The research, led by Lee-Yuan Lin, Wun-Hao Cheng, Chien-Huang Lin and Bing-Chang Chen of Taipei Medical University, together with collaborators at National Taiwan University Hospital and Universitas Gadjah Mada, began with a question that has lingered in the literature. Gene expression analyses had previously hinted that DCLK1 might be implicated in IPF, and earlier work reported that the kinase is markedly enhanced in the alveolar epithelial cells of patients with pulmonary fibrosis and in mice with bleomycin-induced fibrosis. But its function in fibroblast activation—the cellular engine of fibrosis—had remained unexplained.

To begin untangling that role, the team mined a publicly available single-cell RNA sequencing data set containing more than 312,000 cells from healthy lungs, IPF lungs, and lungs with chronic obstructive pulmonary disease. After stringent quality control filtering, they focused on roughly 240,000 cells from the control and IPF groups and mapped DCLK1 expression across the major lung cell lineages: epithelial, endothelial, lymphoid, myeloid, and stromal cells. The signal was unmistakable. DCLK1 was expressed across many cell populations, but the highest expression appeared in the stromal compartment, particularly in myofibroblasts—the specialized, contractile fibroblasts that churn out the extracellular matrix and stiffen lung tissue in IPF.

Human tissue told the same story. The researchers examined lung samples from eleven patients with IPF, obtained during lung transplantation or surgery, alongside fourteen nonfibrotic control samples. Histological staining with hematoxylin and eosin and Masson trichrome confirmed the expected picture of interstitial consolidation and collagen deposition in the IPF specimens. More importantly, immunohistochemistry revealed that both total DCLK1 and its phosphorylated, activated form were significantly upregulated in the fibrotic lung interstitium compared with control tissue. DCLK1, in other words, was not merely present in scarred lungs—it was switched on.

DCLK1 is an intriguing molecule to find at the center of a fibrotic process. It is a serine/threonine kinase belonging to the calcium/calmodulin-dependent kinase family, distinguished by two microtubule-binding domains. In oncology, DCLK1 overexpression has been documented in colorectal, pancreatic, gastric, renal, and hepatocellular carcinomas, where it correlates with poor prognosis, high recurrence, and metastasis, promoting tumor initiation and the epithelial–mesenchymal transition in cancer stem cells. It has also been linked to inflammatory signaling in SARS-CoV-2 infection, where inhibiting it blocks proinflammatory caspase-1/interleukin-1β signaling. The new study extends this portfolio of mischief to the fibrotic lung.

To test causality rather than mere correlation, the researchers turned to mice. They crossed animals carrying loxP sites flanking exon 3 of the DCLK1 locus with Pgk1-RFP-Cre/ERT2 transgenic mice, generating a system in which tamoxifen administration triggers global deletion of the Dclk1 gene. When these DCLK1 knockout mice and littermate controls were given intratracheal bleomycin, a chemotherapy drug used to induce pulmonary fibrosis in laboratory animals, the difference was striking. Knockout mice showed far less lung infiltration and collagen deposition, reduced numbers of cells staining positive for DCLK1 together with fibroblast surface protein and alpha-smooth muscle actin, and significantly lower levels of the profibrotic proteins fibronectin, α-SMA, and connective tissue growth factor, or CTGF.

The protective effect extended well beyond molecular markers. Using the FlexiVent FX system to measure lung mechanics, the team found that bleomycin treatment significantly reduced respiratory system compliance and pressure–volume performance and increased the normalized work of breathing in control mice—hallmarks of a stiffening, fibrotic lung. In the DCLK1 knockout animals, these functional deficits were substantially attenuated. In vivo microcomputed tomography, acquired at 34.75-micrometer voxel resolution, painted the morphological counterpart: bleomycin caused parenchymal destruction and volume loss in control lungs, while knockout mice retained lung structure and volume. Density histograms shifted toward fibrotic tissue in wild-type animals but stayed largely preserved in the knockouts, and peripheral blood neutrophil percentages, which climbed after bleomycin injury, were significantly reduced in the knockout group.

With the in vivo evidence established, the investigators dissected the molecular wiring in cultured normal human lung fibroblasts. Transforming growth factor beta, the master profibrotic cytokine, induced DCLK1 phosphorylation within 30 minutes and DCLK1 expression within 8 hours. Chromatin immunoprecipitation assays showed that after TGF-β stimulation, both Smad3—the canonical transcriptional mediator of TGF-β signaling—and the nuclear factor kappa B subunit p65 enriched at the DCLK1 promoter, indicating that TGF-β switches on DCLK1 through both Smad-dependent and noncanonical NF-κB pathways. Silencing DCLK1 with small interfering RNA then blunted the fibroblast’s profibrotic response, reducing TGF-β-induced expression of fibronectin, collagen 1A1, α-SMA, and CTGF.

