Cancer-associated fibroblasts produce matrix-bound vesicles that influence endothelial cell function.

Intercellular communication between different cell types in solid tumors contributes to tumor growth and metastatic dissemination. The secretome of cancer-associated fibroblasts (CAFs) plays major roles in these processes. Using human mammary CAFs, we showed that CAFs with a myofibroblast phenotype released extracellular vesicles that transferred proteins to endothelial cells (ECs) that affected their interaction with immune cells. Mass spectrometry-based proteomics identified proteins transferred from CAFs to ECs, which included plasma membrane receptors. Using THY1 as an example of a transferred plasma membrane-bound protein, we showed that CAF-derived proteins increased the adhesion of a monocyte cell line to ECs. CAFs produced high amounts of matrix-bound EVs, which were the primary vehicles of protein transfer. Hence, our work paves the way for future studies that investigate how CAF-derived matrix-bound EVs influence tumor pathology by regulating the function of neighboring cancer, stromal, and immune cells.

Exploring factors associated with preferences for human papillomavirus (HPV) self-sampling among racially- and ethnically-diverse women in Minnesota: A cross-sectional study.

Pap tests are still underutilized by minority women due to limited awareness of cervical cancer screening (CCS), inadequate health care access, and cultural or religious beliefs. Human papillomavirus (HPV) self-sampling, a new CCS tool, has demonstrated potential to overcome some of these barriers. In 2021, women aged 30-65 years old were recruited across Minnesota to complete an online survey. The survey assessed five outcome measures related to HPV self-sampling: (1) awareness of test; (2) self-efficacy to conduct test; (3) location preference of test (clinic vs. home); 4) collector preference (self vs. clinician); and (5) preference of CCS strategy (HPV self-sampling vs. Pap test). Modified Poisson regressions tested associations between sociodemographic variables and outcomes. A total of 420 women completed the survey, of which 32.4% identified as Non-Hispanic white, 22.2% as Hispanic, 12.6% as Black/African-American, 28.3% as Asian, 1.9% as American Indian/Alaskan Native, and 1.4% as more than two races. Few women had heard of HPV self-sampling (6.5%), but a majority reported high self-efficacy to perform self-sampling (75.3%). Women also reported higher preferences for completing an HPV test in the clinic (52.2%) and for performing a self-collected HPV test themselves (58.7%), yet would choose a traditional Pap test over HPV self-sampling (56.0%). The low level of HPV self-sampling awareness, across all racial/ethnic groups, suggests a strong opportunity to promote widespread educational efforts around this new tool. Future HPV self-sampling research efforts should examine educational interventions targeted at healthcare providers to educate and encourage women on the importance of self-collection options.

The small GTPase ARF3 controls invasion modality and metastasis by regulating N-cadherin levels.

ARF GTPases are central regulators of membrane trafficking that control local membrane identity and remodeling facilitating vesicle formation. Unraveling their function is complicated by the overlapping association of ARFs with guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs), and numerous interactors. Through a functional genomic screen of three-dimensional (3D) prostate cancer cell behavior, we explore the contribution of ARF GTPases, GEFs, GAPs, and interactors to collective invasion. This revealed that ARF3 GTPase regulates the modality of invasion, acting as a switch between leader cell-led chains of invasion or collective sheet movement. Functionally, the ability of ARF3 to control invasion modality is dependent on association and subsequent control of turnover of N-cadherin. In vivo, ARF3 levels acted as a rheostat for metastasis from intraprostatic tumor transplants and ARF3/N-cadherin expression can be used to identify prostate cancer patients with metastatic, poor-outcome disease. Our analysis defines a unique function for the ARF3 GTPase in controlling how cells collectively organize during invasion and metastasis.

Spatial regulation of the glycocalyx component podocalyxin is a switch for prometastatic function.

