Cancer remains one of the most formidable challenges in the medical field in this century, largely because of its poorly understood pathogenesis. Fortunately, recent advancements in the understanding of cancer pathogenesis have helped identify more therapeutic targets for improved treatment outcomes. The WNT signaling pathways are highly conserved cascades that participate in diverse physiologic processes, such as embryonic development, tissue homeostasis, and tissue regeneration. Ferroptosis, a unique iron-dependent form of cell death that is distinct from apoptosis, is driven by lipid peroxidation and excessive reactive oxygen species production. Emerging evidence shows that the dysregulation of WNT signaling pathways and ferroptosis, as well as their intricate cross-talk, plays crucial roles in cancer progression and therapeutic resistance, indicating their potential as targets for cancer therapies. This review provides a comprehensive overview of the current understanding of the cross-talk between WNT signaling pathways and ferroptosis in the pathogenesis and progression of cancer, with a specific focus on the regulatory role of the canonical WNT cascade in cancer-related ferroptosis. In addition, we discuss the pharmacologic mechanisms of current strategies that inhibit canonical WNT signaling and/or induce ferroptosis in cancer treatment. We propose that combining canonical WNT pathway inhibitors and ferroptosis inducers with current therapies represents a promising therapeutic strategy for personalized cancer treatment.

Patients with triple negative breast cancer (TNBC) and comorbid Type 2 Diabetes (T2D), characterized by insulin resistance of adipose tissue, have higher risk of metastasis and shorter survival. Adipocytes are the main non-malignant cells of the breast tumor microenvironment (TME). However, adipocyte metabolism is usually ignored in oncology and mechanisms that couple T2D to TNBC outcomes are poorly understood. Here we hypothesized that exosomes, small vesicles secreted by TME breast adipocytes, drive epithelial-to-mesenchymal transition (EMT) and metastasis in TNBC via miRNAs. Exosomes were purified from conditioned media of 3T3-L1 mature adipocytes, either insulin-sensitive (IS) or insulin-resistant (IR). Murine 4T1 cells, a TNBC model, were treated with exosomes in vitro (72h). EMT, proliferation and angiogenesis were elevated in IR vs. control and IS. Brain metastases showed more mesenchymal morphology and EMT enrichment in the IR group. MiR- 145a-3p is highly differentially expressed between IS and IR, and potentially regulates metastasis. Implications: IR adipocyte exosomes modify the TME, enhance EMT, and promote brain metastasis-likely via miRNA pathways-suggesting that metabolic diseases like T2D foster a pro-metastatic TME, reducing survival, warranting close monitoring and potential metabolic interventions in TNBC patients with T2D.

Protein homeostasis is critical to the survival of multiple myeloma (MM) cells. While this is targeted with proteasome inhibitors, mRNA translation inhibition has not entered trials. Recent work illustrates broad sensitivity MM cells to the translation inhibitor omacetaxine. We hypothesized that understanding how MM becomes resistant will lead to the development of drug combinations to prevent or delay relapse. We generated omacetaxine resistance in H929 and MM1S MM cell lines and compared them to parental lines. Resistant lines displayed decreased sensitivity to omacetaxine, with EC50 > 100 nM, compared to parental sensitivity of 24-54 nM. Since omacetaxine inhibits protein synthesis, we performed both RNA-sequencing and ribosome profiling (Ribo-seq) to identify shared and unique regulatory strategies of resistance. Transcripts encoding translation factors and containing Terminal OligoPyrimidine (TOP) sequence in their 5' UTR were translationally upregulated in both resistant cell lines. The mTOR pathway promotes the translation of TOP motif containing mRNAs. Indeed, mTOR inhibition with Torin 1 restored partial sensitivity to omacetaxine in both resistant cell lines. The combination was synergistic in omacetaxine naïve MM cell lines, and a combination effect was observed in vivo. Primary MM cells from patient samples were also sensitive to the combination. These results provide a rational approach for omacetaxine-based combination in patients with multiple myeloma, which have historically shown better responses to multi-agent regimens. Implications: Through the use of ribosome profiling, our findings indicate mTOR inhibition as a novel combination therapy for partnering with the translation inhibitor omacetaxine in the treatment of multiple myeloma.

