A Feedback Loop Comprising EGF/TGFα Sustains TFCP2-Mediated Breast Cancer Progression

Upstream-binding protein-1 promotes breast tumorigenesis by inducing NRG2-mediated metastasis, plasticity, and macrophage polarization

Upstream binding protein 1 (UBP1) is a transcription factor (TF) of the CP2/grainyhead family involved in various biological processes, including cancer cell proliferation, differentiation, and embryonic development. While other mammalian grainyhead-like TFs have been linked to different cancers, including breast cancer (BC), the role of UBP1 in BC remains unexplored. In this study, we provide a preliminary investigation into the novel functions of UBP1 in BC. Using online database screening, we first demonstrated that elevated UBP1 levels in breast carcinoma are associated with poor prognosis and adverse clinical outcomes. We further showed that UBP1 promotes epithelial-mesenchymal transition (EMT) and stemness in BC cells while regulating key signaling pathways, including the PI3K-Akt. Additionally, UBP1 modulates tumor metastasis by influencing tumor-associated macrophage (TAM) polarization, promoting an immunosuppressive macrophage phenotype, and driving tumor progression. Our findings highlight UBP1's pivotal role in BC progression through multiple mechanisms, including EMT induction, stemness maintenance, and macrophage polarization via activation of the NRG2/Akt axis. Moreover, higher UBP1 expression correlates with lower overall and recurrence-free survival, underscoring its potential as a prognostic marker and therapeutic target for aggressive BC.

TFCP2 is recognized as a dynamic monitoring index of pneumoconiosis by combining radiomics with transcriptomics

OBJECTIVE

Herein, we employed a novel integrated radiomics and transcriptomics approach to identify key biomarkers for pneumoconiosis. Specifically, we combined thoracic Computed Tomography (CT) imaging-based phenomics and peripheral blood gene expression analysis to improve early diagnosis and risk stratification of pneumoconiosis.

METHODS

The study cohort comprised individuals with diagnosed pneumoconiosis and healthy coal miners. Participants were categorized into low-, medium-, and high-risk groups, as well as a pneumoconiosis group, based on radiomics scoring. Peripheral blood samples were collected for transcriptome sequencing analysis, and key genes were selected through differential expression and trend analysis. Mfuzz clustering analysis and KEGG pathway enrichment analysis were utilized to further investigate gene expression patterns and functions. The expression of key genes was verified using real-time quantitative PCR and western blotting. The diagnostic value of key genes was assessed using Receiver Operating Characteristic (ROC) analysis. A mouse model was constructed to assess the role of TFCP2 in pneumoconiosis and to explore its potential mechanisms.

RESULTS

Our findings revealed that heterogeneous gene expression patterns correlated with an increased pneumoconiosis risk. Additionally, TFCP2 emerged as a significant biomarker (AUC = 0.799), with its expression levels increasing with pneumoconiosis risk. Furthermore, TFCP2 upregulation correlated closely with Extracellular Matrix (ECM)-receptor interactions and AGE-RAGE signaling pathways, which have been associated with fibrosis and inflammatory responses in lung tissue. Moreover, silencing TFCP2 in a mouse model improved silica-induced pulmonary fibrosis, with USP22 identified as a downstream target gene of TFCP2.

CONCLUSION

TFCP2 may serve as a potential biomarker and therapeutic target for the progression of pneumoconiosis. Its high expression in lung epithelial cells may exacerbate pulmonary fibrosis by promoting EMT and ECM deposition. This study provides new molecular targets for the early diagnosis and treatment of pneumoconiosis.

CircUCK2(2,3) promotes cancer progression and enhances synergistic cytotoxicity of lenvatinib with EGFR inhibitors via activating CNIH4-TGFα-EGFR signaling

BACKGROUND

Circular (circ)RNAs have emerged as crucial contributors to cancer progression. Nonetheless, the expression regulation, biological functions, and underlying mechanisms of circRNAs in mediating hepatocellular carcinoma (HCC) progression remain insufficiently elucidated.

