The ubiquitin–proteasome system is the cell’s principal machinery for controlled protein destruction. Small ubiquitin tags are attached to target proteins through an enzymatic cascade involving activating enzymes, conjugating enzymes and ligases, and proteins carrying specific ubiquitin chains are recognized and degraded by the proteasome, a barrel-shaped proteolytic complex. Because the system governs the abundance of virtually every regulatory protein in the cell, including tumor suppressors, cell-cycle drivers and signaling components, it has long been considered a rich source of therapeutic targets. The clinical success of proteasome inhibitors in multiple myeloma, and more recently the explosive growth of targeted protein degrader technologies, have confirmed that manipulating protein turnover can be a powerful anti-cancer strategy.

Deubiquitinases, or DUBs, sit at the opposite end of this pathway. Rather than attaching ubiquitin, these proteases remove it, cleaving ubiquitin chains from substrates or editing the architecture of the chains themselves. In doing so, DUBs stabilize proteins that would otherwise be destroyed, fine-tune signaling complexes and recycle ubiquitin for reuse. The human genome encodes roughly one hundred DUBs, distributed across several mechanistically distinct families, including cysteine proteases of the USP, UCH, OTU and MJD classes and metalloproteases of the JAMM family. Their activities touch nearly every cellular process, and a growing body of evidence shows that many DUBs are dysregulated in cancer, where they act as oncogenes or tumor suppressors depending on the context.

The review’s central thesis is that DUBs are deeply intertwined with KRAS biology, and that this connection creates therapeutic openings that conventional approaches have overlooked. KRAS operates as a molecular switch, cycling between an active, GTP-bound state and an inactive, GDP-bound state, and transmitting signals downstream through the RAF–MEK–ERK and PI3K–AKT pathways. Each stage of this circuit is buffered by ubiquitin-dependent regulation. Ubiquitin ligases such as the CUL3 complex, which recognizes active KRAS through the adaptor protein calcoco-2, can ubiquitinate KRAS and promote its degradation, acting as a built-in brake on signaling. DUBs that remove ubiquitin from KRAS or from components of its downstream pathways effectively remove that brake, amplifying and prolonging the oncogenic signal. Conversely, inhibiting the right DUB could restore the degradation of mutant KRAS or sensitize tumor cells to existing inhibitors.

Several individual DUBs have emerged as particularly compelling nodes in this network. The USP family member USP11, for example, has been reported to stabilize KRAS by removing its ubiquitin marks, thereby sustaining ERK signaling in KRAS-mutant cells. USP21 and USP22 have similarly been implicated in supporting KRAS-driven transcriptional programs, partly through their effects on chromatin regulators and signaling intermediates. On the downstream side, DUBs such as USP9X, USP5 and CYLD regulate the stability of RAF, MEK and ERK pathway components as well as NF-kappaB signaling, shaping both the intensity of the oncogenic output and the inflammatory milieu of the tumor microenvironment. Because these enzymes act at multiple points in the circuit, they offer a way to modulate KRAS signaling even when direct inhibition of the protein itself is technically or clinically difficult.

This matters enormously for the translational landscape. The G12C inhibitors sotorasib and adagrasib demonstrated that covalent drugs can reach mutant KRAS in the recessed pocket of its switch-II region, yet their impact is limited to the roughly one in eight KRAS-mutant tumors that carry the G12C alteration, and resistance through pathway reactivation, tissue plasticity and drug-tolerant persister cells develops within months. Approaches that work through protein turnover are intrinsically broader. A DUB inhibitor, or a degrader built on DUB biology, would not need a druggable pocket on KRAS itself; it would only need to shift the balance of the degradation machinery. The review highlights this as a route toward tumors carrying non-G12C mutations such as G12D, G12V and Q61, which together account for the majority of KRAS-driven cancers and remain without approved targeted therapies.

