The kinase MAPKAPK2 regulates cell survival, proliferation, and death, and is upregulated in colorectal carcinoma (CRC) where it is associated with tumor growth and progression. However, how it regulates tumor progression in conjunction with other signaling pathways, such as MEK/ERK, remains elusive. Solid tumors are often subjected to metabolic stress, notably glucose deprivation. Here, we demonstrate that MAPKAPK2 protein levels in CRC regulate cell fate decision during stress conditions, such as glucose deprivation and therapeutic treatment. While MAPKAPK2 expression is a limiting factor for CRC growth in vitro, depleting MAPKAPK2 or inhibiting its activity pharmacologically provides a survival advantage to CRC cells under glucose limiting conditions. Subjecting CRC cells to low glucose resulted in an ERK1/2-mediated decline in MAPKAPK2 to promote survival. Additionally, cells with reduced MAPKAPK2 activity were less sensitive to trametinib under glucose limiting conditions. Utilizing transcriptomic profiling, we found that glucose deprivation and MAPKAPK2 depletion activate pathways associated with survival during metabolic stress. This relationship was also observed in CRC patients (TCGA), where tumors with low MAPKAPK2 expression had higher ERK1/2 activation and upregulated stress-induced pathways, leading to poor survival. Finally, MAPKAPK2 modulated growth of CRC organoids, subcutaneous tumors, and patient-derived xenografts (PDX), and reduced MAPKAPK2 levels decreased efficacy of trametinib, in vitro and in vivo. Overall, this study identifies an interrelationship between MEK/ERK and p38/MAPKAPK2 signaling pathways during glucose deprivation to support cell survival and features MAPKAPK2 loss as a possible mechanism leading to reduced efficacy of trametinib-based anticancer therapy and poor patient outcomes in CRC.

Targeted drug delivery remains a critical challenge in the treatment of ulcerative colitis, as the side effects of current systemic therapies often outweigh their therapeutic benefits. In this study, we developed a reactive oxygen species (ROS)-responsive nanogel system that releases polymeric chloroquine (PCQ), a macromolecular derivative of hydroxychloroquine (HCQ), for localized treatment of ulcerative colitis. The initial nanogel formulation, measuring 183 nm in size with a surface charge of +13 mV, was synthesized via RAFT polymerization using a thioketal dimethacrylate cross-linker to demonstrate ROS-triggered degradation, physicochemical stability in simulated gastrointestinal fluids, favorable biocompatibility, and preferential accumulation in inflamed colonic tissue. To assess how variations in size and surface charge impact in vivo therapeutic efficacy, additional formulations were synthesized, resulting in a series of nanogels (T1-T4) with hydrodynamic diameters ranging from 180 to 680 nm and surface charges from +13 to +24 mV and tested in a Citrobacter rodentium-induced model of colitis. The nanogels delivered superior therapeutic benefits, including histological recovery, restoration of epithelial architecture, reduced immune cell infiltration, and attenuation of STAT3 activation as compared to the parent drug HCQ. Cytokine and eicosanoid profiling further revealed robust local and partial systemic immunomodulatory effects, with T1 showing the greatest local efficacy but relatively limited systemic eicosanoid suppression. These findings underscore the importance of optimizing nanogel size and surface properties to balance local and systemic therapeutic outcomes. Overall, this inflammation-responsive PCQ nanogel platform represents a promising strategy for targeted ulcerative colitis therapy with potentially no side effects.

Although the etiology of inflammatory bowel disease (IBD) remains unclear, compromised epithelial barrier integrity is believed to promote susceptibility to IBD and be associated with disease severity, suggesting that improving gut barrier integrity may palliate or treat IBD. Such a notion gets support from the clinical findings that mucosal healing in IBD patients is associated with improved prognosis, and reduced risk of relapse or colitis-associated cancer. It therefore becomes critical to understand the intracellular signals that regulate mucosal healing and gut barrier integrity. Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that critically modulates epithelial cell growth and mobility and has been associated with carcinogenesis. However, studies also suggest that FAK activation may promote mucosal healing under conditions of colitis, which should reduce the risk of colitis-associated cancer. These findings highlight a potentially transformative role for FAK in the context of IBD. Understanding the molecular mechanisms by which FAK influences gut barrier repair and mucosal integrity could offer novel therapeutic avenues for treating IBD and preventing its long-term complications. This review focuses on the potential role of FAK in promoting colitis-associated mucosal healing and the underlying molecular mechanisms driving these processes, offering critical insights into IBD pathogenesis and therapy.

