Comparison of Outcomes Between Surveillance Ultrasound and Completion Lymph Node Dissection in Children and Adolescents With Sentinel Lymph Node-Positive Cutaneous Melanoma

OBJECTIVE

To determine the impact of nodal basin ultrasound (US) surveillance versus completion lymph node dissection (CLND) in children and adolescents with sentinel lymph node (SLN) positive melanoma.

BACKGROUND

Treatment for children and adolescents with melanoma are extrapolated from adult trials. However, there is increasing evidence that important clinical and biological differences exist between pediatric and adult melanoma.

METHODS

Patients ≤18 years diagnosed with cutaneous melanoma between 2010 and 2020 from 14 pediatric hospitals were included. Data extracted included demographics, histopathology, nodal basin strategies, surveillance intervals, and survival information.

RESULTS

Of 252 patients, 90.1% (n=227) underwent SLN biopsy (SLNB), 50.9% (n=115) had at least 1 positive node. A total of 67 patients underwent CLND with 97.0% (n=65/67) performed after a positive SLNB. In contrast, 46 total patients underwent US observation of nodal basins with 78.3% (n=36/46) of these occurring after positive SLNB. Younger patients were more likely to undergo US surveillance (median age 8.5 y) than CLND (median age 11.3 y; P =0.0103). Overall, 8.9% (n=21/235) experienced disease recurrence: 6 primary, 6 nodal, and 9 distant. There was no difference in recurrence (11.1% vs 18.8%; P =0.28) or death from disease (2.2% vs 9.7%; P =0.36) for those who underwent US versus CLND, respectively.

CONCLUSIONS

Children and adolescents with cutaneous melanoma frequently have nodal metastases identified by SLN. Recurrence was more common among patients with thicker primary lesions and positive SLN. No significant differences in oncologic outcomes were observed with US surveillance and CLND following the identification of a positive SLN.

Implications of Immunotherapy for Pediatric Malignancies: A Summary from the APSA Cancer Committee

Although survival for many pediatric cancers has improved with advances in conventional chemotherapeutic regimens and surgical techniques in the last several decades, it remains a leading cause of disease-related death in children. Outcomes in patients with recurrent, refractory, or metastatic disease are especially poor. Recently, the advent of alternative classes of therapies, including immunotherapies, have revolutionized systemic treatment for pediatric malignancies. Several classes of immunotherapies, including chimeric antigen receptor (CAR) T cell therapy, transgenic T-cell receptor (TCR)-T cell therapy, bispecific T-cell engagers, and monoclonal antibody checkpoint inhibitors have been FDA-approved or entered early-phase clinical trials in children and young adults. The pediatric surgeon is likely to encounter these therapies during the care of children with malignancies and should be familiar with the classes of therapy, indications, adverse events, and potential need for surgical intervention in these cases. This review from the APSA Cancer Committee offers a brief discussion of the three most encountered classes of immunotherapy in children and young adults and discusses surgical relevance. LEVEL OF EVIDENCE: IV.

Synapse-tuned CARs enhance immune cell anti-tumor activity

Chimeric antigen receptor (CAR) technologies have been clinically implemented for the treatment of hematological malignancies; however, solid tumors remain resilient to CAR therapeutics. Natural killer (NK) cells may provide an optimal class of immune cells for CAR-based approaches due to their inherent anti-tumor functionality. In this study, we sought to tune CAR immune synapses by adding an intracellular scaffolding protein binding site to the CAR. We employ a PDZ binding motif (PDZbm) that enables additional scaffolding crosslinks that enhance synapse formation and NK CAR cell polarization. Combined effects of this CAR design result in increased effector cell functionality in vitro and in vivo. Additionally, we used T cells and observed similar global enhancements in effector function. Synapse-tuned CAR immune cells exhibit amplified synaptic strength, number and abundance of secreted cytokines, enhanced killing of tumor cells and prolonged survival in numerous different tumor models, including solid tumors.

Feasibility of indocyanine green-guided localization of pulmonary nodules in children with solid tumors

BACKGROUND

Clearing all pulmonary metastases is essential for curing pediatric solid tumors. However, intraoperative localization of such pulmonary nodules can be challenging. Therefore, an intraoperative tool that localizes pulmonary metastases is needed to improve diagnostic and therapeutic resections. Indocyanine green (ICG) real-time fluorescence imaging is used for this purpose in adult solid tumors, but its utility in pediatric solid tumors has not been determined.

