CSNK2A1 confers gemcitabine resistance to pancreatic ductal adenocarcinoma via inducing autophagy

Gemcitabine, a pivotal chemotherapeutic agent for pancreatic ductal adenocarcinoma (PDAC), frequently encounters drug resistance, posing a significant clinical challenge with implications for PDAC patient prognosis. In this study, employing an integrated approach involving bioinformatic analyses from multiple databases, we unveil CSNK2A1 as a key regulatory factor. The patient-derived xenograft (PDX) model further substantiates the critical role of CSNK2A1 in gemcitabine resistance within the context of PDAC. Additionally, targeted silencing of CSNK2A1 expression significantly enhances sensitivity of PDAC cells to gemcitabine treatment. Mechanistically, CSNK2A1's transcriptional regulation is mediated by H3K27 acetylation in PDAC. Moreover, we identify CSNK2A1 as a pivotal activator of autophagy, and enhanced autophagy drives gemcitabine resistance. Silmitasertib, an established CSNK2A1 inhibitor, can effectively inhibit autophagy. Notably, the combinatorial treatment of Silmitasertib with gemcitabine demonstrates remarkable efficacy in treating PDAC. In summary, our study reveals CSNK2A1 as a potent predictive factor for gemcitabine resistance in PDAC. Moreover, targeted CSNK2A1 inhibition by Silmitasertib represents a promising therapeutic strategy to restore gemcitabine sensitivity in PDAC, offering hope for improved clinical outcomes.

Development and Verification of a novel cuproptosis- and immune-associated based prognostic genetic signature for pancreatic ductal adenocarcinoma

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) is a malignancy with a dismal prognosis. Cuproptosis, a novel mechanism mediated by protein lipoylation, results in acute proteotoxic stress and ultimately cell death. However, the clinical impacts of cuproptosis-associated genes and their relationship with immune status in PDAC have not been documented. In this study, we aimed at constructing a cuproptosis- and immune-associated prognostic signature to stratify and predict the prognosis for PDAC patients.

METHODS

The gene expression profiles of 176 PDAC patients from The Cancer Genome Atlas and 167 normal pancreas tissues from the Genotype-Tissue Expression Project were analyzed for differentially expressed genes (DEGs) between PDAC and normal tissues. Pearson correlation analyses were performed to screen out cuproptosis- and immune-associated DEGs. The risk signature of DEGs was constructed using the least absolute shrinkage and selection operator (LASSO) Cox regression analysis, which was validated in the Gene Expression Omnibus (GEO) cohort (n = 114). The immune characteristics in the two risk groups were evaluated using single-sample gene set enrichment analysis and ESTIMATE algorithms.

RESULTS

A total of 91 cuproptosis- and immune-associated DEGs were screened out, and eight prognostic-related genes were identified using LASSO Cox regression. The prognostic-related genes were then used to construct a risk scoring model, which stratified patients into low- and high-risk groups and were further verified in the external GEO database. The patients in the high-risk group had significantly shorter overall survival than those in the low-risk group. A nomogram based on the risk signature was then constructed. Immune infiltration evaluation suggested that immune status was more activated in the low-risk group. The mutation spectrum also differed between high- and low-risk groups.

CONCLUSIONS

Our cuproptosis- and immune-associated genetic risk signature could be a prognostic biomarker for PDAC. Cuproptosis might be a promising therapeutic target for PDAC.

