Racial disparity in prostate cancer: an outlook in genetic and molecular landscape.

Prostate cancer (PCa) incidence, morbidity, and mortality rates are significantly impacted by racial disparities. Despite innovative therapeutic approaches and advancements in prevention, men of African American (AA) ancestry are at a higher risk of developing PCa and have a more aggressive and metastatic form of the disease at the time of initial PCa diagnosis than other races. Research on PCa has underlined the biological and molecular basis of racial disparity and emphasized the genetic aspect as the fundamental component of racial inequality. Furthermore, the lower enrollment rate, limited access to national-level cancer facilities, and deferred treatment of AA men and other minorities are hurdles in improving the outcomes of PCa patients. This review provides the most up-to-date information on various biological and molecular contributing factors, such as the single nucleotide polymorphisms (SNPs), mutational spectrum, altered chromosomal loci, differential gene expression, transcriptome analysis, epigenetic factors, tumor microenvironment (TME), and immune modulation of PCa racial disparities. This review also highlights future research avenues to explore the underlying biological factors contributing to PCa disparities, particularly in men of African ancestry.

MUC16 promotes triple-negative breast cancer lung metastasis by modulating RNA-binding protein ELAVL1/HUR.

BACKGROUND: Triple-negative breast cancer (TNBC) is highly aggressive with an increased metastatic incidence compared to other breast cancer subtypes. However, due to the absence of clinically reliable biomarkers and targeted therapy in TNBC, outcomes are suboptimal. Hence, there is an urgent need to understand biological mechanisms that lead to identifying novel therapeutic targets for managing metastatic TNBC. METHODS: The clinical significance of MUC16 and ELAVL1 or Hu antigen R (HuR) was examined using breast cancer TCGA data. Microarray was performed on MUC16 knockdown and scramble TNBC cells and MUC16-associated genes were identified using RNA immunoprecipitation and metastatic cDNA array. Metastatic properties of MUC16 were evaluated using tail vein experiment. MUC16 and HuR downstream pathways were confirmed by ectopic overexpression of MUC16-carboxyl-terminal (MUC16-Cter), HuR and cMyc as well as HuR inhibitors (MS-444 and CMLD-2) in TNBC cells. RESULTS: MUC16 was highly expressed in TNBC and correlated with its target HuR. Depletion of MUC16 showed decreased invasion, migration, and colony formation abilities of human and mouse TNBC cells. Mice injected with MUC16 depleted cells were less likely to develop lung metastasis (P = 0.001). Notably, MUC16 and HuR were highly expressed in the lung tropic TNBC cells and lung metastases. Mechanistically, we identified cMyc as a HuR target in TNBC using RNA immunoprecipitation and metastatic cDNA array. Furthermore, MUC16 knockdown and pharmacological inhibition of HuR (MS-444 and CMLD-2) in TNBC cells showed a reduction in cMyc expression. MUC16-Cter or HuR overexpression models indicated MUC16/HuR/cMyc axis in TNBC cell migration. CONCLUSIONS: Our study identified MUC16 as a TNBC lung metastasis promoter that acts through HuR/cMyc axis. This study will form the basis of future studies to evaluate the targeting of both MUC16 and HuR in TNBC patients.

Pancreatic Tumor Microenvironment Factor Promotes Cancer Stemness via SPP1-CD44 Axis.