METHODS

We identified circUCK2(2,3) through circRNA sequencing, RT-PCR, and Sanger sequencing. CircUCK2(2,3) levels were measured in two independent HCC cohorts using quantitative real-time PCR (qRT-PCR). We explored the functions of circUCK2(2,3) using gain- and loss-of-function assays. Techniques such as RNA-sequencing, RNA immunoprecipitation (RIP), polysome fractionation, RNA pulldown, dual luciferase reporter assay, inhibitors of EGFR downstream signaling, CRISPR-Cas9, and medium transfer assays were employed to investigate the regulatory mechanisms and the protumoral activities of circUCK2(2,3). Additionally, in vitro cytotoxic assays and patient-derived xenograft (PDX) models assessed the effects of circUCK2(2,3) on the cytotoxic synergy of lenvatinib and EGFR inhibitors.

RESULTS

CircUCK2(2,3) is upregulated in HCC tissues and serves as an independent risk factor for poor recurrence-free survival. The expression of circUCK2(2,3) is independent on its host gene, UCK2, but is regulated by its upstream promoter and flanking inverted complementary sequences. Functionally, circUCK2(2,3) enhances HCC proliferation, migration, and invasion, both in vitro and in vivo. Mechanistically, by sponging miR-149-5p, circUCK2(2,3) increases CNIH4 levels, which in turn amplifies TGFα secretion, resulting in the activation of EGFR and downstream pAKT and pERK signaling pathways. Moreover, circUCK2(2,3) overexpression sensitizes HCC cells to EGFR inhibitors, and increases the synergistic cytotoxicity of combined lenvatinib and EGFR inhibitor treatment.

CONCLUSIONS

CircUCK2(2,3) regulates a novel oncogenic pathway, miR-149-5p-CNIH4-TGFα-EGFR, in HCC, presenting a viable therapeutic target and biomarker for the precision treatment of HCC.

TRAF6 enhances PD-L1 expression through YAP1-TFCP2 signaling in melanoma

Immunotherapy represented by programmed cell death protein 1 (PD-1)/programmed death ligand 1 (PD-L1) monoclonal antibodies has led tumor treatment into a new era. However, the low overall response rate and high incidence of drug resistance largely damage the clinical benefits of existing immune checkpoint therapies. Recent studies correlate the response to PD-1/PD-L1 blockade with PD-L1 expression levels in tumor cells. Hence, identifying molecular targets and pathways controlling PD-L1 protein expression and stability in tumor cells is a major priority. In this study, we performed a Stress and Proteostasis CRISPR interference screening to identify PD-L1 positive modulators. Here, we identified TRAF6 as a critical regulator of PD-L1 in melanoma cells. As a non-conventional E3 ubiquitin ligase, TRAF6 is inclined to catalyze the synthesis and linkage of lysine-63 (K63) ubiquitin which is related to the stabilization of substrate proteins. Our results showed that suppression of TRAF6 expression down-regulates PD-L1 expression on the membrane surface of melanoma cells. We then used in vitro and in vivo assays to investigate the biological function and mechanism of TRAF6 and its downstream YAP1/TFCP2 signaling in melanoma. TRAF6 stabilizes YAP1 by K63 poly-ubiquitination modification, subsequently promoting the formation of YAP1/TFCP2 transcriptional complex and PD-L1 transcription. Inhibition of TRAF6 by Bortezomib enhanced cytolytic activity of CD8+ T cells by reduction of endogenous PD-L1. Notably, Bortezomib enhances anti-tumor immunity to an extent comparable to anti-PD-1 therapies with no obvious toxicity. Our findings reveal the potential of inhibiting TRAF6 to stimulate internal anti-tumor immunological effect for TRAF6-PD-L1 overexpressing cancers.

