Arash Radfar

p53 Mediates Apoptotic Crisis in Primary Abelson Virus-Transformed Pre-B Cells

ABSTRACT Transformation of pre-B cells by Abelson murine leukemia virus (Ab-MLV) involves a balance between positive, growth-stimulatory signals from the v-Abl oncoprotein and negative regulatory cues from cellular genes. This phenomenon is reflected by the clonal selection that occurs during Ab-MLV-mediated transformation in vivo and in vitro. About 50% of all Ab-MLV-transformed pre-B cells express mutant forms of p53 as they emerge from this process, suggesting that this protein may play an important role in the transformation process. Consistent with this idea, expression of p19Arf, a protein whose function depends on the presence of a functional p53, is required for the apoptotic crisis that characterizes primary Ab-MLV transformants. To test the role of p53 in pre-B-cell transformation directly, we examined the response of Trp53−/− mice to Ab-MLV. The absence of p53 shortens the latency of Abelson disease induction but does not affect the frequency of cells susceptible to Ab-MLV-induced transformation. However, primary transformants derived from the null animals bypass the apoptotic crisis that characterizes the transition from primary transformant to fully malignant cell line. These effects do not require p21Cip-1, a major downstream target of p53; however, consistent with a role of p19Arf, transformants expressing mutant p53 and abundant p19 retain wild-type p19 sequences.

Effects of High-Dose IFNα2b on Regional Lymph Node Metastases of Human Melanoma: Modulation of STAT5, FOXP3, and IL-17

Purpose: Signal transducer and activator of transcription 5 (STAT5) and STAT3 oppose one another in regulation of the reciprocal development of CD4+CD25+FOXP3+ regulatory T cells (Treg) and T helper 17 (Th17). A reduction in STAT3 is associated with up-regulation of Treg, and STAT5 activation promotes Treg differentiation or function while constraining Th17 generation. The effects of IFNα on STAT signaling in relation to tumor tissue Treg and Th17 have not been documented in humans beyond the observations that IFNα2b down-regulates STAT3. Experimental Design: Following diagnostic biopsy and before definitive surgery, 20 doses of high-dose IFNα2b (HDI) were administered to patients with stage IIIB melanoma who gave written informed consent. Lymph node biopsies, in which both total STAT3 and phosphorylated STAT3 were down-regulated by HDI, were probed with STAT5, FOXP3, CD4, and interleukin 17 (IL-17) with immunohistochemistry and/or immunofluorescence techniques. Results: The percentage of FOXP3+ lymphocytes determined by immunohistochemistry was up-regulated from 3.06 ± 0.65% to 9.86 ± 1.27% (n = 13, P = 0.0002), and this observation was confirmed by immunofluorescence evaluation of CD4+FOXP3+ Tregs. HDI induced STAT5 up-regulation (five cases observed) in melanoma cells and lymphocytes but did not induce the generation of IL-17–expressing lymphocytes. Increased STAT5 expression was associated with increased FOXP3 expression among lymphocytes, and STAT5 was constitutively activated among both melanoma cells and lymphocytes. Conclusion: IFNα2b up-regulates STAT5 and down-regulates STAT3, in conjunction with up-regulation of Treg and inhibition of IL-17–expressing lymphocytes in melanoma tissues. These findings suggest that the effects of IFNα may be potentiated through interference with the response of Tregs and/or STAT5.

Mitoses in conventional melanocytic nevi

Given that nevi may grow in size, mitotic figures may be expected in melanocytic nevi. We reviewed the literature for studies addressing this issue. We sought to determine the number of mitotic figures we might discover upon review of a group of randomly collected, conventional nevi. We reviewed 157 nevi from patients and found seven nevi exhibiting mitotic figures, comprising 4% of our sample. We noted the location of the mitoses within the nevi, the presence of any congenital features, as well as other features such as signs of inflammation or irritation. Through this study we have shown that occasional mitoses occur within unremarkable, conventional nevi.

NGFR (p75) expression in cutaneous scars; Further evidence for a potential pitfall in evaluation of reexcision scars of cutaneous neoplasms, in particular desmoplastic melanoma.

Desmoplastic melanoma is a rare variant of malignant melanoma composed of spindle cells in a collagenous matrix. The antibody against NGFR (low affinity nerve growth factor receptor, also known as p75) stains cells of desmoplastic melanoma with high sensitivity; however, the specificity of this marker is not well established. Although there are established histologic criteria for recognition of desmoplastic melanoma, the evaluation of residual disease in cutaneous reexcision scars can be challenging. If residual spindle cells in scar are sufficiently atypical and NGFR positive, their presence could be interpreted as residual desmoplastic melanoma. In this study, we reevaluated the use of antibody against NGFR to detect residual disease in reexcision specimens of melanocytic neoplasms as the previously published works are contradictory. Our data indicate that anti-NGFR antibody stains many cells in the scar, some of which seem to be myofibroblasts, nerve twigs, and Schwann cells. Our findings further suggest that NGFR is not a suitable marker to evaluate reexcision scars for desmoplastic melanoma, especially as a sole marker, as its specificity is low.

Recurrent erythema multiforme triggered by progesterone sensitivity.

