bims-pimaco 2021-11-07 papers

on PI3K and MAPK signalling in colorectal cancer

Issue of 2021–11–07
seven papers selected by
Lucas B. Zeiger, CRUK Scotland Institute, Beatson Institute for Cancer Research

Aberrant expression and subcellular localization of ECT2 drives colorectal cancer progression and growth.
Genome-wide CRISPR-cas9 knockout screening identifies GRB7 as a driver for MEK inhibitor resistance in KRAS mutant colon cancer.
The Q61H mutation decouples KRAS from upstream regulation and renders cancer cells resistant to SHP2 inhibitors.
Proteomic characterization of GSK3β knockout shows altered cell adhesion and metabolic pathway utilisation in colorectal cancer cells.
The Therapeutic Potential of MAPK/ERK Inhibitors in the Treatment of Colorectal Cancer.
Molecular characteristics and clinical outcomes of patients with Neurofibromin 1-altered metastatic colorectal cancer.
Correlation of PIK3CA mutation with programmed death ligand-1 (PD-L1) expression and their clinicopathological significance in colorectal cancer.

Cancer Res. 2021 Nov 04. pii: canres.4218.2020. [Epub ahead of print]

Aberrant expression and subcellular localization of ECT2 drives colorectal cancer progression and growth.

Danielle R Cook, Melissa Kang, Timothy D Martin, Joseph A Galanko, Gabriela H Loeza, Dimitri G Trembath, Verline Justilien, Karen A Pickering, David F Vincent, Armin Jarosch, Philipp Jurmeister, Andrew M Waters, Priya S Hibshman, Andrew D Campbell, Catriona A Ford, Temitope O Keku, Jen Jen Yeh, Michael S Lee, Adrienne D Cox, Alan P Fields, Robert S Sandler, Owen J Sansom, Christine Sers, Antje Schaefer, Channing J Der.

ECT2 is an activator of RHO GTPases that is essential for cytokinesis. Additionally, ECT2 was identified as an oncoprotein when expressed ectopically in NIH/3T3 fibroblasts. However, oncogenic activation of ECT2 resulted from N-terminal truncation, and such truncated ECT2 proteins have not been found in cancer patients. In this study, we observed elevated expression of full-length ECT2 protein in preneoplastic colon adenomas, driven by increased ECT2 mRNA abundance and associated with APC tumor suppressor loss. Elevated ECT2 levels were detected in the cytoplasm and nucleus of colorectal cancer (CRC) tissue, suggesting cytoplasmic mislocalization as one mechanism of early oncogenic ECT2 activation. Importantly, elevated nuclear ECT2 correlated with poorly differentiated tumors, and a low cytoplasmic:nuclear ratio of ECT2 protein correlated with poor patient survival, suggesting that nuclear and cytoplasmic ECT2 play distinct roles in CRC. Depletion of ECT2 reduced anchorage-independent cancer cell growth and invasion independent of its function in cytokinesis, and loss of Ect2 extended survival in a KrasG12D Apc-null colon cancer mouse model. Expression of ECT2 variants with impaired nuclear localization or guanine nucleotide exchange catalytic activity failed to restore cancer cell growth or invasion, indicating that active, nuclear ECT2 is required to support tumor progression. Nuclear ECT2 promoted ribosomal DNA transcription and ribosome biogenesis in CRC. These results support a driver role for both cytoplasmic and nuclear ECT2 overexpression in CRC and emphasize the critical role of precise subcellular localization in dictating ECT2 function in neoplastic cells.

DOI: https://doi.org/10.1158/0008-5472.CAN-20-4218
Oncogene. 2021 Oct 30.

Genome-wide CRISPR-cas9 knockout screening identifies GRB7 as a driver for MEK inhibitor resistance in KRAS mutant colon cancer.

Chune Yu, Dan Luo, Jing Yu, Min Zhang, Xiaobo Zheng, Guangchao Xu, Jiaxin Wang, Huiling Wang, Yufei Xu, Ke Jiang, Jie Xu, Xuelei Ma, Jing Jing, Hubing Shi.

Targeting the KRAS pathway is a promising but challenging approach for colorectal cancer therapy. Despite showing potent efficacy in BRAF-mutated melanoma, MEK inhibitors appeared to be tolerated by colorectal cancer cells due to their intrinsic compensatory signaling. Here, we performed genome-wide CRISPR/Cas9 screening in the presence of MEK inhibitor to identify genes that are synthetically lethal with MEK inhibition in CRC models harboring KRAS mutations. Several genes were identified as potential functional drivers, which were significantly enriched in the GRB7-mediated RTK pathway. Loss-of-function and gain-of-function assays validated that GRB7 potently rendered CRC cells primary resistance to MEK inhibitors through the RTK pathway. Mass spectrum analysis of GRB7 immunoprecipitates revealed that PLK1 was the predominant interacting kinase of GRB7. Inhibition of PLK1 suppressed downstream signaling of RTK, including FAK, STAT3, AKT, and 4EBP1. The combination of PLK1 and MEK inhibitors synergistically inhibited CRC cell proliferation and induced apoptosis in vitro and in vivo. In conclusion, we identified GRB7-PLK1 as a pivotal axis mediating RTKs, resulting in MEK inhibitor tolerance. PLK1 is therefore a promising target for synergizing MEK inhibitors in the clinical treatment of CRC patients harboring KRAS mutations.