Improved prediction of protein-protein interactions by a modified strategy using three conventional docking software in combination

Proteins play a crucial role in many biological processes, where their interaction with other proteins are integral. Abnormal protein-protein interactions (PPIs) have been linked to various diseases including cancer, and thus targeting PPIs holds promise for drug development. However, experimental confirmation of the peculiarities of PPIs is challenging due to their dynamic and transient nature. As a complement to experimental technologies, multiple computational molecular docking (MD) methods have been developed to predict the structures of protein-protein complexes and their dynamics, still requiring further improvements in several issues. Here, we report an improved MD method, namely three-software docking (3SD), by employing three popular protein-peptide docking software (CABS-dock, HPEPDOCK, and HADDOCK) in combination to ensure constant quality for most targets. We validated our 3SD performance in known protein-peptide interactions (PpIs). We also enhanced MD performance in proteins having intrinsically disordered regions (IDRs) by applying the modified 3SD strategy, the three-software docking after removing random coiled IDR (3SD-RR), to the comparable crystal PpI structures. At the end, we applied 3SD-RR to the AlphaFold2-predicted receptors, yielding an efficient prediction of PpI pose with high relevance to the experimental data regardless of the presence of IDRs or the availability of receptor structures. Our study provides an improved solution to the challenges in studying PPIs through computational docking and has the potential to contribute to PPIs-targeted drug discovery. SIGNIFICANCE STATEMENT: Protein-protein interactions (PPIs) are integral to life, and abnormal PPIs are associated with diseases such as cancer. Studying protein-peptide interactions (PpIs) is challenging due to their dynamic and transient nature. Here we developed improved docking methods (3SD and 3SD-RR) to predict the PpI poses, ensuring constant quality in most targets and also addressing issues like intrinsically disordered regions (IDRs) and artificial intelligence-predicted structures. Our study provides an improved solution to the challenges in studying PpIs through computational docking and has the potential to contribute to PPIs-targeted drug discovery.

MAF amplification licenses ERα through epigenetic remodelling to drive breast cancer metastasis

MAF amplification increases the risk of breast cancer (BCa) metastasis through mechanisms that are still poorly understood yet have important clinical implications. Oestrogen-receptor-positive (ER+) BCa requires oestrogen for both growth and metastasis, albeit by ill-known mechanisms. Here we integrate proteomics, transcriptomics, epigenomics, chromatin accessibility and functional assays from human and syngeneic mouse BCa models to show that MAF directly interacts with oestrogen receptor alpha (ERα), thereby promoting a unique chromatin landscape that favours metastatic spread. We identify metastasis-promoting genes that are de novo licensed following oestrogen exposure in a MAF-dependent manner. The histone demethylase KDM1A is key to the epigenomic remodelling that facilitates the expression of the pro-metastatic MAF/oestrogen-driven gene expression program, and loss of KDM1A activity prevents this metastasis. We have thus determined that the molecular basis underlying MAF/oestrogen-mediated metastasis requires genetic, epigenetic and hormone signals from the systemic environment, which influence the ability of BCa cells to metastasize.

A Cell-Penetrant Peptide Disrupting the Transcription Factor CP2c Complexes Induces Cancer-Specific Synthetic Lethality

Despite advances in precision oncology, cancer remains a global public health issue. In this report, proof-of-principle evidence is presented that a cell-penetrable peptide (ACP52C) dissociates transcription factor CP2c complexes and induces apoptosis in most CP2c oncogene-addicted cancer cells through transcription activity-independent mechanisms. CP2cs dissociated from complexes directly interact with and degrade YY1, leading to apoptosis via the MDM2-p53 pathway. The liberated CP2cs also inhibit TDP2, causing intrinsic genome-wide DNA strand breaks and subsequent catastrophic DNA damage responses. These two mechanisms are independent of cancer driver mutations but are hindered by high MDM2 p60 expression. However, resistance to ACP52C mediated by MDM2 p60 can be sensitized by CASP2 inhibition. Additionally, derivatives of ACP52C conjugated with fatty acid alone or with a CASP2 inhibiting peptide show improved pharmacokinetics and reduced cancer burden, even in ACP52C-resistant cancers. This study enhances the understanding of ACP52C-induced cancer-specific apoptosis induction and supports the use of ACP52C in anticancer drug development.