The therapeutic logic also extends to combination strategies. Preclinical studies indicate that degrading or destabilizing KRAS, whether through ligase recruitment or through DUB inhibition, can cooperate with upstream and downstream blockade, for instance pairing proteasome-directed approaches with SHP2 inhibitors, MEK inhibitors or ERK inhibitors to collapse the adaptive signaling networks that tumors deploy under treatment pressure. In resistant tumors where KRAS amplification or bypass signaling restores ERK output, lowering the total pool of KRAS protein could re-sensitize cells to doses of pathway inhibitors that are otherwise survivable. The review frames DUB targeting as a complementary pillar to the degrader boom: while molecular glue compounds and PROTACs recruit ubiquitin ligases to tag targets for destruction, DUB inhibitors would work by removing the enzymes that protect oncogenic proteins from destruction.

The challenges, however, are substantial, and the review is candid about them. DUBs are proteases, and designing selective inhibitors for cysteine protease active sites has proven difficult, with many early compounds suffering from broad reactivity and poor pharmacology. Redundancy is a second obstacle: multiple DUBs can often compensate for one another, meaning that single-agent inhibition may produce modest effects unless the dominant node in a given tumor is correctly identified. There is also the problem of context. The same DUB can act as an oncogene in one cancer and a tumor suppressor in another, so patient stratification and biomarker development will be essential. Finally, because the ubiquitin system regulates a vast range of non-cancerous processes, including immune signaling and DNA repair, systemic toxicity must be carefully evaluated.

To navigate these difficulties, the review outlines several priorities for the field. Better structural biology and cryo-electron microscopy of DUB-substrate complexes could reveal allosteric and protein-protein interaction surfaces that are more drug-friendly than catalytic sites. Proteomic approaches that map the ubiquitin landscape of KRAS-mutant tumors, increasingly accessible through ubiquitin-remnant mass spectrometry, could identify which DUBs are genuinely rate-limiting in which genetic backgrounds. And emerging chemical modalities, including covalent fragments targeting non-catalytic cysteines, targeted protein degraders and PROTAC-inspired molecules that eliminate DUBs themselves rather than merely inhibiting them, may open doors that classical enzyme inhibitors could not. The authors argue that systematic functional genomics, using CRISPR screens in panels of KRAS-mutant cell lines, will be key to converting the growing catalog of DUB-KRAS interactions into a validated target hierarchy.

The significance of this synthesis lies in its reframing of a familiar problem. Rather than treating KRAS as a target to be occupied, it treats the KRAS-mutant cell as a network whose protein economy can be rewired. The ubiquitin–proteasome system provides the levers, and deubiquitinases, once obscure players in basic cell biology, are now positioned as actionable points of intervention in some of medicine’s most intractable cancers. If the chemical and biological hurdles can be overcome, the coming years could see DUB-directed therapies enter clinical trials for pancreatic, lung and colorectal cancers, offering new hope to patients whose tumors have eluded the first generation of KRAS drugs.

Subject of Research: Therapeutic targeting of deubiquitinases in the ubiquitin–proteasome system to treat KRAS-driven cancers.

Article Title: Rewiring KRAS-driven cancers through the ubiquitin–proteasome system: therapeutic opportunities with a focus on deubiquitinase

Article References: Lee, Y., Hwang, S., Shin, H., Choi, K., Seo, S., Kim, H., Yang, J. S., Kim, Y. J., Kim, Y.-M., & Song, E. J. (2026). Rewiring KRAS-driven cancers through the ubiquitin–proteasome system: therapeutic opportunities with a focus on deubiquitinase. Experimental & Molecular Medicine. https://doi.org/10.1038/s12276-026-01837-6

Image Credits: AI Generated

DOI: 10.1038/s12276-026-01837-6

Keywords: KRAS, deubiquitinase, ubiquitin-proteasome system, targeted cancer therapy, protein degradation, RAS signaling, proteasome inhibitors, oncology, USP family, drug resistance, Rewiring, KRAS-driven