The glycocalyx component and sialomucin podocalyxin (PODXL) is required for normal tissue development by promoting apical membranes to form between cells, triggering lumen formation. Elevated PODXL expression is also associated with metastasis and poor clinical outcome in multiple tumor types. How PODXL presents this duality in effect remains unknown. We identify an unexpected function of PODXL as a decoy receptor for galectin-3 (GAL3), whereby the PODXL-GAL3 interaction releases GAL3 repression of integrin-based invasion. Differential cortical targeting of PODXL, regulated by ubiquitination, is the molecular mechanism controlling alternate fates. Both PODXL high and low surface levels occur in parallel subpopulations within cancer cells. Orthotopic intraprostatic xenograft of PODXL-manipulated cells or those with different surface levels of PODXL define that this axis controls metastasis in vivo. Clinically, interplay between PODXL-GAL3 stratifies prostate cancer patients with poor outcome. Our studies define the molecular mechanisms and context in which PODXL promotes invasion and metastasis.

Health care personnel's perspectives on human papillomavirus (HPV) self-sampling for cervical cancer screening: a pre-implementation, qualitative study.

BACKGROUND: Persistent infection with high-risk human papillomavirus (hrHPV) types is a well-documented cause of cervical cancer. Since the implementation of cervical cancer screening methods (e.g., Pap tests), cervical cancer rates have declined. However, Pap tests are still unacceptable to many women and require complex infrastructure and training. Self-sampling techniques for collecting HPV specimens (or "HPV self-sampling") have been proposed as a possible alternative to overcome these barriers. The objective of this study was to capture perspectives from health care personnel (providers, leaders, and clinic staff) across primary care systems on the potential implementation of an HPV self-sampling practice. METHODS: Between May and July 2021, a study invitation was emailed to various health care professional networks across the Midwest, including a snowball sampling of these networks. Eligible participants were invited to a 45-60-min Zoom-recorded interview session and asked to complete a pre-interview survey. The survey collected sociodemographics on age, occupation, level of educational attainment, race/ethnicity, gender, and awareness of HPV self-sampling. The semi-structured interview was guided by the Consolidated Framework for Implementation Research and asked participants about their views on HPV self-sampling and its potential implementation. All interviews were audio-recorded, transcribed, and analyzed using NVivo 12. RESULTS: Key informant interviews were conducted with thirty health care personnel-13 health care providers, 6 clinic staff, and 11 health care leaders-from various health care systems. Most participants had not heard of HPV self-sampling but reported a general enthusiasm for wanting to implement it as an alternative cervical cancer screening tool. Possible barriers to implementation were knowledge of clinical evidence and ease of integration into existing clinic workflows. Potential facilitators included the previous adoption of similar self-sampling tools (e.g., stool-based testing kits) and key decision-makers. CONCLUSION: Although support for HPV self-sampling is growing, its intervention's characteristics (e.g., advantages, adaptability) and the evidence of its clinical efficacy and feasibility need to be better disseminated across US primary care settings and its potential adopters. Future research is also needed to support the integration of HPV self-sampling within various delivery modalities (mail-based vs. clinic-based).

Associations of abuse and neglect with young adult health in a population-based longitudinal cohort: Findings from Project EAT.

Childhood maltreatment (abuse and neglect) is associated with a range of negative outcomes, but a gap remains in understanding of how specific maltreatment types, particularly neglect and non-familial sexual abuse, relate to health and behavior. This study examined the association of neglect and sexual abuse (both familial and non-familial), as well as familial physical and emotional abuse, with: depressive mood and eating disorders; tobacco and marijuana use; and BMI ≥ 25 kg/m2 and BMI ≥ 30 kg/m2 in young adults. Data came from Project EAT (Eating and Activity in Teens and Young Adults), a population-based longitudinal study of weight-related health from adolescence into young adulthood. Maltreatment before age 18 was retrospectively reported at ages 26-33. Risk differences (RDs) and 95% confidence intervals (CIs) were estimated for those with a given maltreatment type to those without, and also for the cumulative number of maltreatment types experienced. One in 3 participants reported abuse or neglect. All maltreatment types were associated with at least one adverse health outcome, with physical abuse being least consistently related to the outcomes. Emotional abuse showed the strongest association with depressive mood. All maltreatment types were associated with eating disorder diagnosis, tobacco use, and marijuana use (except physical abuse for eating disorder). There was little evidence of a maltreatment association with BMI ≥ 25 kg/m2; emotional abuse and neglect were associated with BMI ≥ 30 kg/m2. Prevention of maltreatment needs to be a top public health priority.

