BackgroundP-21 activated kinase (PAK) overexpression, phosphorylation, and gene amplification have been reported to increase cellular invasion in ovarian cancer (ovcan), worsening patient prognoses. One notable method of ovcan survival is through the PD-(L)1 checkpoint pathway, and PD-L1 expression in ovcan is correlated with poor patient outcomes. However, PD-1 and PD-L1 targeted clinical trials in ovcan have shown modest results. This work has examined the possibility of using PAKi and PD-1 blockade as a combination therapy.MethodsPAK and PD-L1 expression in ovarian cells was determined. A novel 3D spheroid assay was used to assess ovcan invasion. Ovcan cell viability, downstream pathway signalling, and surface PD-L1 expression were evaluated after treatment with PAK inhibitors and co-culture with cytotoxic CD8+ T cells. Ovcan cell and CD8+ T cell co-cultures were treated with a combination of PAK inhibition and PD-1 checkpoint blockade and ovcan cell viability was assessed.ResultsOvcan cells showed significant sensitivity to PAKi. CD8+ T cell killing of ovcan cells improved following pre-treatment with PAK inhibitors, and this was further augmented with PD-1 blockade.DiscussionThe work presented here demonstrates the efficacy of PAK inhibition and PD-1 checkpoint blockade as a combination therapy for high-grade serous ovarian cancer.

In September 2023 members of the cell adhesion and cell migration research community came together to share their latest research and consider how our work might be translated for clinical practice. Alongside invited speakers, selected speakers and poster presentations, the meeting also included a round table discussion of how we might overcome the challenges associated with research translation. This meeting report seeks to highlight the key outcomes of that discussion and spark interest in the cell adhesions and cell migration research community to cross the perceived valley of death and translate our work into therapeutic benefit.

Breast cancer is a heterogeneous disease that remains the most common malignancy among women worldwide. During genomic analysis of breast tumours, mRNA levels of IQGAP3 were found to be upregulated in triple negative tumours. IQGAP3 was subsequently found to be expressed across a panel of triple negative breast cancer (TNBC) cell lines. Depleting expression levels of IQGAP3 delivered elongated cells, disrupted cell migration, and inhibited the ability of cells to form specialised invasive adhesion structures, termed invadopodia. The morphological changes induced by IQGAP3 depletion were found to be dependent on RhoA. Indeed, reduced expression of IQGAP3 disrupted RhoA activity and actomyosin contractility. Interestingly, IQGAP3 was also found to interact with p-21 activated kinase 6 (PAK6); a protein already associated with the regulation of cell morphology. Moreover, PAK6 depletion phenocopied IQGAP3 depletion in these cells. Whereas PAK6 overexpression rescued the IQGAP3 depletion phenotype. Our work points to an important PAK6-IQGAP3-RhoA pathway that drives the cellular contractility of breast cancer cells promoting both cell migration and adhesive invasion of these cells. As this phenotype is relevant to the process of metastasis and re-seeding of metastasis, the pharmacological targeting of PAK6 could lead to clinical benefit in TNBC patients.

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer and the majority of patients present with metastatic disease. Metastatic spread requires a reorganisation of the actin cytoskeleton, a process that is dependent on the Rho family GTPases and their interaction with subsequent downstream effectors. The p21 activated kinases (also known as the PAKs) are effectors of Rho GTPases Cdc42 and Rac and play key roles in cell migration and survival. PAK4 is overexpressed in PDAC and can reciprocally activate the PI3K pathway. Hepatocyte growth factor (HGF), via c-Met, is an established activator of PAK4 and the PI3K pathway and may promote PDAC invasion. Next generation sequencing (NGS) was performed on 31 PDAC tissue using a pre-determined targeted panel to attempt to identify novel mutations in the PAK: PI3K pathway. Targeted NGS identified several recurrent mutations including 5 PAK4 mutations in PDAC tissue.

Pancreatic ductal adenocarcinoma (PDAC) has a very poor prognosis because of its high propensity to metastasize and its immunosuppressive microenvironment. Using a panel of pancreatic cancer cell lines, three-dimensional (3D) invasion systems, microarray gene signatures, microfluidic devices, mouse models, and intravital imaging, we demonstrate that ROCK–Myosin II activity in PDAC cells supports a transcriptional program conferring amoeboid invasive and immunosuppressive traits and in vivo metastatic abilities. Moreover, we find that immune checkpoint CD73 is highly expressed in amoeboid PDAC cells and drives their invasive, metastatic, and immunomodulatory traits. Mechanistically, CD73 activates RhoA–ROCK–Myosin II downstream of PI3K. Tissue microarrays of human PDAC biopsies combined with bioinformatic analysis reveal that rounded-amoeboid invasive cells with high CD73–ROCK–Myosin II activity and their immunosuppressive microenvironment confer poor prognosis to patients. We propose targeting amoeboid PDAC cells as a therapeutic strategy.