The complex composition and dynamic change of the tumor microenvironment (TME), mainly consisting of tumor cells, immune cells, stromal cells and extracellular components, significantly impedes the effector function of cytotoxic T cells (CTLs) and thus represents a major obstacle for tumor immunotherapies. In this review, we summarize and discuss the impacts and underlying mechanisms of major elements in the TME (different cell types, extracellular matrix, nutrients and metabolites, etc.) on the infiltration, survival and effector functions of T cells, mainly CD8+ CTLs. Moreover, we also highlight recent advances that may potentiate endogenous anti-tumor immunity and improve the efficacy of T-cell based immunotherapies in cancer patients by manipulating components inside/outside of the TME. A deeper understanding of the effects and action mechanisms of TME components on the tumor-eradicating ability of CTLs may pave the way for discovering new targets to augment endogenous anti-tumor immunity and for designing combinational therapeutic regimens to enhance the efficacy of tumor immunotherapies in clinic.

The E3 ubiquitin ligase RNF6 has been widely recognized for its role in promoting tumorigenesis in multiple cancers. However, we found it is downregulated in lung adenocarcinoma (LUAD) and the molecular rationale for this discrepancy remains unclear. In the present study, we find that RNF6 but not its ΔRING inactive form inhibits LUAD cell proliferation and migration and sensitizes LUAD to chemotherapy. To understand the molecular mechanism, we utilize affinity purification/tandem mass spectrometry to analyze RNF6-interacting proteins and find that cyclin D2 (CCND2), a key regulator of the G1/S transition in the cell cycle. RNF6 physically binds to CCND2 and mediates its K48-linked polyubiquitination and subsequent degradation. However, ΔRING RNF6 fails to mediate CCND2 for ubiquitination and degradation. Moreover, Thr280 is critically important for CCND2 stability. When Thr280 is mutated, CCND2 becomes more stable and less ubiquitinated by RNF6. Furthermore, RNF6 arrests LUAD cell cycle at the G1 phase by inhibiting the CCND2/pRb signaling pathway, which is consistent with decreased cell proliferation. Lastly, RNF6 curtails the growth of LUAD xenografts in vivo, associated with decreased CCND2 expression. Therefore, RNF6 is a novel E3 ligase of CCND2 and suppresses LUAD cell proliferation. Implications: This study reveals a novel regulation on cell cycle transition in LUAD and suggests the RNF6/CCND2 axis may represent an alternative therapeutic target for the treatment of LUAD.

Activation of lineage-specific gene expression programs is mediated by recruitment of lineage-specific transcription factors and their coactivators to chromatin. The lineage factor PAX8 drives essential gene expression in ovarian cancer cells and is required for tumor proliferation. However, the molecular details surrounding co-factor recruitment and specific activation of transcription by PAX8 remain unknown. Here, we identify an important functional interaction between PAX8 and the SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complex. We show that PAX8 can recruit SWI/SNF complexes to DNA, where they function to open chromatin and facilitate expression of PAX8 target genes. Genetic deletion of PAX8 results in loss of SWI/SNF from PAX8 bound enhancers, loss of expression of associated target genes, and reduced proliferation. These results can be phenocopied by pharmacological inhibition of SWI/SNF ATPase activity. These data indicate that PAX8 mediates the expression of an essential ovarian cancer proliferative program in part by the recruitment of the SWI/SNF complex, highlighting a novel vulnerability in PAX8 dependent ovarian cancer. Implications: PAX8 recruits SWI/SNF complexes to enhancers, to mediate expression of genes essential for ovarian cancer proliferation.

Triple-negative breast cancer (TNBC) presents significant clinical challenges due to its limited treatment options and aggressive behavior, often associated with poor prognosis. This study focuses on Kindlin-2, an adaptor protein, and its role in TNBC progression, particularly in hematopoiesis-mediated immune evasion. TNBC tumors expressing high levels of Kindlin-2 induce a notable reshaping of hematopoiesis, promoting expansion of myeloid cells in bone marrow (BM) and spleen. This shift correlated with increased levels of neutrophils and monocytes in tumor-bearing mice over time. Conversely, genetic knockout of Kindlin-2 mitigated this myeloid bias and fostered T cell infiltration within the tumor microenvironment, indicating Kindlin-2's pivotal role in immune modulation. Further investigations revealed that Kindlin-2 deficiency led to reduced expression of PD-L1, a critical immune checkpoint inhibitor, in TNBC tumors. This molecular change sensitized Kindlin-2-deficient tumors to host anti-tumor immune responses, resulting in enhanced tumor suppression in immune-competent mouse models. Single-cell RNA sequencing, bulk RNA-seq, and immunohistochemistry data supported these findings by highlighting enriched immune-related pathways and increased infiltration of immune cells in Kindlin-2-deficient tumors. Therapeutically, targeting PD-L1 in Kindlin-2-expressing TNBC tumors effectively inhibited tumor growth, akin to the effects observed with genetic Kindlin-2 knockout or PD-L1-KO. Our data underscore Kindlin-2 as a promising therapeutic target in combination with immune checkpoint blockade to bolster anti-tumor immunity and counteract resistance mechanisms typical of TNBC and other immune evasive solid tumors. Implications: Kindlin-2 regulates tumor immune evasion through the systemic modulation of hematopoiesis and PD-L1 expression, which warrants therapeutic targeting of Kindlin-2 in TNBC patients.