METHODS

A single-center, open-label, nonrandomized, prospective clinical trial (NCT04084067) was conducted to assess the ability of ICG to localize pulmonary metastases of pediatric solid tumors. Patients with pulmonary lesions who required resection, either for therapeutic or diagnostic intent, were included. Patients received a 15-minute intravenous infusion of ICG (1.5 mg/kg), and pulmonary metastasectomy was performed the following day. A near-infrared spectroscopy iridium system was optimized to detect ICG, and all procedures were photo-documented and recorded.

RESULTS

ICG-guided pulmonary metastasectomies were performed in 12 patients (median age: 10.5 years). A total of 79 nodules were visualized, 13 of which were not detected by preoperative imaging. Histologic examination confirmed the following histologies: hepatoblastoma (n = 3), osteosarcoma (n = 2), and one each of rhabdomyosarcoma, Ewing sarcoma, inflammatory myofibroblastic tumor, atypical cartilaginous tumor, neuroblastoma, adrenocortical carcinoma, and papillary thyroid carcinoma. ICG guidance failed to localize pulmonary metastases in five (42%) patients who had inflammatory myofibroblastic tumor, atypical cartilaginous tumor, neuroblastoma, adrenocortical carcinoma, or papillary thyroid carcinoma.

CONCLUSIONS

ICG-guided identification of pulmonary nodules is not feasible for all pediatric solid tumors. However, it may localize most metastatic hepatic tumors and high-grade sarcomas in children.

Progressive metastatic infantile fibrosarcoma with multiple acquired mutations

Infantile fibrosarcoma is the most common soft tissue sarcoma in children under the age of 1 year and is defined molecularly by NTRK fusion proteins. This tumor is known to be locally invasive; however, metastasis are rare. The NTRK fusion acts as a driver for tumor formation which can be targeted by first and second generation NTRK inhibitors. While NTRK gatekeeper mutations have been well described as mechanisms of resistance to these agents, alternative pathway acquired mutations are rare. Here we report the case of a patient with infantile sarcoma treated with chemotherapy and NTRK inhibition that developed metastatic, progressive disease with multiple acquired mutations, including TP53, SUFU, and an NTRK F617L gatekeeper mutation. Alterations in pathways of SUFU and TP53 have been widely described in the literature in other tumors, however, not yet in infantile fibrosarcoma. While most patients have a sustained response to TRK inhibitors, a subset will go on to develop mechanisms of resistance that have implications for clinical management, such as in our patient. We hypothesize this constellation of mutations contributed to the patient's aggressive clinical course. Taken together, we report the first case of infantile fibrosarcoma with ETV6::NTRK3 and acquired SUFU, TP53, and NTRK F617L gatekeeper mutation along with detailed clinical course and management. Our report highlights the importance of genomic profiling in recurrent infantile fibrosarcoma to reveal actionable mutations, such as gatekeeper mutations, that can improve patient outcomes.

Why do subcutaneous ports get stuck? A case-control study

PURPOSE

We sought to identify clinical features associated with difficult subcutaneous port removals in children.

METHODS

Ports placed between April 2014 and September 2017 at our institution were prospectively tracked for difficult removals. A case-control analysis was performed. Patients with ports that were difficult to remove (stuck; cases) were compared to biological sex and age-matched controls in a ratio of 1:3. Logistic regression determined the association between case/control status and clinical features adjusting for biological sex and age as covariates. A multivariable analysis was performed to identify independent associations.

RESULTS

57 stuck ports (28 extreme [10 endovascular intervention] and 29 moderate) and 171 controls were analyzed. Stuck ports were associated with a diagnosis of acute lymphoblastic leukemia (86% cases versus 22.2% controls; p < 0.001) and a longer placement duration (median 2.6 years [interquartile range (IQR) 2.5-2.6] versus 0.8 years [IQR 0.5-1.4]; p < 0.001). On univariate analysis, procedural and device features associated with stuck ports included subclavian access (71.9% cases versus 48.5% controls; p = 0.0126), a polyurethane versus silicone catheter (96.5% cases versus 79.9% controls; p = 0.001), and a rough catheter appearance at removal (92.6% cases versus 9.4% controls; p < 0.0001). A diagnosis of ALL and duration of line placement were associated with having a stuck port on multivariate analysis.