Imatinib facilitates gemcitabine sensitivity by targeting epigenetically activated PDGFC signaling in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a malignant tumor with poor prognosis. Gemcitabine-based chemotherapy has become one of the main modalities of its management. However, gemcitabine resistance frequently occurs, leading to failure of PDAC therapy. Platelet-derived growth factors (PDGFs) and their receptors play important roles in cancer progression and chemoresistance. We aimed to investigate the biological function and therapeutic significance of platelet-derived growth factor C (PDGFC) in drug-resistant PDAC. Our study showed that PDGFC was abnormally highly expressed in gemcitabine-resistant PDAC. Silencing PDGFC expression can enhance the therapeutic effect of gemcitabine on PDAC. Mechanistically, the transcription of PDGFC is mediated by H3K27 acetylation, and PDGFC promotes gemcitabine resistance by activating the PDGFR-PI3K-AKT signaling pathway. The PDGFR inhibitor imatinib inhibits the PDGFR pathway. Imatinib and gemcitabine have a synergistic effect on the treatment of PDAC, and imatinib can significantly enhance the anti-tumor effect of gemcitabine in a drug-resistant PDAC patient-derived xenograft model. In conclusion, PDGFC is a potential predictor of gemcitabine-resistant PDAC. Imatinib inhibits PDGFR activation to promote gemcitabine sensitivity in PDAC. Combined modality regimen of imatinib and gemcitabine is likely to translate into clinical trial for the treatment of PDGFC-associated gemcitabine-resistant patients.

METTL3 promotes intrahepatic cholangiocarcinoma progression by regulating IFIT2 expression in an m6A-YTHDF2-dependent manner

N6-methyladenosine (m6A) RNA methylation has recently been found involving in regulatory mechanism of the tumor progression. Our aim was to explore the biological function and clinical significance of the m6A methyltransferase METTL3 in intrahepatic cholangiocarcinoma (ICC). In this study, we revealed that METTL3 was upregulated and predicted poor prognosis of patients with ICC. Multivariate regression analysis demonstrated that METTL3 expression was an independent predictor for overall survival in patients with ICC. Moreover, METTL3 knockdown inhibited ICC progression, while METTL3 overexpression showed the opposite effect. METTL3 inhibitor STM2457 also showed anti-tumor effect in ICC. Mechanistically, METTL3 transcription was driven by H3K4me3 activation. Upregulation of METTL3 mediated m6A modification of IFIT2 mRNA and accelerated IFIT2 mRNA decay in a YTHDF2-dependent manner, which promoted the development of ICC and lead to poorer prognosis. In summary, our findings revealed that H3K4me3 activation-driven METTL3 transcription promotes ICC progression by YTHDF2-mediated IFIT2 mRNA degradation, suggesting that METTL3 may serve as a potential target for human ICC therapy.

Values of a novel pyroptosis-related genetic signature in predicting outcome and immune status of pancreatic ductal adenocarcinoma

Background

Pyroptosis is an emerging form of programmed cell death associated with progression in malignancies. Yet, there are few studies reporting on the association between pancreatic ductal adenocarcinoma (PDAC) and pyroptosis. Therefore, we aimed to construct a pyroptosis-related genetic signature to predict the clinical outcome and immune status in PDAC patients.

Methods

RNA-seq data of 176 PDAC patients from The Cancer Genome Atlas (TCGA) and 167 PDAC patients from the Genotype-Tissue Expression Project were analysed for pyroptosis-related differentially expressed genes (DEGs) between PDAC and normal pancreas. The risk signature of DEGs was analysed using the least absolute shrinkage and selection operator (LASSO) Cox regression analysis and its accuracy was validated in the Gene Expression Omnibus (GEO) cohort (n = 190). Functional enrichment analyses were performed to explore the mechanisms of the DEGs. The immune characteristics were evaluated using single-sample gene set enrichment analysis and ESTIMATE algorithms for each group.

Results

A nine-gene risk signature was generated from LASSO Cox regression analysis and classified PDAC patients into either a high- or low-risk group according to the median risk score. The high-risk group had significantly shorter overall survival than the low-risk group and it was verified in the external GEO database. A nomogram based on the risk signature was constructed and showed an ideal prediction performance. Functional enrichment analyses revealed that pyroptosis might regulate the tumor immune microenvironment in PDAC. Immune infiltration evaluation suggested that immune status was more activated in the low-risk group than in the high-risk group.