Identification of Breast Cancer Metastasis Markers from Gene Expression Profiles Using Machine Learning Approaches

Cancer metastasis accounts for approximately 90% of cancer deaths, and elucidating markers in metastasis is the first step in its prevention. To characterize metastasis marker genes (MGs) of breast cancer, XGBoost models that classify metastasis status were trained with gene expression profiles from TCGA. Then, a metastasis score (MS) was assigned to each gene by calculating the inner product between the feature importance and the AUC performance of the models. As a result, 54, 202, and 357 genes with the highest MS were characterized as MGs by empirical p-value cutoffs of 0.001, 0.005, and 0.01, respectively. The three sets of MGs were compared with those from existing metastasis marker databases, which provided significant results in most comparisons (p-value < 0.05). They were also significantly enriched in biological processes associated with breast cancer metastasis. The three MGs, SPPL2C, KRT23, and RGS7, showed highly significant results (p-value < 0.01) in the survival analysis. The MGs that could not be identified by statistical analysis (e.g., GOLM1, ELAVL1, UBP1, and AZGP1), as well as the MGs with the highest MS (e.g., ZNF676, FAM163B, LDOC2, IRF1, and STK40), were verified via the literature. Additionally, we checked how close the MGs were to each other in the protein-protein interaction networks. We expect that the characterized markers will help understand and prevent breast cancer metastasis.

Epithelioid and spindle cell rhabdomyosarcoma with EWSR1::TFCP2 fusion mimicking metastatic lung cancer: A case report and literature review

Rhabdomyosarcoma (RMS) with EWSR1/FUS::TFCP2 fusion is an emerging, molecularly defined, rare subtype of RMS. It can affect patients in a wide age range and follows an aggressive clinical course according to the reported cases. Due to its unusual clinical and pathohistological features, with a typical intraosseous presentation and common cytokeratin expression, the diagnosis is challenging, and metastatic undifferentiated/sarcomatoid carcinoma can be an important differential diagnosis. We report here a case of a 55-year-old woman with an RMS with EWSR1::TFCP2 fusion mimicking metastatic lung cancer in view of the clinical and microscopic presentation. However, further molecular workup, including RNA sequencing, led to the proper diagnosis. Although these tumors are rare, knowledge of their unique features is essential for correct diagnosis as a basis for clinical management and optimization of therapeutic approaches.

Functional impact of non-coding RNAs in high-grade breast carcinoma: Moving from resistance to clinical applications: A comprehensive review

Despite the recent advances in cancer therapy, triple-negative breast cancers (TNBCs) are the most relapsing cancer sub-type. It is partly due to their propensity to develop resistance against the available therapies. An intricate network of regulatory molecules in cellular mechanisms leads to the development of resistance in tumors. Non-coding RNAs (ncRNAs) have gained widespread attention as critical regulators of cancer hallmarks. Existing research suggests that aberrant expression of ncRNAs modulates the oncogenic or tumor suppressive signaling. This can mitigate the responsiveness of efficacious anti-tumor interventions. This review presents a systematic overview of biogenesis and down streaming molecular mechanism of the subgroups of ncRNAs. Furthermore, it explains ncRNA-based strategies and challenges to target the chemo-, radio-, and immunoresistance in TNBCs from a clinical standpoint.

SUMOylation-mediated PSME3-20S proteasomal degradation of transcription factor CP2c is crucial for cell cycle progression

