Apoptosis mechanisms induced by 15d-PMJ2 in HCT116 colon cancer cells: insights into CHOP10/TRB3/Akt signaling

Agents that stimulate the endoplasmic reticulum (ER) stress pathway are being exploited pharmacologically to induce cancer cell death. Cytotoxic ER stress is typically regulated by the transcription factor, C/EBP homologous protein 10 (CHOP10). Products of CHOP10 transcription include the pro-apoptotic proteins: ER oxidoreductase 1α (ERO1α), death receptor-5 (DR5), and tribbles-related protein 3 (TRB3). Our previous findings showed cell death induced by 15-deoxy- Δ12,14 prostamide J2 (15d-PMJ2) occurred in an ER stress-dependent manner. However, the pathway by which 15d-PMJ2 regulates ER stress-mediated death downstream of CHOP10 has not been identified. Our results demonstrate 5 µM 15d-PMJ2 increased CHOP10 expression and apoptosis in HCT116 colon cancer cells. In cells treated with pharmacological inhibitors of ER stress, 15d-PMJ2-induced apoptosis was reliant upon the ER stress pathway. To investigate the role of CHOP10 and its transcriptional products in apoptosis, genetic deletion of CHOP10 (CHOP10-KO) was performed using the CRISPR/Cas9 system. The apoptotic action of 15d-PMJ2 was blunted in cells lacking CHOP10 expression. The deletion of CHOP10 reduced the expression of DR5, ERO1α, and TRB3 although only the expression of TRB3 was significantly reduced. Therefore, we overexpressed TRB3 in CHOP10-KO cells and observed that the activation of Akt was inhibited and 15d-PMJ2-induced apoptosis was restored. Thus, a mechanism of apoptosis elicited by 15d-PMJ2 includes the stimulation of CHOP10/TRB3/Akt inhibition. Given the important role these signaling molecules play in cancer cell fate, 15d-PMJ2 may be an effective inducer of apoptosis in cancer cells.

Abstract 3873: CHOP10/TRB3/Akt signaling regulates ER stress apoptosis in colon cancer cells treated with prostamide-J

The endoplasmic reticulum (ER) is a cellular organelle that is primarily responsible for oxidative protein folding. When the protein folding load in cells exceeds the protein folding capacity, ER stress occurs. The ER stress pathway is a prominent regulator of cancer cell death and as a result, ER stress inducers are being exploited pharmacologically. Cytotoxic ER stress is typically regulated by the transcription factor, C/EBP homologous protein 10 (CHOP10). Transcriptional products of CHOP10 include pro-apoptotic genes, such as tribbles-related protein 3 (TRB3), death receptor-5 (DR5), and ER oxidoreductase 1α (ERO1α). Our previous data showed that apoptosis mediated by 15deoxy, Δ12,14 prostamide J2 (15dPMJ2) occurred in an ER stress-dependent manner. However, the signaling pathway that regulates 15dPMJ2 mediated ER stress apoptosis has not been identified. Therefore, the goal of this study is to determine the role of CHOP10 and its transcriptional targets in ER stress apoptosis that is induced by 15dPMJ2 in colon cancer cells. According to our data, 15dPMJ2 was 3-fold more effective in inducing apoptosis in the human colon cancer cell line, HCT116, compared to the non-tumorigenic colon cell line, FHC. The induction of apoptosis in HCT116 cells occurred coincident with a significant increase in CHOP10 protein expression. In addition, blockade of the ER stress pathway with 4-phenylbuterate (PBA) or salubrinal prevented apoptosis indicating that cell death is reliant upon ER stress. To determine the role of CHOP10 in this process, CRISPR/Cas9 CHOP10 knockout HCT116 cells (CHOP10-KO-HCT116) were generated. As anticipated, 15dPMJ2 increased CHOP10 expression in wt-HCT116 cells but not in CHOP10-KO-HCT116 cells. Furthermore, 15dPMJ2 increased the expression of ERO1α, DR5, TRB3, and it induced apoptosis in wt-HCT116 cells, but not in CHOP10-KO cells. Interestingly, the induction of TRB3, but not DR5 or ERO1α, was completely inhibited in cells devoid of CHOP10 expression. Therefore, the activity of protein kinase B (PKB)/Akt, a known TRB3 target, was investigated. CHOP10 stimulation by 15dPMJ2 inactivated Akt in wt-HCT116 cells, but not in CHOP10-KO cells. These findings suggest the importance of CHOP10, TRB3, and Akt in the control of the ER stress-mediated apoptosis in response to 15dPMJ2 treatment. Thus, 15dPMJ2 is a potential chemotherapeutic agent that inhibits PKB/Akt survival signaling by upregulating the CHOP10/TRB3 pathway to prevent colon cancer growth.