Small-cell lung cancer (SCLC) has a dismal five-year survival rate of less than 7%, with limited advances in first line treatment over the past four decades. Tumor-initiating cells (TICs) contribute to resistance and relapse, a major impediment to SCLC treatment. Here, we identify Kinase Suppressor of Ras 1 (KSR1), a molecular scaffold for the Raf/MEK/ERK signaling cascade, as a critical regulator of SCLC TIC formation and tumor initiation in vivo. We further show that KSR1 mediates cisplatin resistance in SCLC. While 50-70% of control cells show resistance after 6-week exposure to cisplatin, CRISPR/Cas9-mediated KSR1 knockout prevents resistance in >90% of SCLC cells in ASCL1, NeuroD1, and POU2F3 subtypes. KSR1 KO significantly enhances the ability of cisplatin to decrease SCLC TICs via in vitro extreme limiting dilution analysis (ELDA), indicating that KSR1 disruption enhances the cisplatin toxicity of cells responsible for therapeutic resistance and tumor initiation. The ability of KSR1 disruption to prevent cisplatin resistant in H82 tumor xenograft formation supports this conclusion. Previous studies indicate ERK activation inhibits SCLC tumor growth and development. We observe a minimal effect of pharmacological ERK inhibition on cisplatin resistance and no impact on TIC formation via in vitro ELDA. However, mutational analysis of the KSR1 DEF domain, which mediates interaction with ERK, suggests that ERK interaction with KSR1 is essential for KSR1-driven cisplatin resistance. These findings reveal KSR1 as a potential therapeutic target across multiple SCLC subtypes. Implications: Genetic manipulation of KSR1 in SCLC reveals its contribution to cisplatin resistance and tumor initiation.

Approximately 97% of the human genome comprises non-coding sequences, with nearly half originating from transposable elements. Among these, retrotransposons represent a critical subclass that replicates via a "copy-and-paste" mechanism and significantly influences the regulation of host genomes. In both normal and pathological contexts, retrotransposons contribute a vast reservoir of regulatory elements that can modulate the expression of genes. If left unchecked, retrotransposons can substantially affect host transcriptional programs and genomic integrity. Therefore, various mechanisms, including epigenetic modifications, are employed to mitigate their potentially deleterious effects. In diseases such as cancers, the epigenome is often significantly reprogrammed, which can lead to retrotransposon dysregulation. Drawing insights from recent studies conducted in human and murine cells, this review examines how retrotransposons expand the complexity of mammalian genomes, describes the impact of their epigenetic dysregulation in cancer development, and highlights the potential of targeting these sequences for therapeutic strategies.

Atypical teratoid rhabdoid tumor (ATRT) is a highly aggressive pediatric brain tumor driven by the loss of SMARCB1, which results in epigenetic dysregulation of the genome. SMARCB1 loss affects lineage commitment and differentiation by controlling gene expression. We hypothesized that additional epigenetic factors co-operate with SMARCB1 loss to control cell self-renewal and drive ATRT. We performed an unbiased epigenome targeted screen to identify genes that co-operate with SMARCB1 and identified SIRT2 as a key regulator. Using in vitro pluripotency assays combined with in vivo single cell RNA transcriptomics, we examined the impact of SIRT2 on differentiation of ATRT cells. We employed a series of orthotopic murine models treated with SIRT2 inhibitors to examine the impact on survival and clinical applicability. We found that ATRT cells are highly dependent on SIRT2 for survival. Genetic or chemical inhibition led to decrease cell self-renewal and induction of differentiation in tumor spheres and in vivo models. We found that SIRT2 inhibition can restore gene expression programs lost due to SMARCB1 loss and reverse the differentiation block in ATRT in vivo. Finally, we showed the in vivo efficacy of a clinically relevant inhibitor demonstrating SIRT2 inhibition as a potential therapeutic strategy. We concluded that SIRT2 is a critical dependency in SMARCB1 deficient ATRT cells and acts by controlling the pluripotency-differentiation switch. Thus, SIRT2 inhibition is a promising therapeutic approach that warrants further investigation and clinical development. Implications: SIRT2 inhibition is a molecular vulnerability in SMARCB1-deleted tumors.

