bims-pimaco 2022-11-20 papers

on PI3K and MAPK signalling in colorectal cancer

Issue of 2022–11–20
fourteen papers selected by
Lucas B. Zeiger, CRUK Scotland Institute, Beatson Institute for Cancer Research

Colon tumour cell death causes mTOR dependence by paracrine P2X4 stimulation.
Beyond PI3Ks: targeting phosphoinositide kinases in disease.
mTOR inhibition attenuates chemosensitivity through the induction of chemotherapy resistant persisters.
The role of KRAS splice variants in cancer biology.
Platycodin D sensitizes KRAS-mutant colorectal cancer cells to cetuximab by inhibiting the PI3K/Akt signaling pathway.
Proteomics uncover EPHA2 as a potential novel therapeutic target in colorectal cancer cell lines with acquired cetuximab resistance.
The equilibrium of tumor suppression: DUBs as active regulators of PTEN.
KRAS inhibitors: Going non-covalent.
Structural optimization of novel Ras modulator for treatment of Colorectal cancer by promoting β-catenin and Ras degradation.
WNK1 is a chloride-stimulated scaffold that regulates mTORC2-activity and ion transport.
A new negative feedback mechanism for MAPK pathway inactivation through Srk1 MAPKAP kinase.
The Ras GTPase-activating-like protein IQGAP1 bridges Gasdermin D to the ESCRT system to promote IL-1β release via exosomes.
First-in-human phase Ia study of the PI3Kα inhibitor CYH33 in patients with solid tumors.
Reciprocal effects of mTOR inhibitors on pro-survival proteins dictate therapeutic responses in tuberous sclerosis complex.

Nature. 2022 Nov 16.

Colon tumour cell death causes mTOR dependence by paracrine P2X4 stimulation.

Mark Schmitt, Fatih Ceteci, Jalaj Gupta, Marina Pesic, Tim W Böttger, Adele M Nicolas, Kilian B Kennel, Esther Engel, Matthias Schewe, Asude Callak Kirisözü, Valentina Petrocelli, Yasamin Dabiri, Julia Varga, Mallika Ramakrishnan, Madina Karimova, Andrea Ablasser, Toshiro Sato, Melek C Arkan, Frederic J de Sauvage, Florian R Greten.

Solid cancers exhibit a dynamic balance between cell death and proliferation ensuring continuous tumour maintenance and growth1,2. Increasing evidence links enhanced cancer cell apoptosis to paracrine activation of cells in the tumour microenvironment initiating tissue repair programs that support tumour growth3,4, yet the direct effects of dying cancer cells on neighbouring tumour epithelia and how this paracrine effect potentially contributes to therapy resistance are unclear. Here we demonstrate that chemotherapy-induced tumour cell death in patient-derived colorectal tumour organoids causes ATP release triggering P2X4 (also known as P2RX4) to mediate an mTOR-dependent pro-survival program in neighbouring cancer cells, which renders surviving tumour epithelia sensitive to mTOR inhibition. The induced mTOR addiction in persisting epithelial cells is due to elevated production of reactive oxygen species and subsequent increased DNA damage in response to the death of neighbouring cells. Accordingly, inhibition of the P2X4 receptor or direct mTOR blockade prevents induction of S6 phosphorylation and synergizes with chemotherapy to cause massive cell death induced by reactive oxygen species and marked tumour regression that is not seen when individually applied. Conversely, scavenging of reactive oxygen species prevents cancer cells from becoming reliant on mTOR activation. Collectively, our findings show that dying cancer cells establish a new dependency on anti-apoptotic programs in their surviving neighbours, thereby creating an opportunity for combination therapy in P2X4-expressing epithelial tumours.

DOI: https://doi.org/10.1038/s41586-022-05426-1
Nat Rev Drug Discov. 2022 Nov 14.

Beyond PI3Ks: targeting phosphoinositide kinases in disease.

John E Burke, Joanna Triscott, Brooke M Emerling, Gerald R V Hammond.

