Integrin α3ß1 on Tumor Keratinocytes Is Essential to Maintain Tumor Growth and Promotes a Tumor-Supportive Keratinocyte Secretome.

The development of integrin-targeted cancer therapies is hindered by incomplete understanding of integrin function in tumor cells and the tumor microenvironment. Previous studies showed that mice with epidermis-specific deletion of the α3 integrin subunit fail to form skin tumors during two-step chemical tumorigenesis, indicating a protumorigenic role for integrin α3ß1. Here, we generated mice with tamoxifen-inducible, epidermis-specific α3 knockout to determine the role of α3ß1 in the maintenance of established tumor cells and/or the associated stroma. Genetic ablation of α3 in established skin tumors caused their rapid regression, indicating that α3ß1 is essential to maintain tumor growth. Although reduced proliferation and increased apoptosis were observed in α3ß1-deficient tumor cells, these changes followed a robust increase in stromal apoptosis. Furthermore, macrophages and fibulin-2 levels were reduced in stroma following α3 deletion from tumor cells. Mass spectrometric analysis of conditioned medium from immortalized keratinocytes showed that α3ß1 regulates a substantial fraction of the keratinocyte secretome, including fibulin-2 and macrophage CSF1; RNA in situ hybridization showed that expression of these two genes was reduced in tumor keratinocytes in vivo. Our findings identify α3ß1 as a regulator of the keratinocyte secretome and skin tumor microenvironment and as a potential therapeutic target.

Keratinocyte Integrin α3ß1 Promotes Secretion of IL-1α to Effect Paracrine Regulation of Fibroblast Gene Expression and Differentiation.

After cutaneous injury, keratinocytes secrete paracrine factors that regulate wound cell functions; dysregulation of this signaling can lead to wound pathologies. Previously, we established that keratinocyte integrin α3ß1 promotes wound angiogenesis through paracrine stimulation of endothelial cells. We hypothesize here that α3ß1-dependent paracrine signaling from keratinocytes regulates the differentiation state of myofibroblasts. We report that epidermal α3-knockout mice exhibit more wound myofibroblasts and fewer cyclooxygenase 2 (Cox-2)-positive dermal cells than controls. We also found that conditioned medium from α3-expressing mouse keratinocytes (MKα3+), but not from α3-null MK cells (MKα3-), induces expression of Cox-2 in fibroblasts in a time- and dose-dependent manner and that this induction is mediated by IL-1α. Compared with MKα3- cells, MKα3+ cells secrete more IL-1α and less IL-1RA, a natural IL-1 receptor antagonist. Treatment with an IL-1α neutralizing antibody, recombinant IL-1RA, or IL-1 receptor-targeting small interfering RNA suppresses MKα3+ conditioned medium-dependent induction of Cox-2 expression in fibroblasts. Finally, active recombinant IL-1α is sufficient to induce Cox-2 in fibroblasts and to inhibit transforming growth factor-ß-induced α-SMA expression. Our findings support a role for keratinocyte integrin α3ß1 in controlling the secretion of IL-1α, a paracrine factor that regulates the wound myofibroblast phenotype.

Opposing Roles of Epidermal Integrins α3ß1 and α9ß1 in Regulation of mTLD/BMP-1-Mediated Laminin-γ2 Processing during Wound Healing.

Proteolytic processing of the laminin-γ2 chain is a hallmark of basement membrane maturation in the skin. Integrin α3ß1, a major receptor for epidermal adhesion to laminin-332, is critical for proper basement membrane organization during skin development and wound healing. Previously, we identified a role for α3ß1 in promoting the processing of laminin-γ2 in cultured keratinocytes in vitro and in wound epidermis in vivo. In this study we identify the Bmp1 gene, which encodes variants of the mTLD/BMP-1 metalloproteases, as a critical regulator of α3ß1-dependent laminin-γ2 processing, thereby expanding the role of this integrin in controlling the secretion by the epidermis of factors that modulate the tissue microenvironment. Because our previous studies identified another epidermal integrin, α9ß1, as a suppressive regulator of α3ß1-dependent wound angiogenesis, we investigated whether α9ß1 has a similar cross-suppressive effect on the ability of α3ß1 to promote basement membrane organization. Here, we show that, rather than a cross-suppressive role, α9ß1 has an opposing role in basement membrane assembly/maturation through reduced laminin-γ2 processing via mTLD/BMP-1. Although α3ß1 promotes this process during wound healing, α9ß1 has an inhibitory role, suggesting that regulation of basement membrane assembly requires a complex interplay between these distinct epidermal integrins.

Open reduction and internal fixation of rib fractures in polytrauma patients with flail chest.

