<p>Supplementary Table S3 contains the list of genes that are significantly upregulated by both BCL2 inhibitor and Bcl2 knockout, as well as their link to the Type 1 IFN responses</p>
The excessive prescription of antimicrobial agents and their use as animal growth promoters lead to the spread of resistance among pathogenic bacteria. Consequently, unnecessary use should be minimized, and new chemicals with novel mechanisms of action are needed. The authors have developed a fast method to measure the activity of antibiotics by means of a genetically engineered strain of Escherichia coli K-12. The system is based on the full-length bacterial luciferase operon coupled to the tetracycline-inducible tetA promoter in the reporter plasmid pTetLux1. Sublethal doses of tetracycline are used to start the luciferase synthesis in cultures that were previously incubated with the antibiotic under investigation. After a variable time frame-from 1 to 4 h, depending on the antimicrobial mode of action-the level of light emission from treated cultures is compared to the level obtained in control cultures. The gap in bioluminescence outlines the antibiotic interference in bacterial metabolism. Throughout this study, freeze-dried sensor cells were used to avoid repeated cultures from day to day. The authors show the results of 10 model antibiotics, representing different molecular structures and mechanisms of action. The results show that no actively dividing cells are needed for sensitive responses, especially when transcriptional and translational inhibitors, directly interfering with the luciferase production, are tested. The assay can be easily automated for high-throughput screening purposes of pharmaceutical industry.
By means of an unbiased, automated fluorescence microscopy-based screen, we identified the epidermal growth factor receptor (EGFR) inhibitors erlotinib and gefitinib as potent enhancers of the differentiation of HL-60 acute myeloid leukemia (AML) cells exposed to suboptimal concentrations of vitamin A (all-trans retinoic acid, ATRA) or vitamin D (1α,25-hydroxycholecalciferol, VD). Erlotinib and gefitinib alone did not promote differentiation, yet stimulated the acquisition of morphological and biochemical maturation markers (including the expression of CD11b and CD14 as well as increased NADPH oxidase activity) when combined with either ATRA or VD. Moreover, the combination of erlotinib and ATRA or VD synergistically induced all the processes that are normally linked to terminal hematopoietic differentiation, namely, a delayed proliferation arrest in the G0/G1 phase of the cell cycle, cellular senescence, and apoptosis. Erlotinib potently inhibited the (auto)phosphorylation of mitogen-activated protein kinase 14 (MAPK14, best known as p38MAPK) and SRC family kinases (SFKs). If combined with the administration of ATRA or VD, the inhibition of p38MAPK or SFKs with specific pharmacological agents mimicked the pro-differentiation activity of erlotinib. These data were obtained with 2 distinct AML cell lines (HL-60 and MOLM-13 cells) and could be confirmed on primary leukemic blasts isolated from the circulation of AML patients. Altogether, these findings point to a new regimen for the treatment of AML, in which naturally occurring pro-differentiation agents (ATRA or VD) may be combined with EGFR inhibitors.
BCL2 robustly preserves mitochondrial integrity, hence inhibiting innate immune signaling and apoptotic cell death in several cell types. Here, we comment on our recent data demonstrating that BCL2 also limits the ability of dendritic cells to elicit adaptive immune responses, lending support to a universal immunosuppressive function for the mitochondrial immune checkpoint.
Hormone receptor (HR)+breast cancer (BC) is responsible for the majority of BCs and -related deaths in the US.1 Standard treatment for local disease involves surgery, followed by adjuvant endocrine therapy (ET) ± radiation therapy (RT) and/or chemotherapy (CT), depending on risk for relapse. However, many women receive CT and experience its severe side effect to benefit only a few. Immune checkpoint inhibitors (ICIs) have successfully been implemented in the management of other solid tumors like melanoma.2 Conversely, the clinical experience with single-agent ICIs has been disappointing in patients with HR+ BC3, at least in part reflecting a limited immune infiltration at baseline and calling for the development of combinatorial regimens unlocking ICI efficacy in this patient population. In this setting, progress has also been hampered by the lack of a preclinical model that would faithfully recapitulated key immunobiological features of human HR+ BC. We have recently demonstrated that endogenous mammary carcinomas driven in immunocompetent mice by medroxyprogesterone acetate (M) plus 7,12-dimethylbenz[a]anthracene (D) represent a superior preclinical model to study HR+BC resistance to ICI and identify strategies to overcome it.4
Methods
We established M/D-driven mammary carcinomas in immunocompetent, female C57BL/6 mice and randomized them to: (1) no treatment; (2) PD1 clockers (on d0/d3/d6 or d3/d6/d9); (3) RT (3x10 Gy on d0/d1/d2); (4) recombinant FLT3L (from d0-d9 or d3-d12), or all the 2- and 3-agent combinations thereof. Besides monitoring local and systemic tumor control, we collected tumors for RNAseq, and spleens for immunoprofiling by flow cytometry.
Results
RT controls primary ICI-resistant M/D-driven carcinomas and extends the overall survival (OS) of the hosts, with marginal benefits from the addition of a PD-1 blocker. Recombinant FLT3L improves local tumor control by RT, but fails to ameliorate OS, mainly due to compromised control of distant, unirradiated lesions. RT followed by PD-1 blockage plus recombinant FLT3L is superior to all other approaches at primary tumor control and exhibits a trend for improved OS over RT alone, reflecting partial control of distant lesions.
Conclusions
RT is highly effective in ICI-resistant HR+ BC tumors. Combination of RT with different immunotherapeutics alters the pattern of local vs systemic disease progression. This may define immunological signatures potentially linked to resistance/sensitivity and identify novel target to break through the resistance of HR+ BC to immunotherapy.
References
Siegel RL, KD Miller, and A Jemal. Cancer statistics, 2020. CA Cancer J Clin, 2020. 70(1): 7–30. Girault I, et al. A PD-1/PD-L1 Proximity Assay as a Theranostic Marker for PD-1 Blockade in Patients with Metastatic Melanoma. Clin Cancer Res, 2022;28(3): 518–525. Ascierto PA, et al. Perspectives in immunotherapy: meeting report from the immunotherapy bridge (December 2nd-3rd, 2020, Italy). J Transl Med, 2021;19(1): 238. Buque A, et al. Immunoprophylactic and immunotherapeutic control of hormone receptor-positive breast cancer. Nat Commun, 2020. 11(1): 3819.
Ethics Approval
This study was approved by Weill Cornell Medical College Institutional Animal Care and Use Committee; Protocol Number 2018-0053