Chromosomal instability in gastric cancer cells is associated with the amplification of oncogenes that encode receptor tyrosine kinases (RTKs), such as HER2 and FGFR2; such gene amplification varies from cell to cell and manifests as genetic heterogeneity within tumours. The intratumoural genetic heterogeneity of RTK gene amplification causes heterogeneity in RTK protein expression, which has been suggested to be associated with therapeutic resistance to RTK inhibitors; however, the underlying mechanism is not fully understood. Here, we show that extrachromosomal DNA (ecDNA) causes intratumoural genetic heterogeneity in RTKs and drug resistance due to diverse dynamic changes. We analysed the dynamics of FGFR2 and MYC ecDNA in a gastric cancer cell line after single-cell cloning. Similar to those in parental cells, the copy numbers of FGFR2 and MYC in subclones differed significantly between cells, indicating intraclonal genetic heterogeneity. Furthermore, the ecDNA composition differed between subclones, which affected FGFR2 protein expression and drug sensitivity. Interestingly, clone cells that were resistant to the FGFR2 inhibitor AZD4547 presented diverse changes in ecDNA, including chimeric ecDNA, large ecDNA and increased ecDNA numbers; these changes were associated with high expression and rephosphorylation of FGFR2. Conversely, when resistant clone cells were cultured under conditions that excluded AZD4547, the ecDNA status became similar to that of the original clone cells, and the inhibitory effect on cell growth was restored. Implications: Our results show that dynamic quantitative and qualitative changes in ecDNA can drive the intratumoural genetic heterogeneity of RTKs and resistance to RTK inhibitors.

Cooperativity between mutant p53 and mutant KRAS, although recognized, is poorly understood. In pancreatic cancer, mutant p53 induces splicing factor hnRNPK causing isoform switch producing overexpression of GTPase activating protein 17 isoform 1 (GAP17-1). GAP17-1 is mis-localized in the cytosol, instead of the membrane, due to insertion of exon 17 encoding a PPLP motif, thus allowing mutant KRAS to remain in the GTP bound hyperactive state. However, the role of PPLP in influencing GAP17-1 mis-localization remains unclear. We show that Smad Ubiquitination Regulatory Factor 2 (SMURF2), a known stabilizer of mutant KRAS, interacts with GAP17-1 via the PPLP motif and displaces it from the membrane, facilitating mutant p53 mediated mutant KRAS hyperactivation. We used cell lines with known KRAS and TP53 mutations, characterized Smurf2 expression in multiple pancreatic cancer mouse models (iKras*; iKras*, p53*, and p48-Cre; Kras*) and performed single cell RNAseq and tissue microarray on preclinical and clinical samples. We found that SMURF2 silencing profoundly reduces survival of mutant TP53; KRAS driven cells. We show that a GAP17-1 AALA mutant does not bind to SMURF2, stays in the membrane, and keeps mutant KRAS in the GDP bound state to inhibit downstream signaling. In mouse models, mutant KRAS and SMURF2 upregulation are correlated in pancreatic intraepithelial neoplasia (PanIN) and ductal adenocarcinoma (PDA) lesions. Furthermore, PDA patients who received neoadjuvant therapy and express moderate to high SMURF2 show decreased overall survival (p=0.04). Implications: In TP53 and KRAS double mutated pancreatic cancer, SMURF2 driven GAP17-1 membrane expulsion facilitates mutant p53-KRAS oncogenic synergy.