Conclusion

The risk signature encompassing nine pyroptosis-related genes may be a prognostic marker for PDAC. Pyroptosis might affect the prognosis of PDAC patients via regulating the tumor immune microenvironment.

HNRNPC impedes m6A-dependent anti-metastatic alternative splicing events in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a malignancy with poor prognosis due to early metastasis. The aberrant N6-methyladenosine (m6A) RNA modification has emerged as an important mechanism in cancer progression and metastasis, but its role in PDAC remained largely unknown. Here, we demonstrated that an m6A regulator, heterogeneous nuclear ribonucleoprotein C (HNRNPC), modulated alternative splicing events to promote PDAC metastasis. In clinical PDAC tissues, high expression of HNRNPC was correlated with metastasis, resulting in poor prognosis in PDAC patients. Knockdown of HNRNPC significantly reduced PDAC cell invasion in vitro and metastasis in vivo. In contrast, overexpression of HNRNPC provoked malignant phenotypes of PDAC cells. Mechanistically, HNRNPC antagonized the anti-metastatic isoform of TAF8 (TAF8L) but increased the pro-metastatic alternative splicing isoform of TAF8 (TAF8S). Mutation of the m6A-site of TAF8 attenuated the interaction between HNRNPC and TAF8 transcript, leading to the decrease of TAF8S. Furthermore, experimental manipulation of the anti-metastasis splicing isoform TAF8L revealed that splice isoform switching of TAF8 is crucial for PDAC metastasis. In conclusion, our findings demonstrate the essentiality of HNRNPC-mediated alternative splicing events that impinges on metastatic PDAC.

Nanomaterial-Facilitated Cyclin-Dependent Kinase 7 Inhibition Suppresses Gallbladder Cancer Progression via Targeting Transcriptional Addiction

Gallbladder cancer (GBC) is the most aggressive malignancy of the biliary tract cancer, and there is a lack of effective treatment. Here, we developed a nanoparticle platform (8P4 NP) that can deliver THZ1, a cyclin-dependent kinase 7 (CDK7) inhibitor, to treat GBC. Analysis of datasets demonstrated that CDK7 was positively correlated with poor prognosis. CDK7 inhibition suppressed cell proliferation, induced apoptosis, and caused cell cycle block in GBC cells. THZ1 downregulated CDK7-mediated phosphorylation of RNA polymerase II (RNAPII), resulting in a significant downregulation of transcriptional programs, with a preferential repression of oncogenic transcription factors. To improve the tumor targeting efficiency of THZ1, 8P4 NPs were prepared and assembled with THZ1 to form THZ1@8P4 NPs. Compared with free THZ1, THZ1@8P4 NPs showed more advantages in prolonging blood circulation, escaping from lysosomes and increasing cellular uptake. Importantly, THZ1@8P4 NPs demonstrated a more significant inhibition effect on GBC cells than free THZ1 in vitro. In addition, THZ1@8P4 NPs could efficiently deliver THZ1 to tumor sites in a patient-derived xenograft model of early recurrence, leading to tumor regression and transcriptional inhibition with minimal toxicity. In summary, we conclude that THZ1@8P4 NPs provide a potent therapeutic strategy that targets CDK7-mediated transcriptional addiction in GBC.

Histone methyltransferase G9a inhibitor-loaded redox-responsive nanoparticles for pancreatic ductal adenocarcinoma therapy