Citation Format: Hussam Albassam, Daniel A. Ladin, Rukiyah Van Dross. CHOP10/TRB3/Akt signaling regulates ER stress apoptosis in colon cancer cells treated with prostamide-J [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3873.

Prostaglandin D2-ethanolamide induces skin cancer apoptosis by suppressing the activity of cellular antioxidants

The combined incidence of melanoma and non-melanoma skin cancer (NMSC) is greater than the incidence of all other malignancies in the US. Previously, we demonstrated that the endocannabinoid, arachidonoyl-ethanolamide (AEA), was a potent inducer of apoptosis in NMSC. The metabolism of AEA to the prostaglandin, PGD₂-EA, was a prerequisite for AEA cytotoxicity. However, the mechanism of PGD₂-EA cell death has not been clearly defined. In the present study, we report that PGD₂-EA causes apoptosis in melanoma and NMSC cells. Mass spectrometry analysis revealed that PGD₂-EA was dehydrated to three J-series prostaglandins; PGJ₂-EA, Δ¹²PGJ₂-EA, and 15deoxy,Δ12,14 PGJ₂-EA. PGD₂-EA inhibited the antioxidant activity of glutathione and thioredoxin which then caused oxidative stress. This increase in oxidative stress was accompanied by the activation of endoplasmic reticulum (ER) stress and apoptosis. The effect of PGD₂-EA was independent of DP1, DP2, and PPARγ receptors suggesting that PGD₂-EA cytotoxicity was mediated by its metabolic product, 15dPGJ₂-EA.

Abstract 2097: A novel J-series prostamide induces ER stress-mediated apoptosis and upregulates ER oxidoreductase 1 alpha (ERO1α) in human colon cancer cells

Colon cancer is the third most common cancer and the third leading cause of cancer-related death in the United States. The endoplasmic reticulum (ER) is a cellular organelle responsible for protein synthesis and oxidative folding. ER stress occurs when the protein folding load exceeds the protein folding capacity. Low levels of ER stress promote survival while excessive ER stress causes cell death. An important regulator of the cytotoxic ER stress pathway is the transcription factor, C/EBP homologous protein 10 (CHOP10). It has been shown that CHOP10 regulates the transcription of ER oxidoreductase 1α (ERO1α). ERO1α promotes ER luminal oxidation and under conditions of excessive ER stress releases H2O2 into the cytoplasm, resulting in oxidative stress-mediated apoptosis. Previous studies from our laboratory showed that 15deoxy, Δ12,14 prostamide J2 (15d PMJ2) induced ER stress-mediated apoptosis, leading to a reduction in cell viability in tumorigenic keratinocytes and melanocytes. In addition, 15d PMJ2-induced ER stress-apoptosis was decreased in the presence of ER stress inhibitors, 4-phenylbuterate (PBA) and salubrinal. However, the specific pathway involved in 15d PMJ2-induced ER stress-apoptosis have not been identified. In this study, we hypothesize that 15d PMJ2 causes ER stress-mediated apoptosis in colon tumor cells by activating CHOP10 and its downstream transcriptional target, ERO1α. To examine the anti-proliferative effect of 15d PMJ2, tumorigenic colon cells (HCT116) and non-tumorigenic colon cells (FHC) were treated with different concentrations of 15d PMJ2 or 10µM thapsigargin (TG) for 24 hours and cytotoxicity was measured by lactate dehydrogenase (LDH) assay. A significant increase in cell death was observed in HCT116 cells treated with 5µM 15d PMJ2 and this cytotoxic effect was 3-fold greater in HCT116 compared to FHC cells. Apoptotic measurements showed a significant increase in caspase 3/7 activity and annexin-V positivity following 15d PMJ2 treatment. The expression of CHOP10 was significantly enhanced in the 15d PMJ2-treated group. In addition, 15d PMJ2-induced apoptosis was decreased in the presence of ER stress inhibitors, PBA and salubrinal, suggesting that ER stress is essential for 15d PMJ2-induced apoptosis. Western blot analysis revealed an increase in ERO1α protein expression following 15d PMJ2 treatment. Apoptosis measurements showed a significant inhibition in 15d PMJ2-mediated apoptosis in the presence of ERO1α inhibitor, EN460, suggesting that ERO1α is important for 15d PMJ2-induced apoptosis. These findings suggest that 15d PMJ2-induced apoptosis is mediated via the ER stress pathway. CHOP10 and its transcriptional target, ERO1α, play a potential role in 15d PMJ2-induced ER stress-apoptosis, suggesting that 15d PMJ2 could be a potential anti-neoplastic agent with a unique mechanism for colon cancer.