Metastasis accounts for the overwhelming majority of cancer deaths. In prostate cancer and many other solid tumors, progression to metastasis is associated with drastically reduced survival outcomes, yet the mechanisms behind this progression remain largely unknown. ATAD2 (ATPase family AAA domain containing 2) is an epigenetic reader of acetylated histones that is overexpressed in multiple cancer types and usually associated with poor patient outcomes. However, the functional role of ATAD2 in cancer progression and metastasis has been relatively understudied. Here we employ genetically engineered mouse models of prostate cancer bone metastasis, as well as multiple independent human cohorts, to show that ATAD2 is highly enriched in bone metastasis compared to primary tumors and significantly associated with the development of metastasis. We show that ATAD2 expression is associated with MYC pathway activation in patient datasets and that, at least in a subset of tumors, MYC and ATAD2 can regulate each other's expression. Using functional studies on mouse bone metastatic cell lines and innovative organ-on-a-chip bone invasion assays, we establish a functional role for ATAD2 inhibition in diminishing prostate cancer metastasis and growth in bone. Implications: Our study highlights ATAD2 as a driver of prostate cancer progression and metastasis and suggests it may constitute a promising novel therapeutic target.

Kaposi Sarcoma (KS) is a frequently aggressive malignancy caused by Kaposi sarcoma herpesvirus (KSHV/HHV-8). People with immunodeficiencies, including HIV, are at increased risk for developing KS, but our understanding of the contributions of the cellular genome to KS pathogenesis remains limited. To determine if there are cellular genetic alterations in KS that might provide biological or therapeutic insights, we performed whole exome sequencing on 78 KS tumors and matched normal control skin from 59 adults with KS (46 with HIV-associated KS and 13 with HIV-negative KS) receiving treatment at the Uganda Cancer Institute in Kampala, Uganda. We found a very low mutational burden in all but one specimen (median=11 mutations), which is the lowest number of mutations among all 33 tumor types in The Cancer Genome Atlas (TCGA). No recurrent mutations were seen and the most commonly affected oncogenic pathway was RTK/RAS. Mutational signatures included defective DNA mismatch repair and smoking. There was no evidence suggesting that multiple tumors from the same patient originated from the same original clone. The number of genome copy alterations per genome were higher in tumors from those without HIV infection and in tumors from participants with advanced stage disease, suggesting that lesions that take longer to develop may accumulate more alterations, although the number of alterations remain low compared to other cancers. Implications: Our findings indicate that the pathogenesis of KS differs from other malignancies, and that the primary driver of carcinogenesis is KSHV viral infection and expression of viral oncogenes, rather than clonal oncogenic transformation.

Prostate cancer (PCa) is mainly managed with androgen deprivation therapy (ADT), but this often leads to a dormant state and subsequent relapse as lethal castration-resistant prostate cancer (CRPC). Using our unique PCa patient-derived xenograft (PDX) dormancy models, we investigated this critical dormant phase and discovered a selective increase in B7-H4 expression during the dormancy period following mouse host castration. This finding is supported by observations in clinical specimens of PCa patients treated with ADT. Differential expression analyses revealed the enrichment of extracellular matrix (ECM)-cell interaction pathways in B7-H4-positive cells. Functional assays demonstrated a crucial role of B7-H4 in maintaining dormancy within the ECM niche. Specifically, B7-H4 expression in LNCaP cells reduced proliferation within dormant ECM in vitro and significantly delayed relapse in castrated hosts in vivo. These results shed light on the dynamic regulation of B7-H4 during PCa dormancy and underscore its potential as a therapeutic target for preventing CRPC relapse. Implications: Our study identified membranous B7-H4 expression during ADT-induced dormancy, highlighting its potential as a therapeutic target for managing dormant prostate cancer and preventing fatal CRPC relapse.

Elevated blood levels of estrogens are associated with poor prognosis in estrogen receptor-positive (ER+) breast cancers, but the relationship between circulating blood hormone levels and intracellular hormone concentrations are not well characterized. We observed that MCF-7 cells treated acutely with 17β-estradiol (E2) retain a substantial amount of the hormone even upon removal of the hormone from the culture medium. Moreover, global patterns of E2-dependent gene expression are sustained for hours after acute E2 treatment and hormone removal. While circulating E2 is sequestered by sex hormone binding globulin (SHBG), the potential mechanisms of intracellular E2 retention are poorly understood. We found that a mislocalization of a steroid-binding GRAM-domain containing protein, ASTER-B, to the nucleus, which is observed in a subset of breast cancer patients, is associated with higher cellular E2 retention. Accumulation and retention of E2 are related to the steroidal properties of E2, and require nuclear localization and steroid binding by ASTER-B, as shown using a panel of mutant ASTER-B proteins. Finally, we observed that nuclear ASTER-B-mediated E2 retention is required for sustained hormone-induced ERalpha chromatin occupancy at enhancers and gene expression, as well as subsequent cell growth responses. Our results add intracellular hormone retention as a mechanism controlling E2-dependent gene expression and downstream biological outcomes. Implications: Mislocalized nuclear ASTER-B, which binds estradiol to support the functions of ER, can provide an alternate means of enhancing the biological effects of E2 in breast cancers and may be a potential therapeutic target that addresses multiple aspects of estrogen bioavailability.

