Early nucleolar responses differentiate mechanisms of cell death induced by oxaliplatin and cisplatin.

Recent reports provide evidence that the platinum chemotherapeutic oxaliplatin causes cell death via ribosome biogenesis stress, while cisplatin causes cell death via the DNA damage response (DDR). Underlying differences in mechanisms that might initiate disparate routes to cell death by these two broadly used platinum compounds have not yet been carefully explored. Additionally, prior studies had demonstrated that cisplatin can also inhibit ribosome biogenesis. Therefore, we sought to directly compare the initial influences of oxaliplatin and cisplatin on nucleolar processes and on the DDR. Using pulse-chase experiments, we found that at equivalent doses, oxaliplatin but not cisplatin significantly inhibited ribosomal RNA (rRNA) synthesis by Pol I, but neither compound affected rRNA processing. Inhibition of rRNA synthesis occurred as early as 90 min after oxaliplatin treatment in A549 cells, concurrent with the initial redistribution of the nucleolar protein nucleophosmin (NPM1). We observed that the nucleolar protein fibrillarin began to redistribute by 6 h after oxaliplatin treatment and formed canonical nucleolar caps by 24 h. In cisplatin-treated cells, DNA damage, as measured by γH2AX immunofluorescence, was more extensive, whereas nucleolar organization was unaffected. Taken together, our results demonstrate that oxaliplatin causes early nucleolar disruption via inhibition of rRNA synthesis accompanied by NPM1 relocalization and subsequently causes extensive nucleolar reorganization, while cisplatin causes early DNA damage without significant nucleolar disruption. These data support a model in which, at clinically relevant doses, cisplatin kills cells via the canonical DDR, and oxaliplatin kills cells via ribosome biogenesis stress, specifically via rapid inhibition of rRNA synthesis.

Nucleolar Stress Induction by Oxaliplatin and Derivatives.

Platinum(II) compounds are a critical class of chemotherapeutic agents. Recent studies have highlighted the ability of a subset of Pt(II) compounds, including oxaliplatin but not cisplatin, to induce cytotoxicity via nucleolar stress rather than a canonical DNA damage response. In this study, influential properties of Pt(II) compounds were investigated using redistribution of nucleophosmin (NPM1) as a marker of nucleolar stress. NPM1 assays were coupled to calculated and measured properties such as compound size and hydrophobicity. The oxalate leaving group of oxaliplatin is not required for NPM1 redistribution. Interestingly, although changes in diaminocyclohexane (DACH) ligand ring size and aromaticity can be tolerated, ring orientation appears important for stress induction. The specificity of ligand requirements provides insight into the striking ability of only certain Pt(II) compounds to activate nucleolar processes.

Monofunctional platinum(II) compounds and nucleolar stress: is phenanthriplatin unique?

Platinum anticancer therapeutics are widely used in a variety of chemotherapy regimens. Recent work has revealed that the cytotoxicity of oxaliplatin and phenanthriplatin is through induction of ribosome biogenesis stress pathways, differentiating them from cisplatin and other compounds that mainly work through DNA damage response mechanisms. To probe the structure-activity relationships in phenanthriplatin's ability to cause nucleolar stress, a series of monofunctional platinum(II) compounds differing in ring number, size and orientation was tested by nucleophosmin (NPM1) relocalization assays using A549 cells. Phenanthriplatin was found to be unique among these compounds in inducing NPM1 relocalization. To decipher underlying reasons, computational predictions of steric bulk, platinum(II) compound surface length and hydrophobicity were performed for all compounds. Of the monofunctional platinum(II) compounds tested, phenanthriplatin has the highest calculated hydrophobicity and volume but does not exhibit the largest distance from platinum(II) to the surface. Thus, spatial orientation and/or hydrophobicity caused by the presence of a third aromatic ring may be significant factors in the ability of phenanthriplatin to cause nucleolar stress.