Survival data have shown little therapeutic improvement in pancreatic ductal adenocarcinoma (PDAC) over the past several decades, mostly due to aggressive growth and resistance to therapy. Glutathione (GSH) depletion in PDAC may serve as a strategy to suppress tumour malignancy and sensitize tumour cells to therapy. Herein, novel l-cysteine-based poly(disulfide amide) polymers were fabricated to deliver a histone methyltransferase G9a inhibitor (UNC0638) that can simultaneously block GSH biosynthesis and clear cellular GSH levels in PDAC. The optimal UNC0638 nanodrug (NP_UNC0638) had the desired particle size, reasonable drug loading capacity, and GSH-controlled drug release. Moreover, compared to UNC0638 alone, NP_UNC0638 showed better efficacy in inhibiting cell viability, arresting the cell cycle, inducing apoptosis, and suppressing the invasion and self-renewal capacity of PDAC cells. Furthermore, NP_UNC0638 was found to be tumour-specific and well tolerated with no apparent toxicity to vital organs and haematopoietic stem and progenitor cells. Additionally, treatment with NP_UNC0638 provided favourable outcomes in the PDAC xenograft model. Therefore, this work presents a potent drug delivery platform to overcome the GSH-induced malignant potential of PDAC.

Therapeutic Targeting of CDK7 Suppresses Tumor Progression in Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a lethal malignancy with high mortality and lack of effective therapeutic targets. Here, we found that expression of cyclin-dependent kinase 7 (CDK7) was significantly associated with higher tumor grade and worse prognosis in 96 ICC specimens. Depletion of CDK7 significantly inhibited cell growth, induced a G2/M cell cycle arrest, and reduced the migratory and invasive potential in ICC cells. Subsequent experiments demonstrated that ICC cells were highly sensitive to the CDK7 inhibitor THZ1. A low concentration of THZ1 markedly inhibited cell growth, cell cycle, migration, and invasion in ICC cell lines. RNA-sequencing (RNA-seq) analysis revealed that THZ1 treatment decreased the levels of massive oncogene transcripts, particularly those associated with cell cycle and cell migration. Quantitative reverse transcriptase PCR (qRT-PCR) analysis confirmed that transcription of oncogenes involved in cell cycle regulation (AURKA, AURKB, CDC25B, CDK1, CCNA2, and MKI67) and the c-Met pathway (c-Met, AKT1, PTK2, CRK, PDPK1, and ARF6) was selectively repressed by THZ1. In addition, THZ1 exhibited significant anti-tumor activity in a patient-derived xenograft (PDX) model of ICC, without causing detectable side effects.

MFAP5 facilitates the aggressiveness of intrahepatic Cholangiocarcinoma by activating the Notch1 signaling pathway

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver cancer. The dismal outcome of ICC patients is due to lack of early diagnosis, the aggressive biological behavior of ICC and the lack of effective therapeutic options. Early diagnosis and prognosis of ICC by non-invasive methods would be helpful in providing valuable information and developing effective treatment strategies.

METHODS

Expression of microfibrillar-associated protein 5 (MFAP5) in the serum of ICC patients was detected by ELISA. Human ICC specimens were immunostained by MFAP5 antibodies. The growth rate of human ICC cell lines treated with MFAP5 or MFAP5 shRNAs was examined by CCK8 and colony formation assays. Cell cycle analysis was performed with PI staining. The effect of MFAP5 inhibition was assessed by xenograft models in nude mice. RNA-seq and ATAC-seq analyses were used to dissect the molecular mechanism by which MFAP5 promoted ICC aggressiveness.

RESULTS

We identified MFAP5 as a biomarker for the diagnosis and prognosis of ICC. Upregulated MFAP5 is a common feature in aggressive ICC patients' tissues. Importantly, MFAP5 level in the serum of ICC patients and healthy individuals showed significant differential expression profiles. Furthermore, we showed that MFAP5 promoted ICC cell growth and G1 to S-phase transition. Using RNA-seq expression and ATAC-seq chromatin accessibility profiling of ICC cells with suppressed MFAP5 secretion, we showed that MFAP5 regulated the expression of genes involved in the Notch1 signaling pathway. Furthermore, FLI-06, a Notch signaling inhibitor, completely abolished the MFAP5-dependent transcriptional programs.

CONCLUSIONS

Raised MFAP5 serum level is useful for differentiating ICC patients from healthy individuals, and could be helpful in ICC diagnosis, prognosis and therapies.