Pancreatic Ductal Adenocarcinoma (PDAC) is an aggressive cancer, with over half of patients presenting with metastatic PDAC at diagnosis. Most patients receive conventional chemotherapy which invariably faces resistance, and a key facilitator in this is the PDAC stroma which acts as a functional mediator of disease progression through bilateral crosstalk between stromal cells and cancer cells. ‘Migrastatics’ are a new drug class which target cell migration pathway effector proteins to attenuate cancer cell invasion. Improvement in PDAC treatment strategy is well-overdue and migrastatics as adjuvant therapy is one avenue gaining traction. The p21-activated kinase (PAK) family is frequently overexpressed and/or amplified in PDAC where it regulates cytoskeletal actin contractility as well as transcription. Pre-clinical PAK inhibitors have shown reduced PDAC cell invasion in vitro, yet it is unknown how the PDAC stromal cells would respond to a PAK inhibitor and how this could consequently affect PDAC invasion. My PhD project investigates the Pancreatic stellate cell response to PAK inhibition.

Precisely characterising and quantifying interactions between tumour cells and their environment to understand metastatic mechanisms requires a multi-dimensional, high-speed imaging system. To this end, we report on the development of a compressive full spectrum fluorescence lifetime microscope that exploits a novel SPAD line sensor and a DMD to enable monitoring of dynamic sub-cellular interactions. At no cost to its temporal performance, the hyperspectral nature of the system helps to improve unmixing and, crucially, can detect the small spectral changes in the emission of fluorescent probes and intrinsic fluorophores that can occur in complex environments.

Although spirometry is a simple, portable test and recommended for the diagnosis of asthma and chronic obstructive pulmonary disease (COPD), it is not routinely used in the primary care setting. Minorities and underserved populations are less likely to have spirometry assessment, leading to both over and misdiagnosis of asthma and COPD. Because dyspnea is a common symptom across multiple diseases, use of spirometry as a diagnostic tool is important. Missed, delayed, or misdiagnosis of asthma and COPD, which are considered diagnostic errors (DE), can lead to poor quality of care, increased morbidity and mortality, and increased costs to patients and health systems. Barriers to the use of spirometry have been identified at clinician/clinic and health systems levels. The REDEFINE program is designed to overcome identified barriers to spirometry use in primary care by utilizing health promoters (HPs) who perform spirometry within primary care clinics and work collaboratively with clinicians to incorporate the results at the point of care without interrupting clinic workflow. The REDEFINE trial is a comparative effectiveness study comparing outcomes of the REDEFINE program with usual care (UC) in primary care patients determined to be at increased risk of DE for asthma and COPD. The primary outcome will be all-cause hospitalizations. The secondary outcomes will be the proportion of accurate diagnosis of COPD, asthma, or asthma-COPD overlap based on initial diagnosis and spirometry and all cause and respiratory-related acute outpatient care and emergency department visits. In this report, we describe the design and methods for the REDEFINE trial.

We report the development of a novel confocal line-scanning microscope capable of acquiring video-frame rate TCSPC-based FLIM. The system consists of a one-dimensional laser beam, which is optically conjugated to a 1024×16 single photon avalanche diode(SPAD) based line-imaging CMOS(1), with 23.78 μm pixel pitch at 49.31% fill factor. Incorporation of on-chip histogramming on the line-sensor facilitates the acquisition of up to 16.5 Giga-photon counts/s, enabling operation 66 times faster than our previously reported bespoke high speed FLIM platforms. We will demonstrate its use in live-cell imaging investigating the roles that PAK proteins play in regulation of cytoskeletal dynamics.

Background Invadopodia, actin-rich structures that release metallo-proteases at the interface with extra-cellular matrix, in a punctate manner are thought to be important drivers of tumour invasion. Invadopodia formation has been observed in-vitro and in-vivo in numerous metastatic cell lines derived from multiple tumour types. However, prostate cancer cell lines have not been routinely reported to generate invadopodia and the few instances have always required external stimulation. Methods In this study, the invasive potential of primary prostate adenocarcinoma cell lines, which have never been fully characterised before, was investigated both in-vitro invadopodia assays and in-vivo zebrafish dissemination assay. Subsequently, circulating tumour cells from prostate cancer patients were isolated and tested in the invadopodia assay. Results Retention of E-cadherin and N-cadherin expression indicated a transitional state of EMT progression, consistent with the idea of partial EMT that has been frequently observed in aggressive prostate cancer. All cell lines tested were capable of spontaneous invadopodia formation and possess a significant degradative ability in-vitro under basal conditions. These cell lines were invasive in-vivo and produced visible metastasis in the zebrafish dissemination assay. Importantly we have proceeded to demonstrate that circulating tumour cells isolated from prostate cancer patients exhibit invadopodia-like structures and degrade matrix with visible puncta. This work supports a role for invadopodia activity as one of the mechanisms of dissemination employed by prostate cancer cells. Conclusion The combination of studies presented here provide clear evidence that invadopodia activity can play a role in prostate cancer progression.