Lipid phosphoinositides are master regulators of almost all aspects of a cell's life and death and are generated by the tightly regulated activity of phosphoinositide kinases. Although extensive efforts have focused on drugging class I phosphoinositide 3-kinases (PI3Ks), recent years have revealed opportunities for targeting almost all phosphoinositide kinases in human diseases, including cancer, immunodeficiencies, viral infection and neurodegenerative disease. This has led to widespread efforts in the clinical development of potent and selective inhibitors of phosphoinositide kinases. This Review summarizes our current understanding of the molecular basis for the involvement of phosphoinositide kinases in disease and assesses the preclinical and clinical development of phosphoinositide kinase inhibitors.

DOI: https://doi.org/10.1038/s41573-022-00582-5
Nat Commun. 2022 Nov 17. 13(1): 7047

mTOR inhibition attenuates chemosensitivity through the induction of chemotherapy resistant persisters.

Yuanhui Liu, Nancy G Azizian, Delaney K Sullivan, Yulin Li.

Chemotherapy can eradicate a majority of cancer cells. However, a small population of tumor cells often survives drug treatments through genetic and/or non-genetic mechanisms, leading to tumor recurrence. Here we report a reversible chemoresistance phenotype regulated by the mTOR pathway. Through a genome-wide CRISPR knockout library screen in pancreatic cancer cells treated with chemotherapeutic agents, we have identified the mTOR pathway as a prominent determinant of chemosensitivity. Pharmacological suppression of mTOR activity in cancer cells from diverse tissue origins leads to the persistence of a reversibly resistant population, which is otherwise eliminated by chemotherapeutic agents. Conversely, activation of the mTOR pathway increases chemosensitivity in vitro and in vivo and predicts better survival among various human cancers. Persister cells display a senescence phenotype. Inhibition of mTOR does not induce cellular senescence per se, but rather promotes the survival of senescent cells through regulation of autophagy and G2/M cell cycle arrest, as revealed by a small-molecule chemical library screen. Thus, mTOR plays a causal yet paradoxical role in regulating chemotherapeutic response; inhibition of the mTOR pathway, while suppressing tumor expansion, facilitates the development of a reversible drug-tolerant senescence state.

DOI: https://doi.org/10.1038/s41467-022-34890-6
Front Cell Dev Biol. 2022 ;10 1033348

The role of KRAS splice variants in cancer biology.

Cristina Nuevo-Tapioles, Mark R Philips.

  The three mammalian RAS genes (HRAS, NRAS and KRAS) encode four proteins that play central roles in cancer biology. Among them, KRAS is mutated more frequently in human cancer than any other oncogene. The pre-mRNA of KRAS is alternatively spliced to give rise to two products, KRAS4A and KRAS4B, which differ in the membrane targeting sequences at their respective C-termini. Notably, both KRAS4A and KRAS4B are oncogenic when KRAS is constitutively activated by mutation in exon 2 or 3. Whereas KRAS4B is the most studied oncoprotein, KRAS4A is understudied and until recently considered relatively unimportant. Emerging work has confirmed expression of KRAS4A in cancer and found non-overlapping functions of the splice variants. The most clearly demonstrated of these is direct regulation of hexokinase 1 by KRAS4A, suggesting that the metabolic vulnerabilities of KRAS-mutant tumors may be determined in part by the relative expression of the splice variants. The aim of this review is to address the most relevant characteristics and differential functions of the KRAS splice variants as they relate to cancer onset and progression.

Keywords:  KRAS; KRAS4A; KRAS4B; alternative splicing; glycolysis; oncogene; oncoprotein

DOI:  https://doi.org/10.3389/fcell.2022.1033348
Front Oncol. 2022 ;12 1046143

Platycodin D sensitizes KRAS-mutant colorectal cancer cells to cetuximab by inhibiting the PI3K/Akt signaling pathway.

Yanfei Liu, Shifeng Tian, Ben Yi, Zhiqiang Feng, Tianhao Chu, Jun Liu, Chunze Zhang, Shiwu Zhang, Yijia Wang.