Citation Format: Hussam M. Albassam, Daniel A. Ladin, Rukiyah Van Dross. A novel J-series prostamide induces ER stress-mediated apoptosis and upregulates ER oxidoreductase 1 alpha (ERO1α) in human colon cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2097. doi:10.1158/1538-7445.AM2017-2097

Abstract 3217: Novel prostamide, 15-deoxy-delta12,14 prostamide J2, displays activity against melanoma in vitro and in vivo: potential role of endoplasmic reticulum stress

Melanoma is the most aggressive and deadly form of cutaneous neoplasm in the United States, representing a major clinical challenge. Our lab previously demonstrated that the endocannabinoid, arachidonoyl ethanolamide (AEA), induced cell death in non-melanoma skin cancer (NMSC) cells through the cyclooxygenase-2 (COX-2) mediated formation of novel J-series prostamides (PMJs). We were the first to chemically synthesize the primary metabolite, 15-deoxy-Δ12,14 prostamide J2 (15d-PMJ2), which displayed potent and selective cytotoxicity in NMSC cells. As such, we hypothesize that the selective cytotoxicity of 15d-PMJ2 would be observed in other forms of skin cancer, including melanoma. B16F10 murine melanoma cells and nontumorigenic Melan-A cells were treated with different concentrations of 15d-PMJ2 for 24 hours and cell viability was measured using MTS assays. At 5µM, 15d-PMJ2 decreased viability by 63% in B16F10 cells, while Melan-A viability was not affected. To verify that cell death was due to apoptosis, the cleavage of apoptotic markers caspase-3 and PARP was examined by conducting Western blot analysis. 15d-PMJ2 markedly increased caspase-3 and PARP cleavage only in B16F10 melanoma cells. Previous studies in NMSC indicated that 15d-PMJ2 induced ER-stress and apoptosis. To investigate the mechanism of 15d-PMJ2-mediated death in melanoma, we examined ER-stress responses. Melan-A and B16F10 melanoma cells were treated with 5µM 15d-PMJ2 and evaluated for CHOP10 and p-PERK expression by Western blot analysis. B16F10, but not Melan-A cells exhibited a notable increase in CHOP10 and p-PERK expression when treated with 15d-PMJ2. To further examine the role of ER-stress on 15d-PMJ2 mediated apoptosis, B16F10 cells were pretreated with the ER-stress inhibitors salubrinal and 4-phenylbutyric acid (PBA). Both salubrinal and PBA decreased activation of caspase-3/7, suggesting that ER-stress plays an important role in 15d-PMJ2 mediated tumor cell death. To determine the anti-melanoma activity of 15d-PMJ2 in vivo, B16F10 allograft tumors grown in C57BL/6 mice were dosed subcutaneously with 0.5 or 5.0 mg/kg 15d-PMJ2 for 5 days. Tumors treated with 15d-PMJ2 exhibited significantly reduced growth and mean weights compared to vehicle and untreated animals. TUNEL analysis of tumor tissues indicated a large presence of necrotic and apoptotic cells in 15d-PMJ2-treated tumors compared to vehicle and untreated tumors. To determine whether 15d-PMJ2 induced ER-stress in vivo, tumors were assayed for p-PERK and CHOP10 levels by immunohistochemistry (IHC). These markers were significantly elevated in 15d-PMJ2-treated tumors. Similarly, the viability of primary patient-derived melanoma cells was significantly decreased by 15d-PMJ2. These findings suggest that the novel prostamide, 15d-PMJ2, possesses potent and selective anti-melanoma activity in vitro and in vivo.

