Human basal cell carcinoma: the induction of anagen hair follicle differentiation.

BACKGROUND: Consistent with cancer stem cell driven pattern of growth, human basal cell carcinomas (BCCs) demonstrate differentiation along hair follicle (HF) lineages. AIM: To define the pattern of differentiation and therapeutic targets that promote BCC differentiation and therefore BCC cancer stem cell exhaustion. METHODS: An alkaline phosphatase substrate kit was used to determine dermal papilla cells within the BCC stroma. Autonomous HF cycle-dependent gene expression was identified by analysis of the human homologues of a murine gene set (total 2289 genes) that is differentially expressed in hair cycle phases. The findings were validated by quantitative real-time PCR and immunofluorescence, as well as in vitro transforming growth factor (TGF)-ß2 stimulation of BCC cancer stem cell colonies. RESULTS: As in the HF, keratin expression in the inner root sheath and matrix in BCC correlated with proliferative index and was tightly regulated, despite the absence of dermal papilla cells. Cross-species microarray analysis comparing human BCC and murine synchronous HF growth cycle datasets revealed 74% concordance with telogen differentiation compared with anagen (23%, P < 0.01) and catagen (49%; P < 0.01). Incomplete anagen differentiation within BCC was characterized by reduced expression of the anagen master regulator DLX3 (-5.5-fold), and increased expression of telogen-associated genes: AEBP1 (2.2-fold), DEFB8 (35.3-fold), MMP3 (106.0-fold) and MMP12 (12.9-fold). Restoration of dermal papilla signals by in vitro addition of TGF-ß2 enhanced anagen differentiation. CONCLUSION: Our findings show that BCC cells differentiate along HF lineages and may be susceptible to exogenous HF cycle modulators.

Hair follicle differentiation-specific keratin expression in human basal cell carcinoma.

BACKGROUND: Identification of human basal cell carcinoma (BCC) cancer stem cells and cellular hierarchy inherently implies the presence of differentiation. By conventional histological analysis, BCC demonstrates tumour nodules that appear relatively homogeneous. AIM: As BCCs arise from hair follicle (HF) keratinocytes, we sought to define the pattern of HF differentiation. METHODS: BCC, squamous cell carcinoma (SCC) and normal skin tissues were analysed using a microarray chip. The expression of individual keratins, regulatory pathways and proliferative states were analysed using reverse transcription-PCR and immunofluorescence microscopy. RESULTS: Microarray analysis of BCC, SCC and normal hair-bearing skin revealed that BCCs express a wide range of HF genes, including HF- specific keratins. BCC demonstrated outer (KRT5, KRT514, KRT516, KRT517 and KRT519) and inner (KRT25, KRT27, KRT28, KRT32, KRT35, KRT71, KRT75 and KRT85) root sheath differentiation, but not hair shaft differentiation. As in the HF, differentiation-specific keratins in BCC keratinocytes correlated with a reduced proliferative index and regulatory pathway activation despite the oncogenic drive towards tumour growth. Our findings show the close correlation between HF and BCC keratinocyte differentiation. CONCLUSION: This work has defined the differentiation pattern within BCCs, enabling development of targeted therapies that promote differentiation and result in BCC cancer stem cell exhaustion.

Viral load, tissue distribution and histopathological lesions in goats naturally and experimentally infected with the Small Ruminant Lentivirus Genotype E (subtype E1 Roccaverano strain).

Small Ruminant Lentivirus (SRLV) subtype E1, also known as Roccaverano strain, is considered a low pathogenic virus on the basis of natural genetic deletions, in vitro properties and on-farm observations. In order to gain more knowledge on this atypical lentivirus we investigated the in vivo tropism of Roccaverano strain in both, experimentally and naturally infected goats. Antibody responses were monitored as well as tissue distribution and viral load, evaluated by real time PCR on single spliced (gag/env) and multiple spliced (rev) RNA targets respectively, that were compared to histopathological lesions. Lymph nodes, spleen, alveolar macrophages and mammary gland turned out to be the main tissue reservoirs of genotype E1-provirus. Moreover, mammary gland and/or mammary lymph nodes acted as active replication sites in dairy goats, supporting the lactogenic transmission of this virus. Notably, a direct association between viral load and concomitant infection or inflammatory processes was evident within organs such as spleen, lung and testis. Our results validate the low pathogenicity designation of SRLV genotype E1 in vivo, and confirm the monocyte-macrophage cell lineage as the main virus reservoir of this genotype. Accordingly, SRLV genotype E displays a tropism towards all tissues characterized by an abundant presence of these cells, either for their own anatomical structure or for an occasional infectious/inflammatory status.

Characterization of skin lesions induced by skin-tropic α- and ß-papillomaviruses in a patient with epidermodysplasia verruciformis.

Epidermodysplasia verruciformis (EV) is a rare, lifelong, autosomal recessive skin disease associated with an unusual susceptibility to infections with ubiquitous ß-human papillomaviruses (ß-HPVs), and in some cases also skin-tropic α genotypes. In this case report, HPV infection patterns were correlated with pathology and clinical manifestations of skin lesions from a patient with EV, without loss-of-function mutations in the EVER genes. HPV infection was investigated by both polymerase chain reaction (PCR) and laser capture microdissection (LCM) PCR, alongside immunofluorescence for the viral proteins E4 and L1. Analysis of eyebrow hair bulbs revealed multiple ß-genus HPV infections, including HPV20 and HPV24, which were consistently found in all 11 skin lesions on the patient. Six lesions were also positive for the skin tropic α-genotype, HPV27. Clear-cut differences between two wart-like lesions, one caused by a skin-tropic α-genotype and the other by ß-genotypes (as detected by LCM PCR) are shown, including the high cellular proliferation rate in ß-HPV-induced lesions. Widespread expression of the early protein E4 was also evident in skin lesions positive for HPV20 by LCM PCR in both tumours and nearby intraepidermal proliferative areas. L1 expression was restricted to areas of intraepidermal proliferation showing productive infection. The patient's inability to control HPV infections is conclusive to the uncontrolled replication of few genotypes from both α and ß genera, which cause proliferative lesions with clear-cut clinical and histological features.