The pathway, however, does not stop there. The team found that TGF-β also phosphorylated Akt, and that transfecting fibroblasts with a dominant-negative Akt construct reduced TGF-β-induced DCLK1 phosphorylation and the expression of fibronectin and CTGF—placing Akt upstream of DCLK1. Downstream, DCLK1 knockdown reduced Smad3 phosphorylation while DCLK1 overexpression enhanced it. Coimmunoprecipitation revealed a physical association between DCLK1 and Smad3, and immunofluorescence microscopy showed the two proteins colocalizing in the nucleus within 30 minutes of TGF-β treatment. A ChIP assay using a DCLK1 antibody pulled down DNA from the Smad3-binding region of the CTGF promoter, and pretreatment with the selective DCLK1 inhibitor DCLK1-IN-1 reduced TGF-β-induced CTGF expression. Together, the results sketch an Akt/DCLK1/Smad3 axis through which TGF-β drives the production of connective tissue growth factor, a potent profibrotic mediator.

The clinical payoff came in the pharmacological arm of the study. Mice receiving oral DCLK1-IN-1 at 10 milligrams per kilogram daily, beginning on day 7 after bleomycin instillation and continuing until day 28, showed visibly reduced fibrotic progression on histology, lower expression of fibronectin, α-SMA, and CTGF in lung tissue and lysates, preserved pulmonary compliance, improved pressure–volume loops, and reduced work of breathing. Serial microCT scans on days 7, 17, and 27 documented less severe fibrotic remodeling in the treated animals, with lung attenuation histograms showing a smaller fraction of dense, nonaerated voxels. Blood neutrophil counts were also lower. In short, a pill-like oral inhibitor measurably slowed the disease in a model that mirrors the human condition.

The implications are significant because the current therapeutic landscape for IPF is so thin. Only nintedanib, a tyrosine kinase inhibitor targeting growth factor receptors, and pirfenidone, which suppresses TGF-β production and activity, are approved by the US Food and Drug Administration, and both merely slow progression. The recent failure of pamrevlumab, a monoclonal antibody against CTGF, in the phase 3 ZEPHYRUS-1 trial suggested that targeting downstream fibrotic end products alone may be insufficient—pointing to the value of upstream signaling regulators such as DCLK1. Adding to the appeal, a DCLK1 inhibitor has already been shown to prevent inflammatory responses in acute lung injury, hinting at dual anti-fibrotic and anti-inflammatory potential.

The authors are careful to note limitations. DCLK1 is expressed across multiple lung cell types, and the tamoxifen-inducible knockout used here was global rather than cell-type-specific, so the contributions of fibroblasts versus epithelial, endothelial, and immune cells could not be fully separated. Human control tissue, as in most fibrosis studies, came from heterogeneous sources, including tumor-adjacent lung. The precise subcellular mechanics of the DCLK1–Smad3 interaction, whether DCLK1 inhibition can promote fibrosis resolution rather than merely slow progression, and the systemic safety of long-term DCLK1 blockade—all relevant given the kinase’s role in cancer and other processes—remain open questions.

Even so, the convergence of evidence is striking: DCLK1 is upregulated in human IPF, amplified in experimental fibrosis, mechanistically coupled to the TGF-β–Smad3 engine of fibroblast activation, and its suppression by both genetics and a small molecule preserves lung structure and function. What began as a cancer stem cell marker has now emerged, unexpectedly, as a central node in the scarring of the lung—offering fresh hope that a disease long considered irreversible may one day be stopped at its molecular source.

Bladder cancer is notorious for its high recurrence rate and resistance to chemotherapy, presenting a significant challenge in the clinical setting. Current treatment modalities often lead to limited success, necessitating a deeper understanding of the underlying molecular mechanisms driving this malignancy. The researchers behind this pivotal study have focused their efforts on DCLK1, a member of the doublecortin-like kinase family known to play a role in cellular signaling and proliferation, particularly within cancerous tissues.

DCLK1’s role in oncogenesis has garnered increasing attention, yet its specific contributions to bladder cancer have remained largely unexplored. The study convincingly demonstrates that DCLK1 expression is significantly elevated in bladder cancer samples compared to adjacent normal tissues. This overexpression correlates with poor patient prognosis, establishing DCLK1 as a potential biomarker for disease severity and therapeutic resistance.