Citation Format: Daniel A. Ladin, Li V. Yang, Timothy L. Fitzgerald, Rukiyah Van Dross. Novel prostamide, 15-deoxy-delta12,14 prostamide J2, displays activity against melanoma in vitro and in vivo: potential role of endoplasmic reticulum stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3217. doi:10.1158/1538-7445.AM2017-3217

Synthesis and Evaluation of the Novel Prostamide, 15-Deoxy, Δ12,14-Prostamide J2, as a Selective Antitumor Therapeutic

15-deoxy, Δ^12,14-prostaglandin J₂-ethanolamide, also known as 15-deoxy, Δ^12,14-prostamide J₂ (15d-PMJ₂) is a novel product of the metabolism of arachidonoyl ethanolamide (AEA) by COX-2. 15d-PMJ₂ preferentially induced cell death and apoptosis in tumorigenic A431 keratinocytes and B16F10 melanoma cells compared with nontumorigenic HaCaT keratinocytes and Melan-A melanocytes. Activation of the ER stress execution proteins, PERK and CHOP10, was evaluated to determine whether this process was involved in 15d-PMJ₂ cell death. 15d-PMJ₂ increased the phosphorylation of PERK and expression of CHOP10 in tumorigenic but not nontumorigenic cells. The known ER stress inhibitors, salubrinal and 4-phenylbutaric acid, significantly inhibited 15d-PMJ₂-mediated apoptosis, suggesting ER stress as a primary apoptotic mediator. Furthermore, the reactive double bond present within the cyclopentenone structure of 15d-PMJ₂ was identified as a required moiety for the induction of ER stress apoptosis. The effect of 15d-PMJ₂ on B16F10 melanoma growth was also evaluated by dosing C57BL/6 mice with 0.5 mg/kg 15d-PMJ₂ Tumors of animals treated with 15d-PMJ₂ exhibited significantly reduced growth and mean weights compared with vehicle and untreated animals. TUNEL and IHC analysis of tumor tissues showed significant cell death and ER stress in tumors of 15d-PMJ₂-treated compared with control group animals. Taken together, these findings suggest that the novel prostamide, 15d-PMJ₂, possesses potent antitumor activity in vitro and in vivoMol Cancer Ther; 16(5); 838-49. ©2017 AACR.

Preclinical and Clinical Assessment of Cannabinoids as Anti-Cancer Agents

Cancer is the second leading cause of death in the United States with 1.7 million new cases estimated to be diagnosed in 2016. This disease remains a formidable clinical challenge and represents a substantial financial burden to the US health care system. Therefore, research and development of novel therapeutics for the treatment of cancer is of high priority. Cannabinoids and their derivatives have been utilized for their medicinal and therapeutic properties throughout history. Cannabinoid activity is regulated by the endocannabinoid system (ECS), which is comprised of cannabinoid receptors, transporters, and enzymes involved in cannabinoid synthesis and breakdown. More recently, cannabinoids have gained special attention for their role in cancer cell proliferation and death. However, many studies investigated these effects using in vitro models which may not adequately mimic tumor growth and metastasis. As such, this article aims to review study results which evaluated effects of cannabinoids from plant, synthetic and endogenous origins on cancer development in preclinical animal models and to examine the current standing of cannabinoids that are being tested in human cancer patients.