Inflammatory bowel disease (IBD) is a chronic gut disorder that also elevates the risk of colorectal cancer (CRC). The global incidence and severity of IBD are rising, yet existing therapies often lead to severe side effects. Curcumin offers potent anti-inflammatory and chemotherapeutic properties. However, its clinical translation is hindered by rapid metabolism, as well as poor water solubility and stability, which limits its bioavailability. To address these challenges, we developed OC-S, a water-soluble and colon-targeted curcumin formulation that protects against colitis in mice. The current study advances OC-S as a dietary supplement by establishing its stability and compatibility with various commercial dietary products. Further, OC-S exhibited specific binding to inflamed colon tissue, potentially aiding in targeted drug retention at the inflammation site in colitis with diarrhea symptoms. We further investigated its efficacy in vivo and in vitro using a murine model of colitis and tumoroids from APCmin mice. OC-S significantly reduced colitis severity and pro-inflammatory cytokine expression compared with curcumin, even at very low doses (5 mg/kg/day). It also demonstrated higher anti-proliferative activity in CRC cells and colon cancer tumoroids vs. curcumin. Overall, this study demonstrated that OC-S effectively targets and retains water-soluble curcumin at the inflamed colon sites, while showing promise in addressing both colitis and colorectal cancer, which potentially paves the way for OC-S to advance into clinical development as a dietary product for both IBD and CRC.

Impaired autophagy promotes Inflammatory Bowel Disease (IBD). Claudin-2 is upregulated in IBD however its role in the pathobiology remains uncertain due to its complex regulation, including by autophagy. Irrespective, claudin-2 expression protects mice from DSS colitis. This study was undertaken to examine if an interplay between autophagy and claudin-2 protects from colitis and associated epithelial injury. Crypt culture and intestinal epithelial cells (IECs) are subjected to stress, including starvation or DSS, the chemical that induces colitis in-vivo. Autophagy flux, cell survival, co-immunoprecipitation, proximity ligation assay, and gene mutational studies are performed. These studies reveal that under colitis/stress conditions, claudin-2 undergoes polyubiquitination and P62/SQSTM1-assisted degradation through autophagy. Inhibiting autophagy-mediated claudin-2 degradation promotes cell death and thus suggest that claudin-2 degradation promotes autophagy flux to promote cell survival. Overall, these data inform for the previously undescribed role for claudin-2 in facilitating IECs survival under stress conditions, which can be harnessed for therapeutic advantages.

Dysregulation of both the gut barrier and microbiota (dysbiosis) promotes susceptibility to and severity of Inflammatory Bowel Diseases (IBD). Leaky gut and dysbiosis often coexist; however, potential interdependence and molecular regulation are not well understood. Robust expression of claudin-3 (CLDN3) characterizes the gut epithelium, and studies have demonstrated a positive association between CLDN3 expression and gut barrier maturity and integrity, including in response to probiotics. However, the exact status and causal role of CLDN3 in IBD and regulation of gut dysbiosis remain unknown. Analysis of mouse and human IBD cohorts helped examine CLDN3 expression in IBD. The causal role was determined by modeling CLDN3 loss of expression during experimental colitis. 16S sequencing and in silico analysis helped examine gut microbiota diversity between Cldn3KO and WT mice and potential host metabolic responses. Fecal microbiota transplant (FMT) studies were performed to assess the role of gut dysbiosis in the increased susceptibility of Cldn3KO mice to colitis. A significant decrease in CLDN3 expression characterized IBD and CLDN3 loss of expression promoted colitis. 16S sequencing analysis suggested gut microbiota changes in Cldn3KO mice that were capable of modulating fatty acid metabolism and oxidative stress response. FMT from naïve Cldn3KO mice promoted colitis susceptibility in recipient germ-free mice (GFM) compared with GFM-receiving microbiota from WT mice. Our data demonstrate a critical role of CLDN3 in maintaining normal gut microbiota and inflammatory responses, which can be harnessed to develop novel therapeutic opportunities for patients with IBD.