CONCLUSION

Polyurethane central venous catheters placed for the two-year treatment of acute lymphoblastic leukemia may become difficult to remove. This constellation of factors warrants more extensive preoperative discussion of risk, endovascular backup availability, and scheduling for longer operating room time.

Incidence and Management of Pleural Effusions in Patients with Wilms Tumor: A Pediatric Surgical Oncology Research Collaborative Study

Wilms tumor (WT) is the most common renal malignancy in children. Children with favorable histology WT achieve survival rates of over 90%. Twelve percent of patients present with metastatic disease, most commonly to the lungs. The presence of a pleural effusion at the time of diagnosis of WT may be noted on staging imaging; however, minimal data exist regarding the significance and prognostic importance of this finding. The objectives of this study are to identify the incidence of pleural effusions in patients with WT, and to determine the potential impact on oncologic outcomes. A multi-institutional retrospective review was performed from January 2009 to December 2019, including children with WT and a pleural effusion on diagnostic imaging treated at Pediatric Surgical Oncology Research Collaborative (PSORC) participating institutions. Of 1,259 children with a new WT diagnosis, 94 (7.5%) had a pleural effusion. Patients with a pleural effusion were older than those without (median 4.3 vs 3.5 years; p=0.004), and advanced stages were more common (local stage III 85.9% vs 51.9%; p<0.0001). Only 14 patients underwent a thoracentesis for fluid evaluation; 3 had cytopathologic evidence of malignant cells. Event-free and overall survival of all children with WT and pleural effusions was 86.2% and 91.5%, respectively. The rate and significance of malignant cells present in pleural fluid is unknown due to low incidence of cytopathologic analysis in our cohort; therefore, the presence of an effusion does not appear to necessitate a change in therapy. Excellent survival can be expected with current stage-specific treatment regimens.

Secretory defects in pediatric osteosarcoma result from downregulation of selective COPII coatomer proteins

Pediatric osteosarcomas (OS) exhibit extensive genomic instability that has complicated the identification of new targeted therapies. We found the vast majority of 108 patient tumor samples and patient-derived xenografts (PDXs), which display an unusually dilated endoplasmic reticulum (ER), have reduced expression of four COPII vesicle components that trigger aberrant accumulation of procollagen-I protein within the ER. CRISPR activation technology was used to increase the expression of two of these, SAR1A and SEC24D, to physiological levels. This was sufficient to resolve the dilated ER morphology, restore collagen-I secretion, and enhance secretion of some extracellular matrix (ECM) proteins. However, orthotopic xenograft growth was not adversely affected by restoration of only SAR1A and SEC24D. Our studies reveal the mechanism responsible for the dilated ER that is a hallmark characteristic of OS and identify a highly conserved molecular signature for this genetically unstable tumor. Possible relationships of this phenotype to tumorigenesis are discussed.

Appendectomy Versus Observation for Appendicitis in Neutropenic Children With Cancer

BACKGROUND

Optimal management of neutropenic appendicitis (NA) in children undergoing cancer therapy remains undefined. Management strategies include upfront appendectomy or initial nonoperative management. We aimed to characterize the effect of management strategy on complications and length of stay (LOS) and describe implications for chemotherapy delay or alteration.

METHODS

Sites from the Pediatric Surgery Oncology Research Collaborative performed a retrospective review of children with NA over a 6-year period.

RESULTS

Sixty-six children, with a median age of 11 years (range 1-17), were identified with NA while undergoing cancer treatment. The most common cancer diagnoses were leukemia (62%) and brain tumor (12%). Upfront appendectomy was performed in 41% of patients; the remainder had initial nonoperative management. Rates of abscess or perforation at diagnosis were equivalent in the groups (30% vs 24%; P = .23). Of patients who had initial nonoperative management, 46% (17 of 37) underwent delayed appendectomy during the same hospitalization. Delayed appendectomy was due to failure of initial nonoperative management in 65% (n = 11) and count recovery in 35% (n = 6). Cancer therapy was delayed in 35% (n = 23). Initial nonoperative management was associated with a delay in cancer treatment (46% vs. 22%, P = .05) and longer LOS (29 vs 12 days; P = .01). Patients who had initial nonoperative management and delayed appendectomy had a higher rate of postoperative complications (P < .01).