Short-term efficacy and safety of rituximab therapy in refractory systemic lupus erythematosus: results from the British Isles Lupus Assessment Group Biologics Register.

Objectives: To describe the baseline characteristics of SLE patients requiring biologic therapy in the UK and to explore short term efficacy and infection rates associated with rituximab (RTX) use. Methods: Patients commencing biologic therapy for refractory SLE and who consented to join BILAG-BR were analysed. Baseline characteristics, disease activity (BILAG 2004/SLEDAI-2K) and rates of infection over follow-up were analysed. Response was defined as loss of all A and B BILAG scores to ⩽ 1 B score with no new A/B scores in other organ systems at 6 months. Results: Two hundred and seventy SLE patients commenced biologic therapy from September 2010 to September 2015, most commonly RTX (n = 261). Two hundred and fifty (93%) patients were taking glucocorticoids at baseline at a median [interquartile range (IQR)] oral dose of 10 mg (5-20 mg) daily. Response rates at 6 months were available for 68% of patients. The median (IQR) BILAG score was 15 (10-23) at baseline and 3 (2-12) at 6 months (P < 0.0001). The median (IQR) SLEDAI-2K reduced from 8 (5-12) to 4 (0-7) (P < 0.001). Response was achieved in 49% of patients. There was also a reduction in glucocorticoid use to a median (IQR) dose of 7.5 mg (5-12 mg) at 6 months (P < 0.001). Serious infections occurred in 26 (10%) patients, being more frequent in the first 3 months post-RTX therapy. A higher proportion of early infections were non-respiratory (odds ratio = 1.98, 95% CI: 0.99, 3.9; P = 0.049). Conclusion: RTX is safe and is associated with improvement in disease activity in refractory SLE patients with concomitant reductions in glucocorticoid use. Early vigilance for infection post-infusion is important to further improve treatment risks and benefits.

BRAF mutations are associated with increased iron regulatory protein-2 expression in colorectal tumorigenesis.

A role for iron in carcinogenesis is supported by evidence that iron metabolism proteins are modulated in cancer progression. To date, however, the expression of iron regulatory protein-2 (IRP2), which is known to regulate several iron metabolism proteins, has not been assessed in colorectal cancer. Expression of IRP2 was assessed by quantitative RT-PCR and immunohistochemistry in human colorectal cancer tissue. By interrogating The Cancer Genome Atlas (TCGA) database, expression of IRP2 and transferrin receptor-1 (TfR1) was assessed relative to common mutations that are known to occur in cancer. The impact of suppressing IRP2 on cellular iron metabolism was also determined by using siRNA and by using the MEK inhibitor trametinib. IRP2 was overexpressed in colorectal cancer compared to normal colonic mucosa and its expression was positively correlated with TfR1 expression. In addition, IRP2 expression was associated with mutations in BRAF. The MEK inhibitor trametinib suppressed IRP2 and this was associated with a suppression in TfR1 and the labile iron pool (LIP). Moreover, epidermal growth factor stimulation resulted in decreased ferritin expression and an increase in the LIP which were independent of IRP2. Results presented here suggest that ablating IRP2 provides a therapeutic platform for intervening in colorectal tumorigenesis.

Non-Targeted PFAS Suspect Screening and Quantification of Drinking Water Samples Collected through Community Engaged Research in North Carolina's Cape Fear River Basin.

