Chemotherapy still constitutes the standard of care for the treatment of most neoplastic diseases. Certain chemotherapeutics from the oncological armamentarium are able to trigger pre‐mortem stress ...signals that lead to immunogenic cell death (ICD), thus inducing an antitumor immune response and mediating long‐term tumor growth reduction. Here, we used an established model, built on artificial intelligence to identify, among a library of 50,000 compounds, anticancer agents that, based on their molecular descriptors, were predicted to induce ICD. This algorithm led us to the identification of dactinomycin (DACT, best known as actinomycin D), a highly potent cytotoxicant and ICD inducer that mediates immune‐dependent anticancer effects in vivo. Since DACT is commonly used as an inhibitor of DNA to RNA transcription, we investigated whether other experimentally established or algorithm‐selected, clinically employed ICD inducers would share this characteristic. As a common leitmotif, a panel of pharmacological ICD stimulators inhibited transcription and secondarily translation. These results establish the inhibition of RNA synthesis as an initial event for ICD induction.
Synopsis
Anticancer drugs that trigger immunogenic cell death (ICD) are particularly efficient because they mobilize the host immune system against malignant cells expressing tumor‐associated antigens. Dactinomycin is identified as an ICD inducer and showed to stimulate anticancer immune responses in vivo.
An algorithm designed to discover cancer cell‐killing drugs with immunostimulatory properties led to the identification of dactinomycin (DACT, also known as actinomycin D), as an ICD inducer.
DACT induces all hallmarks ICD including phosphorylation of eukaryotic initiation factor 2a (eIF2a) in the context of a partial endoplasmic reticulum stress response, as well as cell surface exposure of calreticulin.
DACT stimulated anticancer immune responses in vivo with an improvement of the ratio of cytotoxic T lymphocytes over regulatory T cells in tumor‐infiltrating lymphocytes, while sensitizing tumors to subsequent immunotherapy with a PD‐1‐blocking antibody.
DACT is a known transcriptional inhibitor, and a range of distinct ICD inducers were found to potently inhibit transcription and translation, as documented for anthracyclines, crizotinib, lurbinectedin and oxaliplatin.
Artificial intelligence applied to a library of 50,000 drugs corroborated that transcription and translation inhibitors have a higher probability to induce ICD than other classes of antineoplastics.
Anticancer drugs that trigger immunogenic cell death (ICD) are particularly efficient because they mobilize the host immune system against malignant cells expressing tumor‐associated antigens. Dactinomycin is identified as an ICD inducer and showed to stimulate anticancer immune responses in vivo.
Immunogenic cell death (ICD) induced by anticancer chemotherapeutics is usually preceded by premortem stress affecting the endoplasmic reticulum (ER). This ER stress does not reflect a canonical ...unfolded protein response (UPR) but rather manifests solely at the level of the phosphorylation of eIF2α. eIF2α phosphorylation is hence a quintessential hallmark of ICD that can be detected by immunohistochemistry in tumor samples.
IMPORTANCE: The activating mutation of MYD88 L265P is a frequent feature of primary cutaneous diffuse large B-cell lymphoma, leg-type (PCLBCL-LT), reported in up to 69% of the cases. Whether patients ...with MYD88 mutation display specific clinical and evolutive features has not been evaluated. OBJECTIVE: To identify the clinical characteristics associated with MYD88 mutation, confirm its high prevalence, and evaluate its effect on prognosis in patients with PCLBCL-LT. DESIGN, SETTING, AND PARTICIPANTS: A retrospective multicenter study was conducted using the medical records of patients from dermatology departments belonging to the French Study Group for Cutaneous Lymphomas. Sixty-one patients with a diagnosis of PCLBCL-LT made between 1988 and 2010 who were available for molecular study were included. Of these, 58 patients displaying interpretable results constituted the study group. Median follow-up was 33 months, and 39 patients (67%) were monitored until death. MAIN OUTCOMES AND MEASURES: Clinical features (age, sex, number of skin lesions, tumor stage, and location as leg vs elsewhere), MYD88 mutation (allele-specific TaqMan polymerase chain reaction assay), treatment regimen, and outcome were recorded. Baseline characteristics and outcome were compared according to the status of MYD88. RESULTS: The median age of the patients was 79 years, and 59% were female. Skin lesions were located on the leg in 76% of the cases. Thirty-four of 58 patients (59%) harbored the MYD88 L265P mutation. Patients had similar clinical characteristics at presentation regardless of their MYD88 status, except that those harboring the MYD88 mutation were older (P = .006) and had more frequent involvement of the leg (P = .008). Patients harboring the MYD88 mutation had 3- and 5-year–specific survival rates of 65.7% and 60.2% vs 85.4% and 71.7% in patients with the wild-type allele. The MYD88 mutation was significantly associated with shorter disease-specific survival in univariate (P = .03) and multivariate (odds ratio, 3.01; 95% CI, 1.03-8.78; P = .04) analysis. There was no significant difference between the groups in their treatment regimens. Considering overall survival, in univariate (P = .002) and multivariate (odds ratio, 2.94; 95% CI, 1.18-7.30; P = .02) analysis, MYD88 L265P mutation was an independent adverse prognostic factor. CONCLUSIONS AND RELEVANCE: This study confirms the high prevalence of MYD88 L265P mutation in PCLBCL-LT and shows its association with shorter survival. The clinical effect of MYD88 mutation activating the nuclear factor-κB pathway supports the use of targeted therapies at the time of relapse after conventional therapies.
