Transgrediens pachyonychia congenita (PC): case series of a nonclassical PC presentation

BACKGROUND

Pachyonychia congenita (PC) is a rare keratin disorder that typically presents with nail dystrophy and focal plantar keratoderma. We present seven cases of PC with transgrediens involvement of the dorsal feet.

OBJECTIVES

To document the extension of their disease to the dorsum of the feet in patients with mutation-confirmed PC, to report the natural history of PC with such transgrediens involvement, to generate hypotheses regarding aetiology, and to suggest prevention and treatment modalities.

METHODS

Genetically confirmed cases of PC with transgrediens foot involvement were verified through the International Pachyonychia Congenita Research Registry (IPCRR) and characterized via telephone survey and photography.

RESULTS

Seven patients with PC in the IPCRR were confirmed to have transgrediens lesions on the dorsal feet (six KRT6A mutations; one KRT16 mutation). Six cases had pre-existing nontransgrediens keratoderma and all cases reported standing, wearing shoes, foot moisture, and/or infection as exacerbating or predisposing factors. Improvement, reported in six cases, was attributed to use of antibiotics or gentian violet, or improved footwear.

CONCLUSIONS

Transgrediens involvement of the dorsal feet is a rare manifestation of mutation-confirmed PC and may be more common in patients who carry a KRT6A mutation. Trauma, friction, infection and wound healing may exacerbate or predispose toward transgrediens lesions. It remains to be proven whether transgrediens-associated infection is causal or represents a primary or secondary process. Patients with PC who develop transgrediens lesions may benefit from fungal and bacterial cultures, followed by appropriate antimicrobial treatments. Efforts to decrease skin friction and moisture may also improve and/or prevent transgrediens spread.

Genetics of pigmentation and melanoma predisposition

About 5-10% of human cutaneous malignant melanoma is hereditary and known to involve rare germline mutations in highly penetrant, autosomal dominant genes. These genes are important in cell cycle control but are not responsible for all familial cases of melanoma. Epidemiologic studies have linked specific phenotypic traits including fair skin, light-colored eyes, and poor tanning ability to melanoma risks. The ability to visually discern and define pigmentary phenotypes in humans and in animal models has permitted elucidation of many genes involved in pigmentation and melanin biosynthesis. Additional genetic epidemiological studies have recently identified a subset of these pigmentation genes that are associated with risk for melanoma and other cutaneous malignancies as well as photosensitivity. Genome-wide association studies (GWAS) have unveiled single nucleotide polymorphisms (SNPs) or genetic variants in MC1R, TPCN2, ASIP, KITLG, NCKX5, TYR, IRF4, OCA2, and TYRP1 pigmentation genes. These findings emphasize the contribution of pigmentation pathways to melanoma predisposition and tumorigenesis through gene-environment interactions. Since pigmentation genes in the melanin synthesis pathway also confer risk for cutaneous malignancy, a better understanding of the operative molecular mechanisms involved in this relationship has the potential to impact individual risk assessment for cutaneous malignant melanoma in the future. This paper is an overview of our current understanding of pigmentation gene modifications that have been associated with melanoma risk and how these genes can enrich clinical management, prevention, and early detection of malignant melanoma.

Induction of melanoma cell apoptosis and inhibition of tumor growth using a cell-permeable Survivin antagonist

The inhibitor of apoptosis gene family member Survivin is highly expressed in most tumors, and appears to be a promising target for cancer therapy. Although a variety of Survivin antagonists have been shown to induce apoptosis in malignant cells, the potential utility of these agents is limited by inefficient delivery and cell impermeability. We generated recombinant fusion proteins containing the TAT protein transduction domain and either wild-type Survivin (TAT-Surv-WT) or a dominant-negative mutant (TAT-Surv-T34A). The TAT-Surv proteins were purified by sequential affinity and ion-exchange chromatography, and at 30 nM concentration demonstrated rapid entry into cells at 30 min. Whereas TAT-Surv-WT had minimal effect on YUSAC2 or WM793 melanoma cells, TAT-Surv-T34A induced cell detachment, DNA fragmentation, caspase-3 activation and mitochondrial release of apoptosis-inducing factor at low microM concentrations. Intraperitoneal (i.p.) injection of mice bearing subcutaneous YUSAC2 xenografts with TAT-Surv-T34A (10 mg/kg) was associated with rapid tumor accumulation at 1 h, and increased tumor cell apoptosis and aberrant nuclei formation in situ. Repeated i.p. injection of TAT-Surv-T34A resulted in a 40-50% reduction in growth and mass of established tumors, compared to those similarly injected with saline buffer or TAT-Surv-WT. These studies demonstrate the feasibility of systemic tumor treatment using a cell-permeable Survivin antagonist.