A community engaged research (CER) approach was used to provide an exposure assessment of poly- and perfluorinated (PFAS) compounds in North Carolina residential drinking water. Working in concert with community partners, who acted as liaisons to local residents, samples were collected by North Carolina residents from three different locations along the Cape Fear River basin: upper, middle, and lower areas of the river. Residents collected either drinking water samples from their homes or recreational water samples from near their residence that were then submitted by the community partners for PFAS analysis. All samples were processed using weak anion exchange (WAX) solid phase extraction and analyzed using a non-targeted suspect screening approach as well as a quantitative approach that included a panel of 45 PFAS analytes, several of which are specific to chemical industries near the collection site locations. The non-targeted approach, which utilized a suspect screening list (obtained from EPA CompTox database) identified several PFAS compounds at a level two confidence rating (Schymanski scale); compounds identified included a fluorinated insecticide, a fluorinated herbicide, a PFAS used in polymer chemistry, and another that is used in battery production. Notably, at several locations, PFOA (39.8 ng/L) and PFOS (205.3 ng/L) were at levels that exceeded the mandatory EPA maximum contaminant level (MCL) of 4 ng/L. Additionally, several sites had detectable levels of PFAS that are unique to a local chemical manufacturer. These findings were communicated back to the community partners who then disseminated this information to the local residents to help empower and aid in making decisions for reducing their PFAS exposure.

Early infection risk in patients with systemic lupus erythematosus treated with rituximab or belimumab from the British Isles Lupus Assessment Group Biologics Register (BILAG-BR): a prospective longitudinal study.

BACKGROUND: Patients with systemic lupus erythematosus (SLE) are at an increased risk of infection relative to the general population. We aimed to describe the frequency and risk factors for serious infections in patients with moderate-to-severe SLE treated with rituximab, belimumab, and standard of care therapies in a large national observational cohort. METHODS: The British Isles Lupus Assessment Group Biologics Register (BILAG-BR) is a UK-based prospective register of patients with SLE. Patients were recruited by their treating physician as part of their scheduled care from 64 centres across the UK by use of a standardised case report form. Inclusion criteria for the BILAG-BR included age older than 5 years, ability to provide informed consent, a diagnosis of SLE, and starting a new biological therapy within the last 12 months or a new standard of care drug within the last month. The primary outcome for this study was the rate of serious infections within the first 12 months of therapy. Serious infections were defined as those requiring intravenous antibiotic treatment, hospital admission, or resulting in morbidity or death. Infection and mortality data were collected from study centres and further mortality data were collected from the UK Office for National Statistics. The relationship between serious infection and drug type was analysed using a multiple-failure Cox proportional hazards model. FINDINGS: Between July 1, 2010, and Feb 23, 2021, 1383 individuals were recruited to the BILAG-BR. 335 patients were excluded from this analysis. The remaining 1048 participants contributed 1002·7 person-years of follow-up and included 746 (71%) participants on rituximab, 119 (11%) participants on belimumab, and 183 (17%) participants on standard of care. The median age of the cohort was 39 years (IQR 30-50), 942 (90%) of 1048 patients were women and 106 (10%) were men. Of the patients with available ethnicity data, 514 (56%) of 911 were White, 169 (19%) were Asian, 161 (18%) were Black, and 67 (7%) were of multiple-mixed or other ethnic backgrounds. 118 serious infections occurred in 76 individuals during the 12-month study period, which included 92 serious infections in 58 individuals on rituximab, eight serious infections in five individuals receiving belimumab, and 18 serious infections in 13 individuals on standard of care. The overall crude incidence rate of serious infection was 117·7 (95% CI 98·3-141·0) per 1000 person-years. Compared with standard of care, the serious infection risk was similar in the rituximab (adjusted hazard ratio [HR] 1·68 [0·60-4·68]) and belimumab groups (1·01 [0·21-4·80]). Across the whole cohort in multivariate analysis, serious infection risk was associated with prednisolone dose (>10 mg; 2·38 [95%CI 1·47-3·84]), hypogammaglobulinaemia (<6 g/L; 2·16 [1·38-3·37]), and multimorbidity (1·45 [1·17-1·80]). Additional concomitant immunosuppressive use appeared to be associated with a reduced risk (0·60 [0·41-0·90]). We found no significant safety signals regarding atypical infections. Six infection-related deaths occurred at a median of 121 days (IQR 60-151) days from cohort entry. INTERPRETATION: In patients with moderate-to-severe SLE, rituximab, belimumab, and standard immunosuppressive therapy have similar serious infection risks. Key risk factors for serious infections included multimorbidity, hypogammaglobulinaemia, and increased glucocorticoid doses. When considering the risk of serious infection, we propose that immunosupppressives, rituximab, and belimumab should be prioritised as mainstay therapies to optimise SLE management and support proactive minimisation of glucocorticoid use. FUNDING: None.

