Dhanasekaran A, Gruenloh SK, Buonaccorsi JN, Zhang R, Gross GJ, Falck JR, Patel PK, Jacobs ER, Medhora M. Multiple antiapoptotic targets of the PI3K/Akt survival pathway are activated by epoxyeicosatrienoic acids to protect cardiomyocytes from hypoxia/anoxia.

Hydroxyeicosatetraenoic acid (20-HETE) is an endogenous cytochrome P-450 product present in vascular smooth muscle and uniquely located in the vascular endothelium of pulmonary arteries (PAs). 20-HETE enhances reactive oxygen species (ROS) production of bovine PA endothelial cells (BPAECs) in an NADPH oxidase-dependent manner and is postulated to promote angiogenesis via activation of this pathway in systemic vascular beds. We tested the capacity of 20-HETE or a stable analog of this compound, 20-hydroxy-eicosa-5(Z),14(Z)-dienoic acid, to enhance survival and protect against apoptosis in BPAECs stressed with serum starvation. 20-HETE produced a concentration-dependent increase in numbers of starved BPAECs and increased 5-bromo-2Ј-deoxyuridine incorporation. Caspase-3 activity, nuclear fragmentation studies, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays supported protection from apoptosis and enhanced survival of starved BPAECs treated with a single application of 20-HETE. Protection from apoptosis depended on intact NADPH oxidase, phosphatidylinositol 3 (PI3)-kinase, and ROS production. 20-HETE-stimulated ROS generation by BPAECs was blocked by inhibition of PI3-kinase or Akt activity. These data suggest 20-HETEassociated protection from apoptosis in BPAECs required activation of PI3-kinase and Akt and generation of ROS. 20-HETE also protected against apoptosis in BPAECs stressed by lipopolysaccharide, and in mouse PAs exposed to hypoxia reoxygenation ex vivo. In summary, 20-HETE may afford a survival advantage to BPAECs through activation of prosurvival PI3-kinase and Akt pathways, NADPH oxidase activation, and NADPH oxidase-derived superoxide.reduced nicotinamide adenine dinucleotide phosphatase oxidase; reactive oxygen species; phosphatidylinositol 3-kinase; Akt; hypoxia CYTOCHROME P-450 (CYP) ENZYMES can metabolize arachidonic acid into numerous eicosanoids, with the relative abundance dependent on the tissue and species (21). The major products in most tissues are the -hydroxylated metabolite 20-hydroxyeicosatetraenoic acid (20-HETE) and regio-and stereo-specific epoxyeicosatrienoic acids. 20-HETE, a -hydroxylation product of arachidonic acid catalyzed by CYP4A, is a paracrine and autocrine mediator of numerous cellular processes (20,29,35). It is produced in vascular smooth muscle, renal, cerebral, pulmonary, mesenteric, and skeletal muscle beds and acts on the microvasculature and kidney tubules (11,18,22,33,38).Our laboratory has recently reported that 20-HETE/CYP4 enhances reactive oxygen species (ROS) production in bovine pulmonary artery (PA) endothelial cells (BPAECs) in a manner that is associated with activation of NADPH oxidase (24). 20-HETE has been linked to ROS production in other vascular beds (19), with 20-HETE-stimulated production of ROS being reported to exert either positive or negative effects in a tissueand concentration-specific manner (e.g., Refs. 9, 17). In addition, NADPH oxidase is proposed to have a key role in growth and migration of human coronary endot...

The histologic assessment of intraepidermal melanocytic proliferations involving sun-damaged skin may be challenging in scant biopsy material. Melanoma in situ may occasionally be confused with intraepidermal melanocytic hyperplasia on sun-damaged skin; thus, dermatopathologists may use immunohistochemical studies to help distinguish these entities. Historically, melanoma antigen recognized by T-cells 1 (MART-1) has been regarded as a valuable stain to confirm intraepidermal melanocytes; however, MART-1 may overestimate the number of melanocytes because it labels the melanoma dendrites and might also label pigmented keratinocytes, including structures mimicking junctional melanocytic nests in the setting of a lichenoid infiltrate. A total of 70 cases were retrospectively chosen, including 50 cases of melanoma in situ and 20 cases of actinic keratoses. SOX10 and microphthalmia transcription factor 1 (MITF-1) were performed in all cases. In all cases, the number of cells within epidermis that were identified as melanocytes by immunohistochemistry was compared with the number of melanocytes observed by morphology on hematoxylin and eosin sections. All cases of melanoma in situ showed expression of SOX10; however, the proportion of atypical melanocytes showing strong nuclear positivity was variable and did not approach that seen in MITF-1. There was no expression of either MITF-1 or SOX10 in adjacent pigmented keratinocytes in the cases of actinic keratoses. Both MITF-1 and SOX10 can be used to differentiate melanoma in situ from actinic keratosis with melanocytic hyperplasia; however, MITF-1 exhibits slight superior sensitivity and seems to be a more effective immunostain than SOX10 for the identification and quantification of melanocytes in the setting of melanoma in situ, especially in cases where there is limited tissue.