Accumulation, activation and interindividual variation of the epidermal TP53 protein in response to ionizing radiation in organ cultured human skin

In this study, we examined effects of low-dose ionizing radiation on organ cultured human foreskin and, in particular, on the epidermis. Diagnostic, therapeutic, natural environmental and incidental exposures to moderate to low doses of radiation are inevitable and, although information on cultured cells continues to accumulate, little is known about the effects of low-dose radiation on human tissues. Our hypothesis is that ex vivo organ cultured foreskin is a simple and reliable model to study the biochemical effects of low-dose radiation exposure on skin. A model such as this will aid in the identification and quantification of low-dose radiation-induced changes in proteins in human skin and may be useful in the development of a precise, non-invasive, and reliable assay of exposure. In this work, several aspects of skin responses to culture conditions and radiation were examined. The responses of epidermal TP53 from organ cultured skin irradiated in medium with and without serum were found to be similar. TP53 levels in organ cultured neonatal foreskin epidermis were then examined for baseline TP53 expression. After an initial increase at 4 h, the TP53 D01 signal returned to low steady-state levels for at least 72 h. Irradiated skin samples from different individuals revealed variations in the TP53 D01 signal. The dose and temporal response of dermis and epidermis to radiation were examined by Western blotting from 0 to 24 h after exposure. After irradiation and incubation, the epidermis was removed and assayed by Western blotting and was found to have increases in the TP53 D01 epitope and the TP53 phosphoserine 15 (TP53-S15p) epitope that reached a maximum at about 3 h. In the epidermis, doses of 1-5 cGy of radiation were detectable with the TP53 D01, and CDKN1A antibodies and doses greater than 10 cGy were detectable with the TP53-S15p antibody. When the dermis was compared to epidermis, it was found that dermis had a smaller response to radiation and more phosphorylated TP53.

Preservation of RNA for functional genomic studies: a multidisciplinary tumor bank protocol

Few human tumors are collected such that RNA is preserved for molecular analysis. Completion of the Human Genome Project will soon result in the identification of more than 100,000 new genes. Consequently, increasing attention is being diverted to identifying the function of these newly described genes. Here we describe a multidisciplinary tumor bank procurement protocol that preserves both the integrity of tissue for pathologic diagnosis, and the RNA for molecular analyses. Freshly excised normal skin was obtained from five patients undergoing wound reconstruction following Mohs micrographic surgery for cutaneous neoplasia. Tissues treated for 24 hours with RNAlater were compared histologically and immunohistochemically to tissues not treated with RNAlater. Immunohistochemical stains studied included: CD45, CEA, cytokeratin AE1/3, vimentin, S-100, and CD34 on formalin-fixed, paraffin embedded tissue and CD45 staining of frozen tissue. Slides were blinded and evaluated independently by three pathologists. The histologic and immunohistochemical parameters of tissue stored in RNAlater were indistinguishable from tissue processed in standard fashion with the exception of S-100 stain which failed to identify melanocytes or Langerhan's cells within the epidermis in any of the RNAlater-treated tissues. Interestingly, nerve trunks within the dermis stained appropriately for S-100. Multiple non-cutaneous autopsy tissues were treated with RNAlater, formalin, liquid nitrogen (LN2), and TRIzol Reagent. The pathologists were unable to distinguish between tissues treated with RNAlater, formalin, or frozen in LN2, but could easily distinguish tissues treated with TRIzol Reagent because of extensive cytolysis. RNA was isolated from a portion of the tissue treated with RNAlater and used for molecular studies including Northern blotting and microarray analysis. RNA was adequate for Northern blot analysis and mRNA purified from RNAlater-treated tissues consistently provided excellent templates for reverse transcription and subsequent microarray analysis. We conclude that tissues treated with RNAlater before routine processing are indistinguishable histologically and immunohistochemically from tissues processed in routine fashion and that the RNA isolated from these tissues is of high quality and can be used for molecular studies. Based on this study, we developed a multidisciplinary tumor bank procurement protocol in which fresh tissue from resection specimens are routinely stored in RNAlater at the time of preliminary dissection. Thus, precious human tissue can be utilized for functional genomic studies without compromising the tissue's diagnostic and prognostic qualities.