BACKGROUND & AIMS: Tumor-microenvironment factors and cancer stem cells (CSCs) play a critical role in the aggressiveness of pancreatic cancer (PC). However, the degree to which tumor-microenvironment factors promote stemness remains unexplored. Here, we examined whether cancer-associated fibroblasts (CAFs) promote CSC features in PC. METHODS: PC cells were treated long-term (30, 60, and 90 days) with conditioned media (CM)-derived from normal human fibroblasts (NFs) and CAFs. The stemness features of tumorsphere formation and stemness populations, along with CSCs markers, were analyzed using 2-dimensional and 3-dimensional sodium alginate bead-based co-culture models. Immunohistochemistry and immunofluorescence staining were performed for CSCs and fibroblast markers in autochthonous KrasG12D/+; Trp53R172H/+; Pdx1-Cre mice and human pancreatic tumors. Polymerase chain reaction array and gene knockdown were performed to identify the mechanism of stemness enrichment. RESULTS: Long-term treatment of PC cells with CAF-CM enriched stemness, as indicated by significantly higher CD44+, ALDH+, and AF+ populations in PC cells. Increased tumorsphere formation and elevated CSC, self-renewal, and drug-resistance markers in CAF-CM-treated PC cells were observed. In addition, CAFs co-cultured with PC cells in the 3-dimensional model showed a substantial increase in stemness features. CD44 and α-smooth muscle actin were positively correlated and their expressions progressively increased from the early to late stages of KrasG12D/+; Trp53R172H/+; Pdx1-Cre mouse and human pancreatic tumors. Osteopontin/secreted phosphoprotein 1 was identified as the top differentially overexpressed gene in CAF-CM-treated PC cells and knockdown of osteopontin/secreted phosphoprotein 1 significantly reduced stemness characteristics in CAF-CM-treated PC cells. CONCLUSIONS: Our data uncovered novel insight into the interplay between CAF and enrichment of stemness population through the osteopontin/secreted phosphoprotein 1-CD44 axis in PC.

DNA-gold nanoprobe-based integrated biosensing technology for non-invasive liquid biopsy of serum miRNA: A new frontier in prostate cancer diagnosis.

The low specificity of prostate-specific antigen contributes to overdiagnosis and ov ertreatment of prostate cancer (PCa) patients. Hence, there is an urgent need for inclusive diagnostic platforms that could improve the diagnostic accuracy of PCa. Dysregulated miRNAs are closely associated with the progression and recurrence and have emerged as promising diagnostic and prognostic biomarkers for PCa. Nevertheless, simple, rapid, and ultrasensitive quantification of serum miRNAs is highly challenging. This study designed, synthesized, and demonstrated the practicability of DNA-linked gold nanoprobes (DNA-AuNPs) for the single-step quantification of miR-21/miR-141/miR-375. In preclinical study, the assay differented PCa Pten conditional knockout (PtencKO) mice compared to their age-matched Pten wild-type (PtenWT) control mice. In human sera, receiver operating characteristic (ROC) curve-based correlation analyses revealed clear discrimination between PCa patients from normal healthy controls using training and validation sets. Overall, we established integrated nano-biosensing technology for the PCR-free, non-invasive liquid biopsies of multiple miRNAs for PCa diagnosis.

Biological determinants of radioresistance and their remediation in pancreatic cancer.

Despite recent advances in radiotherapy, a majority of patients diagnosed with pancreatic cancer (PC) do not achieve objective responses due to the existence of intrinsic and acquired radioresistance. Identification of molecular mechanisms that compromise the efficacy of radiation therapy and targeting these pathways is paramount for improving radiation response in PC patients. In this review, we have summarized molecular mechanisms associated with the radio-resistant phenotype of PC. Briefly, we discuss the reversible and irreversible biological consequences of radiotherapy, such as DNA damage and DNA repair, mechanisms of cancer cell survival and radiation-induced apoptosis following radiotherapy. We further describe various small molecule inhibitors and molecular targeting agents currently being tested in preclinical and clinical studies as potential radiosensitizers for PC. Notably, we draw attention towards the confounding effects of cancer stem cells, immune system, and the tumor microenvironment in the context of PC radioresistance and radiosensitization. Finally, we discuss the need for examining selective radioprotectors in light of the emerging evidence on radiation toxicity to non-target tissue associated with PC radiotherapy.

Cigarette Smoke Induces Stem Cell Features of Pancreatic Cancer Cells via PAF1.