Adverse childhood experiences and disordered eating among middle-aged adults: Findings from the coronary artery risk development in young adults study.

Adverse childhood experiences (ACEs) include childhood abuse, neglect, and household substance abuse. Childhood abuse is a risk factor for disordered eating (DEB). Less well established are associations of childhood neglect and household substance abuse with DEB, and little research has examined ACE associations with DEB in middle adulthood. The objective of this study was to examine associations between ACEs and DEBs among middle-aged adults and examine sex differences. ACEs prior to age 18 were retrospectively assessed in the Coronary Artery Risk Development in Young Adults study in 2000-2001 (N = 3340, ages 32 to 46). DEB outcomes (i.e., concerns about weight and shape, anxiety about eating or food, unhealthy weight control behaviors, chronic dieting, overeating, and binge eating) were assessed in 1995-1996 (ages 27 to 41). Modified Poisson regressions estimated risk ratios (RRs) for associations of a history of any ACE, each ACE, and cumulative ACEs with DEB outcomes. Among women, emotional abuse, physical neglect, and emotional neglect were each modestly associated with most DEBs (RRs = 1.21-1.35, 1.21-1.45, and 1.23-1.41 across DEBs, respectively) after adjustment for sociodemographic variables, BMI, and depressive symptoms. A cumulative ACE score was associated with all DEBs in a stepwise manner (p for trend ≤0.05) except concerns about weight and shape and overeating. Among men, emotional abuse was most consistently related to the majority of DEBs (RRs = 1.23-1.92); household substance abuse was modestly associated with overeating (RR = 1.26, 95% CI = 1.04-1.53). ACEs were cumulatively associated with unhealthy weight control behaviors, overeating, and binge eating (p for trend <0.01).

The Association of Residential Mobility With Weight-Related Health Behaviors.

OBJECTIVE: To estimate associations of residential mobility with body mass index (BMI), physical activity, and diet and whether associations differ across demographics. DESIGN: Longitudinal cohort with 4 waves of survey follow-up over 15 years. PARTICIPANTS AND SETTING: A total of 2,110 adolescents and young adults originally from the Twin Cities of Minnesota responded to at least 2 waves of follow-up, beginning at ages 15 to 23 years. MAIN OUTCOME MEASURE(S): Self-reported BMI, physical activity, fast food consumption, breakfast frequency, sugary drink consumption, fruit and vegetable consumption, and screen time. ANALYSIS: Each outcome was modeled as a continuous variable using hierarchical linear regression. Residential mobility-change in residential address-was the main effect of interest. Models adjusted for demographics, marriage during follow-up, and previous level of the outcome. Inverse propensity weights accounted for loss to follow up. RESULTS: No weight-related outcomes differed between movers and nonmovers in the whole sample. When examining effect modification by age, as participants aged, moving was increasingly associated with improvements in weight-related outcomes, particularly BMI. CONCLUSIONS AND IMPLICATIONS: Results suggest that moving may be associated with poorer weight-related outcomes during a brief window from late teens and early-20s and less associated with weight-related outcomes in the mid-20s and 30s.

Dual G9A/EZH2 Inhibition Stimulates Antitumor Immune Response in Ovarian High-Grade Serous Carcinoma.