Effects of electrically charged particles in enhancement of rat wound healing

BACKGROUND

Many studies have show that various growth factors enhance wound healing in animal models. However, growth factors are expensive and complex and their wound pharmacokinetics are unknown. The clinical trials with growth factors in the treatment of chronic wounds have produced unsuccessful results. A viable alternative to growth factors may be certain biomaterials such as hydrophilic, carbohydrate beads.

MATERIALS AND METHODS

Positively charged, negatively charged, or uncharged beads were applied to paired 6-cm rat incisions. The following key aspects of the wound healing process were examined: wound breaking strength and histological analysis.

RESULTS

Our data show that wounds treated with positively charged, DEAE Sephadez beads had a 46-50% (P < 0.001) increase in breaking strength over untreated control wounds. A variety of other positively charged, anion exchange materials also elicited a wound healing response, despite the fact that the positively charged chemical moieties as well as the bead matrix were different. In conjunction with the increase in wound breaking strength, an increase in wound macrophage was observed in wounds treated with anion exchangers (P < 0.01). Negatively charged or uncharged beads showed no significant difference from the untreated controls.

CONCLUSION

We conclude from this study that the enhancement of wound healing seen with positively charged beads is due principally to the positive charge on the beads; we postulate that the anion exchange between the positively charged beads and tissue is responsible for this enhancement.

Understanding dressings

Currently our understanding of chronic wound pathophysiology is deficient in knowing what specifically is lacking during arrested wound healing. Autologous or allogenic keratinocytes have been used successfully to treat chronic wounds, as have composites containing diverse substances such as allogenic dermis, polyglycolic acid, or collagen mesh combined with keratinocytes or fibroblasts (Table 6). In spite of great technological advances and increased understanding, there is much work to be done. We look forward to the day when our knowledge of wound healing has progressed to the point when specific deficiencies can be supplemented by dressing contents, and when "smart" dressings can adapt to the changing wound as it progresses through the phases of healing.

The multidisciplinary in-hospital wound care team: two models

The cost of community- and hospital-acquired pressure ulcers is particularly high in terms of both patient morbidity and economics. Multidisciplinary wound care teams were developed independently at two different hospitals to deal with the needs of patients with pressure ulcers and to control costs. Although the goals of the teams at both institutions were similar, the strategies for achieving the goals were different because they were adapted to the needs of the particular institution. As a result, care and prevention of pressure ulcers have improved at both hospitals.

Hydrogels and hydrocolloids: an objective product comparison

It is difficult for providers to make selections from the vast array of currently available wound care products. There has been a paucity of objective data generated by a non-biased source comparing one product to another. In order for our Wound Care Team to recommend products for system-wide formulary purchase and patient use, we needed to develop a process for product comparison. A strategy for objective evaluation of hydrocolloid and amorphous hydrogel products was created, and these products were assessed clinically by experienced wound care providers. Laboratory testing included measurement of each product's ability to absorb water versus normal saline versus actual patient wound fluid. There were major differences in various products' abilities to absorb the fluids. These objective data from the laboratory, along with the subjective comparison of clinical performance, allowed our Wound Care Team to objectively rank the hydrocolloids and hydrogels and include those preferred products in our Wound Care Product Formulary.

