bims-pimaco 2023-04-09 papers

on PI3K and MAPK signalling in colorectal cancer

Issue of 2023–04–09
ten papers selected by
Lucas B. Zeiger, CRUK Scotland Institute, Beatson Institute for Cancer Research

ERK1/2 inhibitors act as monovalent degraders inducing ubiquitylation and proteasome-dependent turnover of ERK2, but not ERK1.
Feedback activation of EGFR/wild-type RAS signaling axis limits KRASG12D inhibitor efficacy in KRASG12D-mutated colorectal cancer.
SOS1-inspired hydrocarbon-stapled peptide as a pan-Ras inhibitor.
RAF1 contributes to cell proliferation and STAT3 activation in colorectal cancer independently of microsatellite and KRAS status.
Oncogenic signaling is coupled to colorectal cancer cell differentiation state.
Activating mutations in EGFR and PI3K promote ATF4 induction for NSCLC cell survival during amino acid deprivation.
Role of mammalian target of rapamycin (mTOR) signalling in oncogenesis.
Identification of novel peptide inhibitors for oncogenic KRAS G12D as therapeutic options using mutagenesis-based remodeling and MD simulations.
The intestinal stem cell niche flexes its muscles.
CMTR1 promotes colorectal cancer cell growth and immune evasion by transcriptionally regulating STAT3.

Biochem J. 2023 Apr 05. pii: BCJ20220598. [Epub ahead of print]

ERK1/2 inhibitors act as monovalent degraders inducing ubiquitylation and proteasome-dependent turnover of ERK2, but not ERK1.

Kathryn Balmanno, Andrew M Kidger, Dominic P Byrne, Matthew J Sale, Nejma Nassman, Patrick A Eyers, Simon J Cook.

  Innate or acquired resistance to small molecule BRAF or MEK1/2 inhibitors (BRAFi or MEKi) typically arises through mechanisms that sustain or reinstate ERK1/2 activation. This has led to the development of a range of ERK1/2 inhibitors (ERKi) that either inhibit kinase catalytic activity (catERKi) or additionally prevent the activating pT-E-pY dual phosphorylation of ERK1/2 by MEK1/2 (dual-mechanism or dmERKi). Here we show that eight different ERKi (both catERKi or dmERKi) drive the turnover of ERK2, the most abundant ERK isoform, with little or no effect on ERK1. Thermal stability assays show that ERKi do not destabilise ERK2 (or ERK1) in vitro, suggesting that ERK2 turnover is a cellular consequence of ERKi binding. ERK2 turnover is not observed upon treatment with MEKi alone, suggesting it is ERKi binding to ERK2 that drives ERK2 turnover. However, MEKi pre-treatment, which blocks ERK2 pT-E-pY phosphorylation and dissociation from MEK1/2, prevents ERK2 turnover. ERKi treatment of cells drives the poly-ubiquitylation and proteasome-dependent turnover of ERK2 and pharmacological or genetic inhibition of Cullin-RING E3 ligases prevents this. Our results suggest that ERKi, including current clinical candidates, act as 'kinase degraders', driving the proteasome-dependent turnover of their major target, ERK2. This may be relevant to the suggestion of kinase-independent effects of ERK1/2 and the therapeutic use of ERKi.

Keywords:  ERK inhibitors; MEK; RAF; RAS; extracellular signal-regulated kinases; ubiquitin proteasome system

DOI:  https://doi.org/10.1042/BCJ20220598
Oncogene. 2023 Apr 05.

Feedback activation of EGFR/wild-type RAS signaling axis limits KRASG12D inhibitor efficacy in KRASG12D-mutated colorectal cancer.

Juanjuan Feng, Zhongwei Hu, Xinting Xia, Xiaogu Liu, Zhengke Lian, Hui Wang, Liren Wang, Cun Wang, Xueli Zhang, Xiufeng Pang.