Breast cancers of the IntClust-2 type, characterized by amplification of a small portion of chromosome 11, have a median survival of only five years. Several cancer-relevant genes occupy this portion of chromosome 11, and it is thought that overexpression of a combination of driver genes in this region is responsible for the poor outcome of women in this group. In this study we used a gene editing method to knock out, one by one, each of 198 genes that are located within the amplified region of chromosome 11 and determined how much each of these genes contributed to the survival of breast cancer cells. In addition to well-known drivers such as CCND1 and PAK1, we identified two different genes (SERPINH1 and P4HA3), that encode proteins involved in collagen synthesis and organization. Using both in vitro and in vivo functional analyses, we determined that P4HA3 and/or SERPINH1 provide a critical driver function on IntClust-2 basic processes, such as viability, proliferation, and migration. Inhibiting these enzymes via genetic or pharmacologic means reduced collagen synthesis and impeded oncogenic signaling transduction in cell culture models, and a small-molecule inhibitor of P4HA3 was effective in treating 11q13 tumor growth in an animal model. As collagen has a well-known association with tissue stiffness and aggressive forms of breast cancer, we believe that the two genes we identified provide an opportunity for a new therapeutic strategy in IntClust-2 breast cancers. Implications: Breast cancers with 11q13/14 chromosomal amplifications may be vulnerable to inhibitors of collagen synthesis.

Epidermal growth factor receptor (EGFR) is a highly expressed driver of many cancers, yet the utility of EGFR inhibitors is limited to cancers that harbor sensitizing mutations in the EGFR gene due to dose limiting toxicities. Rather than conventionally blocking the kinase activity of EGFR, we sought to reduce its transcription as an alternative approach to broaden the therapeutic window for EGFR inhibitors targeting wildtype or mutant EGFR. We found that YES1 is highly expressed in triple negative breast cancer (TNBC) and drives cell growth by elevating EGFR levels. Mechanistically, YES1 stimulates EGFR expression by signaling to JNK and stabilizing the AP-1 transcription factor, c-Jun. This effect extends beyond TNBC as YES1 also sustains EGFR expression in non-small cell lung cancer (NSCLC) cells, including those that harbor the EGFR gatekeeper mutation, T790M. The novel ability of YES1 to regulate the expression of wildtype and mutant EGFR mRNA and protein provides a potential therapeutic opportunity of utilizing YES1 blockade to broadly increase the efficacy of EGFR inhibitors. Indeed, we found synergy within in vitro and in vivo models of TNBC and NSCLC, even in the absence of EGFR activating mutations. Together, these data provide a rationale for blocking YES1 activity as an approach for improving the efficacy of EGFR-targeting drugs in cancers that have generally been refractory to such inhibitors. Implications: YES1 sustains EGFR expression, revealing a therapeutic vulnerability for increasing the efficacy of EGFR inhibitors by lowering the threshold for efficacy in tumors driven by wildtype or mutant receptor.

WD repeat domain 77 protein (WDR77), a WD-40 domain-containing protein, is a crucial regulator of cellular pathways in cancer progression. While much of the past research on WDR77 has focused on its interaction with PRMT5 in histone methylation, WDR77's regulatory functions extend beyond this pathway, influencing diverse mechanisms such as mRNA translation, chromatin assembly, cell cycle regulation, and apoptosis. WDR77 is a key regulator of cell cycle progression, regulating the transition from the G1 phase. WDR77 regulates many signaling pathways such as TGFβ where its role in these cellular pathways underscores its broad oncogenic potential. WDR77 also assists and promotes certain transcription factors such as E2F. Furthermore, in certain cancers, WDR77 enhances steroid hormone receptor activity, uniquely linking it to hormone-driven malignancies. WDR77 often translocates between the nucleus and the cytoplasm, with its location dictating its role in the cell. WDR77 has the ability to adapt its function depending on its location which emphasizes its dynamic role in both promoting and inhibiting tumor growth, depending on cellular context. This dual function makes WDR77 an attractive therapeutic target, as disrupting its interactions with critical signaling pathways or modulating its translocation could yield novel strategies for cancer treatment. Given WDR77's role in oncogenic pathways independent of PRMT5, further exploration of WDR77 and its non-PRMT5-related activities may reveal additional therapeutic opportunities in an array of cancers.