Transcription factor CP2c (also known as TFCP2, α-CP2, LSF, and LBP-1c) is involved in diverse ubiquitous and tissue/stage-specific cellular processes and in human malignancies such as cancer. Despite its importance, many fundamental regulatory mechanisms of CP2c are still unclear. Here, we uncover an unprecedented mechanism of CP2c degradation via a previously unidentified SUMO1/PSME3/20S proteasome pathway and its biological meaning. CP2c is SUMOylated in a SUMO1-dependent way, and SUMOylated CP2c is degraded through the ubiquitin-independent PSME3 (also known as REGγ or PA28)/20S proteasome system. SUMOylated PSME3 could also interact with CP2c to degrade CP2c via the 20S proteasomal pathway. Moreover, precisely timed degradation of CP2c via the SUMO1/PSME3/20S proteasome axis is required for accurate progression of the cell cycle. Therefore, we reveal a unique SUMO1-mediated uncanonical 20S proteasome degradation mechanism via the SUMO1/PSME3 axis involving mutual SUMO-SIM interaction of CP2c and PSME3, providing previously unidentified mechanistic insights into the roles of dynamic degradation of CP2c in cell cycle progression.

The genetic and epigenetic regulation of CD55 and its pathway analysis in colon cancer

Background

CD55 plays an important role in the development of colon cancer. This study aims to evaluate the expression of CD55 in colon cancer and discover how it is regulated by transcriptional factors and miRNA.

Methods

The expression of CD55 was explored by TIMER2.0, UALCAN, and Human Protein Atlas (HPA) databases. TRANSFAC and Contra v3 were used to predict the potential binding sites of transcription factors in the CD55 promoter. TargetScan and starBase v2.0 were used to predict the potential binding ability of miRNAs to the 3' untranslated region (3'UTR) of CD55. SurvivalMeth was used to explore the differentially methylated sites in the CD55 promoter. Western blotting was used to detect the expression of TFCP2 and CD55. Dual-luciferase reporter assay and chromatin immunoprecipitation (ChIP) assay were performed to determine the targeting relationship of TFCP2, NF-κB, or miR-27a-3p with CD55. CD55-related genes were explored by constructing a protein-protein interaction (PPI) network and performing pathway analysis by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG).

Results

CD55 was highly expressed in colon cancer tissues. The mRNA and protein expression levels of TFCP2 were reduced by si-TFCP2. NF-κB mRNA was obviously reduced by NF-κB inhibitor and increased by NF-κB activator. CD55 protein was also inhibited by miR-27a-3p. Dual-luciferase reporter assays showed that after knocking down TFCP2 or inhibiting NF-κB, the promoter activity of CD55 was decreased by 21% and 70%, respectively; after activating NF-κB, the promoter activity of CD55 increased by 2.3 times. As TFCP2 or NF-κB binding site was mutated, the transcriptional activity of CD55 was significantly decreased. ChIP assay showed that TFCP2 and NF-κB combined to the promoter of CD55. The luciferase activity of CD55 3'UTR decreased after being co-transfected with miR-27a-3p mimics and increased by miR-27a-3p antagomir. As the miR-27a-3p binding site was mutated, we did not find any significant effect of miR-27a-3p on reporter activity. PPI network assay revealed a set of CD55-related genes, which included CFP, CFB, C4A, and C4B. GO and KEGG analyses revealed that the target genes occur more frequently in immune-related pathways.

Conclusion

Our results indicated that CD55 is regulated by TFCP2, NF-κB, miR-27a-3p, and several immune-related genes, which in turn affects colon cancer.

Chromatin accessibility landscape and active transcription factors in primary human invasive lobular and ductal breast carcinomas

BACKGROUND

Invasive lobular breast carcinoma (ILC), the second most prevalent histological subtype of breast cancer, exhibits unique molecular features compared with the more common invasive ductal carcinoma (IDC). While genomic and transcriptomic features of ILC and IDC have been characterized, genome-wide chromatin accessibility pattern differences between ILC and IDC remain largely unexplored.

METHODS

Here, we characterized tumor-intrinsic chromatin accessibility differences between ILC and IDC using primary tumors from The Cancer Genome Atlas (TCGA) breast cancer assay for transposase-accessible chromatin with sequencing (ATAC-seq) dataset.

RESULTS

We identified distinct patterns of genome-wide chromatin accessibility in ILC and IDC. Inferred patient-specific transcription factor (TF) motif activities revealed regulatory differences between and within ILC and IDC tumors. EGR1, RUNX3, TP63, STAT6, SOX family, and TEAD family TFs were higher in ILC, while ATF4, PBX3, SPDEF, PITX family, and FOX family TFs were higher in IDC.