  Cetuximab is a monoclonal antibody against epidermal growth factor receptor that blocks downstream signaling pathways of receptor tyrosine kinases, including Ras/Raf/MAPK and PI3K/Akt, thereby inhibiting tumor cell proliferation and inducing cancer cell apoptosis. Owing to KRAS mutations, the effectiveness of cetuximab is usually limited by intrinsic drug resistance. Continuous activation of the PI3K/Akt signaling pathway is another reason for cetuximab resistance. Platycodin-D, a bioactive compound isolated from the Chinese herb Platycodon grandiflorum, regulates Akt in different trends based on tissue types. To investigate whether platycodin-D can sensitize KRAS-mutant colorectal cancer cells to cetuximab by inhibiting the PI3K/Akt signaling pathway, HCT116 and LoVo cells were treated with cetuximab and platycodin-D. LY294002 and SC79 were used to regulate Akt to further evaluate whether platycodin-D sensitizes cells to cetuximab by inhibiting Akt. Our results confirmed that platycodin-D increased the cytotoxic effects of cetuximab, including inhibition of growth, migration, and invasion, via downregulation of PI3K and Akt phosphorylation in HCT116 and LoVo cells both in vitro and in vivo. Given these data, platycodin-D may sensitize KRAS-mutant colorectal cancer cells to cetuximab via inhibition of the PI3K/Akt signaling pathway.

Keywords:  Akt; cetuximab; colorectal cancer; platycodin D; resistance

DOI:  https://doi.org/10.3389/fonc.2022.1046143
J Cancer Res Clin Oncol. 2022 Nov 19.

Proteomics uncover EPHA2 as a potential novel therapeutic target in colorectal cancer cell lines with acquired cetuximab resistance.

Lucien Torlot, Anna Jarzab, Johanna Albert, Ágnes Pók-Udvari, Arndt Stahler, Julian Walter Holch, Marco Gerlinger, Volker Heinemann, Frederick Klauschen, Thomas Kirchner, Jörg Kumbrink, Bernhard Küster, Andreas Jung.

   BACKGROUND: In metastatic colorectal cancer (mCRC), acquired resistance against anti-EGFR targeted monoclonal antibodies, such as cetuximab (CET), was shown to be frequently caused by activating alterations in the RAS genes KRAS or NRAS. To this day, no efficient follow-up treatment option has emerged to treat mCRC in such a setting of resistance.
METHODS: To uncover potential targets for second-line targeted therapies, we used mass-spectrometric proteomics to shed light on kinome reprogramming in an established cellular model of acquired, KRAS-associated CET resistance.
RESULTS: This CET resistance was reflected by significant changes in the kinome, most of them individual to each cell line. Interestingly, all investigated resistant cell lines displayed upregulation of the Ephrin type-A receptor 2 (EPHA2), a well-known driver of traits of progression. Expectedly resistant cell lines displayed increased migration (p < 0.01) that was significantly reduced by targeting the EPHA2 signalling axis using RNA interference (RNAi) (p < 0.001), ephrin-A1 stimulation (p < 0.001), dasatinib (p < 0.01), or anti-EPHA2 antibody treatment (p < 0.001), identifying it as an actionable target in mCRC with acquired CET resistance.
CONCLUSION: These results highlight EPHA2 and its role in mCRC with KRAS-gene mutated acquired CET resistance and support its use as a potential actionable target for the development of future precision medicine therapies.

Keywords:  Cetuximab resistance; Colorectal cancer; EPHA2; Molecular oncology; Proteomics

DOI:  https://doi.org/10.1007/s00432-022-04416-0
Exp Mol Med. 2022 Nov 16.

The equilibrium of tumor suppression: DUBs as active regulators of PTEN.

Audrey Christine, Mi Kyung Park, Su Jung Song, Min Sup Song.

PTEN is among the most commonly lost or mutated tumor suppressor genes in human cancer. PTEN, a bona fide lipid phosphatase that antagonizes the highly oncogenic PI3K-AKT-mTOR pathway, is considered a major dose-dependent tumor suppressor. Although PTEN function can be compromised by genetic mutations in inherited syndromes and cancers, posttranslational modifications of PTEN may also play key roles in the dynamic regulation of its function. Notably, deregulated ubiquitination and deubiquitination lead to detrimental impacts on PTEN levels and subcellular partitioning, promoting tumorigenesis. While PTEN can be targeted by HECT-type E3 ubiquitin ligases for nuclear import and proteasomal degradation, studies have shown that several deubiquitinating enzymes, including HAUSP/USP7, USP10, USP11, USP13, OTUD3 and Ataxin-3, can remove ubiquitin from ubiquitinated PTEN in cancer-specific contexts and thus reverse ubiquitination-mediated PTEN regulation. Researchers continue to reveal the precise molecular mechanisms by which cancer-specific deubiquitinases of PTEN regulate its roles in the pathobiology of cancer, and new methods of pharmacologically for modulating PTEN deubiquitinases are critical areas of investigation for cancer treatment and prevention. Here, we assess the mechanisms and functions of deubiquitination as a recently appreciated mode of PTEN regulation and review the link between deubiquitinases and PTEN reactivation and its implications for therapeutic strategies.