BACKGROUND & AIMS: Cigarette smoking is a major risk factor for pancreatic cancer. Aggressive pancreatic tumors contain cancer cells with stem cell features. We investigated whether cigarette smoke induces stem cell features in pancreatic cancer cells. METHODS: KrasG12D; Pdx1-Cre mice were exposed to cigarette smoke or clean air (controls) for up to 20 weeks; pancreata were collected and analyzed by histology, quantitative reverse transcription polymerase chain reaction, and confocal immunofluorescence microscopy. HPNE and Capan1 cells were exposed to cigarette smoke extract (CSE), nicotine and nicotine-derived carcinogens (NNN or NNK), or clean air (controls) for 80 days and evaluated for stem cell markers and features using flow cytometry-based autofluorescence, sphere formation, and immunoblot assays. Proteins were knocked down in cells with small interfering RNAs. We performed RNA sequencing analyses of CSE-exposed cells. We used chromatin immunoprecipitation assays to confirm the binding of FOS-like 1, AP-1 transcription factor subunit (FOSL1) to RNA polymerase II-associated factor (PAF1) promoter. We obtained pancreatic ductal adenocarcinoma (PDAC) and matched nontumor tissues (n = 15) and performed immunohistochemical analyses. RESULTS: Chronic exposure of HPNE and Capan1 cells to CSE caused them to increase markers of stem cells, including autofluorescence and sphere formation, compared with control cells. These cells increased expression of ABCG2, SOX9, and PAF1, via cholinergic receptor nicotinic alpha 7 subunit (CHRNA7) signaling to mitogen-activated protein kinase 1 and FOSL1. CSE-exposed pancreatic cells with knockdown of PAF1 did not show stem cell features. Exposure of cells to NNN and NNK led to increased expression of CHRNA7, FOSL1, and PAF1 along with stem cell features. Pancreata from KrasG12D; Pdx1-Cre mice exposed to cigarette smoke had increased levels of PAF1 mRNA and protein, compared with control mice, as well as increased expression of SOX9. Levels of PAF1 and FOSL1 were increased in PDAC tissues, especially those from smokers, compared with nontumor pancreatic tissue. CSE exposure increased expression of PHD-finger protein 5A, a pluripotent transcription factor and its interaction with PAF1. CONCLUSIONS: Exposure to cigarette smoke activates stem cell features of pancreatic cells, via CHRNA7 signaling and FOSL1 activation of PAF1 expression. Levels of PAF1 are increased in pancreatic tumors of humans and mice with chronic cigarette smoke exposure.

MUC16: molecular analysis and its functional implications in benign and malignant conditions.

MUC16 is a high-molecular-weight glycoprotein that is expressed by the various epithelial cell surfaces of the human body to protect the cell layer from a myriad of insults. It is the largest mucin known to date, with an ∼22,152 aa sequence. Structurally, MUC16 is characterized into 3 distinct domains: the amino terminal, the tandem repeat, and the carboxyl terminal domain, with each domain having unique attributes. The extracellular portion of MUC16 is shed into the bloodstream and serves as a biomarker for diagnosing and monitoring patients with cancer; however, its functional role in cancer is yet to be elucidated. Several factors contribute to this challenge, which include the large protein size; the extensive glycosylation that the protein undergoes, which confers functional heterogeneity; lack of specific antibodies that detect the unique domains of MUC16; and the existence of splicing variants. Despite these limitations, MUC16 has been established as a molecule of significant application in cancer. Hence, in this review, we discuss the various aspects of MUC16, which include its discovery, structure, and biological significance both in benign and malignant conditions with an attempt to dissect its functional relevance

ASPORIN: A root of the matter in tumors and their host environment.