Ovarian high-grade serous carcinoma (HGSC) prognosis correlates directly with presence of intratumoral lymphocytes. However, cancer immunotherapy has yet to achieve meaningful survival benefit in patients with HGSC. Epigenetic silencing of immunostimulatory genes is implicated in immune evasion in HGSC and re-expression of these genes could promote tumor immune clearance. We discovered that simultaneous inhibition of the histone methyltransferases G9A and EZH2 activates the CXCL10-CXCR3 axis and increases homing of intratumoral effector lymphocytes and natural killer cells while suppressing tumor-promoting FoxP3+ CD4 T cells. The dual G9A/EZH2 inhibitor HKMTI-1-005 induced chromatin changes that resulted in the transcriptional activation of immunostimulatory gene networks, including the re-expression of elements of the ERV-K endogenous retroviral family. Importantly, treatment with HKMTI-1-005 improved the survival of mice bearing Trp53-/- null ID8 ovarian tumors and resulted in tumor burden reduction. These results indicate that inhibiting G9A and EZH2 in ovarian cancer alters the immune microenvironment and reduces tumor growth and therefore positions dual inhibition of G9A/EZH2 as a strategy for clinical development.

THEM6-mediated reprogramming of lipid metabolism supports treatment resistance in prostate cancer.

Despite the clinical benefit of androgen-deprivation therapy (ADT), the majority of patients with advanced prostate cancer (PCa) ultimately develop lethal castration-resistant prostate cancer (CRPC). In this study, we identified thioesterase superfamily member 6 (THEM6) as a marker of ADT resistance in PCa. THEM6 deletion reduces in vivo tumour growth and restores castration sensitivity in orthograft models of CRPC. Mechanistically, we show that the ER membrane-associated protein THEM6 regulates intracellular levels of ether lipids and is essential to trigger the induction of the ER stress response (UPR). Consequently, THEM6 loss in CRPC cells significantly alters ER function, reducing de novo sterol biosynthesis and preventing lipid-mediated activation of ATF4. Finally, we demonstrate that high THEM6 expression is associated with poor survival and correlates with high levels of UPR activation in PCa patients. Altogether, our results highlight THEM6 as a novel driver of therapy resistance in PCa as well as a promising target for the treatment of CRPC.

An academic-practice partnership during COVID-19 pandemic: Transitioning from a clinical to virtual fellowship.

AIMS: Discuss the needed modifications that occurred to the academic-practice oncology partnership during the COVID-19 pandemic. BACKGROUND: To meet the workforce needs of nurses who care for adults with cancer, an academic-practice partnership was created in 2016. The University of North Carolina at Chapel Hill School of Nursing, North Carolina Cancer Hospital and UNC Lineberger Comprehensive Cancer Center collaborated to provide structured clinical and didactic practice experiences for undergraduate nursing students interested in oncology nursing. With COVID-19, nursing students were not permitted to be in the clinical setting. DESIGN: Discursive paper. METHOD: An innovative and collaborative partnership created reflective and interactive activities. The majority of the learning activities were created at the revised Bloom's taxonomy level of application or higher, with some encompassing multiple levels. Students engaged in a variety of meaningful experiences requiring multiple learning processes that promoted professional development in the interpersonal and critical thinking domains. CONCLUSIONS: Despite the challenges of COVID-19, the delivery of oncology nurse fellowship was successful because of innovative virtual strategies. RELEVANCE TO CLINICAL PRACTICE: Our academic-practice partnership allowed the nursing students to develop their interpersonal and critical thinking skills without entering the clinical site. This is an approach encouraged by the authors for other schools of nursing. This manuscript is submitted as a Special Issue Discursive Article, and thus, the authors declare that an EQUATOR Checklist has not been used.

The influence of childhood and early adult adversities on substance use behaviours in racial/ethnically diverse young adult women: a latent class analysis.

Childhood and adult adversities occur more frequently among women and persons of colour, possibly influencing racial/ethnic disparities in substance use behaviours. This study investigates how childhood and adult adversities cluster together by race/ethnicity and how these clusters predict binge drinking, tobacco, e-cigarette, and marijuana use. Latent class analysis (LCA) was used in a combined sample from the 2015 to 2018 Minnesota College Student Health Survey to identify clusters of childhood and adult adversities among Asian, Black, Latina, and White women aged 18-25. Each substance use outcome was regressed on each adversity cluster across each race/ethnicity group. Across all racial/ethnic groups and substance use outcomes, the high adversity cluster exhibited the greatest risk. Significant racial/ethnic disparities were observed across several substance use behaviours; these were attenuated among women with fewer adversities. The reduced substance use disparities found among those with lower adversities suggest that prevention of adversities may advance health equity.