Cutaneous epithelioid and spindle cell neoplasms occasionally pose a significant diagnostic challenge on purely histologic grounds. Given the substantial clinicopathologic overlap between these lesions, especially in small biopsies, the use of immunohistochemical studies are essential. We evaluated the utility of a battery of immunohistochemical markers, including podoplanin (D2-40), CD10, p63, and wide-spectrum cytokeratin, for distinguishing cutaneous epithelioid and spindle cell tumors. A total of 81 cases, including 42 atypical fibroxanthoma (AFX), 13 spindle cell melanoma, 10 sarcomatoid carcinoma, 9 leiomyosarcoma (LMS), and 7 leiomyoma, formed the basis of our study. Immunohistochemical results were as follows-AFX: CD10 (35 of 42), p63 (1 of 42), CK (1 of 42), and podoplanin (19 of 42); spindle cell melanoma: CD10 (7 of 13), p63 (0 of 13), CK (0 of 13), and podoplanin (2 of 13); sarcomatoid carcinoma: CD10 (5 of 10), p63 (7 of 10), CK (4 of 10), and podoplanin (7 of 10); LMS: CD10 (4 of 9), p63 (0 of 9), CK (2 of 9), and podoplanin (1 of 9); and leiomyoma: CD10 (0 of 7), p63 (0 of 7), CK (0 of 7), and podoplanin (1 of 7). Our findings showed that the combination of certain immunohistochemical markers may be a useful adjunct in the evaluation of epithelioid and spindle cell tumors of the skin. In this study, we found that a combination of wide-spectrum cytokeratin and p63 are most helpful in the distinction of sarcomatoid carcinomas from other tumors; however, there remains a substantial minority of cases of sarcomatoid carcinoma that will consistently demonstrate negative staining for these markers. We also found that CD10 and podoplanin (D2-40) have limited diagnostic utility in epithelioid and spindle cell tumors of the skin; however, a strong and diffuse pattern of staining will favor the diagnosis of AFX. Caution should also be observed in the diagnosis of spindle cell malignant melanoma because some cases may express CD10, p63, and podoplanin while being nonreactive to S100 protein. Awareness of the limitations of the use of these stains and familiarity with their staining patterns in spindle and epithelioid cell tumors of the skin are extremely important because the prognostic and therapeutic implications for such neoplasms may be quite different.

Primary cutaneous large B-cell lymphomas (PCLBCL) have historically been a matter of debate in the literature. The 2005 World Health Organization-European Organization for Research and Treatment of Cancer (WHO-EORTC) classification scheme segregated cutaneous B-cell lymphomas into 3 groups: primary cutaneous marginal zone B-cell lymphoma, primary cutaneous follicle center cell lymphoma, and primary cutaneous diffuse large B-cell lymphoma (PCDLBCL), "leg type" (PCDLBCL-LT). Additionally, the WHO-EORTC classification scheme utilized the term PCLBCL "other" not otherwise specified (NOS) type for rare cases of PCLBCL not belonging to either the "leg type" or the primary cutaneous follicle center cell lymphoma group. In this study, we retrospectively assessed the histomorphologic features of 79 cases of PCDLBCLs, including those of "leg type" and "other" NOS type, to further categorize the histologic spectrum of these unusual cutaneous neoplasms. The histologic diagnosis of PCLBCL usually poses little diagnostic difficulty; however, some cases may adopt unusual or unfamiliar appearances mimicking other lymphoproliferative disorders or other malignant neoplasms. Seventy-nine cases, occurring in 37 men and 42 women, aged 34-94 years, were analyzed. Fifty-three cases were classified as "leg type" and 26 cases were classified as "other" NOS type using the WHO-EORTC classification. Of the 53 cases classified as "leg type," 33 were women and 20 were men; of the 26 cases of "other" NOS type, 9 were women and 17 were men. In the "leg type" category, 31 cases were located on the lower extremities, 5 cases on the face, 5 cases on the arm, 3 cases on the chest, 2 cases on the shoulder, 2 cases on the back, 1 case on the trunk, 1 case on the buttock, 1 case on the supraclavicular area, 1 case on the head, and 1 case on the flank. Of the "other" NOS type category, 8 cases were located on the face, 5 cases on the shoulder, 3 cases on the head, 2 cases on the abdomen, 2 cases on the chest, 1 case on the trunk, 1 on the vulva, 1 on the axilla, 1 on the back, 1 on the neck, and 1 on the hip. Most cases assessed showed the classic morphologic appearance of PCDLBCL, but cases mimicking Burkitt lymphoma (starry-sky pattern), natural killer-cell (NK) lymphoma, mycosis fungoides (epidermotropism), low-grade B-cell lymphomas, epithelial malignancies, and Merkel cell carcinoma were encountered in this series. The high frequency of these rare histologic patterns can be explained by a bias associated with consultation practice. Careful histologic examination and immunohistochemical stains were used to establish the correct diagnosis. The differential diagnosis of PCDLBCL is broad and difficult to define histologically. Knowledge of these rare histologic variants is necessary to avoid misinterpretation of these cases as nonlymphoid malignancies.