Deconvolution of whole blood transcriptomics identifies changes in immune cell composition in patients with systemic lupus erythematosus (SLE) treated with mycophenolate mofetil.

BACKGROUND: Systemic lupus erythematosus (SLE) is a clinically and biologically heterogeneous autoimmune disease. We explored whether the deconvolution of whole blood transcriptomic data could identify differences in predicted immune cell frequency between active SLE patients, and whether these differences are associated with clinical features and/or medication use. METHODS: Patients with active SLE (BILAG-2004 Index) enrolled in the BILAG-Biologics Registry (BILAG-BR), prior to change in therapy, were studied as part of the MASTERPLANS Stratified Medicine consortium. Whole blood RNA-sequencing (RNA-seq) was conducted at enrolment into the registry. Data were deconvoluted using CIBERSORTx. Predicted immune cell frequencies were compared between active and inactive disease in the nine BILAG-2004 domains and according to immunosuppressant use (current and past). RESULTS: Predicted cell frequency varied between 109 patients. Patients currently, or previously, exposed to mycophenolate mofetil (MMF) had fewer inactivated macrophages (0.435% vs 1.391%, p = 0.001), naïve CD4 T cells (0.961% vs 2.251%, p = 0.002), and regulatory T cells (1.858% vs 3.574%, p = 0.007), as well as a higher proportion of memory activated CD4 T cells (1.826% vs 1.113%, p = 0.015), compared to patients never exposed to MMF. These differences remained statistically significant after adjusting for age, gender, ethnicity, disease duration, renal disease, and corticosteroid use. There were 2607 differentially expressed genes (DEGs) in patients exposed to MMF with over-representation of pathways relating to eosinophil function and erythrocyte development and function. Within CD4 + T cells, there were fewer predicted DEGs related to MMF exposure. No significant differences were observed for the other conventional immunosuppressants nor between patients according disease activity in any of the nine organ domains. CONCLUSION: MMF has a significant and persisting effect on the whole blood transcriptomic signature in patients with SLE. This highlights the need to adequately adjust for background medication use in future studies using whole blood transcriptomics.

Gene Expression and Autoantibody Analysis Revealing Distinct Ancestry-Specific Profiles Associated With Response to Rituximab in Refractory Systemic Lupus Erythematosus.

OBJECTIVE: Gene expression profiles are associated with the clinical heterogeneity of systemic lupus erythematosus (SLE) but are not well studied as biomarkers for therapy. We studied gene expression and response to rituximab in a multiethnic UK cohort who were refractory to standard therapy. METHODS: We evaluated baseline expression levels of transcripts known to associate with clinical features of SLE using a 96-probe TaqMan array and whole blood samples from 213 patients with active SLE who had been prospectively enrolled in the British Isles Lupus Assessment Group (BILAG) Biologics Register. We measured autoantibodies using immunoprecipitation and enzyme-linked immunosorbent assays. We determined responses to first-cycle rituximab at 6 months from treatment start in 110 SLE patients by assessing BILAG 2004 disease activity. RESULTS: Interferon gene expression scores were lower in patients of European ancestry than in all other ancestry groups. The relationship between blood interferon gene expression scores and scores annotated to plasmablasts, neutrophils, myeloid lineage, inflammation, and erythropoiesis differed between patients of European and non-European ancestries. Hierarchical clustering revealed 3 distinct non-European ancestry patient subsets with stratified responses to rituximab that were not explained by sociodemographic and clinical variables, with responses lowest in an interferon-low, neutrophil-high cluster and highest in a cluster with high expression levels across all signatures (P < 0.001). Clusters in European ancestry patients did not predict response to rituximab but segregated patients by global disease activity and renal involvement. In both ancestral groups, interferon-high clusters were associated with U1 RNP/Sm antibodies. CONCLUSION: Ancestry appears central to the immunologic and clinical heterogeneity in SLE. These results suggest that ancestry, disease activity, and transcriptional signatures could each assist in predicting the effectiveness of B cell depletion therapies.

