CD73-Dependent Adenosine Signaling through Adora2b Drives Immunosuppression in Ductal Pancreatic Cancer

The microenvironment that surrounds pancreatic ductal adenocarcinoma (PDAC) is profoundly desmoplastic and immunosuppressive. Understanding triggers of immunosuppression during the process of pancreatic tumorigenesis would aid in establishing targets for effective prevention and therapy. Here, we interrogated differential molecular mechanisms dependent on cell of origin and subtype that promote immunosuppression during PDAC initiation and in established tumors. Transcriptomic analysis of cell-of-origin-dependent epithelial gene signatures revealed that Nt5e/CD73, a cell-surface enzyme required for extracellular adenosine generation, is one of the top 10% of genes overexpressed in murine tumors arising from the ductal pancreatic epithelium as opposed to those rising from acinar cells. These findings were confirmed by IHC and high-performance liquid chromatography. Analysis in human PDAC subtypes indicated that high Nt5e in murine ductal PDAC models overlaps with high NT5E in human PDAC squamous and basal subtypes, considered to have the highest immunosuppression and worst prognosis. Multiplex immunofluorescent analysis showed that activated CD8+ T cells in the PDAC tumor microenvironment express high levels of CD73, indicating an opportunity for immunotherapeutic targeting. Delivery of CD73 small-molecule inhibitors through various delivery routes reduced tumor development and growth in genetically engineered and syngeneic mouse models. In addition, the adenosine receptor Adora2b was a determinant of adenosine-mediated immunosuppression in PDAC. These findings highlight a molecular trigger of the immunosuppressive PDAC microenvironment elevated in the ductal cell of origin, linking biology with subtype classification, critical components for PDAC immunoprevention and personalized approaches for immunotherapeutic intervention.

SIGNIFICANCE

Ductal-derived pancreatic tumors have elevated epithelial and CD8+GZM+ T-cell CD73 expression that confers sensitivity to small-molecule inhibition of CD73 or Adora2b to promote CD8+ T-cell-mediated tumor regression. See related commentary by DelGiorno, p. 977.

Impad1 and Syt11 work in an epistatic pathway that regulates EMT-mediated vesicular trafficking to drive lung cancer invasion and metastasis

Lung cancer is a highly aggressive and metastatic disease responsible for approximately 25% of all cancer-related deaths in the United States. Using high-throughput in vitro and in vivo screens, we have previously established Impad1 as a driver of lung cancer invasion and metastasis. Here we elucidate that Impad1 is a direct target of the epithelial microRNAs (miRNAs) miR-200 and miR~96 and is de-repressed during epithelial-to-mesenchymal transition (EMT); thus, we establish a mode of regulation of the protein. Impad1 modulates Golgi apparatus morphology and vesicular trafficking through its interaction with a trafficking protein, Syt11. These changes in Golgi apparatus dynamics alter the extracellular matrix and the tumor microenvironment (TME) to promote invasion and metastasis. Inhibiting Impad1 or Syt11 disrupts the cancer cell secretome, regulates the TME, and reverses the invasive or metastatic phenotype. This work identifies Impad1 as a regulator of EMT and secretome-mediated changes during lung cancer progression.

Metastasis remains the primary cause of cancer-related deaths, and a better understanding of the process will determine new therapeutic avenues. Bajaj et al. show that the Golgi apparatus and Golgi apparatus-associated proteins play a key role in determining tumor metastasis, indicating the importance of targeting the organelle during cancer.

The microRNA-183/96/182 cluster inhibits lung cancer progression and metastasis by inducing an interleukin-2-mediated antitumor CD8+ cytotoxic T-cell response

Here, Kundu et al. investigated the role of the microRNA-183/96/182 cluster (m96cl) in lung cancer and used a novel conditional m96cl mouse to establish that loss of m96cl accelerated the growth of K-Ras mutant autochthonous lung adenocarcinomas. Overall, the authors identified a novel mechanistic role of the m96cl in the suppression of lung cancer growth and metastasis by inducing an IL2-mediated systemic CD8⁺ CTL immune response.

One of the mechanisms by which cancer cells acquire hyperinvasive and migratory properties with progressive loss of epithelial markers is the epithelial-to-mesenchymal transition (EMT). We have previously reported that in different cancer types, including nonsmall cell lung cancer (NSCLC), the microRNA-183/96/182 cluster (m96cl) is highly repressed in cells that have undergone EMT. In the present study, we used a novel conditional m96cl mouse to establish that loss of m96cl accelerated the growth of Kras mutant autochthonous lung adenocarcinomas. In contrast, ectopic expression of the m96cl in NSCLC cells results in a robust suppression of migration and invasion in vitro, and tumor growth and metastasis in vivo. Detailed immune profiling of the tumors revealed a significant enrichment of activated CD8⁺ cytotoxic T lymphocytes (CD8⁺ CTLs) in m96cl-expressing tumors, and m96cl-mediated suppression of tumor growth and metastasis was CD8⁺ CTL-dependent. Using coculture assays with naïve immune cells, we show that m96cl expression drives paracrine stimulation of CD8⁺ CTL proliferation and function. Using tumor microenvironment-associated gene expression profiling, we identified that m96cl elevates the interleukin-2 (IL2) signaling pathway and results in increased IL2-mediated paracrine stimulation of CD8⁺ CTLs. Furthermore, we identified that the m96cl modulates the expression of IL2 in cancer cells by regulating the expression of transcriptional repressors Foxf2 and Zeb1, and thereby alters the levels of secreted IL2 in the tumor microenvironment. Last, we show that in vivo depletion of IL2 abrogates m96cl-mediated activation of CD8⁺ CTLs and results in loss of metastatic suppression. Therefore, we have identified a novel mechanistic role of the m96cl in the suppression of lung cancer growth and metastasis by inducing an IL2-mediated systemic CD8⁺ CTL immune response.