Pistacia integerrima, known in traditional medicine systems for its distinctive leaf galls, is a rich source of flavonoids, steroids, terpenoids and phenolic compounds. Previous pharmacological work has hinted at anti-inflammatory and cytotoxic properties, but the molecular basis of any anticancer effect has remained poorly defined. In the new study, the researchers prepared an ethyl acetate fraction of the plant, a fraction enriched for moderately polar phytochemicals, and tested it against A549 cells, a widely used human lung adenocarcinoma cell line that models NSCLC. The choice of fraction was deliberate: ethyl acetate extracts typically concentrate flavonoids such as kaempferol, quercetin and luteolin, along with the phytosterol beta-sitosterol, all of which have been implicated in anticancer activity in earlier literature.

The cytotoxic results were striking. In the MTT assay, a colorimetric test that measures metabolic activity as a proxy for cell viability, the ethyl acetate fraction produced significant, dose-dependent killing of A549 cells, with statistically robust effects at a concentration of 100 micrograms per millilitre (p < 0.0001). In other words, as the dose increased, progressively fewer cancer cells survived, a dose-response relationship that is a hallmark of genuine cytotoxic activity rather than experimental noise. The team then examined whether the fraction could stop cancer cells from replicating over longer periods using a colony formation assay, which tests the ability of individual cells to divide repeatedly and establish new colonies, a key measure of proliferative capacity.

Colony formation collapsed after treatment. The ethyl acetate fraction reduced colony formation to just 18.41 percent of control levels, a statistically significant decrease (p < 0.002) indicating that surviving cells had lost much of their ability to seed new populations. This distinction matters clinically: a drug that merely slows growth may delay tumour expansion, but one that erodes clonogenic capacity strikes at the self-renewing behaviour that drives relapse. The researchers interpret the combined cytotoxicity and anti-clonogenic data as evidence that the plant fraction attacks fundamental proliferative machinery in NSCLC cells rather than exerting a transient, non-specific toxic effect.

Perhaps more important for metastasis, the fraction also crippled the migratory behaviour of the cancer cells. Using two complementary assays, the wound healing assay, in which a scratch is made across a confluent cell layer and the rate of closure is measured, and the Transwell migration assay, in which cells are challenged to move through a porous membrane, the team showed that treated A549 cells migrated markedly less than untreated controls (p < 0.01). Migration is the cellular behaviour that underpins invasion and metastatic spread, the processes responsible for most cancer deaths. Suppressing it suggests the phytochemicals may interfere with the epithelial-mesenchymal transition and the extracellular matrix remodelling programmes that lung tumours exploit to colonise distant tissues.

To understand what was happening at the molecular level, the researchers turned to proteomic profiling with the Human XL Oncology protein array, a platform that simultaneously quantifies dozens of cancer-relevant proteins. Treatment with the ethyl acetate fraction significantly downregulated three proteins: endoglin (CD105), kallikrein-related peptidase 5 (KLK5) and matrix metalloproteinase-2 (MMP-2). Each of these tells a coherent story. Endoglin is a co-receptor in the TGF-beta signalling pathway that promotes angiogenesis, the formation of new blood vessels that feed tumours. KLK5 is a protease associated with tumour progression, and MMP-2 degrades the extracellular matrix, clearing a physical path for invading cells. Their coordinated downregulation indicates that the plant fraction suppresses both the angiogenic and metastatic signalling networks that NSCLC depends on for spread.

The team then asked which individual phytochemicals might be responsible, and against which protein targets they act. Molecular docking, a computational technique that predicts how small molecules fit into the binding pockets of proteins, revealed favourable binding affinities for the major Pistacia integerrima compounds against several oncogenic targets central to NSCLC biology. Kaempferol bound AKT1 with a docking score of -7.6 kcal/mol, while beta-sitosterol showed strong affinity for PI3K at -9.4 kcal/mol, quercetin engaged KRAS at -8.5 kcal/mol, and luteolin docked to MMP9 at -8.1 kcal/mol. These are not arbitrary targets. The PI3K/AKT1 axis is a master regulator of cell survival and proliferation that is frequently hyperactivated in lung cancer, KRAS is one of the most notorious oncogenes in NSCLC and has historically been considered nearly undruggable, and MMP9 drives matrix degradation and invasion.