CONCLUSIONS

This study reveals the distinct epigenomic features of ILC and IDC and the active TFs driving cancer progression that may provide valuable information on patient prognosis.

Structural and Functional Insights into CP2c Transcription Factor Complexes

CP2c, also known as TFCP2, α-CP2, LSF, and LBP-1c, is a prototypic member of the transcription factor (TF) CP2 subfamily involved in diverse ubiquitous and tissue/stage-specific cellular processes and in human malignancies including cancer. Despite its importance, many fundamental regulatory mechanisms of CP2c are still unclear. Here, we uncover unprecedented structural and functional aspects of CP2c using DSP crosslinking and Western blot in addition to conventional methods. We found that a monomeric form of a CP2c homotetramer (tCP2c; [C4]) binds to the known CP2c-binding DNA motif (CNRG-N(5~6)-CNRG), whereas a dimeric form of a CP2c, CP2b, and PIAS1 heterohexamer ([C2B2P2]₂) binds to the three consecutive CP2c half-sites or two staggered CP2c binding motifs, where the [C4] exerts a pioneering function for recruiting the [C2B2P2]₂ to the target. All CP2c exists as a [C4], or as a [C2B2P2]₂ or [C2B2P2]₄ in the nucleus. Importantly, one additional cytosolic heterotetrameric CP2c and CP2a complex, ([C2A2]), exerts some homeostatic regulation of the nuclear complexes. These data indicate that these findings are essential for the transcriptional regulation of CP2c in cells within relevant timescales, providing clues not only for the transcriptional regulation mechanism by CP2c but also for future therapeutics targeting CP2c function.

A novel EHD1/CD44/Hippo/SP1 positive feedback loop potentiates stemness and metastasis in lung adenocarcinoma

BACKGROUND

There is growing evidence that endocytosis plays a pivotal role in cancer metastasis. In this study, we first identified endocytic and metastasis-associated genes (EMGs) and then investigated the biological functions and mechanisms of EMGs.

METHODS

Cancer stem cells (CSCs)-like characteristics were evaluated by tumour limiting dilution assays, three-dimensional (3D) spheroid cancer models. Microarray analysis was used to identify the pathways significantly regulated by mammalian Eps15 homology domain protein 1 (EHD1) knockdown. Mass spectrometry (MS) was performed to identify EHD1-interacting proteins. The function of EHD1 as a regulator of cluster of differentiation 44 (CD44) endocytic recycling and lysosomal degradation was determined by CD44 biotinylation and recycling assays.

RESULTS

EHD1 was identified as a significant EMG. Knockdown of EHD1 suppressed CSCs-like characteristics, epithelial-mesenchymal transition (EMT), migration and invasion of lung adenocarcinoma (LUAD) cells by increasing Hippo kinase cascade activation. Conversely, EHD1 overexpression inhibited the Hippo pathway to promote cancer stemness and metastasis. Notably, utilising MS analysis, the CD44 protein was identified as a potential binding partner of EHD1. Furthermore, EHD1 enhanced CD44 recycling and stability. Indeed, silencing of CD44 or disruption of the EHD1/CD44 interaction enhanced Hippo pathway activity and reduced CSCs-like traits, EMT and metastasis. Interestingly, specificity protein 1 (SP1), a known downstream target gene of the Hippo-TEA-domain family members 1 (TEAD1) pathway, was found to directly bind to the EHD1 promoter region and induce its expression. Among clinical specimens, the EHD1 expression level in LUAD tissues of metastatic patients was higher than that of non-metastatic patients.

CONCLUSIONS

Our findings emphasise that EHD1 might be a potent anti-metastatic target and present a novel regulatory mechanism by which the EHD1/CD44/Hippo/SP1 positive feedback circuit plays pivotal roles in coupling modules of CSCs-like properties and EMT in LUAD. Targeting this loop may serve as a remedy for patients with advanced metastatic LUAD.

