Effect of immediate cold formalin fixation on phosphoprotein IHC tumor biomarker signal in liver tumors using a cold
Melissa L Lerch1, Heidi L Kenerson2, David Chafin3
1Department of Laboratory Medicine, University of Washington Medical Center, Seattle, WA, USA.
Abstract:
Phosphoproteins are the key indicators of signaling network pathway activation. Many disease treatment therapies are designed to inhibit these pathways and effective diagnostics are required to evaluate the efficacy of these treatments. Phosphoprotein IHC have been impractical for diagnostics due to inconsistent results occurring from technical limitations. We have designed and tested a novel cold transport device and rapid cold plus warm formalin fixation protocol using phosphoproteins IHC. We collected 50 liver tumors that were split into two experimental conditions: 2 + 2 rapid fixation (2 hours cold then 2 hour warm formalin) or 4 hour room-temperature formalin. We analyzed primary hepatocellular carcinoma (n = 10) and metastatic gastrointestinal tumors (n = 28) for phosphoprotein IHC markers pAKT, pERK, pSRC, pSTAT3, and pSMAD2 and compared them to slides obtained from the clinical blocks. Expression of pERK and pSRC, present in the metastatic colorectal carcinoma, were better preserved with the rapid processing protocol while pSTAT3 expression was detected in hepatocellular carcinoma. Differences in pSMAD2 expression were difficult to detect due to the ubiquitous nature of protein expression. There were only 3 cases expressing pAKT and all exhibited a dramatic loss of signal for the standard clinical workflow. The rapid cold preservation shows improvement in phosphoprotein preservation.
Insights
A novel rapid cold fixation protocol improved phosphoprotein immunohistochemistry (IHC) preservation in liver tumors. This technique enhances diagnostic accuracy for signaling pathway activation, crucial for evaluating cancer therapies.
Area of Science:
- Oncology
- Biopathology
- Diagnostic Pathology
Background:
- Phosphoproteins are critical biomarkers for signaling pathway activation, essential for monitoring cancer therapies.
- Current phosphoprotein immunohistochemistry (IHC) methods face technical limitations, leading to inconsistent diagnostic results.
- Improved diagnostic tools are needed to assess the efficacy of targeted therapies inhibiting signaling pathways.
Purpose of the Study:
- To develop and evaluate a novel cold transport device and rapid fixation protocol for phosphoprotein IHC.
- To assess the preservation of key phosphoprotein markers (pAKT, pERK, pSRC, pSTAT3, pSMAD2) in liver tumors using the new protocol.
- To compare the efficacy of the rapid fixation protocol against standard room-temperature formalin fixation for phosphoprotein IHC.
Main Methods:
- A novel cold transport device and a rapid cold plus warm formalin fixation protocol (2+2 hours) were designed and tested.
- Fifty liver tumors were processed: 10 primary hepatocellular carcinomas and 28 metastatic gastrointestinal tumors.
- Samples were analyzed for pAKT, pERK, pSRC, pSTAT3, and pSMAD2 expression via IHC, comparing rapid fixation to standard 4-hour room-temperature fixation.
Main Results:
- The rapid processing protocol demonstrated improved preservation of pERK and pSRC in metastatic colorectal carcinoma.
- pSTAT3 expression was successfully detected in hepatocellular carcinoma using the rapid protocol.
- The rapid cold preservation method showed significant improvement in overall phosphoprotein preservation compared to standard methods, especially for pAKT.
Conclusions:
- The novel rapid cold fixation protocol significantly enhances phosphoprotein preservation for IHC analysis in liver tumors.
- This improved method offers a more reliable diagnostic approach for evaluating signaling pathway activation in cancer.
- The findings support the clinical utility of rapid cold preservation for phosphoprotein IHC in assessing treatment efficacy.