CONCLUSIONS

In pediatric patients with NA from oncologic treatment, upfront appendectomy resulted in lower complication rates, reduced LOS, and fewer alterations in chemotherapy regimens compared to initial nonoperative management.

Comparing oncologic outcomes after minimally invasive and open surgery for pediatric neuroblastoma and Wilms tumor

BACKGROUND

Minimally invasive surgery (MIS) has been widely adopted for common operations in pediatric surgery; however, its role in childhood tumors is limited by concerns about oncologic outcomes. We compared open and MIS approaches for pediatric neuroblastoma and Wilms tumor (WT) using a national database.

METHODS

The National Cancer Data Base from 2010 to 2012 was queried for cases of neuroblastoma and WT in children ≤21 years old. Children were classified as receiving open or MIS surgery for definitive resection, with clinical outcomes compared using a propensity matching methodology (two open:one MIS).

RESULTS

For children with neuroblastoma, 17% (98 of 579) underwent MIS, while only 5% of children with WT (35 of 695) had an MIS approach for tumor resection. After propensity matching, there was no difference between open and MIS surgery for either tumor for 30-day mortality, readmissions, surgical margin status, and 1- and 3-year survival. However, in both tumors, open surgery more often evaluated lymph nodes and had larger lymph node harvest.

CONCLUSION

Our retrospective review suggests that the use of MIS appears to be a safe method of oncologic resection for select children with neuroblastoma and WT. Further research should clarify which children are the optimal candidates for this approach.

Influence of weight at enterostomy reversal on surgical outcomes in infants after emergent neonatal stoma creation

PURPOSE

Neonates after emergent enterostomy creation frequently require reversal at low weight because of complications including cholestasis, dehydration, dumping, failure to thrive, and failure to achieve enteral independence. We investigated whether stoma reversal at low weight (< 2.5kg) is associated with poor surgical outcomes.

METHODS

Patients who underwent enterostomy reversal from 2005 to 2013 at less than 6months old were identified in our institutional database. Only patients who underwent emergent enterostomy creation (i.e. for necrotizing enterocolitis or spontaneous perforation) were included. Demographics, disease process, comorbidities, stoma type, reversal indication, operative details, and complications were examined. Patients were categorized by weight at reversal of less than 2kg, 2.01-2.5kg, 2.51-3.5kg, and greater than 3.5kg. Data were analyzed using univariable and multivariable regression with significance level of p<0.05. The primary outcome examined was major morbidity, defined as the presence of anastomotic leak, obstruction, hernia, EC fistula, perforation, wound infection, sepsis, or death.

RESULTS

Eighty-nine patients met inclusion criteria. Demographics (sex, ethnicity, surgical disease process, reversal indication, and ASA score) were similar. The lowest weight group had lower gestational age (p<0.001) and birth weight (p=0.005), and contained a higher proportion of jejunostomies to ileostomies (p=0.013). On univariable analysis, only incisional hernia was significantly different as a complication between weight groups. On multivariable analysis controlling for gestational age and ASA, there was no significant difference in odds of major operative morbidity between groups.

CONCLUSIONS

Enterostomy reversal at lower weight may not be associated with increased risk of perioperative complications. Early stoma reversal may be acceptable when required for progression of neonatal care.

LEVEL OF EVIDENCE

Level III, Treatment Study (Retrospective comparative study).

Factors associated with survival in pediatric adrenocortical carcinoma: An analysis of the National Cancer Data Base (NCDB)

PURPOSE

Adrenocortical carcinoma (ACC) is a rare tumor in children with important distinctions from the adult disease. We reviewed the National Cancer Data Base (NCDB) to determine factors associated with long-term survival.

METHODS

The NCDB was queried for patients less than 18 years of age who were diagnosed with ACC between 1998 and 2011. Kaplan-Meier analysis was utilized to determine factors significantly associated with overall survival.