DOI: https://doi.org/10.1038/s41388-021-02077-w
Nat Commun. 2021 Nov 01. 12(1): 6274

The Q61H mutation decouples KRAS from upstream regulation and renders cancer cells resistant to SHP2 inhibitors.

Teklab Gebregiworgis, Yoshihito Kano, Jonathan St-Germain, Nikolina Radulovich, Molly L Udaskin, Ahmet Mentes, Richard Huang, Betty P K Poon, Wenguang He, Ivette Valencia-Sama, Claire M Robinson, Melissa Huestis, Jinmin Miao, Jen Jen Yeh, Zhong-Yin Zhang, Meredith S Irwin, Jeffrey E Lee, Ming-Sound Tsao, Brian Raught, Christopher B Marshall, Michael Ohh, Mitsuhiko Ikura.

Cancer cells bearing distinct KRAS mutations exhibit variable sensitivity to SHP2 inhibitors (SHP2i). Here we show that cells harboring KRAS Q61H are uniquely resistant to SHP2i, and investigate the underlying mechanisms using biophysics, molecular dynamics, and cell-based approaches. Q61H mutation impairs intrinsic and GAP-mediated GTP hydrolysis, and impedes activation by SOS1, but does not alter tyrosyl phosphorylation. Wild-type and Q61H-mutant KRAS are both phosphorylated by Src on Tyr32 and Tyr64 and dephosphorylated by SHP2, however, SHP2i does not reduce ERK phosphorylation in KRAS Q61H cells. Phosphorylation of wild-type and Gly12-mutant KRAS, which are associated with sensitivity to SHP2i, confers resistance to regulation by GAP and GEF activities and impairs binding to RAF, whereas the near-complete GAP/GEF-resistance of KRAS Q61H remains unaltered, and high-affinity RAF interaction is retained. SHP2 can stimulate KRAS signaling by modulating GEF/GAP activities and dephosphorylating KRAS, processes that fail to regulate signaling of the Q61H mutant.

DOI: https://doi.org/10.1038/s41467-021-26526-y
PLoS One. 2021 ;16(11): e0246707

Proteomic characterization of GSK3β knockout shows altered cell adhesion and metabolic pathway utilisation in colorectal cancer cells.

Emily Bowler-Barnett, Francisco D Martinez-Garcia, Matthew Sherwood, Ahood Aleidan, Steve John, Sara Weston, Yihua Wang, Nullin Divecha, Paul Skipp, Rob M Ewing.

Glycogen-specific kinase (GSK3β) is an integral regulator of the Wnt signalling pathway as well as many other diverse signalling pathways and processes. Dys-regulation of GSK3β is implicated in many different pathologies, including neurodegenerative disorders as well as many different tumour types. In the context of tumour development, GSK3β has been shown to play both oncogenic and tumour suppressor roles, depending upon tissue, signalling environment or disease progression. Although multiple substrates of the GSK3β kinase have been identified, the wider protein networks within which GSK3β participates are not well known, and the consequences of these interactions not well understood. In this study, LC-MS/MS expression analysis was performed using knockout GSK3β colorectal cancer cells and isogenic controls in colorectal cancer cell lines carrying dominant stabilizing mutations of β-catenin. Consistent with the role of GSK3β, we found that β-catenin levels and canonical Wnt activity are unaffected by knockout of GSK3β and therefore used this knockout cell model to identify other processes in which GSK3β is implicated. Quantitative proteomic analysis revealed perturbation of proteins involved in cell-cell adhesion, and we characterized the phenotype and altered proteomic profiles associated with this. We also characterized the perturbation of metabolic pathways resulting from GSK3β knockout and identified defects in glycogen metabolism. In summary, using a precision colorectal cancer cell-line knockout model with constitutively activated β-catenin we identified several of the diverse pathways and processes associated with GSK3β function.

DOI: https://doi.org/10.1371/journal.pone.0246707
Curr Cancer Drug Targets. 2021 Nov 03.

The Therapeutic Potential of MAPK/ERK Inhibitors in the Treatment of Colorectal Cancer.

Mehran Pashirzad, Reihaneh Khorasanian, Maryam Mahmoudi Fard, Mohammad-Hassan Arjmand, Hadis Langari, Majid Khazaei, Saman Soleimanpour, Majid Rezayi, Gordon A Ferns, Seyed Mahdi Hassanian, Amir Avan.