Osteosarcoma is the main malignant primary bone tumor in children and adolescents for whom the prognosis remains poor, especially when metastasis is present at diagnosis. Because transforming growth ...factor-β (TGFβ) has been shown to promote metastasis in many solid tumors, we investigated the effect of the natural TGFβ/Smad signaling inhibitor Smad7 and the TβRI inhibitor SD-208 on osteosarcoma behavior.
By using a mouse model of osteosarcoma induced by paratibial injection of cells, we assessed the impact of Smad7 overexpression or SD-208 on tumor growth, tumor microenvironment, bone remodeling, and metastasis development.
First, we demonstrated that TGFβ levels are higher in serum samples from patients with osteosarcoma compared with healthy volunteers and that TGFβ/Smad3 signaling pathway is activated in clinical samples. Second, we showed that Smad7 slows the growth of the primary tumor and increases mice survival. We furthermore demonstrated that Smad7 expression does not affect in vitro osteosarcoma cell proliferation but affects the microarchitectural parameters of bone. In addition, Smad7-osteosarcoma bone tumors expressed lower levels of osteolytic factors such as RANKL, suggesting that Smad7 overexpression affects the "vicious cycle" established between tumor cells and bone cells by its ability to decrease osteoclast activity. Finally, we showed that Smad7 overexpression in osteosarcoma cells and the treatment of mice with SD208 inhibit the development of lung metastasis.
Taken together, these results demonstrate that the inhibition of the TGFβ/Smad signaling pathway may be a promising therapeutic strategy against tumor progression of osteosarcoma, specifically against the development of lung metastasis.
The integrated stress response manifests with the phosphorylation of eukaryotic initiation factor 2α (eIF2α) on serine residue 51 and plays a major role in the adaptation of cells to endoplasmic ...reticulum stress in the initiation of autophagy and in the ignition of immune responses. Here, we report that lysosomotropic agents, including azithromycin, chloroquine, and hydroxychloroquine, can trigger eIF2α phosphorylation in vitro (in cultured human cells) and, as validated for hydroxychloroquine, in vivo (in mice). Cells bearing a non-phosphorylatable eIF2α mutant (S51A) failed to accumulate autophagic puncta in response to azithromycin, chloroquine, and hydroxychloroquine. Conversely, two inhibitors of eIF2α dephosphorylation, nelfinavir and salubrinal, enhanced the induction of such autophagic puncta. Altogether, these results point to the unexpected capacity of azithromycin, chloroquine, and hydroxychloroquine to elicit the integrated stress response.
BackgroundPharmacological autophagy enhancement constitutes a preclinically validated strategy for preventing or treating most major age-associated diseases. Driven by this consideration, we ...performed a high-content/high-throughput screen on 65 000 distinct compounds on a robotized fluorescence microscopy platform to identify novel autophagy inducers.ResultsHere, we report the discovery of picropodophyllin (PPP) as a potent inducer of autophagic flux that acts on-target, as an inhibitor of the tyrosine kinase activity of the insulin-like growth factor-1 receptor (IGF1R). Thus, PPP lost its autophagy-stimulatory activity in cells engineered to lack IGF1R or to express a constitutively active AKT serine/threonine kinase 1 (AKT1) mutant. When administered to cancer-bearing mice, PPP improved the therapeutic efficacy of chemoimmunotherapy with a combination of immunogenic cytotoxicants and programmed cell death 1 (PDCD1, better known as PD-1) blockade. These PPP effects were lost when tumors were rendered PPP-insensitive or autophagy-incompetent. In combination with chemotherapy, PPP enhanced the infiltration of tumors by cytotoxic T lymphocytes, while reducing regulatory T cells. In human triple-negative breast cancer patients, the activating phosphorylation of IGF1R correlated with inhibited autophagy, an unfavorable local immune profile, and poor prognosis.ConclusionAltogether, these results suggest that IGF1R may constitute a novel and druggable therapeutic target for the treatment of cancer in conjunction with chemoimmunotherapies.
