Phospho-ERK1/2 levels in cancer cell nuclei predict responsiveness to radiochemotherapy of rectal adenocarcinoma

Abstract

Locally advanced rectal adenocarcinoma is treated with radiochemotherapy (RCT) before surgery. The response to RCT is heterogeneous and consensus regarding reliable predictors is lacking. Since the ERK pathway is implicated in radioprotection, we examined pretreatment biopsies from 52 patients by immunohistochemistry for phosphorylated ERK (pERK). Immunostaining for pERK was considerably enhanced by use of alkaline demasking. Nuclear staining occurred in both cancer cells and stromal cells. Blind-coded sections were scored by 2 independent investigators. In patients showing no residual tumor after RCT (TRG1), staining for pERK in cancer, but not stromal, cell nuclei was significantly weaker than in patients showing a poor RCT response (TRG1 vs TRG4: p = 0.0001). Nuclear staining for pERK predicted poor responders, as illustrated by receiver operating characteristic curves with an area under curve of 0.86 (p = 0.0007) and also predicted downstaging (area under curve: 0.76; p = 0.01). A number of controls documented the specificity of the optimized staining method and results were confirmed with another pERK antibody. Thus, staining for pERK in cancer cell nuclei can predict the response to RCT and may help spare poor responders this treatment. These results also raise the question whether inhibitors of ERK activation may serve as response modifiers of RCT.

Downregulation of dual‐specificity phosphatase 4 enhances cell proliferation and invasiveness in colorectal carcinomas

“…Then, we further attempted to determine the phosphorylation levels of ERKs in CRC tissues using immunohistochemistry. However, commercially available antibodies failed to detect phosphorylated ERKs on formalin‐fixed, paraffin‐embedded sections, as had been reported previously . Therefore, we attempted to compare the phosphorylation status of ERK between the superficial and deep regions of fresh CRC tissues by Western blot analysis.…”

Phospho-ERK levels as predictors for chemotherapy of rectal carcinoma

“…MEKs activate ERKs by dual phosphorylation to phospho-ERKs. Most phospho-ERKs translocate to the nucleus, where they stimulate transcription of genes regulating cell cycle progression and apoptosis [6, 7, 10–12]. MAPK phosphatases (MKPs, also referred to as dual specificity phosphatases; DUSPs) remove the activating phosphorylations on both threonines and tyrosines in phospho-ERKs and, thus, terminate their activity.…”

“…ERKs are activated by an array of upstream regulators, including the EGF receptor (EGFR), RAS, and RAF. Activating mutations in genes encoding these regulators are central to the development and/or progression of colorectal and other cancers [ 8 – 10 ]. ERK activation proceeds through a cascade that is initiated by binding of EGF (or other growth factors) to cell surface receptors.…”

“…In vitro studies have demonstrated that MEK inhibitors (which abolish ERK phosphorylation) sensitize cultured cancer cells to 5-fluorouracil (5FU) as well as to radiation [ 13 – 15 ]. Using diagnostic (pre-treatment) biopsies, we have previously demonstrated that high phospho-ERK levels in rectal cancer cells are associated with poor RCT responses in terms of tumor regression and downstaging [ 10 ]. We now report that high cancer cell levels of phospho-ERK also subdivide high-risk patients into a favourable and less favourable group with respect to recurrence-free survival (RFS).…”

The first thermic treatment predicts following chemoradiation response with concurrent thermal therapy for the treatment of rectal cancer

“…Neoadjuvant management philosophy depends on the ability to predict the extent of pathological response using clinical, imaging, and molecular parameters (1)(2)(3). Thus far, no parameters have been validated in multi-institutional prospective trials or used prior to starting treatment.…”