EYA4 inhibits hepatocellular carcinoma by repressing MYCBP by dephosphorylating β-catenin at Ser552

Hepatocellular carcinoma (HCC) is one of the most common malignancies and the fourth leading cause of cancer-related death worldwide. Our previous study showed that EYA4 functioned by suppressing growth of HCC tumor cells, but its molecular mechanism is still not elucidated. Based on the results of gene microassay, EYA4 was inversely correlated with MYCBP and was verified in human HCC tissues by immunohistochemistry and western blot. Overexpressed and KO EYA4 in human HCC cell lines confirmed the negative correlation between EYA4 and MYCBP by qRT-PCR and western blot. Transfected siRNA of MYCBP in EYA4 overexpressed cells and overexpressed MYCBP in EYA4 KO cells could efficiently rescue the proliferation and G2/M arrest effects of EYA4 on HCC cells. Mechanistically, armed with serine/threonine-specific protein phosphatase activity, EYA4 reduced nuclear translocation of β-catenin by dephosphorylating β-catenin at Ser552, thereby suppressing the transcription of MYCBP which was induced by β-catenin/LEF1 binding to the promoter of MYCBP. Clinically, HCC patients with highly expressed EYA4 and poorly expressed MYCBP had significantly longer disease-free survival and overall survival than HCC patients with poorly expressed EYA4 and highly expressed MYCBP. In conclusion, EYA4 suppressed HCC tumor cell growth by repressing MYCBP by dephosphorylating β-catenin S552. EYA4 combined with MYCBP could be potential prognostic biomarkers in HCC.

Abstract P3-08-03: Dissecting the heterogeneity of metaplastic breast cancer: A morphological, immunohistochemical and genomic analysis of a large cohort

Although rare, Metaplastic Breast Carcinomas (MBC) account for significant global breast cancer mortality. This subgroup is extremely heterogeneous and by definition exhibits metaplastic change to squamous and/or mesenchymal elements, including but not limited to spindle, squamous, chondroid, osseous and rhabdomyoid elements. The WHO working group recognizes that the current classification is inadequate and in the interim, has suggested a purely descriptive classification. The mixed epithelial-mesenchymal morphology has led to speculation that MBC represent 'stem cell tumours'; in support of this, MBC have been shown to have a CD44+/CD24-/low phenotype. Clinically, patients present with tumours that are larger (higher stage), have increased likelihood of distant metastases at presentation and overall, have a reduced 5-year survival rate compared to Invasive Carcinoma-NST. Hence, this is a unique subtype with poor outcome but without a robust classification or understanding of the biology to aid clinical management. We present a detailed morphological, immunohistochemical and genomic analysis of a large series of MBC (n=347), as amassed through the Asia-Pacific MBC consortium. We consider our morphological dissection using the WHO subtyping guidelines and show that an increasing number of phenotypes in a mixed MBC (classified as WHO_1) significantly associates with a poor prognosis. Immunohistochemical analysis showed that a pure spindle (WHO_5) is significantly less likely to express vimentin, CK5/6, CK14, and CK19 than a mixed WHO_1 with spindle features. Similarly, a WHO_1 with chondroid features is less likely to express EGFR than WHO_1 with chondroid features and rhabdoid or osseous differentiation. Across the cohort, positivity for the AE1/3 antibody and a lack of EGFR expression both significantly associate with a better outcome. We report no significant association between patient age at diagnosis and breast cancer specific survival, nor between age and specific WHO MBC subtypes. We report a significant association between WHO_1 types and increasing tumour grade, and also between tumour size and grade, with tumour size being a highly significant prognostic indicator in this cohort. Our exome sequencing confirms a significant enrichment for TP53 and PTEN mutations in MBC, and intriguingly for concurrent mutations of TP53, PTEN and PIK3CA. A novel enrichment for NF1 mutations is also presented. In summary, we provide a thorough assessment of a large cohort of MBC, including morphology, survival, IHC and exome sequencing, and present our analysis contextualized by the WHO guidelines, extending the existing knowledge base of this rare tumour type.