One of the critical mechanisms by which DCLK1 promotes malignancy is through its influence on the deubiquitinating enzyme, HDAC6. Ubiquitination is a vital post-translational modification that regulates protein stability and function, with deubiquitination reversing this process. HDAC6 is particularly important in cancer because it plays a role in cellular stress responses, apoptosis, and the regulation of key oncogenic pathways. DCLK1’s ability to deubiquitinate HDAC6 creates a stable environment for survival and proliferation of cancer cells in the face of chemotherapeutic agents.

The findings indicate that targeting the DCLK1-HDAC6 axis could offer a novel therapeutic strategy. By inhibiting DCLK1, researchers were able to enhance the efficacy of standard chemotherapy agents. This revelation is monumental as it implies that combinatorial treatment approaches could substantially improve patient outcomes in bladder cancer. The study underscores the importance of addressing both the molecular mechanisms of tumor growth and the resistance pathways that characterize this formidable disease.

In the realm of translational research, the DCLK1-driven pathways present an exciting target. The development of small molecule inhibitors or monoclonal antibodies aimed at DCLK1 holds promise for augmenting existing treatment regimens. Furthermore, the study invites further inquiry into the potential of DCLK1 as a therapeutic target in other malignancies where its expression and function may similarly influence disease progression and treatment resistance.

As researchers continue to delineate the oncogenic roles of various proteins, understanding DCLK1’s contributions will likely spur additional investigations into its upstream and downstream effects within cellular networks. For instance, identifying the signaling pathways that lead to DCLK1 activation in bladder cancer cells could uncover critical cancer-driving events, paving the way for more personalized therapeutic approaches based on individual genomic and proteomic profiles.

Moreover, complementing these findings with patient-derived xenografts could offer deeper insights into the in vivo relevance of DCLK1 as a therapeutic target. By modeling the disease more accurately, researchers can assess the therapeutic efficacy of DCLK1 inhibition in a preclinical setting, which is crucial for translating these findings into clinical practice.

The implications of these findings extend beyond bladder cancer, as DCLK1 may have a broader role across various tumor types. The potential for cross-cancer applications highlights the need for continued exploration into the biology of DCLK1 and its interactions with other oncogenic factors. As researchers unearth the complexities of cancer biology, targets like DCLK1 could become foundational components of multi-faceted treatment strategies aimed at overcoming the challenges posed by chemoresistance.

In conclusion, the work by Du et al. not only identifies DCLK1 as a pivotal player in the malignancy of bladder cancer but also suggests a promising path forward in terms of therapeutic development. Their findings contribute significantly to the growing body of evidence that underscores the necessity of targeted molecular interventions in the fight against cancer. As the scientific community continues to unravel the intricate interplay of cells within the tumor microenvironment, the role of DCLK1 remains central to developing a comprehensive understanding of bladder cancer biology.

With these insights, researchers are positioned to push the boundaries of cancer treatment paradigms, offering hope for improved outcomes in patients afflicted by this aggressive disease. The implications derived from this study resonate throughout the field, promoting an urgent need for advanced research and clinical trials aimed at integrating these molecular targets into effective therapeutic strategies against bladder cancer.

Advancements in understanding DCLK1 and its mechanisms will undoubtedly lead to innovative treatment modalities, fostering a new era in cancer therapy. As we forge ahead, the collaborative efforts of researchers, clinicians, and pharmaceutical companies are essential for translating these findings into tangible benefits for patients battling bladder cancer and beyond.

This research represents a significant milestone in oncology, reaffirming the critical importance of ongoing exploration into the molecular underpinnings of malignancies. With DCLK1 at the forefront, the future of bladder cancer treatment looks promising as we continue to innovate and adapt to the challenges posed by this complex disease.

Subject of Research: DCLK1 in bladder cancer progression and chemoresistance.

Article Title: DCLK1 drives malignant progression and chemoresistance of bladder cancer by deubiquitinating HDAC6.

Article References:

Du, A., Zhou, Y., Deng, X. et al. DCLK1 drives malignant progression and chemoresistance of bladder cancer by deubiquitinating HDAC6.
Mol Cancer (2026). https://doi.org/10.1186/s12943-025-02560-y

Image Credits: AI Generated

DOI: 10.1186/s12943-025-02560-y

Keywords: DCLK1, bladder cancer, chemoresistance, HDAC6, deubiquitination, oncogenesis, therapeutic target, molecular cancer research, cancer therapy.