BACKGROUND: Open reduction and internal fixation (ORIF) of fractured ribs for flail chest is safe and effective but who is most likely to benefit is unknown. Our purpose is to compare ORIF with nonoperative management (NOM) in polytrauma patients. METHODS: Albany Medical Center Hospital Trauma Registry was queried for adult patients with flail chest admitted over 7 years. RESULTS: Eighty-six patients with radiographic flail chest were identified who met inclusion criteria. The 41 ORIF and 45 NOM patients had similar demographics and injury severity. Hospital length of stay and intensive care unit length of stay were significantly longer in the ORIF group than that of the NOM group. There was a trend toward longer time on the ventilator in the ORIF group. CONCLUSIONS: In this retrospective study, patients treated by ORIF had longer hospitalization and ventilator duration. Future studies should be designed to optimally identify patients who are most likely to benefit from ORIF.

Laparoscopic-assisted percutaneous cecostomy for antegrade continence enema.

PURPOSE: The antegrade continence enema (ACE) is an option in the management of fecal incontinence and chronic constipation. We report our experience with a simple laparoscopic technique. SUBJECTS AND METHODS: Data were collected on 16 children (8 boys) who underwent laparoscopic cecostomy for ACE. Success was defined as cessation of fecal soiling with no need for diapers. RESULTS: Mean age at laparoscopic cecostomy was 11 years (range, 6-16 years). Mean follow-up after initial cecostomy was 22 months (range, 6-51 months). Diagnoses in 16 patients were functional constipation with soiling (n=14), incontinence after surgery for Hirschsprung's disease (n=1), and constipation secondary to mitochondrial disease (n=1). Seven had significant developmental or psychiatric problems. Three patients had primary placement of a trapdoor device (Chait); 13 had placement of a long tube, with later replacement by a skin-level device. We have evolved a laparoscopic-assisted percutaneous technique, using metallic anchor sutures on the cecum, and a dilator and peel-away sheath for introduction of the catheter. Complications occurred in 5 patients; 3 returned to the operating room: 1 for tube occlusion, 1 for suture granuloma, and 1 for a dislodged tube at 7 months postoperatively. One patient received intravenous antibiotics because of suspected peritonitis on the first postoperative day. One was re-admitted with abdominal pain. Five of 16 patients have failed therapy (four tubes removed and one tube in situ). Three have had only minor improvement. Eight have had successful ACE management, of whom 1 patient has had his tube removed after resolution of symptoms. Of 8 patients with no or minimal improvement with ACE, 5 have significant psychiatric problems. CONCLUSIONS: Laparoscopic-assisted percutaneous cecostomy has an excellent safety profile and patient comfort. The procedure is simple, secure, and reversible. Results were excellent in half of the patients. Associated psychiatric or behavioral problems may predict poor response to ACE.

AFPep: an anti-breast cancer peptide that is orally active.

BACKGROUND: We have synthesized a cyclic nonapeptide (AFPep) that is effective, after being administered by parenteral routes, for the treatment or the prevention of breast cancer. To test the hypothesis that AFPep remains safe and efficacious after oral administration, three different whole-animal bioassays were utilized, and the mechanism by which AFPep functions was investigated. METHODS: Using a human breast cancer xenograft model in mice for therapeutic activity, a carcinogen-induced breast cancer model in rats for prevention efficacy, and a mouse uterus growth inhibition model of anti-estrogenic activity, AFPep was administered by oral gavage (p.o.) and its effects compared to those following intraperitoneal (i.p.) and subcutaneous (s.c.) administration. Toxicity studies evaluated body weights and organ weights in mice and rats receiving AFPep. Preliminary mechanistic studies were carried out in T47D human breast cancer cells growing in culture and evaluated the effect of AFPep on estrogen-stimulated cell growth, phosphorylation of the estrogen receptor (ER), and on level of ER-related kinases. RESULTS: Orally administered AFPep stopped the growth of human tumor xenografts in mice, decreased the incidence and multiplicity of breast cancers in carcinogen-exposed rats, and inhibited the estrogen-stimulated growth of mouse uteri. In each of these systems, orally administered AFPep produced an effect similar to that obtained for AFPep administered by either i.p or s.c. routes. In rodents, no evidence of toxicity was seen for the peptide, even at very high doses. In culture, AFPep inhibited the estrogen-stimulated growth, but not the basal growth, of T47D cells, and it inhibited the estrogen-stimulated phosphorylation of Serine 118 in the ER of these cells, which was not explainable by early changes in ER-related kinases. CONCLUSIONS: Chronic oral administration of AFPep appears to be safe and effective for the treatment or prevention of breast cancer in animal models.