Asporin (ASPN) has been identified as one of the members of the class I small leucine-rich proteoglycans (SLRPs) family in the extracellular matrix (ECM). It is involved in classic ensigns of cancers such as self-dependent growth, resistance to growth inhibitors, restricting apoptosis, cancer metastasis, and bone-related disorders. ASPN is different from other members of SLRPs, such as decorin (DCN) and biglycan (BGN), in a way that it contains a distinctive length of aspartate (D) residues in the amino (N) -terminal region. These D-repeats residues possess germline polymorphisms and are identified to be linked with cancer progression and osteoarthritis (OA). The polyaspartate stretch in the N-terminal region of the protein and its resemblance to DCN are the reasons it is called asporin. In this review, we comprehensively summarized and updated the dual role of ASPN in various malignancies, its structure in mice and humans, variants, mutations, cancer-associated signalings and functions, the relationship between ASPN and cancer-epithelial, stromal fibroblast crosstalk, immune cells and immunosuppression in cancer and other diseases. In cancer and other bone-related diseases, ASPN is identified to be regulating various signaling pathways such as TGFß, Wnt/ß-catenin, notch, hedgehog, EGFR, HER2, and CD44-mediated Rac1. These pathways promote cancer cell invasion, proliferation, and migration by mediating the epithelial-to-mesenchymal transition (EMT) process. Finally, we discussed mouse models mimicking ASPN in vivo function in cancers and the probability of therapeutic targeting of ASPN in cancer cells, fibrosis, and other bone-related diseases.

Connectivity mapping-based identification of pharmacological inhibitor targeting HDAC6 in aggressive pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) remains highly lethal due to limited therapeutic options and expensive/burdensome drug discovery processes. Utilizing genomic-data-driven Connectivity Mapping (CMAP) to identify a drug closer to real-world PC targeting may improve pancreatic cancer (PC) patient outcomes. Initially, we mapped CMAP data to gene expression from 106 PC patients, identifying nine negatively connected drugs. These drugs were further narrowed down using a similar analysis for PC cell lines, human tumoroids, and patient-derived xenografts datasets, where ISOX emerged as the most potent agent to target PC. We used human and mouse syngeneic PC cells, human and mouse tumoroids, and in vivo mice to assess the ability of ISOX alone and in combination with 5FU to inhibit tumor growth. Global transcriptomic and pathway analysis of the ISOX-LINCS signature identified HDAC 6/cMyc as the target axis for ISOX. Specifically, we discovered that genetic and pharmacological targeting of HDAC 6 affected non-histone protein cMyc acetylation, leading to cMyc instability, thereby disrupting PC growth and metastasis by affecting cancer stemness. Finally, KrasG12D harboring tumoroids and mice responded effectively against ISOX and 5FU treatment by enhancing survival and controlling metastasis incidence. Overall, our data validate ISOX as a new drug to treat advanced PC patients without toxicity to normal cells. Our study supports the clinical utility of ISOX along with 5FU in future PC clinical trials.

Understanding the function of Pax5 in development of docetaxel-resistant neuroendocrine-like prostate cancers.

Resistance to the current Androgen Receptor Signaling Inhibitor (ARSI) therapies has led to higher incidences of therapy-induced neuroendocrine-like prostate cancer (t-NEPC). This highly aggressive subtype with predominant small-cell-like characteristics is resistant to taxane chemotherapies and has a dismal overall survival. t-NEPCs are mostly treated with platinum-based drugs with a combination of etoposide or taxane and have less selectivity and high systemic toxicity, which often limit their clinical potential. During t-NEPC transformation, adenocarcinomas lose their luminal features and adopt neuro-basal characteristics. Whether the adaptive neuronal characteristics of t-NEPC are responsible for such taxane resistance remains unknown. Pathway analysis from patient gene-expression databases indicates that t-NEPC upregulates various neuronal pathways associated with enhanced cellular networks. To identify transcription factor(s) (TF) that could be important for promoting the gene expression for neuronal characters in t-NEPC, we performed ATAC-Seq, acetylated-histone ChIP-seq, and RNA-seq in our NE-like cell line models and analyzed the promoters of transcriptionally active and significantly enriched neuroendocrine-like (NE-like) cancer-specific genes. Our results indicate that Pax5 could be an important transcription factor for neuronal gene expression and specific to t-NEPC. Pathway analysis revealed that Pax5 expression is involved in axonal guidance, neurotransmitter regulation, and neuronal adhesion, which are critical for strong cellular communications. Further results suggest that depletion of Pax5 disrupts neurite-mediated cellular communication in NE-like cells and reduces surface growth factor receptor activation, thereby, sensitizing them to docetaxel therapies. Moreover, t-NEPC-specific hydroxymethylation of Pax5 promoter CpG islands favors Pbx1 binding to induce Pax5 expression. Based on our study, we concluded that continuous exposure to ARSI therapies leads to epigenetic modifications and Pax5 activation in t-NEPC, which promotes the expression of genes necessary to adopt taxane-resistant NE-like cancer. Thus, targeting the Pax5 axis can be beneficial for reverting their taxane sensitivity.

