Induction of tumor cell death is the therapeutic goal for most anticancer drugs. Yet, a mode of drug-induced cell death, known as immunogenic cell death (ICD), can propagate antitumoral immunity to augment therapeutic efficacy. Currently, the molecular hallmark of ICD features the release of damage-associated molecular patterns (DAMPs) by dying cancer cells. Here, we show that gemcitabine, a standard chemotherapy for various solid tumors, triggers hallmark immunostimualtory DAMP release (e.g., calreticulin, HSP70, and HMGB1); however, is unable to induce ICD. Mechanistic studies reveal gemcitabine concurrently triggers prostaglandin E2 release as an inhibitory DAMP to counterpoise the adjuvanticity of immunostimulatory DAMPs. Pharmacological blockade of prostaglandin E2 biosythesis favors CD103+ dendritic cell activation that primes a Tc1-polarized CD8+ T cell response to bolster tumor rejection. Herein, we postulate that an intricate balance between immunostimulatory and inhibitory DAMPs could determine the outcome of drug-induced ICD and pose COX-2/prostaglandin E2 blockade as a strategy to harness ICD.
Existence of humoral immunity has been previously demonstrated in malignant ascitic fluids. However, only a limited number of immunogenic tumor-associated antigens (TAAs) were identified, and few of which are associated with ovarian cancer. Here, we identified saltinducible kinase 3 (SIK3) as a TAA through screening of a random peptide library in the phage display system. Overexpression of SIK3 markedly promoted cell proliferation, attenuated p21 Waf/Cip1 and p27 Kip expressions in low-grade OVCAR3 cells, and permitted the cells to grow in mice. Decrease in SIK3 expression in high-grade SK-OV3 cells consistently demonstrated its tumorigenic potency by modulating the protein levels of cell cycle regulators. When the expressions of SIK3 and CA125 were compared in cancer tissues, immunohistochemical (IHC) studies indicated that cytoplasm-localized SIK3 was highly expressed in 55% of the ovarian cancer samples. In contrast, it was rarely detected in adenomyosis, leiomyoma and normal ovary tissues, showing its higher specificity (97%) to CA125 (65%) in ovarian cancer. Moreover, experiments using pharmacological inhibitors to block SIK3-induced p21 Waf/Cip1 expression revealed that activation of c-Src and phosphoinositide-3-kinase were critically required for its biological activity, suggesting that they are the downstream signaling mediators of SIK3. These data were further supported by IHC studies, showing coexpression of c-Src with SIK3 in 85% of the ovarian tumor samples stained positive for SIK3. Collectively, our findings indicate that SIK3 is a novel ovarian TAA. Overexpression of SIK3 promotes G1/S cell cycle progression, bestows survival advantages to cancer cells for growth and correlates the clinicopathological conditions of patients with ovarian cancer.
A relationship feature is a functional word that can reveal the relationship between one single gene and a disease. By incorporating many modern IR techniques, we found that BLRS is a very powerful information discovery tool for literature searching. A relationship network which contains the information on gene symbol, relationship feature, and disease MeSH term can provide an integrated view to discover gene-disease relationships.
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