Metastatic Breast Cancer has a poor 25% survival rate and currently there are no clinical therapeutics which target metastasis. ‘Migrastatics’ are a new drug class which target migration pathway effector proteins in order to inhibit cancer cell invasion and metastasis. The p21-activated kinases (PAKs) are essential drivers of breast cancer cell migration and invasion through their regulation of actin cytoskeletal dynamics. Therefore, the PAKs present as attractive migrastatic candidates. Here we review how PAKs regulate distinct aspects of breast cancer actin dynamics focussing on cytoskeletal reorganisation, cell:matrix adhesion, actomyosin contractility and degradative invasion. Lastly, we discuss the introduction of PAK migrastatics into the well-honed breast cancer clinical pipeline.

The protein kinases PAK4, PAK5 and PAK6 comprise a family of ohnologues. In multiple cancers including melanomas PAK5 most frequently carries non-synonymous mutations; PAK6 and PAK4 have fewer; and PAK4 is often amplified. To help interpret these genomic data, initially we compared the cellular regulation of the sister kinases and their roles in melanoma cells. In common with many ohnologue protein kinases, PAK4, PAK5 and PAK6 each have two 14-3-3-binding phosphosites of which phosphoSer99 is conserved. PAK4 localises to the leading edge of cells in response to phorbol ester-stimulated binding of 14-3-3 to phosphoSer99 and phosphoSer181, which are phosphorylated by two different PKCs or PKDs. These phosphorylations of PAK4 are essential for its phorbol ester-stimulated phosphorylation of downstream substrates. In contrast, 14-3-3 interacts with PAK5 in response to phorbol ester-stimulated phosphorylation of Ser99 and epidermal growth factor-stimulated phosphorylation of Ser288; whereas PAK6 docks onto 14-3-3 and is prevented from localising to cell-cell junctions when Ser133 is phosphorylated in response to cAMP-elevating agents via PKA and insulin-like growth factor 1 via PKB/Akt. Silencing of PAK4 impairs viability, migration and invasive behaviour of melanoma cells carrying BRAFV600E or NRASQ61K mutations. These defects are rescued by ectopic expression of PAK4, more so by a 14-3-3-binding deficient PAK4, and barely by PAK5 or PAK6. Together these genomic, biochemical and cellular data suggest that the oncogenic properties of PAK4 are regulated by PKC-PKD signalling in melanoma, while PAK5 and PAK6 are dispensable in this cancer.

p21-Activated kinase-1 (Pak1) is frequently overexpressed and/or amplified in human breast cancer and is necessary for transformation of mammary epithelial cells. Here, we show that Pak1 interacts with and phosphorylates the Calcium/Calmodulin-dependent Protein Kinase II (CaMKII), and that pharmacological inhibition or depletion of Pak1 leads to diminished activity of CaMKII. We found a strong correlation between Pak1 and CaMKII expression in human breast cancer samples, and combined inhibition of Pak1 and CaMKII with small-molecule inhibitors was synergistic and induced apoptosis more potently in Her2 positive and triple negative breast cancer (TNBC) cells. Co-adminstration of Pak and CaMKII small-molecule inhibitors resulted in a dramatic reduction of proliferation and an increase in apoptosis in a 3D cell culture setting, as well as an impairment in migration and invasion of TNBC cells. Finally, mice bearing xenografts of TNBC cells showed a significant delay in tumor growth when treated with small-molecule inhibitors of Pak and CaMKII. These data delineate a signaling pathway from Pak1 to CaMKII that is required for efficient proliferation, migration and invasion of mammary epithelial cells, and suggest new therapeutic strategies in breast cancer.