DOI: https://doi.org/10.1038/s12276-022-00887-w
Mol Oncol. 2022 Nov 16.

KRAS inhibitors: Going non-covalent.

Matthias Drosten, Mariano Barbacid.

  KRASG12D is the most frequent KRAS mutation in human cancer with particularly high frequencies in pancreatic and colorectal cancer. Informed by the structure of the KRASG12C inhibitor adagrasib, Hallin et al have now, through multiple rounds of structure-based drug design, identified and validated a potent, selective, and non-covalent KRASG12D inhibitor, MRTX1133. This study demonstrated that MRTX1133 inhibited both the inactive and active state of KRASG12D and showed potent anti-tumor activity in several pre-clinical models of pancreatic and colorectal cancer, especially when combined with cetuximab, a monoclonal antibody against the EGFR, or BYL-719, a potent PI3Kα inhibitor.

Keywords:  KRASG12D; colorectal cancer; combination therapies; non-covalent binding; pancreatic ductal adenocarcinoma

DOI:  https://doi.org/10.1002/1878-0261.13341
Bioorg Chem. 2022 Nov 04. pii: S0045-2068(22)00640-X. [Epub ahead of print]130 106234

Structural optimization of novel Ras modulator for treatment of Colorectal cancer by promoting β-catenin and Ras degradation.

Seonghwi Choi, Hyuntae Kim, Won-Ji Ryu, Kang-Yell Choi, Taegun Kim, Doona Song, Gyoonhee Han.

  Ras protein has been considered a fascinating target for anticancer therapy because its malfunction is closely related to cancer. However, Ras has been considered undruggable because of the failure to regulate its malfunction by controlling the Ras activation mechanism. Recently, Lumakras targeting the G12C mutation was approved, and therapeutic interest in Ras for anticancer therapy has been rejuvenated. Here, we present a series of compounds that inhibit Ras via a unique mechanism of action that exploits the relationship between the Wnt/β-catenin pathway and Ras. KYA1797K (1) binds to axin to stabilize the β-catenin destruction complex that causes the phosphorylation and subsequent degradation of Ras, similar to canonical β-catenin regulation. Based on the chemical structure of 1, we performed a structural optimization and identified 3-(2-hydroxyethyl)-5-((6-(4-nitrophenyl)pyridin-2-yl)methylene)thiazolidine-2,4-dione (13d) as the most potent compound. 13d displayed antitumor effects in a colorectal cancer model with enhanced inhibition activity on Ras. The results of this study suggest that the further development of 13d could contribute to the development of Ras inhibitors with novel mechanisms of action.

Keywords:  Axin; Colorectal cancer; Ras; β-catenin; β-catenin Destruction complex

DOI:  https://doi.org/10.1016/j.bioorg.2022.106234
J Cell Sci. 2022 Nov 14. pii: jcs.260313. [Epub ahead of print]

WNK1 is a chloride-stimulated scaffold that regulates mTORC2-activity and ion transport.