Colorectal cancer (CRC), which shows a high degree of heterogeneity, is the third most deadly cancer worldwide. Mutational activation of KRASG12D occurs in approximately 10-12% of CRC cases, but the susceptibility of KRASG12D-mutated CRC to the recently discovered KRASG12D inhibitor MRTX1133 has not been fully defined. Here, we report that MRTX1133 treatment caused reversible growth arrest in KRASG12D-mutated CRC cells, accompanied by partial reactivation of RAS effector signaling. Through a drug-anchored synthetic lethality screen, we discovered that epidermal growth factor receptor (EGFR) inhibition was synthetic lethal with MRTX1133. Mechanistically, MRTX1133 treatment downregulated the expression of ERBB receptor feedback inhibitor 1 (ERRFI1), a crucial negative regulator of EGFR, thereby causing EGFR feedback activation. Notably, wild-type isoforms of RAS, including H-RAS and N-RAS, but not oncogenic K-RAS, mediated signaling downstream of activated EGFR, leading to RAS effector signaling rebound and reduced MRTX1133 efficacy. Blockade of activated EGFR with clinically used antibodies or kinase inhibitors suppressed the EGFR/wild-type RAS signaling axis, sensitized MRTX1133 monotherapy, and caused the regression of KRASG12D-mutant CRC organoids and cell line-derived xenografts. Overall, this study uncovers feedback activation of EGFR as a prominent molecular event that restricts KRASG12D inhibitor efficacy and establishes a potential combination therapy consisting of KRASG12D and EGFR inhibitors for patients with KRASG12D-mutated CRC.

DOI: https://doi.org/10.1038/s41388-023-02676-9
Bioorg Chem. 2023 Mar 25. pii: S0045-2068(23)00160-8. [Epub ahead of print]135 106500

SOS1-inspired hydrocarbon-stapled peptide as a pan-Ras inhibitor.

Anpeng Li, Xiang Li, Jihua Zou, Xiaobin Zhuo, Shuai Chen, Xiaoyun Chai, Conghao Gai, Weiheng Xu, Qingjie Zhao, Yan Zou.

  Blocking the interaction between Ras and Son of Sevenless homolog 1 (SOS1) has been an attractive therapeutic strategy for treating cancers involving oncogenic Ras mutations. K-Ras mutation is the most common in Ras-driven cancers, accounting for 86%, with N-Ras mutation and H-Ras mutation accounting for 11% and 3%, respectively. Here, we report the design and synthesis of a series of hydrocarbon-stapled peptides to mimic the alpha-helix of SOS1 as pan-Ras inhibitors. Among these stapled peptides, SSOSH-5 was identified to maintain a well-constrained alpha-helical structure and bind to H-Ras with high affinity. SSOSH-5 was furthermore validated to bind with Ras similarly to the parent linear peptide through structural modeling analysis. This optimized stapled peptide was proven to be capable of effectively inhibiting the proliferation of pan-Ras-mutated cancer cells and inducing apoptosis in a dose-dependent manner by modulating downstream kinase signaling. Of note, SSOSH-5 exhibited a high capability of crossing cell membranes and strong proteolytic resistance. We demonstrated that the peptide stapling strategy is a feasible approach for developing peptide-based pan-Ras inhibitors. Furthermore, we expect that SSOSH-5 can be further characterized and optimized for the treatment of Ras-driven cancers.

Keywords:  Ras mutant cancer cells; Ras–SOS1 interaction; Stapled peptides; Undruggable protein–protein interactions; pan-Ras inhibitors

DOI:  https://doi.org/10.1016/j.bioorg.2023.106500
Oncogene. 2023 Apr 05.

RAF1 contributes to cell proliferation and STAT3 activation in colorectal cancer independently of microsatellite and KRAS status.

Coralie Dorard, Claire Madry, Olivier Buhard, Stefanie Toifl, Sebastian Didusch, Toky Ratovomanana, Quentin Letourneur, Helmut Dolznig, Mathew J Garnett, Alex Duval, Manuela Baccarini.

More than 30% of all human cancers are driven by RAS mutations and activating KRAS mutations are present in 40% of colorectal cancer (CRC) in the two main CRC subgroups, MSS (Microsatellite Stable) and MSI (Microsatellite Instable). Studies in RAS-driven tumors have shown essential roles of the RAS effectors RAF and specifically of RAF1, which can be dependent or independent of RAF's ability to activate the MEK/ERK module. In this study, we demonstrate that RAF1, but not its kinase activity, plays a crucial role in the proliferation of both MSI and MSS CRC cell line-derived spheroids and patient-derived organoids, and independently of KRAS mutation status. Moreover, we could define a RAF1 transcriptomic signature which includes genes that contribute to STAT3 activation, and could demonstrate that RAF1 ablation decreases STAT3 phosphorylation in all CRC spheroids tested. The genes involved in STAT3 activation as well as STAT3 targets promoting angiogenesis were also downregulated in human primary tumors expressing low levels of RAF1. These results indicate that RAF1 could be an attractive therapeutic target in both MSI and MSS CRC regardless of their KRAS status and support the development of selective RAF1 degraders rather than RAF1 inhibitors for clinical use in combination therapies.