p53 and apoptosis alterations in keloids and keloid fibroblasts

Keloids are the result of a dysregulated wound-healing process and are characterized by formation of excess scar tissue that proliferates beyond the boundaries of the inciting wound. In this study, we investigated the expression of key proteins involved in regulating apoptosis in keloids. Twenty archival paraffin-embedded keloid samples were randomly selected for an immunoperoxidase assay with antibodies against fas, p53, bcl-2, and bcl-x proteins using the target antigen-retrieval technique. Apoptosis was assessed in keloids and normal skin and in keloid and normal fibroblasts by the TdT-mediated dUTP nick-end labeling (tunel) assay on tissue sections, fibroblast cultures, and by flow cytometry for cell suspensions. We found that 18 of 20 keloids expressed p53 protein; bcl-2 was expressed by keloid fibroblasts in 19 of 20 keloids, and all specimens had prominent fas expression throughout the tissue. The distribution of these three antigens was regional within each lesion and followed a consistent pattern of p53 and bcl-2 expression colocalized to the hypercellular, peripheral areas of each keloid in a perinuclear pattern (p < .001). In contrast, an inverse distribution of fas expression was shown, with staining being more diffuse across the cell surfaces and limited to the central, more hypocellular regions in16 of 17 keloids (p < .001). There was no specific staining pattern in these keloids with antihuman bcl-x. In vitro studies on cultured keloid fibroblasts (derived from six patients) revealed maintenance of the p53+, bcl-2+ phenotype up to passage 10. Neither neonatal nor normal adult skin fibroblasts expressed either antigen but could be induced to express p53 by exposure to adriamycin. Keloid lesions and keloid fibroblasts were found to have lower rates of apoptosis than normal controls. Keloid fibroblasts displayed enhanced apoptosis rates in response to hydrocortisone, gamma interferon, and hypoxia treatment as compared with normal adult fibroblasts. Focal dysregulation of p53 combined with upregulation of bcl-2 may help produce a combination of increased cell proliferation and decreased cell death in the younger, hypercellular areas of the keloid. This phenotype is reversed in the older areas of the keloid and may prevent malignant degeneration, thus favoring normal apoptosis as evidenced by prominent fas expression.

Acute and chronic animal models for excessive dermal scarring: quantitative studies

Excessive scarring in the form of keloids and hypertrophic scars continues to be a clinical problem for some patients. The lack of an animal model for such scarring has been an obstacle to studying the cellular and molecular biology of these entities. Previous observations made by the authors that some surgical scars in the rabbit ear remain raised for months after wounding prompted us to investigate whether the rabbit ear might provide a model by which to study excessive dermal scarring. After establishing the model in preliminary study, 40 excisional wounds, 6 mm in diameter, were created over the ventral surface of rabbit ears. Elevated scars were treated with either intralesional triamcinolone acetonide or saline at day 16 postwounding. On day 22, 25 scar wounds were used for thorough histomorphometric analysis, 15 wounds were eliminated prior to analysis because of invagination of epithelial tissue, which made analysis difficult. Total area of scar and Hypertrophic Index, a ratio comparing scar prominence with the thickness of adjacent unwounded tissue, were measured for 25 (62 percent) of the resulting scars. Both total area of scar and Hypertrophic Index were found to be significantly decreased in the steroid-treated group (p < 0.02 and < 0.03, respectively). In a chronic form of this model, in which larger excisions were taken, an excessive accumulation of both new collagen and cartilage over 9 months was observed. An animal model for excessive dermal scarring that allows quantitation of scar formation and, at an early stage, can be modulated in a predictable way with intralesional corticosteroid treatment is presented. This model may parallel hypertrophic scarring in humans and thus might provide a tool by which to study its pathophysiology and objectively evaluate therapeutic modalities.

Alpha 1-antitrypsin is degraded and non-functional in chronic wounds but intact and functional in acute wounds: the inhibitor protects fibronectin from degradation by chronic wound fluid enzymes

