Tropism of herpes simplex virus type 1 to nonmelanoma skin cancers

Background Current treatments for nonmelanoma skin cancer include surgery, Mohs micrographic surgery, radiation, cryosurgery, photodynamic therapy, local chemotherapy and application of immunomodulators such as imiquimod. However, all have a 5‐year recurrence rate of 1–40%. Gene therapy for the treatment of skin cancers is a promising new approach, as delivery of the vectors to the skin is simple and safety issues can be properly addressed. Objectives To develop an ex‐vivo organ culture system for basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) tumours, and to test the feasibility of applying oncolytic viruses to these tumours. Methods We first optimized conditions for the maintenance of BCC and SCC tissues in organ culture, and demonstrated viability of the tissues ex vivo for 3–7 days. The tropism of two potential oncolytic viral vectors, herpes simplex virus type 1 (HSV‐1) and adenovirus (AD), was next evaluated. Results Immunohistological analysis revealed that HSV‐1 targeted tumour cells that expressed p63 and did not express keratin 15 or keratin 14 markers of keratinocytes. Further examination indicated that uninfected BCC and SCC tissues express two isoforms of p63 mRNA, and HSV‐1 infection specifically enhanced expression of the TAp63 isoform. Furthermore, following infection, both HSV‐1 and AD induced apoptosis in the BCC and SCC cells as indicated by the induction of activated caspase‐3. Conclusions The results indicated a specific pattern of viral tropism to skin cancer cells that are critical for maintenance of the tumour. This new experimental system should aid in the analysis of new therapeutic modalities, such as oncolytic viruses, for future treatment of these skin tumours.     

Nutrition and nonmelanoma skin cancers

The incidence of nonmelanoma skin cancer is increasing every year. Basal cell carcinoma and squamous cell carcinoma are the two major types of nonmelanoma skin cancer. Among other factors, understanding the potential role of nutrients in the development, progression, and treatment of nonmelanoma skin cancer is critical. This contribution provides a review of the nutrients that have been more extensively investigated in the literature with regard to nonmelanoma skin cancer, including dietary fats, retinol, carotenoids, vitamin C, vitamin D, vitamin E, selenium, copper, iron, zinc, green tea, and black tea.     

Nutrition and nonmelanoma skin cancers

Nonmelanoma skin cancer (NMSC), the most widely diagnosed cancer in the United States, is rising in incidence despite public health and educational campaigns that highlight the importance of sun avoidance. It is,therefore, important to establish other modifiable risk factors that may be contributing to this increase. There is a growing body of evidence in the literature suggesting certain nutrients may have protective or harmful effects on NMSC. We review the current literature on nutrition and its effect on NMSC with a focus on dietary fat, vitamin A, nicotinamide, folate, vitamin C, vitamin D, vitamin E, polyphenols, and selenium.     

Human papillomavirus status in extragenital nonmelanoma skin cancers

About 5% of all cancers worldwide can be attributed to human papillomaviruses (HPVs); namely, six sites are strongly associated with HPV infections: cervix, penis, vulva, vagina, anus, and oropharynx. Nonmelanoma skin cancers (NMSC), basal cell carcinoma (BCC), and squamous cell carcinoma (SCC) are the most common malignancies in Caucasians. In fact, there is an intense connection between sunlight exposure, fair skin, HPV, and development of NMSC. We have conducted a pilot study that included tissue samples from 26 carcinoma patients, of which there were 13 BCC and 13 SCC. HPV detection and typing was done with DNA amplification and sequencing, respectively. In total, 23.1% of SCC samples (3/13) and 7.7% of BCC samples (1/13) were positive for HPV DNA. The importance of understanding all aspects of NMSC carcinogenesis may be to reveal novel therapeutic options or preventive measures for HPV containing NMSC patients.     

Molecularly targeted therapies for nonmelanoma skin cancers

Over the past two decades, advances in the fields of cancer genetics and molecular biology have elucidated molecular pathways that cause numerous cutaneous malignancies. This in turn has spurred the rational design of molecularly targeted therapies. In this review, we discuss the molecular pathways critical to the development of nonmelanoma skin cancers and the novel pharmacologic agents that target them. Included is a review of vismodegib for basal cell carcinoma, cetuximab for squamous cell carcinomas, imatinib for dermatofibrosarcoma protuberans, and sirolimus for Kaposi's sarcoma.     