Dance of The Golgi: Understanding Golgi Dynamics in Cancer Metastasis

The Golgi apparatus is at the center of protein processing and trafficking in normal cells. Under pathological conditions, such as in cancer, aberrant Golgi dynamics alter the tumor microenvironment and the immune landscape, which enhances the invasive and metastatic potential of cancer cells. Among these changes in the Golgi in cancer include altered Golgi orientation and morphology that contribute to atypical Golgi function in protein trafficking, post-translational modification, and exocytosis. Golgi-associated gene mutations are ubiquitous across most cancers and are responsible for modifying Golgi function to become pro-metastatic. The pharmacological targeting of the Golgi or its associated genes has been difficult in the clinic; thus, studying the Golgi and its role in cancer is critical to developing novel therapeutic agents that limit cancer progression and metastasis. In this review, we aim to discuss how disrupted Golgi function in cancer cells promotes invasion and metastasis.

Molecular evidence for an intrinsic circadian pacemaker in the cardiac ganglion of the American lobster, Homarus americanus - Is diel cycling of heartbeat frequency controlled by a peripheral clock system?

Whether cardiac output in decapod crustaceans is under circadian control has long been debated, with mixed evidence for and against the hypothesis. Moreover, the locus of the clock system controlling cardiac activity, if it is under circadian control, is unknown. However, a report that the crayfish heart in organ culture maintains a circadian oscillation in heartbeat frequency suggests the presence of a peripheral pacemaker within the cardiac neuromuscular system itself. Because the decapod heart is neurogenic, with contractions controlled by the five motor and four premotor neurons that make up the cardiac ganglion (CG), a likely locus for a circadian clock is the CG itself. Here, a CG-specific transcriptome was generated for the lobster, Homarus americanus, and was used to assess the presence/absence of transcripts encoding putative clock-related proteins in the ganglion. Using known Homarus brain/eyestalk ganglia clock-related proteins as queries, BLAST searches of the CG transcriptome were conducted for the five proteins that form the core clock, i.e., clock, cryptochrome 2, cycle, period and timeless, as well as for a variety of clock-associated, clock input pathway and clock output pathway proteins. With the exception of pigment dispersing hormone receptor [PDHR], a putative clock output pathway protein, one or more transcripts encoding each of the proteins searched for were identified from the CG assembly; no PDHR-encoding transcripts were found. RT-PCR confirmed the expression of all core clock transcripts in multiple independent CG cDNAs; RNA-Seq data suggest that both the motor and premotor neurons could contribute to the cellular locus of a pacemaker. These data provide support for the possible existence of an intrinsic circadian clock in the H. americanus CG, and form a foundation for guiding future anatomical, molecular and physiological investigations of circadian signaling in the lobster cardiac neuromuscular system.

Circadian signaling in Homarus americanus: Region-specific de novo assembled transcriptomes show that both the brain and eyestalk ganglia possess the molecular components of a putative clock system

Essentially all organisms exhibit recurring patterns of physiology/behavior that oscillate with a period of ~24-h and are synchronized to the solar day. Crustaceans are no exception, with robust circadian rhythms having been documented in many members of this arthropod subphylum. However, little is known about the molecular underpinnings of their circadian rhythmicity. Moreover, the location of the crustacean central clock has not been firmly established, although both the brain and eyestalk ganglia have been hypothesized as loci. The American lobster, Homarus americanus, is known to exhibit multiple circadian rhythms, and immunodetection data suggest that its central clock is located within the eyestalk ganglia rather than in the brain. Here, brain- and eyestalk ganglia-specific transcriptomes were generated and used to assess the presence/absence of transcripts encoding the commonly recognized protein components of arthropod circadian signaling systems in these two regions of the lobster central nervous system. Transcripts encoding putative homologs of the core clock proteins clock, cryptochrome 2, cycle, period and timeless were found in both the brain and eyestalk ganglia assemblies, as were transcripts encoding similar complements of putative clock-associated, clock input pathway and clock output pathway proteins. The presence and identity of transcripts encoding core clock proteins in both regions were confirmed using PCR. These findings suggest that both the brain and eyestalk ganglia possess all of the molecular components needed for the establishment of a circadian signaling system. Whether the brain and eyestalk clocks are independent of one another or represent a single timekeeping system remains to be determined. Interestingly, while most of the proteins deduced from the identified transcripts are shared by both the brain and eyestalk ganglia, assembly-specific isoforms were also identified, e.g., several period variants, suggesting the possibility of region-specific variation in clock function, especially if the brain and eyestalk clocks represent independent oscillators.