Malignant neoplasms arise within a region of chronic inflammation caused by tissue injuries. Inflammation is a key factor involved in all aspects of tumorigenesis including initiation, proliferation, invasion, angiogenesis, and metastasis. Interleukin-1 (IL-1) plays critical functions in tumor development with influencing the tumor microenvironment and promoting cancer progression. However, the mechanism of continuous activation of IL-1-mediated inflammatory pathway in tumor has not been fully elucidated. This study provides a novel mechanism of the autocrine activation of IL-1 signaling in squamous cell carcinoma (SCC) through a novel oncoprotein, TSC-22 homologous gene-1 (THG-1, also known as TSD22D4). The RNA sequencing analysis revealed that THG-1 overexpression enhances the transcription of NF-κB targets including IL1A, IL1B, TNFA, and IL8. Furthermore, THG-1 knockdown reduced the responsiveness to IL-1 through suppression of NF-κB nuclear translocation. To elucidate the mechanism, we focused on a THG-1 interacting protein, NRBP1. We found that NRBP1 facilitates the degradation of TRAF6 through its E3 ubiquitin ligase activity. THG-1 bound to NRBP1 and suppressed the degradation of TRAF6. Furthermore, THG-1 knockdown reduced TRAF6 abundance and NF-κB activity in SCC cells. Public database analyses of head and neck SCC revealed that high expression of THG-1 is associated with activation of the IL-1 and TNF pathways, which share TRAF6 in the signal transductions. Finally, THG-1 abundance in laryngeal SCC specimens is elevated in patients with recurrence. These results indicated that THG-1 drives the self-sufficiency of IL-1-mediated inflammatory pathway, which could contribute to the future diagnosis and immune therapy of SCCs. Implications: An oncoprotein THG-1/TSD22D4 activates the IL-1-mediated inflammatory pathway through suppression of TRAF6 degradation, which mediates the continuous inflammation in tumors.

BRAF mutations in colorectal cancer (CRC) comprise three functional classes: Class 1 (V600E) with strong constitutive activation, Class 2 with pathogenic kinase activity lower than Class 1, and Class 3 which paradoxically lacks kinase activity. Non-Class 1 mutations associate with better prognosis, microsatellite stability, distal tumour location and better anti-EGFR response. Analysis of 13 CRC cohorts (n=6,605 tumours) compared Class 1 (n=709, 10.7% of CRCs), Class 2 (n=31, 0.47%) and Class 3 (n=81, 1.22%) mutations. Class 2- and Class 3-mutant CRCs frequently co-occurred with additional Ras pathway mutations (29.0% and 45.7% respectively vs 2.40% in Class 1, p<0.001), often at atypical sites (KRAS non-codon 12/13/61, NRAS, or NF1). Ras pathway activation was highest in Class 1 and lowest in Class 3, with greater distal expression of EGFR ligands (AREG/EREG) supporting weaker BRAF driver mutations. Unlike Class 1 mutants, Class 3 tumours resembled chromosomally-unstable CRCs in mutation burdens, signatures, driver mutations and transcriptional subtypes, while Class 2 mutants displayed intermediate characteristics. Atypical BRAF mutations were associated with longer overall survival than Class 1 (HR=0.25, p=0.011), but lost this advantage in cancers with additional Ras mutation (HR=0.93, p=0.86). This study supports the suggestion that Class 3 BRAF mutations amplify existing Ras signalling in a two-mutation model and that enhancement of weak/atypical Ras mutations may suffice for tumorigenesis, with potentially clinically-important heterogeneity in the Class 2/3 sub-group. Implications: The heterogeneous nature of BRAF-mutant CRCs, particularly among Class 2/3 mutations which frequently harbour additional Ras mutations, highlights the necessity of comprehensive molecular profiling.