Roles for growth factors and mutations in metastatic dissemination

Cancer is initiated largely by specific cohorts of genetic aberrations, which are generated by mutagens and often mimic active growth factor receptors, or downstream effectors. Once initiated cells outgrow and attract blood vessels, a multi-step process, called metastasis, disseminates cancer cells primarily through vascular routes. The major steps of the metastatic cascade comprise intravasation into blood vessels, circulation as single or collectives of cells, and eventual colonization of distant organs. Herein, we consider metastasis as a multi-step process that seized principles and molecular players employed by physiological processes, such as tissue regeneration and migration of neural crest progenitors. Our discussion contrasts the irreversible nature of mutagenesis, which establishes primary tumors, and the reversible epigenetic processes (e.g. epithelial-mesenchymal transition) underlying the establishment of micro-metastases and secondary tumors. Interestingly, analyses of sequencing data from untreated metastases inferred depletion of putative driver mutations among metastases, in line with the pivotal role played by growth factors and epigenetic processes in metastasis. Conceivably, driver mutations may not confer the same advantage in the microenvironment of the primary tumor and of the colonization site, hence phenotypic plasticity rather than rigid cellular states hardwired by mutations becomes advantageous during metastasis. We review the latest reported examples of growth factors harnessed by the metastatic cascade, with the goal of identifying opportunities for anti-metastasis interventions. In summary, because the overwhelming majority of cancer-associated deaths are caused by metastatic disease, understanding the complexity of metastasis, especially the roles played by growth factors, is vital for preventing, diagnosing and treating metastasis.

Conditional Ror1 knockout reveals crucial involvement in lung adenocarcinoma development and identifies novel HIF-1α regulator

We previously reported that ROR1 is a crucial downstream gene for the TTF‐1/NKX2‐1 lineage‐survival oncogene in lung adenocarcinoma, while others have found altered expression of ROR1 in multiple cancer types. Accumulated evidence therefore indicates ROR1 as an attractive molecular target, though it has yet to be determined whether targeting Ror1 can inhibit tumor development and growth in vivo. To this end, genetically engineered mice carrying homozygously floxed Ror1 alleles and an SP‐C promoter–driven human mutant EGFR transgene were generated. Ror1 ablation resulted in marked retardation of tumor development and progression in association with reduced malignant characteristics and significantly better survival. Interestingly, gene set enrichment analysis identified a hypoxia‐induced gene set (HALLMARK_HYPOXIA) as most significantly downregulated by Ror1 ablation in vivo, which led to findings showing that ROR1 knockdown diminished HIF‐1α expression under normoxia and clearly hampered HIF‐1α induction in response to hypoxia in human lung adenocarcinoma cell lines. The present results directly demonstrate the importance of Ror1 for in vivo development and progression of lung adenocarcinoma, and also identify Ror1 as a novel regulator of Hif‐1α. Thus, a future study aimed at the development of a novel therapeutic targeting ROR1 for treatment of solid tumors such as seen in lung cancer, which are frequently accompanied with a hypoxic tumor microenvironment, is warranted.

FET(EWSR1)-TFCP2 Rhabdomyosarcoma: An Additional Example of this Aggressive Variant with Predilection for the Gnathic Bones

An example of a mandibular rhabdomyosarcoma in a 15-year-old male is described featuring EWSR1-TFCP2 fusion with homolateral lymph node metastasis and apparent metastasis to the thoracic vertebra T7. This type of rhabdomyosarcoma has preference for the craniofacial skeleton. Histologically, the tumor was composed of spindle and epithelioid cells characterized by nuclear pleomorphism, cytologic atypia and brisk mitotic activity. Immunohistochemically, it featured diffuse positive nuclear staining MYOD1, only focal staining for myogenin and patchy cytoplasmic staining for desmin. Tumor cells were positive for keratins and nuclear staining for SATB2 was also observed. Interestingly, tumor cells were diffusely positive for calponin. Currently, the patient is under chemotherapy treatment.