Viral DNA detection and RAS mutations in actinic keratosis and nonmelanoma skin cancers

Background Actinic keratosis (AK) is a well‐established precancerous skin lesion that has the potential to progress to squamous cell carcinoma (SCC). Basal cell carcinoma (BCC) is a locally aggressive slowly growing tumour that rarely metastasizes. A number of viruses have been proposed to play a role in the development of nonmelanoma skin cancers (NMSC), but the most plausible evidence to date suggests that cutaneous human papillomavirus (HPV) is the key instigating factor. Objectives To evaluate the prevalence of HPV, cytomegalovirus (CMV), herpes simplex virus (HSV) and Epstein–Barr virus (EBV) and investigate their relationship with the presence of RAS gene mutations in cutaneous lesions obtained from nonimmunosuppressed patients. Methods HPV, CMV, HSV and EBV detection was performed using polymerase chain reaction (PCR) in skin biopsies (26 AK, 12 SCC and 15 BCC samples) that were collected from immunocompetent patients. The RAS mutation incidence was also investigated in all cutaneous lesions by use of PCR/restriction fragment length polymorphism and direct DNA sequencing. Results Seventeen out of 53 (32%) skin lesions were found to be positive for HPV DNA. The highest incidences of HPV infection were five of 15 (33%) in BCC and four of 12 (33%) in SCC specimens. The HPV incidence was eight of 26 (31%) in AK and eight of 53 (15%) in normal skin tissue. Twelve out of 53 (23%) skin lesions were CMV‐positive. The highest incidence of CMV infection was six of 15 (40%), observed in BCC specimens. The CMV incidence was two of 26 (8%) in AK and four of 12 (33%) in SCC. No normal skin biopsy was found to be positive for CMV. All cutaneous samples were negative for HSV and EBV DNA, as assessed by our PCR‐based assays. Only three samples, one AK (4%), one BCC (6%) and one SCC (8%), were found to carry a G>T transversion at the second position of HRAS codon 12. Both HRAS mutant SCC and BCC biopsies were HPV‐ and CMV‐positive, as well. Conclusions HPV DNA is detected in NMSC, AK and normal skin biopsies. Our results also indicate that CMV is involved in NMSC at higher levels than in premalignant lesions, whereas the virus was not detected in normal skin biopsies. HSV and EBV do not appear to be involved in the pathogenesis of cutaneous lesions. Moreover, we suggest that the HRAS codon 12 mutation is not a very common event in AK or NMSC. Finally, both viral infection and HRAS activation appear to represent independent factors in the aetiology of NMSC, samples of which were obtained from immunocompetent patients.     

The sap from Euphorbia peplus is effective against human nonmelanoma skin cancers

Background The sap from Euphorbia peplus, commonly known as petty spurge in the U.K. or radium weed in Australia, has been used as a traditional treatment for a number of cancers. Objective To determine the effectiveness of E. peplus sap in a phase I/II clinical study for the topical treatment of basal cell carcinomas (BCC), squamous cell carcinomas (SCC) and intraepidermal carcinomas (IEC). Methods Thirty‐six patients, who had refused, failed or were unsuitable for conventional treatment, were enrolled in a phase I/II clinical study. A total of 48 skin cancer lesions were treated topically with 100–300 μL of E. peplus sap once daily for 3 days. Results The complete clinical response rates at 1 month were 82% (n = 28) for BCC, 94% (n = 16) for IEC and 75% (n = 4) for SCC. After a mean follow‐up of 15 months these rates were 57%, 75% and 50%, respectively. For superficial lesions < 16 mm, the response rates after follow‐up were 100% for IEC (n = 10) and 78% for BCC (n = 9). Conclusions The clinical responses for these relatively unfavourable lesions (43% had failed previous treatments, 35% were situated in the head and neck region and 30% were > 2 cm in diameter), are comparable with existing nonsurgical treatments. An active ingredient of E. peplus sap has been identified as ingenol mebutate (PEP005). This clinical study affirms community experience with E. peplus sap, and supports further clinical development of PEP005 for the treatment of BCC, SCC and IEC.     

