Cancer-cell-intrinsic mechanisms shaping the immunosuppressive landscape of prostate cancer

Rebooting the Adaptive Immune Response in Immunotherapy-Resistant Lung Adenocarcinoma Using a Supramolecular Albumin

Despite the availability of immune checkpoint inhibitors (ICBs) significantly prolonging the life expectancy of some lung adenocarcinoma (LUAD) patients, their implementation and long-term effectiveness are hampered by the growing issue of acquired resistance. Herein, the bioinformatics analysis of immunotherapy-resistant LUAD patients and the system analysis of Anti-PD1-resistant mice models once again validate that the resistance-associated Wnt/β-catenin pathway offers a promising avenue for ICB sensitization. Consequently, a mild and convenient self-assembly between albumin and carnosic acid (CA), a Wnt inhibitor is employed, to develop a supramolecular albumin known as ABCA, serving as a reactivator for ICB. As anticipated, ABCA effectively suppress the Wnt/β-catenin cascade in vitro and leads to significant inhibition of cell proliferation while promoting apoptosis. Most notably, ABCA restores the anticancer efficacy of Anti-PD1 in immunotherapy-resistant LUAD orthotopic allografting mice models by reinvigorating the adaptive immune response mediated by T lymphocytes. Furthermore, ABCA exhibits minimal adverse effects during treatment and high-dose toxicity tests, underscoring its excellent potential for clinical translation. Collectively, the present work possesses the potential to provide innovative perspectives on the advancement of optimized immunotherapies targeting drug resistance, while also presenting a promising avenue for translating Wnt inhibitors into immunotherapeutic drugs for their clinical application.

Master Transcription Factor Reprogramming Unleashes Selective Translation Promoting Castration Resistance and Immune Evasion in Lethal Prostate Cancer

Signaling rewiring allows tumors to survive therapy. Here we show that the decrease of the master regulator microphthalmia transcription factor (MITF) in lethal prostate cancer unleashes eukaryotic initiation factor 3B (eIF3B)-dependent translation reprogramming of key mRNAs conferring resistance to androgen deprivation therapy (ADT) and promoting immune evasion. Mechanistically, MITF represses through direct promoter binding eIF3B, which in turn regulates the translation of specific mRNAs. Genome-wide eIF3B enhanced cross-linking immunoprecipitation sequencing (eCLIP-seq) showed specialized binding to a UC-rich motif present in subsets of 5' untranslated regions. Indeed, translation of the androgen receptor and major histocompatibility complex I (MHC-I) through this motif is sensitive to eIF3B amount. Notably, pharmacologic targeting of eIF3B-dependent translation in preclinical models sensitizes prostate cancer to ADT and anti-PD-1 therapy. These findings uncover a hidden connection between transcriptional and translational rewiring promoting therapy-refractory lethal prostate cancer and provide a druggable mechanism that may transcend into effective combined therapeutic strategies.

SIGNIFICANCE

Our study shows that specialized eIF3B-dependent translation of specific mRNAs released upon downregulation of the master transcription factor MITF confers castration resistance and immune evasion in lethal prostate cancer. Pharmacologic targeting of this mechanism delays castration resistance and increases immune-checkpoint efficacy. This article is featured in Selected Articles from This Issue, p. 2489.

Genetic alterations shape innate immune cells to foster immunosuppression and cancer immunotherapy resistance

Cancer immunotherapy, particularly immune checkpoint inhibitors, has opened a new avenue for cancer treatment following the durable clinical benefits. Despite the clinical successes across several cancer types, primary or acquired resistance might eventually lead to cancer progression in patients with clinical responses. Hence, to broaden the clinical applicability of these treatments, a detailed understanding of the mechanisms limiting the efficacy of cancer immunotherapy is needed. Evidence provided thus far has implicated immunosuppressive innate immune cells infiltrating the tumor microenvironment as key players in immunotherapy resistance. According to the available data, genetic alterations can shape the innate immune response to promote immunotherapy resistance and tumor progression. Herein, this review has discussed the current understanding of the underlying mechanisms where genetic alterations modulate the innate immune milieu to drive immunosuppression and immunotherapy resistance.