Autophagy inducers can prevent cardiovascular aging and age-associated diseases including atherosclerosis. Therefore, we hypothesized that autophagy-inducing compounds that act on ...atherosclerosis-relevant cells might have a protective role in the development of atherosclerosis. Here we identified 3,4-dimethoxychalcone (3,4-DC) as an inducer of autophagy in several cell lines from endothelial, myocardial and myeloid/macrophagic origin, as demonstrated by the aggregation of the autophagosome marker GFP-LC3 in the cytoplasm of cells, as well as the downregulation of its nuclear pool indicative of autophagic flux. In this respect, 3,4-DC showed a broader autophagy-inducing activity than another chalcone (4,4- dimethoxychalcone), spermidine and triethylene tetramine. Thus, we characterized the potential antiatherogenic activity of 3,4-DC in two different mouse models, namely, (i) neointima formation with smooth muscle expansion of vein segments grafted to the carotid artery and (ii) genetically predisposed ApoE
mice fed an atherogenic diet. In the vein graft model, local application of 3,4-DC was able to maintain the lumen of vessels and to reduce neointima lesions. In the diet-induced model, intraperitoneal injections of 3,4-DC significantly reduced the number of atherosclerotic lesions in the aorta. In conclusion, 3,4-DC stands out as an autophagy inducer with potent antiatherogenic activity.
Colorectal cancers (CRC) can be classified into four consensus molecular subtypes (CMS), among which CMS1 has the best prognosis, contrasting with CMS4 that has the worst outcome. CMS4 CRC is ...notoriously resistant against therapeutic interventions, as demonstrated by preclinical studies and retrospective clinical observations. Here, we report the finding that two clinically employed agents, everolimus (EVE) and plicamycin (PLI), efficiently target the prototypic CMS4 cell line MDST8. As compared to the prototypic CMS1 cell line LoVo, MDST8 cells treated with EVE or PLI demonstrated stronger cytostatic and cytotoxic effects, increased signs of apoptosis and autophagy, as well as a more pronounced inhibition of DNA-to-RNA transcription and RNA-to-protein translation. Moreover, nontoxic doses of EVE and PLI induced the shrinkage of MDST8 tumors in mice, yet had only minor tumor growth-reducing effects on LoVo tumors. Altogether, these results suggest that EVE and PLI should be evaluated for their clinical activity against CMS4 CRC.
Unlocking cell secretion capacity is of paramount interest for the pharmaceutical industry focused on biologics. Here, we leveraged retention using a selective hook (RUSH) system for the ...identification of human osteosarcoma U2OS cell secretion modulators, through automated, high-throughput screening of small compound libraries. We created a U2OS cell line which co-expresses a variant of streptavidin addressed to the lumen-facing membrane of the endoplasmic reticulum (ER) and a recombinant anti-PD-L1 antibody. The heavy chain of the antibody was modified at its C-terminus, to which a furin cleavage site, a green fluorescent protein (GFP), and a streptavidin binding peptide (SBP) were added. We show that the U2OS cell line stably expresses the streptavidin hook and the recombinant antibody bait, which is retained in the ER through the streptavidin-SBP interaction. We further document that the addition of biotin to the culture medium triggers the antibody release from the ER, its trafficking through the Golgi where the GFP-SBP moiety is clipped off, and eventually its release in the extra cellular space, with specific antigen-binding properties. The use of this clone in screening campaigns led to the identification of lycorine as a secretion enhancer, and nigericin and tyrphostin AG-879 as secretion inhibitors. Altogether, our data support the utility of this approach for the identification of agents that could be used to improve recombinant production yields and also for a better understanding of the regulatory mechanism at work in the conventional secretion pathway.
Melt occurrence in Antarctica is derived from L-band observations from the Soil Moisture and Ocean Salinity (SMOS) satellite between the austral summer 2010–2011 and 2017–2018. The detection ...algorithm is adapted from a threshold method previously developed for 19 GHz passive microwave measurements from the special sensor microwave imager (SSM/I) and special sensor microwave imager sounder (SSMIS). The comparison of daily melt occurrence retrieved from 1.4 and 19 GHz observations shows an overall close agreement, but a lag of few days is usually observed by SMOS at the beginning of the melt season. To understand the difference, a theoretical analysis is performed using a microwave emission radiative transfer model. It shows that the sensitivity of 1.4 GHz signal to liquid water is significantly weaker than at 19 GHz if the water is only present in the uppermost tens of centimetres of the snowpack. Conversely, 1.4 GHz measurements are sensitive to water when spread over at least 1 m and when present in depths up to hundreds of metres. This is explained by the large penetration depth in dry snow and by the long wavelength (21 cm). We conclude that SMOS and higher-frequency radiometers provide interesting complementary information on melt occurrence and on the location of the water in the snowpack.
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