasm Recurrence, Local / metabolism
  • Neoplasm Recurrence, Local / pathology
  • Neoplasm Staging
  • Prognosis
  • Receptor, ErbB-2 / metabolism
  • Receptors, Estrogen / metabolism
  • Receptors, Progesterone / metabolism
  • STAT3 Transcription Factor / metabolism*
  • Signal Transduction / drug effects
  • Survival Rate
  • TOR Serine-Threonine Kinases / metabolism*


  • Biomarkers, Tumor
  • Receptors, Estrogen
  • Receptors, Progesterone
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • MTOR protein, human
  • ERBB2 protein, human
  • Receptor, ErbB-2
  • JAK2 protein, human
  • Janus Kinase 2
  • TOR Serine-Threonine Kinases