Background: Despite significant progress in clinical management, colorectal cancer (CRC) remains the third most common cause of cancer-related deaths. A positive association between PYCR2 (pyrroline-5-carboxylate reductase-2), a terminal enzyme of proline metabolism, and CRC aggressiveness was recently reported. However, how PYCR2 promotes colon carcinogenesis remains ill understood. Methods: A comprehensive analysis was performed using publicly available cancer databases and CRC patient cohorts. Proteomics and biochemical evaluations were performed along with genetic manipulations and in vivo tumor growth assays to gain a mechanistic understanding. Results: PYCR2 expression was significantly upregulated in CRC and associated with poor patient survival, specifically among PYCR isoforms (PYCR1, 2, and 3). The genetic inhibition of PYCR2 inhibited the tumorigenic abilities of CRC cells and in vivo tumor growth. Coinciding with these observations was a significant decrease in cellular proline content. PYCR2 overexpression promoted the tumorigenic abilities of CRC cells. Proteomics (LC-MS/MS) analysis further demonstrated that PYCR2 loss of expression in CRC cells inhibits survival and cell cycle pathways. A subsequent biochemical analysis supported the causal role of PYCR2 in regulating CRC cell survival and the cell cycle, potentially by regulating the expression of MASTL, a cell-cycle-regulating protein upregulated in CRC. Further studies revealed that PYCR2 regulates Wnt/β-catenin-signaling in manners dependent on the expression of MASTL and the cancer stem cell niche. Conclusions: PYCR2 promotes MASTL/Wnt/β-catenin signaling that, in turn, promotes cancer stem cell populations and, thus, colon carcinogenesis. Taken together, our data highlight the significance of PYCR2 as a novel therapeutic target for effectively treating aggressive colon cancer.

Objective: Inflammatory Bowel Disease (IBD) is multifactorial autoimmune disorder where dysregulation of the gut barrier and gut microbiota (Dysbiosis) play critical role in disease onset and progression. A leaky gut often coexists with the dysbiotic gut microbiota, however a pathobiological integration is not well understood. Intestinal claudin-3 expression is robust, and we have reported that its loss promotes gut permeability and colon cancer. Increased gut permeability and colon cancer risk characterize Inflammatory Bowel Disease (IBD). The current study was undertaken to delineate the status and role of claudin-3 expression in IBD. Methods: Multiple murine models of colitis and IBD patient biopsy were used. Claudin-3KO mice were used to determine causal role. Multiplex ELISA, RNAseq and 16S DNA sequencing helped determine inflammatory cytokines, transcriptomic changes, and gut microbiota diversity, respectively. Fecal microbiota transplantation (FMT) and antibiotic treatment studies were done to test the role of claudin-3/gut dysbiosis axis in promoting IBD. Results: A significant decrease in claudin-3 expression was observed in IBD patient samples or the colon of mice subjected to DSS- (2.5% w/v) or C. rodentium-colitis (5 x108 CFU/oral). colitis (p<0.001). To test the causal role, claudin-3KO mice were subjected to DSS-colitis (acute and chronic), and infectious colitis. A significant change in the body weight, colon thickness, and mucosal injury score (p<0.001) characterized the colitis challenged claudin-3KO versus WT mice. P-Stat3 expression was highly upregulated in colitis challenged claudin-3KO mice. Interestingly, administration of an antibiotic cocktail rescued the colitis severity in claudin-3KO mice. The 16s metagenomics further revealed that the gut microbiota of claudin-3KO mice is diverse and clustered distinctly from the WT mice. To determine if gut dysbiosis in claudin-3KO mice promotes susceptibility to colitis, we performed FMT from naïve Claudin-3KO mice to germ-free WT mice. When subjected to DSS-colitis, germ-free mice transplanted with Claudin3-KO gut microbiota showed significantly higher colitis severity versus WT (p<0.05). Conclusion: We summarize that the loss of colonic Cldn3 deregulates mucosal barrier integrity to induce gut dysbiosis and susceptibility to IBD. We propose that claudin-3 can be a novel therapeutic target in strengthening the gut barrier integrity to diminish IBD susceptibility. National Institute of Health, Veterans Administration This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Patients with inflammatory bowel disease (IBD) are susceptible to colitis-associated cancer (CAC). Chronic inflammation promotes the risk for CAC. In contrast, mucosal healing predicts improved prognosis in IBD and reduced risk of CAC. However, the molecular integration among colitis, mucosal healing, and CAC remains poorly understood. Claudin-2 (CLDN2) expression is upregulated in IBD; however, its role in CAC is not known. The current study was undertaken to examine the role for CLDN2 in CAC. The AOM/DSS-induced CAC model was used with WT and CLDN2-modified mice. High-throughput expression analyses, murine models of colitis/recovery, chronic colitis, ex vivo crypt culture, and pharmacological manipulations were employed in order to increase our mechanistic understanding. The Cldn2KO mice showed significant inhibition of CAC despite severe colitis compared with WT littermates. Cldn2 loss also resulted in impaired recovery from colitis and increased injury when mice were subjected to intestinal injury by other methods. Mechanistic studies demonstrated a possibly novel role of CLDN2 in promotion of mucosal healing downstream of EGFR signaling and by regulation of Survivin expression. An upregulated CLDN2 expression protected from CAC and associated positively with crypt regeneration and Survivin expression in patients with IBD. We demonstrate a potentially novel role of CLDN2 in promotion of mucosal healing in patients with IBD and thus regulation of vulnerability to colitis severity and CAC, which can be exploited for improved clinical management.