Docking scores alone can be misleading, because a molecule may fit well in a static protein structure yet fail to remain bound in the dynamic environment of the cell. To address this, the researchers ran molecular dynamics simulations, which track the physical motion of atoms over time using the laws of classical mechanics. The kaempferol-AKT1 complex remained structurally stable throughout a 100-nanosecond simulation, with root mean square deviation and fluctuation analyses indicating that the ligand stayed anchored in the binding pocket without destabilising the protein fold. This kind of sustained stability strengthens the argument that kaempferol is a plausible direct modulator of AKT1 rather than an artefact of the docking algorithm, and it provides a structural starting point for medicinal chemists interested in optimising flavonoid-based AKT inhibitors.

Taken together, the study weaves a consistent narrative from cell culture to proteomics to computational structural biology. A plant fraction rich in flavonoids and phytosterols kills NSCLC cells, blocks their ability to form new colonies, suppresses their migration, and pushes cancer-relevant proteins away from an angiogenic and metastatic state, all while its principal constituents show computationally predicted and dynamically stable interactions with the PI3K/AKT1/KRAS signalling core and matrix metalloproteinases. The authors conclude that Pistacia integerrima bioactives exhibit significant anti-proliferative, anti-migratory and anti-metastatic activities in vitro, providing a scientific rationale for identifying newer promising candidates for NSCLC.

Important caveats remain. All of the experimental evidence comes from a single cell line in vitro, and the concentrations used, particularly the 100 micrograms per millilitre dose in the cytotoxicity assay, are far removed from anything a patient could achieve through an extract or supplement. The docking and dynamics work, however rigorous, generates hypotheses about direct target engagement that still need confirmation with techniques such as surface plasmon resonance, cellular thermal shift assays or kinase activity measurements. No animal data or pharmacokinetic information exists yet, and the fraction itself is a complex mixture whose active constituents and their relative contributions have not been disentangled. Nevertheless, the convergence of phenotypic, proteomic and computational evidence makes Pistacia integerrima a credible candidate for further preclinical development, and it adds to a growing body of work suggesting that flavonoids such as kaempferol and quercetin, and phytosterols such as beta-sitosterol, deserve systematic evaluation as leads against some of the most stubborn signalling pathways in lung cancer. As the search for new weapons against NSCLC intensifies, an old medicinal tree may yet yield distinctly modern drug candidates.

Subject of Research: Anticancer activity of Pistacia integerrima phytochemicals against non-small cell lung cancer via PI3K, AKT1 and KRAS signalling

Article Title: Proteomic regulation of anti-proliferative and anti-migratory activity by potent phytochemicals from Pistacia integerrima J.L. Steward Ex Brandis via PI3K, AKT1, and KRAS for Lung Cancer

Article References: Jamwal, A., Paudel, K., Dua, K., Kulkarni, M. P., Mujwar, S., Dhiman, S., Dalwal, V., Negi, P., & Goyal, R. (2026). Proteomic regulation of anti-proliferative and anti-migratory activity by potent phytochemicals from Pistacia integerrima J.L. Steward Ex Brandis via PI3K, AKT1, and KRAS for Lung Cancer. Molecular Biology Reports, 53(1), Article 1571. https://doi.org/10.1007/s11033-026-12743-5

Image Credits: AI Generated

DOI: 10.1007/s11033-026-12743-5

Keywords: non-small cell lung cancer, Pistacia integerrima, A549 cells, PI3K/AKT1 signalling, KRAS, molecular docking, molecular dynamics simulation, flavonoids, kaempferol, quercetin, MMP-2, anti-migratory activity