Repetitive DNA alterations in human skin cancers

Repetitive sequences constitute landmarks for genome regulation, evolution, and chromatin architecture. Patterns of specific and non-specific repetitive sequences change in many types and stages of tumor cells, characterized by band loss, gain, and (de) increased staining of pre-existing bands. In this work, repetitive DNA was studied in search of genome instability of skin cancers: basal and squamous cell carcinomas (BCC and SCC), malignant melanoma (MM), melanocytic nevus (MN), and actinic keratosis (AK) lesions. DNAs were extracted from blood and tumor samples from 21 BCC, 7 SCC, 11 MM and 7 lesions. Banding patterns were obtained by random amplification of polymorphic DNA (RAPD), and specific D9S50 and D9S52 microsatellites (9p21). D9S50 patterns revealed microsatellite instability (MSI) and/or loss of heterozygosity (LOH) in 36% BCC, 25% SCC, and 57% MM tumors. D9S52 microsatellite showed 28.5%; 42.8%; and 71.4% altered tumors, respectively. No microsatellite alterations were found in MN and AK. On the other hand, genomic rearrangements detected by RAPD were present in 100% tumors. In BCC, the mean number of tumor DNA alterations showed predominant gain of bands. On the contrary, MM samples presented loss, or decreased intensity signal of RAPD bands. Genome alterations in skin cancers would result from chromosomal rearrangements, aneuploidy and/or polysomies. The low-cost and quick RAPD technique may reveal unknown genes or DNA sequences associated with tumor development and progression, and may be easily implemented in clinical diagnosis.     

Mitochondrial DNA deletions serve as biomarkers of aging in the skin, but are typically absent in nonmelanoma skin cancers

The potential role of mitochondrial DNA (mtDNA) deletions in nonmelanoma skin cancer (NMSC) and in cutaneous photoaging was explored using a genetic approach. Tumors and photodamaged tumor-free "margin" skin were obtained from NMSC patients undergoing excision and the mtDNA from these specimens was screened for the presence of deletions using long extension PCR. mtDNA deletions were abundant in margin tissue specimens from older patients and their number correlated with the patient age. There was a statistically significant difference between the number of mtDNA deletions in tumors and margins. Fewer deletions were detected in the tumors than the margins and the tumors often had no deletions, implying a potential selection for full-length mtDNA or perhaps a protective role for mtDNA deletions in the process of tumorigenesis. The observed mtDNA deletions from skin were often unreported (19 of 21 deletions), but typically shared structural features with mtDNA deletions reported in other tissues. Some mtDNA deletions were detected from the skin of multiple individuals, including 3,715 and 6,278-base pair (bp) deletions, whose frequencies approached that of the previously well-characterized 4977-bp "common" deletion. These data support the use of mtDNA mutations as biomarkers of photoaging in the skin.     

Evidence that dysregulated DNA mismatch repair characterizes human nonmelanoma skin cancer

BACKGROUND: In addition to an established role in the repair of postreplicative DNA errors, DNA mismatch repair (MMR) proteins also contribute to cellular responses to exogenous DNA damage. Previously, we have shown that Msh2-null mice display increased sensitivity to ultraviolet (UV) B-induced tumorigenesis, but squamous cell carcinomas (SCC) generated are microsatellite stable, suggesting a role for MMR other than postreplicative repair in UV-induced cutaneous tumour formation. OBJECTIVES: We questioned whether there was evidence of MMR dysfunction in human SCC, thus validating the mouse models of MMR-dependent UVB-induced skin cancer. METHODS: Using tissue microarrays we examined both nuclear and cytoplasmic levels of MMR proteins MSH2, MSH6, MSH3, MLH1 and PMS2 in more than 200 cases of cutaneous SCC and basal cell carcinoma (BCC). RESULTS: We found that subsets of these 10 MMR protein measures were increased in nonmelanoma skin cancer (NMSC) compared with normal epidermal samples; this was particularly true of SCC. In fact, based on post hoc tests and MMR protein distribution patterns, BCC was distinct from SCC. With the exception of nuclear MSH2, the BCC had lower levels of identified MMR protein measures than SCC. We believe this to be important because not only is SCC more aggressive than BCC, but evidence suggests that these two NMSC subtypes arise through different molecular pathways. CONCLUSIONS: In combination with previously established roles for MMR proteins in response to UVB-induced DNA damage, our data point towards an expanded perspective of the importance of MMR proteins in the suppression of UVB-induced tumorigenesis and, potentially, tumour behaviour.     

手术治疗人乳头瘤病毒感染皮损

目的分析手术治疗人乳头瘤病毒感染所致的巨大或广泛性皮损的疗效。方法对有巨大或广泛性皮损的10例寻常疣、20例尖锐湿疣、8例疣状表皮发育不良难治性病例进行外科手术治疗。结果术后6个月,10例寻常疣患者中,有2例部分原位复发。20例尖锐湿疣患者,5例复发,复发率为25%。8例疣状表皮发育不良患者经手术将严重皮损去除,所有病例肢体功能均恢复正常,但并不能完全彻底根治,后经长期给予外用维A酸类等药物,病情得以控制,增生皮损均未超出原病变皮损,肢体功能无障碍。结论外科手术是治疗巨大或广泛性人乳头瘤病毒感染皮损可选择的手段。