  The MAPK/ERK signaling pathway regulates cancer cell proliferation, apoptosis, inflammation, angiogenesis, metastasis and drug resistance. Mutations and up-regulation of components of the MAPK/ERK signaling pathway, as well as over-activation of this critical signaling pathway, are frequently observed in colorectal carcinomas. Targeting the MAPK/ERK signaling pathway, using specific pharmacological inhibitors, elicits potent anti-tumor effects, supporting the therapeutic potential of these inhibitors in the treatment of CRC. Several drugs have recently been developed for the inhibition of the MEK/ERK pathway in preclinical and clinical settings, such as MEK162 and MK-2206. MEK1/2 inhibitors demonstrate promising efficacy and anticancer activity for the treatment of this malignancy. This review summarizes the current knowledge on the role of the MAPK/ERK signaling pathway in the pathogenesis of CRC and the potential clinical value of synthetic inhibitors of this pathway in preventing CRC progression for a better understanding, and hence, better management of colorectal cancer.

Keywords:  ERK inhibitors; ERK signaling pathway; MAPK signaling pathway; MEK1/2 inhibitors; colorectal cancer; tumor progression

DOI:  https://doi.org/10.2174/1568009621666211103113339
Oncogene. 2021 Nov 02.

Molecular characteristics and clinical outcomes of patients with Neurofibromin 1-altered metastatic colorectal cancer.

Hiroyuki Arai, Andrew Elliott, Joshua Millstein, Joanne Xiu, Fang-Shu Ou, Federico Innocenti, Jingyuan Wang, Francesca Battaglin, Priya Jayachandran, Natsuko Kawanishi, Shivani Soni, Wu Zhang, Davendra Sohal, Richard M Goldberg, Michael J Hall, Aaron J Scott, Mohd Khushman, Jimmy J Hwang, Emil Lou, Benjamin A Weinberg, Albert Craig Lockhart, Anthony Frank Shields, Jim P Abraham, Daniel Magee, Phillip Stafford, Jian Zhang, Alan P Venook, W Michael Korn, Heinz-Josef Lenz.

Loss-of-function alterations of Neurofibromin 1 (NF1) activate RAS, a driver of colorectal cancer. However, the clinical implications of NF1 alterations are largely unknown. We performed a comprehensive molecular profiling of NF1-mutant colorectal cancer using data from 8150 patients included in a dataset of commercial CLIA-certified laboratory (Caris Life Sciences). In addition, NF1 expression levels were tested for associations with clinical outcomes using data from 431 patients in the CALGB/SWOG 80405 trial. In the Caris dataset, 2.2% of patients had pathogenic or presumed pathogenic NF1 mutations. NF1-mutant tumors more frequently harbored PIK3CA (25.0% vs. 16.7%) and PTEN mutations (24.0% vs. 4.2%) than wild type tumors. Gene set enrichment analysis revealed that MAPK and PI3K pathway signatures were enriched in NF1-mutant tumors. In the CALGB/SWOG 80405 cohort, low NF1 expression was associated with poor prognosis, and high NF1 expression was associated with better efficacy of cetuximab than bevacizumab. Together, we revealed concurrent genetic alterations in the PI3K pathways in NF1-mutant tumors, suggesting the need to simultaneously block MAPK and PI3K pathways in treatment. The potential of NF1 alteration as a novel biomarker for targeted therapy was highlighted, warranting further investigations in clinical settings.

DOI: https://doi.org/10.1038/s41388-021-02074-z
Ann Transl Med. 2021 Sep;9(18): 1406

Correlation of PIK3CA mutation with programmed death ligand-1 (PD-L1) expression and their clinicopathological significance in colorectal cancer.

Ae Ri Ahn, Kyoung Min Kim, Kyu Yun Jang, Woo Sung Moon, Gi Won Ha, Min Ro Lee, Myoung Ja Chung.

   Background: The prognostic significance of PIK3CA mutations in colorectal cancer (CRC) remains controversial. Recently, an association between programmed death ligand-1 (PD-L1) and PIK3CA mutations has been reported. The study presented here was conducted to investigate the effect of PIK3CA mutations on the prognosis of CRC patients and the association between PIK3CA mutations and PD-L1.
Methods: PIK3CA mutations were analyzed by targeted next-generation sequencing using formalin-fixed paraffin-embedded specimens from 224 primary CRC patients. PD-L1 expression was evaluated by immunohistochemical staining.
Results: PIK3CA mutations and PD-L1 expression were detected in 21.4% and 10.3% of CRC patients, respectively. PIK3CA mutations were significantly correlated with right-side colon cancer (P=0.011) and were correlated inversely with lymph node metastasis (P=0.026), distant metastasis (P=0.047), and high TNM stage (P=0.036). In univariate analysis, PIK3CA mutations were correlated with longer relapse-free survival in CRC patients. PD-L1 expression was correlated significantly with PIK3CA mutations (P<0.001).
Conclusions: PIK3CA mutations were associated with favorable prognostic factors, longer relapse-free survival, and expression of PD-L1. Further investigation is needed to identify whether PIK3CA mutations are a good prognostic factor. Additionally, further studies are needed to understand the mechanisms behind the correlation between PIK3CA mutations and PD-L1 expression.

Keywords:  Colorectal cancer (CRC); PIK3CA; programmed death ligand-1 (PD-L1)

DOI:  https://doi.org/10.21037/atm-21-2315