HER2 Phosphorylation Is Maintained by a PKB Negative Feedback Loop in Response to Anti-HER2 Herceptin in Breast Cancer

A feedback loop maintains HER2 receptor signalling and cell survival in response to Herceptin treatment in HER2-positive breast cancers, but this Herceptin resistance may be bypassed by pan-HER inhibitors

A biosensor to monitor dynamic regulation and function of tumour suppressor PTEN in living cells

Tumour suppressor ​PTEN is a phosphatase that negatively regulates the PI3K/AKT pathway. The ability to directly monitor ​PTEN conformation and function in a rapid, sensitive manner is a key step towards developing anti-cancer drugs aimed at enhancing or restoring ​PTEN-dependent pathways. Here we developed an intramolecular bioluminescence resonance energy transfer (BRET)-based biosensor, capable of detecting signal-dependent ​PTEN conformational changes in live cells. The biosensor retains intrinsic properties of ​PTEN, enabling structure–function and kinetic analyses. BRET shifts, indicating conformational change, were detected following mutations that disrupt intramolecular ​PTEN interactions, promoting plasma membrane targeting and also following physiological ​PTEN activation. Using the biosensor as a reporter, we uncovered ​PTEN activation by several G protein-coupled receptors, previously unknown as ​PTEN regulators. Trastuzumab, used to treat ​ERBB2-overexpressing breast cancers also elicited activation-associated ​PTEN conformational rearrangement. We propose the biosensor can be used to identify pathways regulating ​PTEN or molecules that enhance its anti-tumour activity

SRC signaling in cancer and tumor microenvironment

PubMed: 33123993Pioneering experiments performed by Harold Varmus and Mike Bishop in 1976 led to one of the most influential discoveries in cancer research and identified the first cancer-causing oncogene called Src. Later experimental and clinical evidence suggested that Src kinase plays a significant role in promoting tumor growth and progression and its activity is associated with poor patient survival. Thus, several Src inhibitors were developed and approved by FDA for treatment of cancer patients. Tumor microenvironment (TME) is a highly complex and dynamic milieu where significant cross-talk occurs between cancer cells and TME components, which consist of tumor-associated macrophages, fibroblasts, and other immune and vascular cells. Growth factors and chemokines activate multiple signaling cascades in TME and induce multiple kinases and pathways, including Src, leading to tumor growth, invasion/metastasis, angiogenesis, drug resistance, and progression. Here, we will systemically evaluate recent findings regarding regulation of Src and significance of targeting Src in cancer therapy. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2021