Fluid obtained from chronic and acute wounds were examined for the presence of fibronectin, alpha 1-antitrypsin, and proteinases capable of degrading both proteins. Immunoblot analysis of fluids from ten chronic wounds revealed that fibronectin and alpha 1-antitrypsin were degraded in nine of ten samples. In contrast, both fibronectin and alpha 1-antitrypsin were intact in acute wound fluids. The degradation of the inhibitor and fibronectin occurred in the same wound fluids, and these two events correlated perfectly. Chronic or acute wound fluid proteins were coupled to benzamidine Sepharose 6B beads and incubated with fibronectin or alpha 1-antitrypsin. Chronic wound fluid proteins degraded fibronectin in the presence of ethylenediaminetetraacetate, leupeptin, cystatin, and pepstatin but not in the presence of phenylmethylsulfonyl fluoride. Acute wound fluids and normal human serum did not contain enzymes capable of degrading fibronectin. These data suggest that serine proteinases are responsible for fibronectin degradation in chronic wound fluids. Chronic wound fluids that contained degraded alpha 1-antitrypsin also contain proteinases capable of degrading alpha 1-antitrypsin from human serum. Acute wound fluids and normal human serum did not contain enzymes capable of degrading alpha 1-antitrypsin. The inhibitor from acute wound fluids bound to one of its targets, trypsin. In contrast, the fragment(s) of alpha 1-antitrypsin from chronic wound fluids did not bind trypsin. Chronic wounds associated with degraded fibronectin and the inhibitor contained ten- to forty-fold more elastase activity than acute wounds. The degradation of fibronectin by chronic wound fluid enzymes was inhibited by alpha 1-antitrypsin in a dose-dependent manner. Collectively, these results demonstrate that there are enzymes in chronic wounds that perturb the function of alpha 1-antitrypsin and allow fibronectin degradation by uninhibited serine proteinases.

Effects of oxygen on wound responses to growth factors: Kaposi's FGF, but not basic FGF stimulates repair in ischemic wounds

Kaposi's fibroblast growth factor (K-FGF, FGF-4) is a newer member of FGF family with uncharacterized wound healing properties. Basic fibroblast growth factor (bFGF, FGF-2) has been well studied and accelerates repair in normal and impaired wound healing models. K-FGF and bFGF are known to have similar biological effects in tissue culture, and both stimulate fibroblast and endothelial cell proliferation. The rabbit dermal ulcer model was used to examine the effects of bFGF and K-FGF under ischemic and nonischemic conditions. We found bFGF was ineffective in stimulating healing under ischemic conditions even at high doses (30 micrograms/wound). However, when the ischemic wounds were treated with bFGF (5 micrograms/wound) plus hyperbaric oxygen therapy, it was highly effective again as previously found under nonischemic conditions (P < 0.05). In contrast K-FGF stimulated repair in both nonischemic and ischemic wounds (P < 0.05). These results suggest that wound oxygen content differentially regulates responsiveness to bFGF and that K-FGF is biologically active in hypoxic wounds.

Excessive scarring as a consequence of healing

Synthesis and degradation of collagen is an essential component of wound healing. In most persons, this deposition of collagen results in the formation of a fine line scar which restores much of the tensile strength to the injured tissue and is cosmetically acceptable. However, in certain individuals, the result of wound healing is the excessive accumulation of collagen, resulting in a hypertrophic scar or keloid. The precise origin of this abnormal collagen deposition is unknown, but recent studies have begun to identify potential mechanisms for these disfiguring and painful lesions. This article will review the clinical and laboratory findings pertinent to understanding the origin and treatment of excessive scarring.

Acute repair of a full-thickness right ventricular defect with a composite myofascial pedicle flap

A full-thickness defect of the right ventricle presented acutely after mediastinitis and sternal dehiscence. This developed 29 days after bilateral internal mammary artery harvest for coronary artery bypass grafting. The defect was managed successfully with a pedicled left rectus abdominis muscle flap using an attached island of the anterior rectus sheath for endocardial lining. The vascular anatomic basis for viability of the rectus abdominis muscle flap after internal mammary artery harvest is derived primarily from musculophrenic, lumbar, lower sixth intercostal, and subcostal artery communications. In addition, the advantages of a myofascial pedicle flap for reconstruction of full-thickness cardiac defects are its ready availability and a strong anterior fascial sheath that can be used as a neoendocardial lining. The patient did well and remains asymptomatic after 3 years.