Bidisha Saha, Deise Carla Almeida Leite Dellova, John Demko, Mads Vaarby Sørensen, Enzo Takagi, Catherine E Gleason, Waheed Shabbir, David Pearce.

  mTORC2 is a kinase complex that targets predominantly Akt, SGK1, and PKC, and has well characterized roles in mediating hormone and growth factor effects on a wide array of cellular processes. Recent evidence suggests that mTORC2 is also directly stimulated in renal tubule cells by increased extracellular potassium (K+) concentration, leading to activation of the Na+ channel, ENaC, and increasing the electrical driving force for K+ secretion. We identify here a signaling mechanism for this local effect of K+. We show that an increase in extracellular [K+] leads to a rise in intracellular chloride (Cl-), which stimulates a previously unknown scaffolding activity of With No Lysine-1 (WNK1) kinase. WNK1 interacts selectively with SGK1 and recruits it to mTORC2 resulting in enhanced SGK1 phosphorylation, and SGK1-dependent activation of ENaC. This scaffolding effect of WNK1 is independent of its own kinase activity and does not cause a generalized stimulation of mTORC2 kinase activity. These findings establish a novel WNK1- dependent regulatory mechanism, which harnesses mTORC2 kinase activity selectively toward SGK1 to control epithelial ion transport and electrolyte homeostasis.

Keywords:  ENaC; Electrolytes; Ion transport; K+ homeostasis; Kidney epithelial cells; MTOR; MTORC2; Protein-protein interactions.; Rictor; SGK1; WNK kinases; WNK1

DOI:  https://doi.org/10.1242/jcs.260313
Sci Rep. 2022 Nov 14. 12(1): 19501

A new negative feedback mechanism for MAPK pathway inactivation through Srk1 MAPKAP kinase.

Maribel Marquina, Eva Lambea, Mercé Carmona, Marta Sánchez-Marinas, Sandra López-Aviles, José Ayte, Elena Hidalgo, Rosa Aligue.

The fission yeast mitogen-activated kinase (MAPK) Sty1 is essential for cell survival in response to different environmental insults. In unstimulated cells, Sty1 forms an inactive ternary cytoplasmatic complex with the MAPKK Wis1 and the MAPKAP kinase Srk1. Wis1 phosphorylates and activates Sty1, inducing the nuclear translocation of the complex. Once in the nucleus, Sty1 phosphorylates and activates Srk1, which in turns inhibits Cdc25 and cell cycle progression, before being degraded in a proteasome-dependent manner. In parallel, active nuclear Sty1 activates the transcription factor Atf1, which results in the expression of stress response genes including pyp2 (a MAPK phosphatase) and srk1. Despite its essentiality in response to stress, persistent activation of the MAPK pathway can be deleterious and induces cell death. Thus, timely pathway inactivation is essential to ensure an appropriate response and cell viability. Here, uncover a role for the MAPKAP kinase Srk1 as an essential component of a negative feedback loop regulating the Sty1 pathway through phosphorylation and inhibition of the Wis1 MAPKK. This feedback regulation by a downstream kinase in the pathway highlights an additional mechanism for fine-tuning of MAPK signaling. Thus, our results indicate that Srk1 not only facilitates the adaptation to stress conditions by preventing cell cycle progression, but also plays an instrumental role regulating the upstream kinases in the stress MAPK pathway.

DOI: https://doi.org/10.1038/s41598-022-23970-8
EMBO J. 2022 Nov 14. e110780

The Ras GTPase-activating-like protein IQGAP1 bridges Gasdermin D to the ESCRT system to promote IL-1β release via exosomes.

Yun Liao, Xing Chen, William Miller-Little, Han Wang, Belinda Willard, Katarzyna Bulek, Junjie Zhao, Xiaoxia Li.

  IL-1β can exit the cytosol as an exosomal cargo following inflammasome activation in intestinal epithelial cells (IECs) in a Gasdermin D (GSDMD)-dependent manner. The mechanistic connection linking inflammasome activation and the biogenesis of exosomes has so far remained largely elusive. Here, we report the Ras GTPase-activating-like protein IQGAP1 functions as an adaptor, bridging GSDMD to the endosomal sorting complexes required for transport (ESCRT) machinery to promote the biogenesis of pro-IL-1β-containing exosomes in response to NLPR3 inflammasome activation. We identified IQGAP1 as a GSDMD-interacting protein through a non-biased proteomic analysis. Functional investigation indicated the IQGAP1-GSDMD interaction is required for LPS and ATP-induced exosome release. Further analysis revealed that IQGAP1 serves as an adaptor which bridges GSDMD and associated IL-1β complex to Tsg101, a component of the ESCRT complex, and enables the packaging of GSDMD and IL-1β into exosomes. Importantly, this process is dependent on an LPS-induced increase in GTP-bound CDC42, a small GTPase known to activate IQGAP1. Taken together, this study reveals IQGAP1 as a link between inflammasome activation and GSDMD-dependent, ESCRT-mediated exosomal release of IL-1β.