Targeting the EGFR signaling pathway in cancer therapy: What's new in 2023?

INTRODUCTION: Epidermal growth factor receptor (EGFR) is frequently amplified, overexpressed, and mutated in multiple cancers. In normal cell physiology, EGFR signaling controls cellular differentiation, proliferation, growth, and survival. During tumorigenesis, mutations in EGFR lead to increased kinase activity supporting survival, uncontrolled proliferation, and migratory functions of cancer cells. Molecular agents targeting the EGFR pathway have been discovered, and their efficacy has been demonstrated in clinical trials. To date, 14 EGFR-targeted agents have been approved for cancer treatments. AREAS COVERED: This review describes the newly identified pathways in EGFR signaling, the evolution of novel EGFR-acquired and innate resistance mechanisms, mutations, and adverse side effects of EGFR signaling inhibitors. Subsequently, the latest EGFR/panEGFR inhibitors in preclinical and clinical studies have been summarized. Finally, the consequences of combining immune checkpoint inhibitors and EGFR inhibitors have also been discussed. EXPERT OPINION: As new mutations are threatened against EGFR-tyrosine kinase inhibitors (TKIs), we suggest the development of new compounds targeting specific mutations without inducing new mutations. We discuss potential future research on developing EGFR-TKIs specific for exact allosteric sites to overcome acquired resistance and reduce adverse events. The rising trend of EGFR inhibitors in the pharma market and their economic impact on real-world clinical practice are discussed.

Understanding the role of Pax5 in development of taxane-resistant neuroendocrine like prostate cancers.

Resistance to the current Androgen Receptor Signaling Inhibitor (ARSI) therapies has led to higher incidences of therapy-induced neuroendocrine-like prostate cancer (t-NEPC). This highly aggressive subtype with predominant small cell-like characteristics is resistant to taxane chemotherapies and has a dismal overall survival. t-NEPCs are mostly treated with platinum-based drugs with a combination of etoposide or taxane and have less selectivity and high systemic toxicity, which often limit their clinical potential. During t-NEPC transformation, adenocarcinomas lose their luminal features and adopt neuro-basal characteristics. Whether the adaptive neuronal characteristics of t-NEPC are responsible for such taxane resistance remains unknown. Pathway analysis from patient gene-expression databases indicates that t-NEPC upregulates various neuronal pathways associated with enhanced cellular networks. To identify transcription factor(s) (TF) that could be important for promoting the gene expression for neuronal characters in t-NEPC, we performed ATAC-Seq, acetylated-histone ChIP-seq, and RNA-seq in our NE-like cell line models and analyzed the promoters of transcriptionally active and significantly enriched neuroendocrine-like (NE-like) cancer-specific genes. Our results indicate that Pax5 could be an important transcription factor for neuronal gene expression and specific to t-NEPC. Pathway analysis revealed that Pax5 expression is involved in axonal guidance, neurotransmitter regulation, and neuronal adhesion, which are critical for strong cellular communications. Further results suggest that depletion of Pax5 disrupts cellular interaction in NE-like cells and reduces surface growth factor receptor activation, thereby, sensitizing them to taxane therapies. Moreover, t-NEPC specific hydroxymethylation of Pax5 promoter CpG islands favors Pbx1 binding to induce Pax5 expression. Based on our study, we concluded that continuous exposure to ARSI therapies leads to epigenetic modifications and Pax5 activation in t-NEPC, which promotes the expression of genes necessary to adopt taxane-resistant NE-like cancer. Thus, targeting the Pax5 axis can be beneficial for reverting their taxane sensitivity.

