The Journal of Experimental Medicine

Inhibition of the proximal B cell receptor (BCR) signaling pathway by BTK inhibitors is highly effective in the treatment of CLL, but drug resistance or intolerance occurs. Here, we investigated c-Jun N-terminal protein kinase 1 (JNK1) as an alternative drug target in the distal BCR pathway. JNK1 was preferentially overexpressed and activated in poor prognostic CLL with unmutated IGHV. Proximal BCR inhibition (BTK, PI3K, or SYK inhibitors) or SYK knockdown efficiently dephosphorylated JNK1, identifying JNK1 as a critical BCR downstream kinase in CLL. JNK1 inhibition induced apoptosis in primary CLL cells, resulting in the downregulation of BCL2, MCL1, and c-JUN. JNK1 inhibition in patient-derived CLL xenografted mice and Eµ-TCL1-tg mice prevented CLL progression, reduced splenic infiltration, and restored T cell function and normal hematopoiesis. JNK1 inhibitors even remained effective in ibrutinib refractory CLL. In conclusion, our study revealed JNK1 as a promising drug target in CLL downstream of the BCR, overcoming ibrutinib resistance, blocking the protective microenvironment, and improving CLL-specific immunosuppressive mechanisms.

doi: 10.1084/jem.20231106pmid: 39585348

Despite the established use of immune checkpoint inhibitors (ICIs) to treat non-small cell lung cancer (NSCLC), only a subset of patients benefit from treatment and ∼50% of patients whose tumors respond eventually develop acquired resistance (AR). To identify novel drivers of AR, we generated murine Msh2 knock-out (KO) lung tumors that initially responded but eventually developed AR to anti-PD-1, alone or in combination with anti-CTLA-4. Resistant tumors harbored decreased infiltrating T cells and reduced cancer cell-intrinsic MHC-I and MHC-II levels, yet remained responsive to IFNγ. Resistant tumors contained extensive regions of hypoxia, and a hypoxia signature derived from single-cell transcriptional profiling of resistant cancer cells was associated with decreased progression-free survival in a cohort of NSCLC patients treated with anti-PD-1/PD-L1 therapy. Targeting hypoxic tumor regions using a hypoxia-activated pro-drug delayed AR to ICIs in murine Msh2 KO tumors. Thus, this work provides a rationale for targeting tumor metabolic features, such as hypoxia, in combination with immune checkpoint inhibition.

doi: 10.1084/jem.20241442pmid: 39636298

Tumor-associated neutrophils (TANs) are heterogeneous; thus, their roles in tumor development could vary depending on the cancer type. Here, we showed that TANs affect metabolic dysfunction-associated steatohepatitis hepatocellular carcinoma (MASH-related HCC) more than viral-associated HCC. We attributed this difference to the predominance of SiglecFhi TANs in MASH-related HCC tumors. Linoleic acid and GM-CSF, which are commonly elevated in the MASH-related HCC microenvironment, fostered the development of this c-Myc–driven TAN subset. Through TGFβ secretion, SiglecFhi TANs promoted HCC stemness, proliferation, and migration. Importantly, SiglecFhi TANs supported immune evasion by directly suppressing the antigen presentation machinery of tumor cells. SiglecFhi TAN removal increased the immunogenicity of a MASH-related HCC model and sensitized it to immunotherapy. Likewise, a high SiglecFhi TAN signature was associated with poor prognosis and immunotherapy resistance in HCC patients. Overall, our study highlights the importance of understanding TAN heterogeneity in cancer to improve therapeutic development.

doi: 10.1084/jem.20240765pmid: 39652422

The cohesin complex is a critical regulator of gene expression. STAG2 is the most frequently mutated cohesin subunit across several cancer types and is a key tumor suppressor in lung cancer. Here, we coupled somatic CRISPR-Cas9 genome editing and tumor barcoding with an autochthonous oncogenic KRAS-driven lung cancer model and showed that STAG2 is uniquely tumor-suppressive among all core and auxiliary cohesin components. The heterodimeric complex components PAXIP1 and PAGR1 have highly correlated effects with STAG2 in human lung cancer cell lines, are tumor suppressors in vivo, and are epistatic to STAG2 in oncogenic KRAS-driven lung tumorigenesis in vivo. STAG2 inactivation elicits changes in gene expression, chromatin accessibility, and 3D genome conformation that impact the cancer cell state. Gene expression and chromatin accessibility similarities between STAG2- and PAXIP1-deficient neoplastic cells further relate STAG2-cohesin to PAXIP1/PAGR1. These findings reveal a STAG2-PAXIP1/PAGR1 tumor-suppressive axis and uncover novel PAXIP1-dependent and PAXIP1-independent STAG2-cohesin–mediated mechanisms of lung tumor suppression.

doi: 10.1084/jem.20220979pmid: 39560673

The importance of calcium (Ca2+) as a second messenger in T cell signaling is exemplified by genetic deficiencies of STIM1 and ORAI1, which abolish store-operated Ca2+ entry (SOCE) resulting in combined immunodeficiency (CID). We report five unrelated patients with de novo missense variants in ITPR3, encoding a subunit of the inositol 1,4,5-trisphosphate receptor (IP3R), which forms a Ca2+ channel in the endoplasmic reticulum (ER) membrane responsible for the release of ER Ca2+ required to trigger SOCE, and for Ca2+ transfer to other organelles. The patients presented with CID, abnormal T cell Ca2+ homeostasis, incompletely penetrant ectodermal dysplasia, and multisystem disease. Their predominant T cell immunodeficiency is characterized by significant T cell lymphopenia, defects in late stages of thymic T cell development, and impaired function of peripheral T cells, including inadequate NF-κB- and NFAT-mediated, proliferative, and metabolic responses to activation. Pathogenicity is not due to haploinsufficiency, rather ITPR3 protein variants interfere with IP3R channel function leading to depletion of ER Ca2+ stores and blunted SOCE in T cells.