Yet the celebration was always tempered by an uncomfortable arithmetic problem. KRAS G12C accounts for only a minority of KRAS-driven cancers. The most common oncogenic variants, including G12D, G12V, and Q61 mutations, dominate pancreatic and colorectal disease and lack the reactive cysteine that made the first-generation inhibitors possible. A comprehensive review published in Medical Oncology by Srijita Chatterjee, Swati Arya, and colleagues surveys this rapidly shifting landscape, arguing that the field is now moving decisively beyond allele-specific G12C inhibition toward a strategy that is mutation- and context-dependent. The review synthesizes patent filings, clinical trial data, and preclinical discoveries to map where KRAS drug development is heading next.

Among the most consequential new chemical entities are non-covalent inhibitors that do not depend on a cysteine residue. MRTX1133, developed through structure-based design, binds the inactive, GDP-bound state of KRAS G12D with nanomolar selectivity and demonstrated striking anti-tumor activity in preclinical pancreatic cancer models. Its clinical descendants are now in human trials, and the commercial stakes are enormous. In 2025, Bayer announced a global license agreement with Kumquat Biosciences for the KRAS G12D inhibitor KBQ548, a deal valued at up to 1.3 billion dollars, while Verastem Oncology exercised its option for rights outside China to the G12D inhibitor GFH375, also known as VS-7375. These transactions signal that major pharmaceutical companies view non-G12C KRAS inhibition as the next major oncology franchise.

Perhaps the most conceptually ambitious approach comes from a different mechanistic family altogether: the tri-complex, or molecular glue, inhibitors. Compounds such as RMC-6236, a pan-RAS(ON) antagonist, do not simply occupy a pocket on KRAS. Instead, they chaperone KRAS into a complex with cyclophilin A, remodeling the protein’s surface so that it can no longer engage its downstream effectors, regardless of which mutation drives the cancer. Because this mechanism is largely mutation-agnostic, a single drug could in principle treat the entire spectrum of RAS-driven tumors. The related molecule RMC-9805 applies the same logic selectively to KRAS G12D, and early clinical presentations have reported encouraging antitumor activity with favorable safety profiles. The review highlights how these agents, discussed intensively at recent ESMO congresses, have moved from academic curiosity to some of the most closely watched programs in clinical oncology.

A third frontier is protein degradation rather than inhibition. ASP3082, a KRAS-directed degrader, recruits the cell’s ubiquitin-proteasome machinery to eliminate mutant KRAS itself rather than merely silencing it. Early reports describe efficacy in KRAS G12D-mutant non-small-cell lung cancer with a manageable toxicity profile. Degradation offers theoretical advantages over occupancy-based inhibition: it removes all of the protein’s scaffolding and effector functions at once, and it may sidestep some resistance mechanisms that arise when residual inhibitor-bound protein retains partial activity. The patent landscape reflects this diversification. World Intellectual Property Organization filings now cover KRAS G12D inhibitors, deuterated KRAS G12D compounds, macrocyclic RAS inhibitors, pan-KRAS inhibitors spanning G12A, G12C, G12D, G12R, G12S, G12V, G13D, and Q61H variants, KRAS G12V-specific inhibitors, and even farnesyltransferase inhibitors repurposed for KRAS-dependent cancers.

