Urinary bladder cancer is one of the leading malignancies worldwide, with the highest recurrence rates. A diet rich in vitamin A has proven to lower the risk of cancer, yet the molecular mechanisms underlying this effect are unknown. We found that vitamin A decreased urothelial atypia and apoptosis during early bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN). Vitamin A did not alter urothelial cell desquamation, differentiation, or proliferation rate. Genes like Wnt5a, involved in retinoic acid signaling, and transcription factors Pparg, Ppara, Rxra, and Hoxa5 were downregulated, while Sox9 and Stra6 were upregulated in early urothelial carcinogenesis. When a vitamin A rich diet was provided during BBN treatment, none of these genes was up- or downregulated; only Lrat and Neurod1 were upregulated. The lecithin retinol acyltransferase (LRAT) enzyme that produces all-trans retinyl esters was translocated from the cytoplasm to the nuclei in urothelial cells as a consequence of BBN treatment regardless of vitamin A rich diet. A vitamin A-rich diet altered retinoic acid signaling, decreased atypia and apoptosis of urothelial cells, and consequently diminished early urothelial carcinogenesis.

Laryngeal cancer is the second most common malignancy of the head and neck, worldwide. Immunotherapy targeting checkpoint inhibitors has been approved for the treatment of patients with recurrent or metastatic laryngeal cancer but has a relatively low response rate and outcomes that leave many patients underserved. Targeting the cGAS–STING signaling pathway can potentially improve the activation of immune effector cells, although its role in the development and progression of laryngeal cancer has not yet been investigated in depth. Fifty-nine tumor samples from patients with pathologically confirmed squamous cell carcinoma of the larynx, stage I–IV non-metastatic disease, who were treated at the University Hospital of Split, were immunohistochemically stained for the expression of STING, cGAS, CD8, CD68, and CD163. Elevated tumor cell-intrinsic STING expression was positively associated with stage IV (p = 0.0031), pT3, and pT4 laryngeal cancers (p = 0.0336) as well as with higher histological grades (G2 and G3) (p = 0.0204) and lymph node-positive tumors (p = 0.0371). After adjusting for age, sex, location, and cGAS expression, elevated STING expression was significantly associated with stage IV cancer in a multiple logistic regression model (β = 1.849, SE = ±0.8643, p = 0.0324). Elevated STING expression represents a potentially favorable predictive biomarker for new therapeutic approaches involving STING agonists combined with immunotherapy and DNA-damaging agents (radiotherapy, cisplatin, and PARP inhibitors) in laryngeal cancer.

Urinary bladder cancer (BC) inflicts a significant impairment of life quality and poses a high mortality risk. Schistosoma haematobium infection can cause BC, and the urinary microbiota of BC patients differs from healthy controls. Importantly, intravesical instillation of the bacterium Bacillus Calmette-Guerin stands as the foremost therapy for non-muscle invasive BC. Hence, studying the receptors and signaling molecules orchestrating bacterial recognition and the cellular response in the context of BC is of paramount importance. Thus, we challenged Toll-like receptor 4 (Tlr4) and myeloid differentiation factor 88 (Myd88) knock-out (KO) mice with N-butyl-N-(4-hydroxylbutyl)-nitrosamine (BBN), a well-known urinary bladder carcinogen. Gut microbiota, gene expression, and urinary bladder pathology were followed. Acute exposure to BBN did not reveal a difference in bladder pathology despite differences in the animal’s ability to recognize and react to bacteria. However, chronic treatment resulted in reduced cancer invasiveness among Myd88^KO mice while the absence of functional Tlr4 did not influence BC development or progression. These differences correlate with a heightened abundance of the Faecalibaculum genus and the lowest microbial diversity observed among Myd88^KO mice. The presented data underscore the important role of microbiota composition and MyD88-mediated signaling during bladder carcinogenesis.

Globally, bladder cancer is the sixth most frequently diagnosed cancer among men. Despite the increasing availability of immunomodulatory treatments for bladder cancer, the survival rates are still low, which calls for potential new drug-repurposing targets. This study aimed to investigate the effects of cromolyn, a mast cell (MC) stabilizer in allergic reactions, on a subcutaneous tumor model with a syngeneic mouse MB49 bladder cancer cell line. A concentration of 50 mg/kg of cromolyn was daily administered intraperitoneally in a 4-day therapeutic protocol to mice with established tumors and in a continuous 11-day protocol which started one day prior to the subcutaneous injection of tumor cells. Therapeutic treatment demonstrated a marked downregulation of genes related to angiogenesis and upregulation of genes related to cytotoxic T-cell and NK cell activity. Conversely, continuous cromolyn treatment suppressed genes involved in immune cell recruitment and activation, as well as apoptotic and necroptotic pathways, leading to a greater tumor burden (+142.4 mg [95CI + 28.42, +256.4], p = 0.0158). The same pro-tumorigenic effect was found in mast cell-deficient mice (Kit^W-sh/W-sh + 301.7 mg [95CI + 87.99, 515.4], p = 0.0079; Cpa3^Cre/+ +107.2 mg [95CI − 39.37, +253.57], p = 0.1423), indicating that continuous cromolyn treatment mostly acts through the inhibition of mast cell degranulation. In summary, our results demonstrate the distinct effects of cromolyn on tumor progression, which depend on the protocol of cromolyn administration.