Three-Dimensional Structure of Novel Liver Cancer Biomarker Liver Cancer-Specific Serine Protease Inhibitor Kazal (LC-SPIK) and Its Performance in Clinical Diagnosis of Hepatocellular Carcinoma (HCC).

LC-SPIK is a liver cancer-specific isoform of Serine Protease Inhibitor Kazal and has been proposed as a new biomarker for the detection of HCC given its unique 3D structure, which differs from normal pancreatic SPIK. An ELISA technology based on its unique structure was developed to use LC-SPIK as an effective biomarker for the clinical diagnosis of HCC. AFP, the most widely used biomarker for HCC surveillance currently, suffers from poor clinical performance, especially in the detection of early-stage HCC. In one case-control study, which included 164 HCC patients and 324 controls, LC-SPIK had an AUC of 0.87 compared to only 0.70 for AFP in distinguishing HCC from liver disease controls (cirrhosis, HBV/HCV). LC-SPIK also performed significantly better than AFP for the 81 patients with early-stage HCC (BCLC stage 0 and A), with an AUC of 0.85 compared to only 0.61 for AFP. Cirrhosis is the major risk factor for HCC; about 80% of patients with newly diagnosed HCC have preexisting cirrhosis. LC-SPIK's clinical performance was also studied in HCC patients with viral and non-viral cirrhosis, including cirrhosis caused by metabolic dysfunction-associated steatotic liver disease (MASLD) and alcoholic liver disease (ALD). In a total of 163 viral cirrhosis patients with 93 HCC patients (50 early-stage), LC-SPIK had an AUC of 0.85, while AFP had an AUC of 0.70. For patients with early-stage HCC, LC-SPIK had a similar AUC of 0.83, while AFP had an AUC of only 0.60. For 120 patients with nonviral cirrhosis, including 62 HCC (23 early-stage) patients, LC-SPIK had an AUC of 0.84, while AFP had an AUC of only 0.72. For the 23 patients with early-stage HCC, LC-SPIK had a similar AUC of 0.83, while the AUC for AFP decreased to 0.65. All these results suggest that LC-SPIK exhibits significantly better performance in the detection of HCC than AFP in all etiologies of liver diseases. In addition, LC-SPIK accurately detected the presence of HCC in 71-91% of HCC patients with false-negative AFP test results in viral-associated HCC and non-viral-associated HCC.

SOX10 Loss Sensitizes Melanoma Cells to Cytokine-Mediated Inflammatory Cell Death.

The transcription factor, SOX10, plays an important role in the differentiation of neural crest precursors to the melanocytic lineage. Malignant transformation of melanocytes leads to the development of melanoma, and SOX10 promotes melanoma cell proliferation and tumor formation. SOX10 expression in melanomas is heterogeneous, and loss of SOX10 causes a phenotypic switch toward an invasive, mesenchymal-like cell state and therapy resistance; hence, strategies to target SOX10-deficient cells are an active area of investigation. The impact of cell state and SOX10 expression on antitumor immunity is not well understood but will likely have important implications for immunotherapeutic interventions. To this end, we tested whether SOX10 status affects the response to CD8+ T cell-mediated killing and T cell-secreted cytokines, TNFα and IFNγ, which are critical effectors in the cytotoxic killing of cancer cells. We observed that genetic ablation of SOX10 rendered melanoma cells more sensitive to CD8+ T cell-mediated killing and cell death induction by either TNFα or IFNγ. Cytokine-mediated cell death in SOX10-deficient cells was associated with features of caspase-dependent pyroptosis, an inflammatory form of cell death that has the potential to increase immune responses. IMPLICATIONS: These data support a role for SOX10 expression altering the response to T cell-mediated cell death and contribute to a broader understanding of the interaction between immune cells and melanoma cells.

Targeting TEAD-ious resistance.

Recent advances in targeting mutant KRAS are limited by resistance. A recent study in Nature Cancer by Hagenbeek et al. utilizes a novel inhibitor that targets the TEAD transcription factor, GNE-7883, to overcome resistance to KRAS inhibitors. Thus, TEAD inhibitors may maximize the durability of KRAS inhibitors in patients with cancer.

Host obesity alters the ovarian tumor immune microenvironment and impacts response to standard of care chemotherapy.

BACKGROUND: The majority of women with epithelial ovarian cancer (OvCa) are diagnosed with metastatic disease, resulting in a poor 5-year survival of 31%. Obesity is a recognized non-infectious pandemic that increases OvCa incidence, enhances metastatic success and reduces survival. We have previously demonstrated a link between obesity and OvCa metastatic success in a diet-induced obesity mouse model wherein a significantly enhanced tumor burden was associated with a decreased M1/M2 tumor-associated macrophage ratio (Liu Y et al. Can, Res. 2015; 75:5046-57). METHODS: The objective of this study was to use pre-clinical murine models of diet-induced obesity to evaluate the effect of a high fat diet (HFD) on response to standard of care chemotherapy and to assess obesity-associated changes in the tumor microenvironment. Archived tumor tissues from ovarian cancer patients of defined body mass index (BMI) were also evaluated using multiplexed immunofluorescence analysis of immune markers. RESULTS: We observed a significantly diminished response to standard of care paclitaxel/carboplatin chemotherapy in HFD mice relative to low fat diet (LFD) controls. A corresponding decrease in the M1/M2 macrophage ratio and enhanced tumor fibrosis were observed both in murine DIO studies and in human tumors from women with BMI > 30. CONCLUSIONS: Our data suggest that the reported negative impact of obesity on OvCa patient survival may be due in part to the effect of the altered M1/M2 tumor-associated macrophage ratio and enhanced fibrosis on chemosensitivity. These data demonstrate a contribution of host obesity to ovarian tumor progression and therapeutic response and support future combination strategies targeting macrophage polarization and/or fibrosis in the obese host.