Everyday discrimination as a predictor of maladaptive and adaptive eating: Findings from EAT 2018.

Various types of stressors are associated with maladaptive eating, but how the stressor of everyday discrimination (e.g., less respect, poorer service) relates to maladaptive eating and adaptive eating remains unclear. We examined everyday discrimination as a predictor of maladaptive and adaptive eating. Data were collected in a population-based study, Eating and Activity over Time (N = 1410, ages 18-30). Everyday discrimination was categorized as none, low, moderate, or high. Outcomes included maladaptive eating (i.e., overeating and binge eating) and adaptive eating (i.e., intuitive eating and mindful eating). Modified Poisson regressions estimated the prevalence ratios (PRs) for overeating and binge eating associated with everyday discrimination. Linear regressions estimated associations between everyday discrimination and intuitive and mindful eating scores. After adjustment for age, ethnicity/race, gender, and socioeconomic status, moderate and high levels of discriminatory experiences were each associated with a significantly greater prevalence of binge eating (PR = 2.2, [95% CI = 1.3-3.7] and PR = 3.1, [95% CI = 2.0-4.7], respectively) and lower intuitive (ß = -0.4, [95% CI = -0.7, -0.2] and ß = -0.5 [95% CI = -0.8, -0.3], respectively), and mindful eating scores (ß = -0.3, [95% CI = -0.6, -0.1] and ß = -0.5 [95% CI = -0.8, -0.3], respectively) compared to young adults with no discriminatory experience. Public health efforts to prevent maladaptive eating and encourage the adoption of adaptive eating should consider the potential contribution of everyday discrimination and the need to advocate for equity and inclusion.

Monocytes mediate Salmonella Typhimurium-induced tumor growth inhibition in a mouse melanoma model.

The use of bacteria as an alternative cancer therapy has been reinvestigated in recent years. SL7207: an auxotrophic Salmonella enterica serovar Typhimurium aroA mutant with immune-stimulatory potential has proven a promising strain for this purpose. Here, we show that systemic administration of SL7207 induces melanoma tumor growth arrest in vivo, with greater survival of the SL7207-treated group compared to control PBS-treated mice. Administration of SL7207 is accompanied by a change in the immune phenotype of the tumor-infiltrating cells toward pro-inflammatory, with expression of the TH 1 cytokines IFN-γ, TNF-α, and IL-12 significantly increased. Interestingly, Ly6C+ MHCII+ monocytes were recruited to the tumors following SL7207 treatment and were pro-inflammatory. Accordingly, the abrogation of these infiltrating monocytes using clodronate liposomes prevented SL7207-induced tumor growth inhibition. These data demonstrate a previously unappreciated role for infiltrating inflammatory monocytes underlying bacterial-mediated tumor growth inhibition. This information highlights a possible novel role for monocytes in controlling tumor growth, contributing to our understanding of the immune responses required for successful immunotherapy of cancer.

Sexual and physical abuse and identity of the perpetrator: Associations with binge eating and overeating in Project EAT 2018.