DOI: https://doi.org/10.1038/s41388-023-02683-w
J Cell Biol. 2023 Jun 05. pii: e202204001. [Epub ahead of print]222(6):

Oncogenic signaling is coupled to colorectal cancer cell differentiation state.

Thomas Sell, Christian Klotz, Matthias M Fischer, Rosario Astaburuaga-García, Susanne Krug, Jarno Drost, Hans Clevers, Christine Sers, Markus Morkel, Nils Blüthgen.

Colorectal cancer progression is intrinsically linked to stepwise deregulation of the intestinal differentiation trajectory. In this process, sequential mutations of APC, KRAS, TP53, and SMAD4 enable oncogenic signaling and establish the hallmarks of cancer. Here, we use mass cytometry of isogenic human colon organoids and patient-derived cancer organoids to capture oncogenic signaling, cell phenotypes, and differentiation states in a high-dimensional single-cell map. We define a differentiation axis in all tumor progression states from normal to cancer. Our data show that colorectal cancer driver mutations shape the distribution of cells along the differentiation axis. In this regard, subsequent mutations can have stem cell promoting or restricting effects. Individual nodes of the cancer cell signaling network remain coupled to the differentiation state, regardless of the presence of driver mutations. We use single-cell RNA sequencing to link the (phospho-)protein signaling network to transcriptomic states with biological and clinical relevance. Our work highlights how oncogenes gradually shape signaling and transcriptomes during tumor progression.

DOI: https://doi.org/10.1083/jcb.202204001
Heliyon. 2023 Apr;9(4): e14799

Activating mutations in EGFR and PI3K promote ATF4 induction for NSCLC cell survival during amino acid deprivation.

Mizuki Takahashi, Yuka Okamoto, Yu Kato, Hitomi Shirahama, Satomi Tsukahara, Yoshikazu Sugimoto, Akihiro Tomida.

  Some oncoproteins along with stress kinase general control non-derepressible 2 (GCN2) can ensure the induction of activating transcription factor 4 (ATF4) to counteract amino acid deprivation; however, little is known regarding the role of the oncogenic EGFR-PI3K pathway. In this study, we demonstrate that both mutated EGFR and PIK3CA contribute to ATF4 induction following GCN2 activation in NSCLC cells. The inhibition of EGFR or PI3K mutant proteins, pharmacologically or through genetic knockdown, inhibited ATF4 induction without affecting GCN2 activation. A downstream analysis revealed that the oncogenic EGFR-PI3K pathway may utilize mTOR-mediated translation control mechanisms for ATF4 induction. Furthermore, in NSCLC cells harboring co-mutations in EGFR and PIK3CA, the combined inhibition of these oncoproteins markedly suppressed ATF4 induction and the subsequent gene expression program as well as cell viability during amino acid deprivation. Our findings establish a role for the oncogenic EGFR-PI3K pathway in the adaptive stress response and provide a strategy to improve EGFR-targeted NSCLC therapy.

Keywords:  ATF4; EGFR; ISR; NSCLC; Oncogenic mutation; PI3K

DOI:  https://doi.org/10.1016/j.heliyon.2023.e14799
Life Sci. 2023 Apr 05. pii: S0024-3205(23)00296-5. [Epub ahead of print] 121662

Role of mammalian target of rapamycin (mTOR) signalling in oncogenesis.

Mohamed El-Tanani, Hamdi Nsairat, Alaa A Aljabali, Ángel Serrano-Aroca-Angel, Vijay Mishra, Yachana Mishra, Gowhar A Naikoo, Walhan Alshaer, Murtaza M Tambuwala.

  The signalling system known as mammalian target of rapamycin (mTOR) is believed to be required for several biological activities involving cell proliferation. The serine-threonine kinase identified as mTOR recognises PI3K-AKT stress signals. It is well established in the scientific literature that the deregulation of the mTOR pathway plays a crucial role in cancer growth and advancement. This review focuses on the normal functions of mTOR as well as its abnormal roles in cancer development.