Targeting Upregulated cIAP2 in SOX10-Deficient Drug Tolerant Melanoma.

Drug tolerance and minimal residual disease (MRD) are likely to prelude acquired resistance to targeted therapy. Mechanisms that allow persister cells to survive in the presence of targeted therapy are being characterized but selective vulnerabilities for these subpopulations remain uncertain. We identified cellular inhibitor of apoptosis protein 2 (cIAP2) as being highly expressed in SOX10-deficient drug tolerant persister (DTP) melanoma cells. Here, we show that cIAP2 is sufficient to induce tolerance to MEK inhibitors, likely by decreasing the levels of cell death. Mechanistically, cIAP2 is upregulated at the transcript level in SOX10-deficient cells and the AP-1 complex protein, JUND, is required for its expression. Using a patient-derived xenograft model, we demonstrate that treatment with the cIAP1/2 inhibitor, birinapant, during the MRD phase delays the onset of resistance to BRAF inhibitor and MEK inhibitor combination therapy. Together, our data suggest that cIAP2 upregulation in SOX10-deficient subpopulations of melanoma cells induces drug tolerance to MAPK targeting agents and provides a rationale to test a novel therapeutical approach to target MRD.

Differential recognition of canonical NF-κB dimers by Importin α3.

Nuclear translocation of the p50/p65 heterodimer is essential for NF-κB signaling. In unstimulated cells, p50/p65 is retained by the inhibitor IκBα in the cytoplasm that masks the p65-nuclear localization sequence (NLS). Upon activation, p50/p65 is translocated into the nucleus by the adapter importin α3 and the receptor importin ß. Here, we describe a bipartite NLS in p50/p65, analogous to nucleoplasmin NLS but exposed in trans. Importin α3 accommodates the p50- and p65-NLSs at the major and minor NLS-binding pockets, respectively. The p50-NLS is the predominant binding determinant, while the p65-NLS induces a conformational change in the Armadillo 7 of importin α3 that stabilizes a helical conformation of the p65-NLS. Neither conformational change was observed for importin α1, which makes fewer bonds with the p50/p65 NLSs, explaining the preference for α3. We propose that importin α3 discriminates between the transcriptionally active p50/p65 heterodimer and p50/p50 and p65/65 homodimers, ensuring fidelity in NF-κB signaling.

Inability to switch from ARID1A-BAF to ARID1B-BAF impairs exit from pluripotency and commitment towards neural crest formation in ARID1B-related neurodevelopmental disorders.

Subunit switches in the BAF chromatin remodeler are essential during development. ARID1B and its paralog ARID1A encode for mutually exclusive BAF subunits. De novo ARID1B haploinsufficient mutations cause neurodevelopmental disorders, including Coffin-Siris syndrome, which is characterized by neurological and craniofacial features. Here, we leveraged ARID1B+/- Coffin-Siris patient-derived iPSCs and modeled cranial neural crest cell (CNCC) formation. We discovered that ARID1B is active only during the first stage of this process, coinciding with neuroectoderm specification, where it is part of a lineage-specific BAF configuration (ARID1B-BAF). ARID1B-BAF regulates exit from pluripotency and lineage commitment by attenuating thousands of enhancers and genes of the NANOG and SOX2 networks. In iPSCs, these enhancers are maintained active by ARID1A-containing BAF. At the onset of differentiation, cells transition from ARID1A- to ARID1B-BAF, eliciting attenuation of the NANOG/SOX2 networks and triggering pluripotency exit. Coffin-Siris patient cells fail to perform the ARID1A/ARID1B switch, and maintain ARID1A-BAF at the pluripotency enhancers throughout all stages of CNCC formation. This leads to persistent NANOG/SOX2 activity which impairs CNCC formation. Despite showing the typical neural crest signature (TFAP2A/SOX9-positive), ARID1B-haploinsufficient CNCCs are also aberrantly NANOG-positive. These findings suggest a connection between ARID1B mutations, neuroectoderm specification and a pathogenic mechanism for Coffin-Siris syndrome.

In vivo selection of highly metastatic human ovarian cancer sublines reveals role for AMIGO2 in intra-peritoneal metastatic regulation.

The majority of women with ovarian cancer are diagnosed with metastatic disease, therefore elucidating molecular events that contribute to successful metastatic dissemination may identify additional targets for therapeutic intervention and thereby positively impact survival. Using two human high grade serous ovarian cancer cell lines with inactive TP53 and multiple rounds of serial in vivo passaging, we generated sublines with significantly accelerated intra-peritoneal (IP) growth. Comparative analysis of the parental and IP sublines identified a common panel of differentially expressed genes. The most highly differentially expressed gene, upregulated by 60-65-fold in IP-selected sublines, was the type I transmembrane protein AMIGO2. As the role of AMIGO2 in ovarian cancer metastasis remains unexplored, CRISPR/Cas9 was used to reduce AMIGO2 expression, followed by in vitro and in vivo functional analyses. Knockdown of AMIGO2 modified the sphere-forming potential of ovarian cancer cells, reduced adhesion and invasion in vitro, and significantly attenuated IP metastasis. These data highlight AMIGO2 as a new target for a novel anti-metastatic therapeutic approach aimed at blocking cohesion, survival, and adhesion of metastatic tumorspheres.