No single agent, however, is likely to conquer KRAS-driven cancer alone, and the review devotes substantial attention to rational combination strategies. Upstream of KRAS, the guanine nucleotide exchange factors SOS1 and SHP2 regulate reactivation of the pathway, and blocking them can prevent the feedback activation of wild-type RAS that otherwise constrains G12C inhibitor efficacy. Downstream, MEK inhibitors such as VS-6766 have shown clinical activity in KRAS-mutant cancers, and SHP2 inhibition has been shown to prevent adaptive resistance to MEK blockade across multiple models. In colorectal cancer, where EGFR signaling provides a potent escape route, combining KRAS G12C inhibitors with anti-EGFR antibodies has produced some of the field’s most impressive results: sotorasib plus panitumumab, adagrasib with or without cetuximab, and the next-generation inhibitor divarasib plus cetuximab have all demonstrated substantially improved response rates in refractory disease. Other rational pairings include CDK4/6 inhibitors for KRAS-mutant pancreatic cancer and immune checkpoint inhibitors, exploiting the fact that some KRAS inhibitors appear to enhance anti-tumor immunity.

Resistance, predictably, has emerged as the central clinical challenge. Acquired resistance to sotorasib and adagrasib arises through secondary mutations in KRAS itself, bypass activation of downstream MAPK signaling, and histologic transformation. Co-mutation patterns matter enormously: tumors harboring concurrent STK11/LKB1 alterations show both reduced immunotherapy benefit and distinctive resistance to KRAS inhibition, partly through an adeno-to-squamous transition that reprograms tumor identity. Epithelial-to-mesenchymal transition, a developmental program hijacked by cancer cells, drives both intrinsic and acquired resistance, while non-genetic adaptive mechanisms, including cell-type-specific rewiring of signaling networks, allow tumors to tolerate drug pressure without any new mutation at all. Liquid biopsies that detect circulating tumor DNA are becoming essential tools for monitoring these resistance mechanisms in real time, offering a dynamic alternative to tissue re-biopsy and enabling earlier switches in therapy.

The synthetic lethality concept, first articulated in the 1990s as a framework for anticancer drug discovery, provides another lens for exploiting KRAS addiction. Because mutant KRAS forces cancer cells into a state of profound dependency on compensatory pathways, inhibiting a partner gene that the cancer cell cannot survive without, even when that gene is dispensable in healthy cells, offers a therapeutic window. Screening efforts continue to identify such vulnerabilities, and the review argues that pairing these genetic insights with the new inhibitor classes could produce combinations tailored to the specific constellation of mutations within each patient’s tumor, an approach squarely aligned with the goals of precision oncology.

The regulatory and commercial environment surrounding these advances is itself a story of global competition and opportunity. Patent filings from Mirati Therapeutics, Array Biopharma, and numerous other applicants reveal an intense race to claim chemical space around KRAS, including combination patents pairing G12D inhibitors with SOS1 inhibitors. Clinical trial registries list dozens of active studies, and press releases announcing billion-dollar licensing deals now arrive with regularity. For patients with pancreatic cancer, where KRAS mutation is essentially universal and five-year survival remains dismal, the acceleration cannot come soon enough. The review’s authors conclude that the field has entered a genuinely new era: the question is no longer whether KRAS can be drugged, but which drug, which combination, and which molecular context will deliver the greatest benefit. As allele-specific inhibitors give way to pan-KRAS antagonists, degraders, and intelligently designed combinations, KRAS-mutant cancers are being transformed from a monolithic, untreatable category into a set of molecularly defined diseases, each with its own map of vulnerabilities and its own path to clinical translation.

Subject of Research: Emerging therapeutic strategies and clinical progress in targeting KRAS-mutant cancers beyond KRAS G12C inhibition

Article Title: Beyond KRASG12C: emerging therapeutic strategies, patent landscape, and clinical progress in targeting KRAS-mutant cancers

Article References: Beyond KRASG12C: emerging therapeutic strategies, patent landscape, and clinical progress in targeting KRAS-mutant cancers. (n.d.). https://doi.org/10.1007/s12032-026-03392-6

Image Credits: AI Generated

DOI: 10.1007/s12032-026-03392-6

Keywords: KRAS, KRAS G12C, KRAS G12D inhibitors, pan-KRAS inhibitors, RMC-6236, sotorasib, adagrasib, protein degraders, SHP2 inhibition, drug resistance, pancreatic cancer, precision oncology