Granulocyte-macrophage colony-stimulating factor priming plus papillomavirus E6 DNA vaccination: effects on papilloma formation and regression in the cottontail rabbit papillomavirus--rabbit model

A cottontail rabbit papillomavirus (CRPV) E6 DNA vaccine that induces significant protection against CRPV challenge was used in a superior vaccination regimen in which the cutaneous sites of vaccination were primed with an expression vector encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that induces differentiation and local recruitment of professional antigen-presenting cells. This treatment induced a massive influx of major histocompatibility complex class II-positive cells. In a vaccination-challenge experiment, rabbit groups were treated by E6 DNA vaccination, GM-CSF DNA inoculation, or a combination of both treatments. After two immunizations, rabbits were challenged with CRPV at low, moderate, and high stringencies and monitored for papilloma formation. As expected, all clinical outcomes were monotonically related to the stringency of the viral challenge. The results demonstrate that GM-CSF priming greatly augmented the effects of CRPV E6 vaccination. First, challenge sites in control rabbits (at the moderate challenge stringency) had a 0% probability of remaining disease free, versus a 50% probability in E6-vaccinated rabbits, and whereas GM-CSF alone had no effect, the interaction between GM-CSF priming and E6 vaccination increased disease-free survival to 67%. Second, the incubation period before papilloma onset was lengthened by E6 DNA vaccination alone or to some extent by GM-CSF DNA inoculation alone, and the combination of treatments induced additive effects. Third, the rate of papilloma growth was reduced by E6 vaccination and, to a lesser extent, by GM-CSF treatment. In addition, the interaction between the E6 and GM-CSF treatments was synergistic and yielded more than a 99% reduction in papilloma volume. Finally, regression occurred among the papillomas that formed in rabbits treated with the E6 vaccine and/or with GM-CSF, with the highest regression frequency occurring in rabbits that received the combination treatment.

Bone densities in patients receiving isotretinoin for cystic acne

BACKGROUND

Few studies have been done of bone densities in humans receiving retinoids, despite a substantial amount of literature concerning retinoid-induced osteoporosis in animals. We prospectively measured bone density and calcium metabolism in young men (aged 17-25 years) receiving oral isotretinoin for cystic acne and in a group of healthy volunteers (aged 19-26 years).

OBSERVATIONS

Compared with that in healthy control subjects, mean bone density was lower at all sites (spine, femoral neck, and Ward triangle) and was considerably more variable at the spine in young men with cystic acne even before treatment. Bone density at the Ward triangle decreased a mean of 4.4% (P = .03) after 6 months of isotretinoin use (1 mg/kg of body weight). Four patients showed decreased density of more than 9% at the Ward triangle. The difference between the mean change in bone density in the patient group and in the control group was significant at the Ward triangle (P = .04) but not at the other sites. Measurements of calcium metabolism did not change over time in either group.

CONCLUSIONS

A loss of bone density occurring in the absence of measurable alterations of calcium metabolism is likely to be a direct effect of retinoids on bone. Further study of retinoid-induced osteoporosis in humans and of bone density in patients with cystic acne is needed.

Biochemical properties of chimeric skeletal and smooth muscle myosin light chain kinases

The molecular and biochemical properties of myosin light chain kinases from chicken skeletal and smooth muscle were investigated by recombinant DNA techniques. Deletion of the amino-terminal region of either the smooth or skeletal muscle myosin light chain kinase resulted in a decrease in Vmax with no significant change in Km values for light chain substrates. Skeletal/smooth muscle chimeric kinases were inactive when a 65-residue region amino-terminal of the catalytic core was exchanged between the two forms. Changing alanine 494 to glutamic acid within this region in the chicken skeletal muscle myosin light chain kinase increased the Km values for light chains 10-fold. These results are consistent with the hypothesis that the region amino-terminal of the catalytic core in myosin light chain kinases is involved in light chain recognition. A skeletal muscle kinase which contained the smooth muscle calmodulin binding domain remained regulated by Ca2+/calmodulin. Thus, the calmodulin binding domains of smooth and skeletal muscle myosin light chain kinases share structural elements necessary for regulation.