RESULTS

A total of 111 patients were included (median age: 4 years, 69% female). ACC was more common in the youngest cohort, with 48% of cases occurring in children younger than the age of 3. Median tumor size was 9.5 cm (IQR: 6.5-13.0), and 87% of patients underwent some form of surgical resection. Among children with available data, 19 of 62 presented with metastases. Overall 1- and 3-year survival was 70% and 64%, respectively. Age, tumor size, extension of tumor into surrounding tissue, and metastatic disease were all found to be significantly associated with survival. Among patients who underwent a surgical procedure, margin status was also found to be significantly associated with survival.

CONCLUSION

Age, tumor size, extension of tumor, metastatic disease, and margin status are significantly associated with long-term survival in children with adrenocortical carcinoma.

Impact of business infrastructure on financial metrics in departments of surgery

BACKGROUND

In the current environment, pressure is ever increasing to maximize financial performance in surgery departments. Factors such as physician extenders, billing and collection, payor mix, contracting, incentives from the Centers for Medicare and Medicaid Services, and administrative incentives may greatly influence financial performance. However, despite a plethora of information from the University HealthSystem Consortium and the Association of American Medical Colleges, best-practice information for business infrastructure is lacking. To obtain a sampling of current practices, we conducted a survey of departments of surgery.

METHODS

An anonymous 30-question survey addressing demographics, productivity, revenue and expense profile, payor mix, physician extender and staff personnel, billing and collections methodology, and financial performance was distributed among members of the Society of Surgical Chairs via SurveyMonkey. This was approved by the Loyola Institutional Research Board. Multivariate linear regression analyses and t tests/rank-sum tests were performed, as appropriate. Data are presented as mean ± SEM.

RESULTS

A total of 25 (19%) departments responded; 14 were integrated with the hospital/health system, and 11 were integrated with the medical school. In 60% (n = 15), the main hospital had 500 to 1,000 beds; 48% (n = 12) had >4 hospitals in their system. For FY10, MD clinical full-time equivalents (FTEs) were 49 ± 10; total work relative value units (wRVUs) were 320 ± 8 k; and total billed cases were 43 ± 16 k. A total of 23 of 25 used physician-extenders with an average of 18 ± 5 per department and in 22 of 23, the physician extenders billed. On average, there were 18 ± 6 clinical-support staff, 25 ± 11 front-office staff, and 13 ± 3 back-office support staff FTEs. Among these FTEs, there were 16 ± 5 devoted to business operations (billing, coding, denial/claims management, financial oversight). Collections/wRVUs were $60 ± 3 (range, 39-80). Regression modeling demonstrated that total wRVUs were determined by the number of MD FTEs (P = .01), number of physician extenders (P = .01), number of front-office staff (P = .01), number of back-office staff (P = .02), and number of total business staff (P = .01). Collections/wRVUs were predicted by number of hospitals (P = .04), number of MD FTEs (P = .03), number of physician extenders (P = .01), and number of cases/total business staff (P = .02). Interestingly, wRVUs/MD was predicted by number of MD FTEs (P = .01) but were not greatly impacted by numbers of clinical or business support staff. In 4 of 25, the billing and coding staff were incentivized and had a Collections/wRVU = 64 ± 5 whereas nonincentivized staff had collections/wRVU = 59 ± 3. (P = NS) Also, %Accounts receivable >90 days (15% vs 25%) were not substantially different. Only 48% (12/25) have departments have recouped Centers for Medicare and Medicaid dollars for Physician Quality Reporting Initiative, Meaningful Use, Patient-Centered Medical Homes, or other Accountable Care-like programs. One-half (13) of the departments had both an inpatient and outpatient electronic medical record. Finally, on a scale of 1-10 (10 = highest), the average level of satisfaction with billing and collections processes was 6.

CONCLUSION

Our results indicate that the physician extender, clinical support staff, and business staff environment can impact surgeon productivity, and there is opportunity for improvement. Determining best practices for ratios of support staff/MD and optimizing the role of electronic medical record in workflow and billing/collections are critical in the current environment. Our pilot study requires extension across more institutions for validation.

Human mesenchymal stem cell and epithelial hepatic carcinoma cell lines in admixture: concurrent stimulation of cancer-associated fibroblasts and epithelial-to-mesenchymal transition markers

BACKGROUND

The microenvironments of neoplasms influence both mesenchymal stem cell differentiation into cancer-associated fibroblasts (CAF) and tumor cell line differentiation to mesenchymal phenotypes via epithelial-to-mesenchymal transition (EMT). Using direct cell-cell contact approximating the microenvironment of a neoplasm, we investigated the role of this interaction in human mesenchymal stem cells (hMSCs) and epithelial hepatic carcinoma SK-Hep1 cells by evaluating CAF differentiation and EMT.