Determining the underlying etiology of recurrent erythema multiforme (EM) can be a difficult endeavor. Although infection with herpes simplex virus (HSV) has been implicated in some cases, the precise trigger of a given patients recurrent EM often remains elusive. We discuss the case of a woman with a recurrent blistering eruption that was clinically and histopathologically consistent with EM. An investigation into the etiology of the patients EM suggested that HSV was not the causative factor but instead pointed toward a hormonal influence that we interpret as autoimmune progesterone dermatitis (APD). This case is presented to highlight the importance of considering hormonal triggers in women with recurrent EM that consistently flares during the luteal phase of the menstrual cycle, the point at which serum progesterone levels peak. A brief review of the literature regarding the diagnosis, histopathology, etiology and treatment of APD is further provided.

Cutaneous oncocytoma – a report of three cases and review of the literature

Abstract:  The oncocyte is a cell characterized by capacious, eosinophilic, finely granular cytoplasm, and lesions composed primarily of oncocytes are termed oncocytomas. Whereas oncocytic metaplasia has been reported in various cutaneous neoplasms, oncocytomas typically occur in the kidneys, thyroid and salivary glands and are uncommon in the dermatopathology literature. We present three cases of cutaneous oncocytoma so that dermatopathologists are cognizant of this uncommon entity. Although some believe that oncocytomas are locally aggressive lesions, our cases indicate that their clinical course is perhaps as banal as their histology.

Merkel cell carcinoma (primary neuroendocrine carcinoma of skin) mimicking basal cell carcinoma with review of different histopathologic features.

Abstract:Merkel cell carcinoma (MCC) is a rare but highly aggressive malignancy, which often has typical histopathologic and immunohistochemical (IHC) features. Sometimes the diagnosis is missed because of atypical histological or aberrant IHC findings. A case of MCC that showed irregular lobules of basaloid cells with keratotic areas on the initial shave biopsy is being reported. IHC showed positive staining for high–molecular weight cytokeratin but negative staining for cytokeratin 20, findings consistent with basal cell carcinoma. Subsequent excision specimen showed histopathologic features more typical of MCC. IHC still was negative for cytokeratin 20 but positive for synaptophysin. Review of the literature shows other examples of MCC with basal cell carcinoma–like features. Various other histopathologic differentiations of MCC include those that demonstrate squamous cell and eccrine carcinoma features and those that show melanocytic, lymphomatous, sarcomatous, muscular, and atypical fibroxanthoma-like features. Different histopathologic patterns and mimics of MCC are reviewed to help prevent dermatopathologists from misdiagnosing this aggressive tumor.

Skeletal muscle regeneration: report of a case presenting as a cutaneous nodule following blunt trauma to the lip

Abstract:  Skeletal muscle (SM) regeneration is a pleomorphic yet benign reaction pattern that follows injury to SM and has been reported to simulate histologically various malignancies such as squamous cell carcinoma and rhabdomyosarcoma.

Loss of Heterozygosity at the Ink4a/Arf Locus Facilitates Abelson Virus Transformation of Pre-B Cells

ABSTRACT In many tumor systems, analysis of cells for loss of heterozygosity (LOH) has helped to clarify the role of tumor suppressor genes in oncogenesis. Two important tumor suppressor genes, p53 and the Ink4a/Arf locus, play central roles in the multistep process of Abelson murine leukemia virus (Ab-MLV) transformation. p53 and the p53 regulatory protein, p19Arf, are required for the apoptotic crisis that characterizes the progression of primary transformed pre-B cells to fully malignant cell lines. To search for other tumor suppressor genes which may be involved in the Ab-MLV transformation process, we used endogenous proviral markers and simple-sequence length polymorphism analysis to screen Abelson virus-transformed pre-B cells for evidence of LOH. Our survey reinforces the role of the p53-p19 regulatory pathway in transformation; 6 of 58 cell lines tested had lost sequences on mouse chromosome 4, including theInk4a/Arf locus. Consistent with this pattern, a high frequency of primary pre-B-cell transformants derived fromInk4a/Arf +/− mice became established cell lines. In addition, half of them retained the single copy of the locus when the transformation process was complete. These data demonstrate that a single copy of the Ink4a/Arf locus is not sufficient to fully mediate the effects of these genes on transformation.

Two cutaneous malignant melanomas at the same anatomic site: a case report with molecular evaluation.

Patients who have had malignant melanoma are at an increased risk of developing a second primary melanoma compared with the general population risk of developing a first melanoma. Many of these second primary melanomas occur at a similar anatomic site as the first lesion. Determining whether a second lesion is indeed a separate primary vs. a metastasis or locoregional recurrence can be very difficult histologically. We report the case of a patient who developed a second melanoma, 2 years after the initial diagnosis, within 3 cm of the site of the original lesion. Because of distinct histomorphologic features, the second lesion was favored to be a separate primary. However, because of the nearly identical anatomic location, molecular testing for loss of heterozygosity and BRAF mutation was performed to help further make this distinction. The first lesion was found to have loss of heterozygosity and a BRAF mutation that were not present in the second lesion. While these tests cannot elucidate the true molecular origin of these lesions, they provide a useful clinical tool to assess whether a second lesion should be treated as a recurrence or as a separate lesion with unique biologic potential.