Macrophage inhibitory cytokine-1 in cancer: Beyond the cellular phenotype.

Despite technological advances in diagnostic abilities and improved treatment methods, the burden of cancers remains high, leading to significant morbidity and mortality. One primary reason is that cancer cell secretory factors modulate the tumor microenvironment, supporting tumor growth and circumvents anticancer activities of conventional therapies. Macrophage inhibitory cytokine-1 (MIC-1) is a pleiotropic cytokine elevated in various cancers. MIC-1 regulates various cancer hallmarks, including sustained proliferation, tumor-promoting inflammation, avoiding immune destruction, inducing invasion, metastasis, angiogenesis, and resisting cell death. Despite these facts, the molecular regulation and downstream signaling of MIC-1 in cancer remain elusive, partly because its receptor (GFRAL) was unknown until recently. Binding of MIC-1 to GFRAL recruits the coreceptor tyrosine kinase RET to execute its downstream signaling. So far, studies have shown that GFRAL expression is restricted to the brain stem and is responsible for MIC-1/GFRAL/RET-mediated metabolic disorders. Nevertheless, abundant levels of MIC-1 expression have been reported in all cancer types and have been proposed as a surrogate biomarker. Given the ubiquitous expression of MIC-1 in cancers, it is crucial to understand both upstream regulation and downstream MIC-1/GFRAL/RET signaling in cancer hallmark traits.

The Pleiotropic role, functions and targeted therapies of LIF/LIFR axis in cancer: Old spectacles with new insights.

The dysregulation of leukemia inhibitory factor (LIF) and its cognate receptor (LIFR) has been associated with multiple cancer initiation, progression, and metastasis. LIF plays a significant tumor-promoting role in cancer, while LIFR functions as a tumor promoter and suppressor. Epithelial and stromal cells secrete LIF via autocrine and paracrine signaling mechanism(s) that bind with LIFR and subsequently with co-receptor glycoprotein 130 (gp130) to activate JAK/STAT1/3, PI3K/AKT, mTORC1/p70s6K, Hippo/YAP, and MAPK signaling pathways. Clinically, activating the LIF/LIFR axis is associated with poor survival and anti-cancer therapy resistance. This review article provides an overview of the structure and ligands of LIFR, LIF/LIFR signaling in developmental biology, stem cells, cancer stem cells, genetics and epigenetics of LIFR, LIFR regulation by long non-coding RNAs and miRNAs, and LIF/LIFR signaling in cancers. Finally, neutralizing antibodies and small molecule inhibitors preferentially blocking LIF interaction with LIFR and antagonists against LIFR under pre-clinical and early-phase pre-clinical trials were discussed.

The GSK3 kinase and LZTR1 protein regulate the stability of Ras family proteins and the proliferation of pancreatic cancer cells.

Ras family proteins are membrane-bound GTPases that control proliferation, survival, and motility. Many forms of cancers are driven by the acquisition of somatic mutations in a RAS gene. In pancreatic cancer (PC), more than 90% of tumors carry an activating mutation in KRAS. Mutations in components of the Ras signaling pathway can also be the cause of RASopathies, a group of developmental disorders. In a subset of RASopathies, the causal mutations are in the LZTR1 protein, a substrate adaptor for E3 ubiquitin ligases that promote the degradation of Ras proteins. Here, we show that the function of LZTR1 is regulated by the glycogen synthase kinase 3 (GSK3). In PC cells, inhibiting or silencing GSK3 led to a decline in the level of Ras proteins, including both wild type Ras proteins and the oncogenic Kras protein. This decline was accompanied by a 3-fold decrease in the half-life of Ras proteins and was blocked by the inhibition of the proteasome or the knockdown of LZTR1. Irrespective of the mutational status of KRAS, the decline in Ras proteins was observed and accompanied by a loss of cell proliferation. This loss of proliferation was blocked by the knockdown of LZTR1 and could be recapitulated by the silencing of either KRAS or GSK3. These results reveal a novel GSK3-regulated LZTR1-dependent mechanism that controls the stability of Ras proteins and proliferation of PC cells. The significance of this novel pathway to Ras signaling and its contribution to the therapeutic properties of GSK3 inhibitors are both discussed.