METHODS

hMSCs and SK-Hep1 cells were homogenously cultured for 12 hours with media only, OPN-R3 aptamer blockade of OPN, or RGD peptide blockade of integrin receptor, negative control mutant OPN-R3 aptamer, and RGE peptide blockade. mRNA was isolated from each subpopulation, and real-time-polymerase chain reaction was performed for CAF markers and EMT transcription factors and structural proteins.

RESULTS

SK-Hep1 cells in admixture with hMSCs showed increased EMT marker vimentin expression that was ablated with OPN-R3 aptamer or RGD blockade. SK-Hep1 cells when cultured with hMSC admixture increased Snail and Slug expression that was hindered with OPN-R3 aptamer. hMSCs acquired CAF markers tenascin-c and SDF-1 in admixture that was ablated with either OPN-R3 aptamer or RGD blockade. All SK-Hep1 and hMSC negative control subpopulations were statistically equivalent to media-only groups. Fluorescence photography exhibited the critical cell-cell interfaces and acquired EMT traits of SK-Hep1.

CONCLUSION

We conclude that direct interaction of cell lines closely replicates the native neoplasm microenvironment. Our experiments reveal soluble OPN or integrin receptor blockade independently prevents progression to metastatic phenotype by acquisition of CAF and EMT markers.

FGFR4 blockade exerts distinct antitumorigenic effects in human embryonal versus alveolar rhabdomyosarcoma

PURPOSE

Rhabdomyosarcoma (RMS) is a malignancy with features of skeletal muscle, and the most common soft tissue sarcoma of childhood. Survival for high-risk groups is approximately 30% at 5 years and there are no durable therapies tailored to its genetic aberrations. During genetic modeling of the common RMS variants, embryonal RMS (eRMS) and alveolar RMS (aRMS), we noted that the receptor tyrosine kinase (RTK) fibroblast growth factor receptor 4 (FGFR4) was upregulated as an early event in aRMS. Herein, we evaluated the expression of FGFR4 in eRMS compared with aRMS, and whether FGFR4 had similar or distinct roles in their tumorigenesis.

EXPERIMENTAL DESIGN

Human RMS cell lines and tumor tissue were analyzed for FGFR4 expression by immunoblot and immunohistochemistry. Genetic and pharmacologic loss-of-function of FGFR4 using virally transduced short hairpin RNA (shRNA) and the FGFR small-molecule inhibitor PD173074, respectively, were used to study the role of FGFR4 in RMS cell lines in vitro and xenografts in vivo. Expression of the antiapoptotic protein BCL2L1 was also examined.

RESULTS

FGFR4 is expressed in both RMS subtypes, but protein expression is higher in aRMS. The signature aRMS gene fusion product, PAX3-FOXO1, induced FGFR4 expression in primary human myoblasts. In eRMS, FGFR4 loss-of-function reduced cell proliferation in vitro and xenograft formation in vivo. In aRMS, it diminished cell survival in vitro. In myoblasts and aRMS, FGFR4 was necessary and sufficient for expression of BCL2L1 whereas in eRMS, this induction was not observed, suggesting differential FGFR4 signaling.

CONCLUSION

These studies define dichotomous roles for FGFR4 in RMS subtypes, and support further study of FGFR4 as a therapeutic target.

Epithelial-mesenchymal transition, the tumor microenvironment, and metastatic behavior of epithelial malignancies

OBJECTIVE

The mechanisms of cancer metastasis have been intensely studied recently and may provide vital therapeutic targets for metastasis prevention. We sought to review the contribution of epithelial-mesenchymal transition and the tumor microenvironment to cancer metastasis.

SUMMARY BACKGROUND DATA

Epithelial-mesenchymal transition is the process by which epithelial cells lose cell-cell junctions and baso-apical polarity and acquire plasticity, mobility, invasive capacity, stemlike characteristics, and resistance to apoptosis. This cell biology program is active in embryology, wound healing, and pathologically in cancer metastasis, and along with the mechanical and cellular components of the tumor microenvironment, provides critical impetus for epithelial malignancies to acquire metastatic capability.