Denosumab, a RANK ligand inhibitor, for postmenopausal women with osteoporosis.

OBJECTIVE: To review the evidence for use of denosumab for the treatment of postmenopausal osteoporosis. DATA SOURCES: A search of MEDLINE and EMBASE databases was conducted during January 2012, using the terms denosumab and osteoporosis, with index dates of 2000 to 2011. Additional information was gathered from Amgen and references cited in articles retrieved. STUDY SELECTION AND DATA EXTRACTION: English-language articles including clinical trials involving denosumab for treatment of osteoporosis and review articles were reviewed. Articles using denosumab in males or as treatment for conditions other than osteoporosis or osteopenia were excluded. DATA SYNTHESIS: Many clinical trials have supported the safety and efficacy of denosumab in postmenopausal women with bone loss. It has been shown to improve bone mineral density, decrease markers of bone turnover, and prevent new vertebral fractures. It shows improvement over placebo in studies and has at least similar efficacy to alendronate in measurements of bone mineral density, with less risk for osteonecrosis of the jaw and atypical fracture, but with an increased risk of infections and neoplasms. European cost-effectiveness studies have also demonstrated that denosumab is a cost-effective choice compared to risedronate and no treatment for fracture prevention for postmenopausal women with osteoporosis. CONCLUSIONS: Denosumab has demonstrated efficacy and safety as a first-line treatment for postmenopausal osteoporosis in multiple clinical trials over at least 6 years. It may be most cost-effective for women who are unable or refuse to take bisphosphonate drugs.

Time-Dependent Studies of Oxaliplatin and Other Nucleolar Stress-Inducing Pt(II) Derivatives.

The properties of small molecule Pt(II) compounds that drive specific cellular responses are of interest due to their broad clinical use as chemotherapeutics as well as to provide a better mechanistic understanding of bioinorganic processes. The chemotherapeutic compound cisplatin causes cell death through DNA damage, while oxaliplatin may induce cell death through inhibition of ribosome biogenesis, also referred to as nucleolar stress induction. Previous work has found a subset of oxaliplatin derivatives that cause nucleolar stress at 24 h drug treatment. Here we report that these different Pt(II) derivatives exhibit a range of rates and degrees of global nucleolar stress induction as well as inhibition of rRNA transcription. Potential explanations for these variations include both the ring size and stereochemistry of the non-aquation-labile ligand. We observe that Pt(II) compounds containing a 6-membered ring show faster onset and a higher overall degree of nucleolar stress than those containing a 5-membered ring, and that compounds having the 1R,2R-stereoisomeric conformation show faster onset and a higher overall degree of stress than those having the 1S,2S-conformation. Pt(II) cellular accumulation and cellular Pt(II)-DNA adduct formation did not correlate with nucleolar stress induction, indicating that the effect is not due to global interactions. Together these results suggest that Pt(II) compounds induce nucleolar stress through a mechanism that likely involves one or a few key intermolecular interactions.

Lupus clinical trial eligibility in a real-world setting: results from the British Isles Lupus Assessment Group-Biologics Register (BILAG-BR).