Pathophysiological role of growth differentiation factor 15 (GDF15) in obesity, cancer, and cachexia.

Growth differentiation factor 15 or macrophage inhibitory cytokine-1 (GDF15/MIC-1) is a divergent member of the transforming growth factor ß superfamily and has a diverse pathophysiological roles in cancers, cardiometabolic disorders, and other diseases. GDF15 controls hematopoietic growth, energy homeostasis, adipose tissue metabolism, body growth, bone remodeling, and response to stress signals. The role of GDF15 in cancer development and progression is complicated and depends on the specific cancer type, stage, and tumor microenvironment. Recently, research on GDF15 and GDF15-associated signaling has accelerated due to the identification of the GDF15 receptor: glial cell line-derived neurotrophic factor (GDNF) family receptor α-like (GFRAL). Therapeutic interventions to target GDF15 and/or GFRAL revealed the mechanisms that drive its activity and might improve overall outcomes of patients with metabolic disorders and cancer. This review highlights the structure and functions of GDF15 and its receptor, emphasizing the pleiotropic role of GDF15 in obesity, tumorigenesis, metastasis, immunomodulation, and cachexia.

GDF15 promotes prostate cancer bone metastasis and colonization through osteoblastic CCL2 and RANKL activation.

Bone metastases occur in patients with advanced-stage prostate cancer (PCa). The cell-cell interaction between PCa and the bone microenvironment forms a vicious cycle that modulates the bone microenvironment, increases bone deformities, and drives tumor growth in the bone. However, the molecular mechanisms of PCa-mediated modulation of the bone microenvironment are complex and remain poorly defined. Here, we evaluated growth differentiation factor-15 (GDF15) function using in vivo preclinical PCa-bone metastasis mouse models and an in vitro bone cell coculture system. Our results suggest that PCa-secreted GDF15 promotes bone metastases and induces bone microarchitectural alterations in a preclinical xenograft model. Mechanistic studies revealed that GDF15 increases osteoblast function and facilitates the growth of PCa in bone by activating osteoclastogenesis through osteoblastic production of CCL2 and RANKL and recruitment of osteomacs. Altogether, our findings demonstrate the critical role of GDF15 in the modulation of the bone microenvironment and subsequent development of PCa bone metastasis.

Reduction in O-glycome induces differentially glycosylated CD44 to promote stemness and metastasis in pancreatic cancer.

Aberrant protein glycosylation has been shown to have a significant contribution in aggressive cancer, including pancreatic cancer (PC). Emerging evidence has implicated the involvement of cancer stem cells (CSCs) in PC aggressiveness; however, the contribution of glycosylation on self-renewal properties and maintenance of CSC is understudied. Here, using several in vitro and in vivo models lacking C1GALT1 expression, we identified the role of aberrant O-glycosylation in stemness properties and aggressive PC metastasis. A loss in C1GALT1 was found to result in the truncation of O-glycosylation on several glycoproteins with an enrichment of Tn carbohydrate antigen. Mapping of Tn-bearing glycoproteins in C1GALT1 KO cells identified significant Tn enrichment on CSC glycoprotein CD44. Notably, a loss of C1GALT1 in PC cells was found to enhance CSC features (side population-SP, ALDH1+, and tumorspheres) and self-renewal markers NANOG, SOX9, and KLF4. Furthermore, a loss of CD44 in existing C1GALT1 KO cells decreased NANOG expression and CSC features. We determined that O-glycosylation of CD44 activates ERK/NF-kB signaling, which results in increased NANOG expression in PC cells that facilitated the alteration of CSC features, suggesting that NANOG is essential for PC stemness. Finally, we identified that loss of C1GALT1 expression was found to augment tumorigenic and metastatic potential, while an additional loss of CD44 in these cells reversed the effects. Overall, our results identified that truncation of O-glycans on CD44 increases NANOG activation that mediates increased CSC activation.