With a dismal survival rate, pancreatic cancer (PC) remains one of the most aggressive and devastating malignancies, predominantly due to the absence of a valid biomarker for diagnosis and limited therapeutic options for advanced diseases. Exosomes (Exo) as cell-derived vesicles, are widely used as natural nanocarriers for drug delivery. P21-activated kinase 4 (PAK4) is oncogenic when overexpressed, promoting cell survival, migration and anchorage-independent growth. Herein we validated PAK4 as a therapeutic target in an in vivo PC tumour mouse model using Exo-mediated RNAi following intra-tumoural administration. PC derived Exo were firstly isolated by ultracentrifugation on sucrose cushion and characterised for their surface marker expression, size, number, purity and morphology. SiRNA was encapsulated into Exo via electroporation and dual uptake of Exo and siRNA was investigated by flow cytometry and confocal microscopy. In vitro siPAK4 silencing in PC cells following uptake was assessed by flow cytometry, western blotting, and in vitro scratch assay. In vivo efficacy (tumour growth delay and mouse survival) of siPAK4 was evaluated in PC bearing NSG mouse model. Ex vivo tumours were examined using Haematoxylin and eosin (H&E) staining and immunohistochemistry. Results showed high quality PC-derived PANC-1 Exo were obtained. SiRNA was incorporated in Exo with 16.5% encapsulation efficiency. In vitro imaging confirmed Exo and siRNA co-localisation in cells. PAK4 knockdown was successful with 30 nM Exo-siPAK4 at 24 h post incubation in vitro. Intra-tumoural administration of Exo-siPAK4 (0.03 mg/kg siPAK4 and 6.1 × 1011 Exo, each dose, two doses) reduced PC tumour growth in vivo and enhanced mice survival (p < 0.001), with minimal toxicity observed compared to polyethylenimine (PEI) used as a commercial transfection reagent. H&E staining of tumours showed significant tissue apoptosis in siPAK4 treated groups. PAK4 knockdown prolongs survival of PC-bearing mice suggesting its potential as a new therapeutic target for PC. PANC-1 Exo demonstrated comparable efficacy but safer profile than PEI as in vivo RNAi transfection reagent.

Androgen receptor (AR) and glucocorticoid receptor (GR) are nuclear receptors whose function depends on their entry into the nucleus where they activate transcription of an overlapping set of genes. Both AR and GR have a role in resistance to androgen deprivation therapy (ADT), the mainstay of treatment for late stage prostate cancer. PlexinB1, a receptor for semaphorins, has been implicated in various cancers including prostate cancer and has a role in resistance to ADT. We show here that activation of PlexinB1 by Sema4D and Sema3C results in translocation of endogenous GR to the nucleus in prostate cancer cells, and that this effect is dependent on PlexinB1 expression. Sema4D/Sema3C promotes the translocation of GR-GFP to the nucleus and mutation of the nuclear localization sequence (NLS1) of GR abrogates this response. These findings implicate the importin α/β system in the Sema4D/Sema3C-mediated nuclear import of GR. Knockdown of PlexinB1 in prostate cancer cells decreases the levels of glucocorticoid-responsive gene products and antagonizes the decrease in cell motility and cell area of prostate cancer cells upon dexamethasone treatment, demonstrating the functional significance of these findings. These results show that PlexinB1 activation has a role in the trafficking and activation of the nuclear receptor GR and thus may have a role in resistance to androgen deprivation therapy in late stage prostate cancer.

Fatty acid synthase (FASN) is commonly overexpressed in prostate cancer and associated with tumour progression. FASN is responsible for de novo synthesis of the fatty acid palmitate; the building block for protein palmitoylation. Recent work has suggested that alongside its established role in promoting cell proliferation FASN may also promote invasion. We now find depletion of FASN expression increases prostate cancer cell adhesiveness, impairs HGF-mediated cell migration and reduces 3D invasion. These changes in motility suggest that FASN can mediate actin cytoskeletal remodelling; a process known to be downstream of Rho family GTPases. Here, we demonstrate that modulation of FASN expression specifically impacts on the palmitoylation of the atypical GTPase RhoU. Impaired RhoU activity in FASN depleted cells leads to reduced adhesion turnover downstream of paxillin serine phosphorylation, which is rescued by addition of exogenous palmitate. Moreover, canonical Cdc42 expression is dependent on the palmitoylation status of RhoU. Thus we uncover a novel relationship between FASN, RhoU and Cdc42 that directly influences cell migration potential. These results provide compelling evidence that FASN activity directly promotes cell migration and supports FASN as a potential therapeutic target in metastatic prostate cancer.

Fatty acid synthase (FASN) is commonly overexpressed in prostate cancer and associated with tumour progression. FASN is responsible for de novo synthesis of the fatty acid palmitate; the building block for protein palmitoylation. A functional role for FASN in regulating cell proliferation is widely accepted. We recently reported that FASN activity can also mediate prostate cancer HGF-mediated cell motility. Moreover, we found that modulation of FASN expression specifically impacts on the palmitoylation of RhoU. Findings we will describe here. We now report that loss of FASN expression also impairs HGF-mediated cell dissociation responses. Taken together our results provide compelling evidence that FASN activity directly promotes cell migration and supports FASN as a potential therapeutic target in metastatic prostate cancer.