OBJECTIVE: To quantify how well phase III randomised clinical trials in both SLE and lupus nephritis (LN) represents a real-world SLE cohort. METHODS: Literature reviews were performed of major published phase III SLE (n=12) and LN (n=6) clinical trials (ClinicalTrials.gov). Inclusion and exclusion criteria common across these trials were collated for non-renal SLE or LN trials, and applied to patients recruited to the British Isles Lupus Assessment Group-Biologics Register (BILAG-BR) starting either biological or standard-of-care (SOC) therapies. RESULTS: We recruited 837 patients to the BILAG-BR from September 2010 to June 2018, starting either SOC (n=125, 15%) or a biological medication (n=712, 85%). Active LN, defined as a BILAG A in the renal domain occurred in 20% (n=166). Overall, 530 (63%) patients were ineligible to participate in non-renal SLE clinical trials and 72 (43%) patients with active LN would be ineligible for LN trials. The most common reasons for ineligibility from the non-renal lupus trials included active renal involvement (n=166, 20%) and low disease activity (n=114, 15%). For LN trials, the most common exclusion met was pre-existing renal impairment (n=15, 9%). Patients with fewer comorbidities were more likely to be eligible to participate in non-renal SLE trials. CONCLUSIONS: In this national register of patients with moderate-to-severe SLE, nearly two-thirds would not be eligible for recruitment to key SLE clinical trials nor would almost half of those with active LN. Eligibility criteria may excessively constrain enrolment and thus, how we can generalise trial results in a real-world setting.

Osteoporosis in men: epidemiology and treatment with denosumab.

Osteoporosis is a major public health care concern. Although often described as a disease affecting postmenopausal women, researchers and clinicians have emphasized its prevalence in men in recent years. The National Osteoporosis Foundation has stated that up to 25% of men over the age of 50 years will experience a fracture due to osteoporosis. Men who suffer from a major fracture have higher mortality rates than women. Pharmacologic therapy options for treating osteoporosis are limited for men as compared with women, so each medication approved for use in this population represents an important clinical option. In September 2012, the US Food and Drug Administration approved a new indication for denosumab to increase bone mass in men with osteoporosis at high risk for fracture. Denosumab is a fully human monoclonal antibody and novel antiresorptive agent that works by binding receptor activator of nuclear factor kappa-ß ligand (RANKL) and inhibiting the signaling cascade that causes osteoclast maturation, activity, and survival. Ultimately, denosumab suppresses bone turnover and increases bone mineral density in both trabecular and cortical bone. Approval for treating osteoporosis in men was based on data from the ADAMO trial which displayed efficacy in increasing bone mineral density at the lumbar spine, total hip, femoral neck, hip trochanter, and one-third radius. Studies indicate that denosumab is effective and safe, and has superior adherence rates and patient satisfaction. Although long-term data and further research on fracture reduction rates in men should be explored, at this time denosumab is one of several appropriate first-line treatment options for men with osteoporosis.

The systemic lupus international collaborating clinics (SLICC) damage index: a systematic literature review.

OBJECTIVES: We performed a systematic literature review to determine factors that influence damage and damage progression in SLE patients and how damage relates to mortality in this population. METHODS: A search of Medline, Embase and Web of Science was performed, with papers included if they met the requirements of containing keywords relating to SLE and damage assessment using the SDI, published between 1990 and October 2012. RESULTS: A total of 358 articles were identified, with 50 included in this review. From 17 studies reporting damage at more than 2 time points, damage progressed over time, but the rate of damage accrual reported was variable across studies. Demographic factors that influence the accrual of damage in several reports include male gender, older age, longer disease duration, Afro-Caribbean and Indo-Asian ethnicity. Patients with higher disease activity at a single time point or over time accrue greater damage. Certain organ system involvement also predicts damage accrual, in particular renal and neuropsychiatric involvement. Corticosteroids, cyclophosphamide and azathioprine all show an association with damage accrual, while hydroxychloroquine appears to have a "protective" effect. Four studies, which examined prognosis, all demonstrated that damage is a predictor of future mortality. CONCLUSIONS: Damage in SLE patients increases over time and predicts future mortality. Patients at risk of damage can be identified from demographics factors and the pattern of clinical involvement. Disease activity, corticosteroids and immunosuppressive therapy are also associated with future damage but further studies are needed to separate the mechanisms of these associations from the problem of residual confounding.