Small molecule inhibitor against onco-mucins disrupts Src/FosL1 axis to enhance gemcitabine efficacy in pancreatic ductal adenocarcinoma.

Mucin MUC4 is an aberrantly expressed oncogene in pancreatic ductal adenocarcinoma (PDAC), yet no pharmacological inhibitors have been identified to target MUC4. Here, we adapted an in silico screening method using the Cancer Therapeutic Response Database (CTRD) to Identify Small Molecule Inhibitors against Mucins (SMIMs). We identified Bosutinib as a candidate drug to target oncogenic mucins among 126 FDA-approved drugs from CTRD screening. Functionally, Bosutinib treatment alone/and in combination with gemcitabine (Gem)/5' fluorouracil (5FU) reduced in vitro viability, migration, and colony formation in multiple PDAC cell lines as well as human PDAC organoid prolifertaion and growth and in vivo xenograft growth. Further, biochemical and molecular analyses showed that Bosutinib exhibited these functional effects by downregulating MUC4 mucin at both transcript and translation levels in a dose- and time-dependent manner. Mechanistically, global transcriptome analysis in PDAC cells upon treatment with Bosutinib revealed disruption of the Src-ERK/AKT-FosL1 pathway, leading to decreased expression of MUC4 and MUC5AC mucins. Taken together, Bosutinib is a promising, novel, and highly potent SMIMs to target MUC4/MUC5AC mucins. This mucin-targeting effect of Bosutinib can be exploited in the future with cytotoxic agents to treat mucinous tumors.

Disruption of FDPS/Rac1 axis radiosensitizes pancreatic ductal adenocarcinoma by attenuating DNA damage response and immunosuppressive signalling.

BACKGROUND: Radiation therapy (RT) has a suboptimal effect in patients with pancreatic ductal adenocarcinoma (PDAC) due to intrinsic and acquired radioresistance (RR). Comprehensive bioinformatics and microarray analysis revealed that cholesterol biosynthesis (CBS) is involved in the RR of PDAC. We now tested the inhibition of the CBS pathway enzyme, farnesyl diphosphate synthase (FDPS), by zoledronic acid (Zol) to enhance radiation and activate immune cells. METHODS: We investigated the role of FDPS in PDAC RR using the following methods: in vitro cell-based assay, immunohistochemistry, immunofluorescence, immunoblot, cell-based cholesterol assay, RNA sequencing, tumouroids (KPC-murine and PDAC patient-derived), orthotopic models, and PDAC patient's clinical study. FINDINGS: FDPS overexpression in PDAC tissues and cells (P < 0.01 and P < 0.05) is associated with poor RT response and survival (P = 0.024). CRISPR/Cas9 and pharmacological inhibition (Zol) of FDPS in human and mouse syngeneic PDAC cells in conjunction with RT conferred higher PDAC radiosensitivity in vitro (P < 0.05, P < 0.01, and P < 0.001) and in vivo (P < 0.05). Interestingly, murine (P = 0.01) and human (P = 0.0159) tumouroids treated with Zol+RT showed a significant growth reduction. Mechanistically, RNA-Seq analysis of the PDAC xenografts and patients-PBMCs revealed that Zol exerts radiosensitization by affecting Rac1 and Rho prenylation, thereby modulating DNA damage and radiation response signalling along with improved systemic immune cells activation. An ongoing phase I/II trial (NCT03073785) showed improved failure-free survival (FFS), enhanced immune cell activation, and decreased microenvironment-related genes upon Zol+RT treatment. INTERPRETATION: Our findings suggest that FDPS is a novel radiosensitization target for PDAC therapy. This study also provides a rationale to utilize Zol as a potential radiosensitizer and as an immunomodulator in PDAC and other cancers. FUNDING: National Institutes of Health (P50, P01, and R01).