METHODS

A literature review was performed using PubMed for "epithelial-mesenchymal transition", "tumor microenvironment", "TGF-β and cancer", "Wnt and epithelial-mesenchymal transition", "Notch and epithelial-mesenchymal transition", "Hedgehog and epithelial-mesenchymal transition" and "hypoxia and metastasis". Relevant primary studies and review articles were assessed.

RESULTS

Major signaling pathways involved in epithelial-mesenchymal transition include TGF-β, Wnt, Notch, Hedgehog, and others. These pathways converge on several transcription factors, including zinc finger proteins Snail and Slug, Twist, ZEB 1/2, and Smads. These factors interact with one another and others to provide crosstalk between the relevant signaling pathways. MicroRNA suppression and epigenetic changes also influence the changes involved in epithelial-mesenchymal transition. Cellular and mechanical components of the tumor microenvironment are also critical in determining metastatic potential.

CONCLUSIONS

While the mechanisms promoting metastasis are extremely wide ranging and still under intense investigation, the epithelial-mesenchymal transition program and the tumor microenvironment are both critically involved in the acquisition of metastatic potential. As our understanding of these complexities increases, the ability to target these processes for therapy will offer new promise in the treatment of epithelial malignancy and metastasis.

Osteopontin promotes CCL5-mesenchymal stromal cell-mediated breast cancer metastasis

The interaction between cancer and its local microenvironment can determine properties of growth and metastasis. A critical component of the tumor microenvironment in this context is the cancer-associated fibroblast (CAF), which can promote tumor growth, angiogenesis and metastasis. It has been hypothesized that CAF may be derived from mesenchymal stromal cells (MSC), derived from local or distant sources. However, the signaling mechanisms by which tumors and MSCs interact to promote CAF-dependent cancer growth are largely unknown. In this study with in vitro and in vivo models using MDA-MB231 human breast cancer cells, we demonstrate that tumor-derived osteopontin (OPN) induces MSC production of CCL5; the mechanism involves OPN binding to integrin cell surface receptors and activator protein-1 c-jun homodimer transactivation. In a murine xenograft model, concomitant inoculation of MSC with MDA-MB231 cells induces: (i) significantly increased growth and metastasis of MB231 cells and (ii) increased MSC migration to metastatic sites in lung and liver; this mechanism is both OPN and CCL5 dependent. MSCs retrieved from sites of metastases exhibit OPN-dependent expression of the CAF markers, α-smooth muscle actin, tenascin-c, CXCL12 (or stromal cell-derived factor 1) and fibroblast-specific protein-1 and the matrix metalloproteinases (MMP)-2 and MMP-9. Based upon these results, we propose that tumor-derived OPN promotes tumor progression via the transformation of MSC into CAF.

Splenectomy and partial splenectomy improve hematopoietic stem cell engraftment in hypersplenic mice

BACKGROUND

Hematopoietic stem cell (HSC) engraftment is delayed after transplantation in children with hypersplenism, increasing the morbidity and costs of care. Preliminary clinical data suggest that splenectomy before HSC transplantation may improve HSC engraftment, although this observation has not been tested in an animal model.

METHODS

We performed total splenectomy (n = 22), partial splenectomy (n = 16), or sham laparotomy (n = 21) on erythrocyte protein 4.2 knockout mice, a murine model of hereditary spherocytosis with hypersplenism. After 10 days, we lethally irradiated the mice, transplanted 3 x 10(6) allogeneic bone marrow cells, and then assessed engraftment using serial complete blood counts. Successful engraftment was defined as recovery of hemoglobin, neutrophil, or platelet counts. We compared engraftment rate using chi(2) test and time to engraftment using Student's t test analysis, with significance defined as P < .05.

RESULTS

Total splenectomy increased the rate of successful HSC engraftment and decreased the interval to HSC engraftment compared with controls. Similarly, partial splenectomy decreased the interval to HSC engraftment, with a nonsignificant trend toward improved overall rate of successful HSC engraftment.

CONCLUSION

Partial or total splenectomy before HSC transplantation improves HSC engraftment in hypersplenic mice. This model supports consideration of splenic resection in hypersplenic children requiring HSC transplantation.