SDF-1α mediates wound-promoted tumor growth in a syngeneic orthotopic mouse model of breast cancer.

Increased growth of residual tumors in the proximity of acute surgical wounds has been reported; however, the mechanisms of wound-promoted tumor growth remain unknown. Here, we used a syngeneic, orthotopic mouse model of breast cancer to study mechanisms of wound-promoted tumor growth. Our results demonstrate that exposure of metastatic mouse breast cancer cells (4T1) to SDF-1α, which is increased in wound fluid, results in increased tumor growth. Both, wounding and exposure of 4T1 cells to SDF-1α not only increased tumor growth, but also tumor cell proliferation rate and stromal collagen deposition. Conversely, systemic inhibition of SDF-1α signaling with the small molecule AMD 3100 abolished the effect of wounding, and decreased cell proliferation, collagen deposition, and neoangiogenesis to the levels observed in control animals. Furthermore, using different mouse strains we could demonstrate that the effect of wounding on tumor growth and SDF-1α levels is host dependent and varies between mouse strains. Our results show that wound-promoted tumor growth is mediated by elevated SDF-1α levels and indicate that the effect of acute wounds on tumor growth depends on the predetermined wound response of the host background and its predetermined wound response.

Why physicians do not prescribe a thiazide diuretic.

The purpose of this study was to evaluate the reasons physicians provided when the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7) guidelines recommending a thiazide diuretic as a first line treatment for hypertension were not followed. A subsample of patients from a randomized controlled study who had uncontrolled blood pressure at an index visit and were not prescribed a thiazide were evaluated. Differences in groups that received any medication change or therapeutic lifestyle changes counseling and those that did not were compared. Differences in treatment were also compared for patients who received educational materials with or without telephone calls and financial incentive with a control group. The authors examined whether patients achieved blood pressure control in 12 months. The results show providers are not aggressive enough with getting blood pressure to goal and patients who are more educated about hypertension may be less likely to experience clinical inertia.

Transient tumor-fibroblast interactions increase tumor cell malignancy by a TGF-Beta mediated mechanism in a mouse xenograft model of breast cancer.

Carcinoma are complex societies of mutually interacting cells in which there is a progressive failure of normal homeostatic mechanisms, causing the parenchymal component to expand inappropriately and ultimately to disseminate to distant sites. When a cancer cell metastasizes, it first will be exposed to cancer associated fibroblasts in the immediate tumor microenvironment and then to normal fibroblasts as it traverses the underlying connective tissue towards the bloodstream. The interaction of tumor cells with stromal fibroblasts influences tumor biology by mechanisms that are not yet fully understood. Here, we report a role for normal stroma fibroblasts in the progression of invasive tumors to metastatic tumors. Using a coculture system of human metastatic breast cancer cells (MCF10CA1a) and normal murine dermal fibroblasts, we found that medium conditioned by cocultures of the two cell types (CoCM) increased migration and scattering of MCF10CA1a cells in vitro, whereas medium conditioned by homotypic cultures had little effect. Transient treatment of MCF10CA1a cells with CoCM in vitro accelerated tumor growth at orthotopic sites in vivo, and resulted in an expanded pattern of metastatic engraftment. The effects of CoCM on MCF10CA1a cells were dependent on small amounts of active TGF-beta1 secreted by fibroblasts under the influence of the tumor cells, and required intact ALK5-, p38-, and JNK signaling in the tumor cells. In conclusion, these results demonstrate that transient interactions between tumor cells and normal fibroblasts can modify the acellular component of the local microenvironment such that it induces long-lasting increases in tumorigenicity and alters the metastatic pattern of the cancer cells in vivo. TGF-beta appears to be a key player in this process, providing further rationale for the development of anti-cancer therapeutics that target the TGF-beta pathway.