Citation Format: McCart Reed AE, Kalaw E, Nones K, Bettington M, Lim M, Bennett J, Johnstone K, Kutasovic JR, Kazakoff S, Xu QC, Saunus JM, Reid LE, Black D, Niland C, Ferguson K, Gresshoff I, Raghavendra A, Liu JC, Kalinowski L, Reid AS, Davidson M, Pearson JV, Yamaguchi R, Harris G, Tse G, Papadimos D, Pathmanathan R, Pathmanathan N, Tan PH, Fox S, O'Toole S, Waddell N, Simpson PT, Lakhani SR. Dissecting the heterogeneity of metaplastic breast cancer: A morphological, immunohistochemical and genomic analysis of a large cohort [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-08-03.

Molecular cloning of HSP70 in Mycoplasma ovipneumoniae and comparison with that of other mycoplasmas

Mycoplasma ovipneumoniae, a bacterial species that specifically affects ovine and goat, is the cause of ovine infectious pleuropneumonia. We cloned, sequenced and analyzed heat shock protein 70 (HSP70) (dnaK) gene of M. ovipneumoniae. The full length open reading frame of the M. ovipneumoniae HSP70 gene consists of 1812 nucleotides, with a G+C content of 34.16%, encoding 604 amino acids. Comparative analysis with the HSP70 sequences of 15 Mycoplasma species revealed 59 to 87% DNA sequence identity, with an amino acid sequence identity range of 58 to 94%. M. ovipneumoniae and M. hyopneumoniae shared the highest DNA and amino acid sequence identity (87 and 94%, respectively). Based on phylogenetic analysis, both the DNA and amino acid identities of M. ovipneumoniae with other mycoplasmal HSP70 were correlated with the degree of relationship between the species. The C-terminus of the HSP70 was cloned into a bacterial expression vector and expressed in Escherichia coli cells. The recombinant C-terminal portion of HSP70 protein strongly reacted with convalescent sera from M. ovipneumoniae-infected sheep, based on an immunoblotting assay. This indicates that HSP70 is immunogenic in a natural M. ovipneumoniae infection and may be a relevant antigen for vaccine development.

Piezoelectric composites with high sensitivity and high capacitance for use at high pressures

A type of piezoelectric composite has been developed for oceanographic applications. The composites have a large figure of merit (d(h)xg(h) or d(h )xg(h)/tan delta, where d(h ) is the hydrostatic piezoelectric voltage coefficient), a large dielectric constant (K) and low dielectric loss, and great mechanical strength. A shallow cavity between the PZT ceramics and thick metallic electrode is designed to convert a portion of the z-direction stress into a large radial and tangential stress of opposite sign. thereby causing the d(33) and d(31) contributions to d(h) to add rather than subtract, and raising the figure of merit. Theoretical stress analysis was carried out using an axisymmetric finite element method. Experimental results show that the d(h)x g(h), K, and withstandable pressure are extremely high.

A modified thickness extensional disk transducer

Photolithography and chemical etching were investigated as a means of patterning miniature piezoelectric devices. Using a processing procedure analogous to that utilized in the production of integrated circuitry, concentrated hydrochloric acid and a commercially available photoresist were used to fabricate a number of complex structures from soft lead zirconate titanate (PZT) substrates. Among the devices produced in this manner was a modified thickness-mode resonator etched to destroy the simple geometry responsible for radial vibrations. The resultant transducer demonstrated significantly smaller amplitudes for lateral resonances and a marked reduction in the effective planar coupling coefficient over the unaltered disk. The results indicate that photolithographic patterning is useful both for eliminating spurious resonances from transducers for medical imaging or nondestructive evaluation and for engineering low planar coupling coefficients into a variety of substrate materials.