BACKGROUND: Sexual and physical abuse are risk factors for binge eating and overeating, but few studies have examined association of the identity of the perpetrator with survivors' risk of binge eating and overeating. PURPOSE: To examine the risk of binge eating and overeating by (1) type of abuse and identity of the perpetrators and (2) cumulative abuse experiences/perpetrators. METHODS: Data came from Eating and Activity over Time (N = 1407; ages 18-30 during 2017-2018). Sexual abuse perpetrators included family members, non-family members, and intimate partners. Physical abuse perpetrators included family members and intimate partners. Cumulative abuse experiences were defined as the number of types of abuse experienced. Modified Poisson regressions were used to examine the risk of binge eating (overeating with loss of control) and overeating (without loss of control), by (1) abuse type and perpetrator and (2) cumulative abuse experiences. RESULTS: Abuse was more strongly associated with binge eating than overeating. For binge eating, risk factors included familial and intimate partner sexual abuse (RR = 1.48 [95% CI = 1.01-2.17] and 2.41, [95% CI = 1.70-3.41], respectively) and physical abuse (RR = 1.84, [95% CI = 1.33-2.53] and 1.95, [95% CI = 1.35-2.81], respectively), after adjustment for sociodemographic variables. For overeating, associations with physical abuse were close to the null, and those with sexual abuse were modest, with wide CIs that overlapped the null. Abuse experiences were cumulatively associated with binge eating, but not overeating. CONCLUSION: Assessment of identity of the perpetrator, and cumulative abuse experiences/perpetrators may assist in identifying people at the greatest risk of binge eating.

Optimizing metastatic-cascade-dependent Rac1 targeting in breast cancer: Guidance using optical window intravital FRET imaging.

Assessing drug response within live native tissue provides increased fidelity with regards to optimizing efficacy while minimizing off-target effects. Here, using longitudinal intravital imaging of a Rac1-Förster resonance energy transfer (FRET) biosensor mouse coupled with in vivo photoswitching to track intratumoral movement, we help guide treatment scheduling in a live breast cancer setting to impair metastatic progression. We uncover altered Rac1 activity at the center versus invasive border of tumors and demonstrate enhanced Rac1 activity of cells in close proximity to live tumor vasculature using optical window imaging. We further reveal that Rac1 inhibition can enhance tumor cell vulnerability to fluid-flow-induced shear stress and therefore improves overall anti-metastatic response to therapy during transit to secondary sites such as the lung. Collectively, this study demonstrates the utility of single-cell intravital imaging in vivo to demonstrate that Rac1 inhibition can reduce tumor progression and metastases in an autochthonous setting to improve overall survival.

MICAL1 regulates actin cytoskeleton organization, directional cell migration and the growth of human breast cancer cells as orthotopic xenograft tumours.

The Molecule Interacting with CasL 1 (MICAL1) monooxygenase has emerged as an important regulator of cytoskeleton organization via actin oxidation. Although filamentous actin (F-actin) increases MICAL1 monooxygenase activity, hydrogen peroxide (H2O2) is also generated in the absence of F-actin, suggesting that diffusible H2O2 might have additional functions. MICAL1 gene disruption by CRISPR/Cas9 in MDA MB 231 human breast cancer cells knocked out (KO) protein expression, which affected F-actin organization, cell size and motility. Transcriptomic profiling revealed that MICAL1 deletion significantly affected the expression of over 700 genes, with the majority being reduced in their expression levels. In addition, the absolute magnitudes of reduced gene expression were significantly greater than the magnitudes of increased gene expression. Gene set enrichment analysis (GSEA) identified receptor regulator activity as the most significant negatively enriched molecular function gene set. The prominent influence exerted by MICAL1 on F-actin structures was also associated with changes in the expression of several serum-response factor (SRF) regulated genes in KO cells. Moreover, MICAL1 disruption attenuated breast cancer tumour growth in vivo. Elevated MICAL1 gene expression was observed in invasive breast cancer samples from human patients relative to normal tissue, while MICAL1 amplification or point mutations were associated with reduced progression free survival. Collectively, these results demonstrate that MICAL1 gene disruption altered cytoskeleton organization, cell morphology and migration, gene expression, and impaired tumour growth in an orthotopic in vivo breast cancer model, suggesting that pharmacological MICAL1 inhibition could have therapeutic benefits for cancer patients.

Breast cancer dependence on MCL-1 is due to its canonical anti-apoptotic function.