Keywords:  Apoptosis; Pathological angiogenesis; Rapamycin and rapalogues; Signalling cascade; mTOR

DOI:  https://doi.org/10.1016/j.lfs.2023.121662
J Biomol Struct Dyn. 2023 Apr 03. 1-13

Identification of novel peptide inhibitors for oncogenic KRAS G12D as therapeutic options using mutagenesis-based remodeling and MD simulations.

Abdus Samad, Beenish Khurshid, Arif Mahmood, Ashfaq Ur Rehman, Asaad Khalid, Ashraf N Abdalla, Alanood S Algarni, Abdul Wadood.

  The Kirsten rat sarcoma 2 viral oncogene homolog (KRAS) serves as a molecular switch, cycling between guanosine triphosphate (GTP)-bound and inactive guanosine diphosphate (GDP)-bound states. KRAS modulates numerous signal transduction pathways including the conventional RAF-MEK-ERK pathway. Mutations in the RAS genes have been linked to the formation of malignant tumors. Human malignancies typically show mutations in the Ras gene including HRAS, KRAS, and NRAS. Among all the mutations in exon 12 and exon 13 of the KRAS gene, the G12D mutation is more prevalent in pancreatic and lung cancer and accounts for around 41% of all G12 mutations, making them potential anticancer therapeutic targets. The present study is aimed at repurposing the peptide inhibitor KD2 of the KRAS G12D mutant. We employed an in-silico mutagenesis approach to design novel peptide inhibitors from the experimentally reported peptide inhibitor, and it was found that substitutions (N8W, N8I, and N8Y) might enhance the peptide's binding affinity toward the KRAS. Molecular dynamics simulations and binding energy calculations confirmed that the newly designed peptide inhibitors are stable and that their binding affinities are stronger as compared to the wild-type peptide. The detailed analysis revealed that newly designed peptides have the potential to inhibit KRAS/Raf interaction and the oncogenic signal of the KRAS G12D mutant. Our findings strongly suggest that these peptides should be tested and clinically validated to combat the oncogenic activity of KRAS.Communicated by Ramaswamy H. Sarma.

Keywords:  Binding energy calculation; KRAS G12D mutant; MD simulation; peptide inhibitors

DOI:  https://doi.org/10.1080/07391102.2023.2192298
Nat Rev Mol Cell Biol. 2023 Apr 05.

The intestinal stem cell niche flexes its muscles.

Lisa Heinke.

DOI: https://doi.org/10.1038/s41580-023-00605-y
Cell Death Dis. 2023 Apr 06. 14(4): 245

CMTR1 promotes colorectal cancer cell growth and immune evasion by transcriptionally regulating STAT3.

A-Bin You, Hu Yang, Chun-Ping Lai, Wen Lei, Lu Yang, Jia-Lin Lin, Shun-Cui Liu, Nan Ding, Feng Ye.

CMTR1, also called IFN-stimulated gene 95 kDa protein (ISG95), is elevated by viral infection in a variety of cells. However, the functions of CMTR1 in colorectal cancer (CRC), especially its roles in tumorigenesis and immune regulation, remain unclear. Here, we first identified CMTR1 as a novel oncogene in colorectal cancer. Based on The Cancer Genome Atlas (TCGA) database exploration and human tissue microarray (TMA) analysis, we found that CMTR1 expression was markedly higher in CRC tissues than in adjacent normal tissues. High CMTR1 expression was correlated with poor prognosis in CRC patients. Knockdown (KD) of CMTR1 significantly suppressed cell proliferation and tumorigenicity both in vitro and in vivo, whereas overexpression of CMTR1 resulted in the opposite effects. KEGG pathway analysis revealed differential enrichment in the JAK/STAT signaling pathway in colorectal cancer cells with CMTR1 KD. Mechanistically, suppression of CMTR1 expression inhibited RNAPII recruitment to the transcription start site (TSS) of STAT3 and suppressed STAT3 expression and activation. Furthermore, the efficacy of PD1 blockade immunotherapy was prominently enhanced in the presence of CMTR1 KD via increased infiltration of CD8 + T cells into the tumor microenvironment. Overall, it appears that CMTR1 plays a key role in regulating tumor cell proliferation and antitumor immunity.

DOI: https://doi.org/10.1038/s41419-023-05767-3