Keywords:  ESCRT; GSDMD; IQGAP1; exosome; inflammasome

DOI:  https://doi.org/10.15252/embj.2022110780
Nat Commun. 2022 Nov 16. 13(1): 7012

First-in-human phase Ia study of the PI3Kα inhibitor CYH33 in patients with solid tumors.

Xiao-Li Wei, Fu-Rong Liu, Ji-Hong Liu, Hong-Yun Zhao, Yang Zhang, Zhi-Qiang Wang, Miao-Zhen Qiu, Fei Xu, Qiu-Qiong Yu, Yi-Wu Du, Yan-Xia Shi, De-Sheng Wang, Feng-Hua Wang, Rui-Hua Xu.

PIK3CA mutations are highly prevalent in solid tumors. Targeting phosphatidylinositol 3-kinase α is therefore an attractive strategy for treating cancers harboring PIK3CA mutations. Here, we report the results from a phase Ia, open label, dose-escalation and -expansion study (NCT03544905) of CYH33, a highly selective PI3Kα inhibitor, in advanced solid tumors. The primary outcomes were the safety, tolerability, maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D) of CYH33. The secondary outcomes included evaluation of pharmacokinetics, preliminary efficacy and changes in pharmacodynamic biomarkers in response to CYH33 treatment. The exploratory outcome was the relationship between the efficacy of CYH33 treatment and tumor biomarker status, including PIK3CA mutations. A total of 51 patients (19 in the dose escalation stage and 32 in the dose expansion stage) including 36 (70.6%) patients (4 in the dose escalation stage and 32 in the dose expansion stage) with PIK3CA mutations received CYH33 1-60 mg. The MTD of CYH33 was 40 mg once daily, which was also selected as the RP2D. The most common grade 3/4 treatment-related adverse events were hyperglycemia, rash, platelet count decreased, peripheral edema, and fatigue. Forty-two out of 51 patients were evaluable for response, the confirmed objective response rate was 11.9% (5/42). Among 36 patients harboring PIK3CA mutations, 28 patients were evaluable for response, the confirmed objective response rate was 14.3% (4/28). In conclusion, CYH33 exhibits a manageable safety profile and preliminary anti-tumor efficacy in solid tumors harboring PIK3CA mutations.

DOI: https://doi.org/10.1038/s41467-022-34782-9
iScience. 2022 Nov 18. 25(11): 105458

Reciprocal effects of mTOR inhibitors on pro-survival proteins dictate therapeutic responses in tuberous sclerosis complex.

Molly C McNamara, Aaron M Hosios, Margaret E Torrence, Ting Zhao, Cameron Fraser, Meghan Wilkinson, David J Kwiatkowski, Elizabeth P Henske, Chin-Lee Wu, Kristopher A Sarosiek, Alexander J Valvezan, Brendan D Manning.

  mTORC1 is aberrantly activated in cancer and in the genetic tumor syndrome tuberous sclerosis complex (TSC), which is caused by loss-of-function mutations in the TSC complex, a negative regulator of mTORC1. Clinically approved mTORC1 inhibitors, such as rapamycin, elicit a cytostatic effect that fails to eliminate tumors and is rapidly reversible. We sought to determine the effects of mTORC1 on the core regulators of intrinsic apoptosis. In TSC2-deficient cells and tumors, we find that mTORC1 inhibitors shift cellular dependence from MCL-1 to BCL-2 and BCL-XL for survival, thereby altering susceptibility to BH3 mimetics that target specific pro-survival BCL-2 proteins. The BCL-2/BCL-XL inhibitor ABT-263 synergizes with rapamycin to induce apoptosis in TSC-deficient cells and in a mouse tumor model of TSC, resulting in a more complete and durable response. These data expose a therapeutic vulnerability in regulation of the apoptotic machinery downstream of mTORC1 that promotes a cytotoxic response to rapamycin.

Keywords:  Biological sciences; Cancer; Cell biology; Molecular biology

DOI:  https://doi.org/10.1016/j.isci.2022.105458