High levels of the anti-apoptotic BCL-2 family member MCL-1 are frequently found in breast cancer and, appropriately, BH3-mimetic drugs that specifically target MCL-1's function in apoptosis are in development as anti-cancer therapy. MCL-1 also has reported non-canonical roles that may be relevant in its tumour-promoting effect. Here we investigate the role of MCL-1 in clinically relevant breast cancer models and address whether the canonical role of MCL-1 in apoptosis, which can be targeted using BH3-mimetic drugs, is the major function for MCL-1 in breast cancer. We show that MCL-1 is essential in established tumours with genetic deletion inducing tumour regression and inhibition with the MCL-1-specific BH3-mimetic drug S63845 significantly impeding tumour growth. Importantly, we found that the anti-tumour functions achieved by MCL-1 deletion or inhibition were completely dependent on pro-apoptotic BAX/BAK. Interestingly, we find that MCL-1 is also critical for stem cell activity in human breast cancer cells and high MCL1 expression correlates with stemness markers in tumours. This strongly supports the idea that the key function of MCL-1 in breast cancer is through its anti-apoptotic function. This has important implications for the future use of MCL-1-specific BH3-mimetic drugs in breast cancer treatment.

An ARF GTPase module promoting invasion and metastasis through regulating phosphoinositide metabolism.

The signalling pathways underpinning cell growth and invasion use overlapping components, yet how mutually exclusive cellular responses occur is unclear. Here, we report development of 3-Dimensional culture analyses to separately quantify growth and invasion. We identify that alternate variants of IQSEC1, an ARF GTPase Exchange Factor, act as switches to promote invasion over growth by controlling phosphoinositide metabolism. All IQSEC1 variants activate ARF5- and ARF6-dependent PIP5-kinase to promote PI(3,4,5)P3-AKT signalling and growth. In contrast, select pro-invasive IQSEC1 variants promote PI(3,4,5)P3 production to form invasion-driving protrusions. Inhibition of IQSEC1 attenuates invasion in vitro and metastasis in vivo. Induction of pro-invasive IQSEC1 variants and elevated IQSEC1 expression occurs in a number of tumour types and is associated with higher-grade metastatic cancer, activation of PI(3,4,5)P3 signalling, and predicts long-term poor outcome across multiple cancers. IQSEC1-regulated phosphoinositide metabolism therefore is a switch to induce invasion over growth in response to the same external signal. Targeting IQSEC1 as the central regulator of this switch may represent a therapeutic vulnerability to stop metastasis.

Selection of established tumour cells through narrow diameter micropores enriches for elevated Ras/Raf/MEK/ERK MAPK signalling and enhanced tumour growth.

As normal cells become cancer cells, and progress towards malignancy, they become progressively softer. Advantages of this change are that tumour cells become more deformable, and better able to move through narrow constraints. We designed a positive selection strategy that enriched for cells which could move through narrow diameter micropores to identify cell phenotypes that enabled constrained migration. Using human MDA MB 231 breast cancer and MDA MB 435 melanoma cancer cells, we found that micropore selection favoured cells with relatively higher Ras/Raf/MEK/ERK mitogen-activated protein kinase (MAPK) signalling, which affected actin cytoskeleton organization, focal adhesion density and cell elasticity. In this follow-up study, we provide further evidence that selection through micropores enriched for cells with altered cell morphology and adhesion. Additional analysis of RNA sequencing data revealed a set of transcripts associated with small cell size that was independent of constrained migration. Gene set enrichment analysis identified the 'matrisome' as the most significantly altered gene set linked with small size. When grown as orthotopic xenograft tumours in immunocompromised mice, micropore selected cells grew significantly faster than Parent or Flow-Sorted cells. Using mathematical modelling, we determined that there is an interaction between 1) the cell to gap size ratio; 2) the bending rigidity of the cell, which enable movement through narrow gaps. These results extend our previous conclusion that Ras/Raf/MEK/ERK MAPK signalling has a significant role in regulating cell biomechanics by showing that the selective pressure of movement through narrow gaps also enriches for increased tumour growth in vivo.