Investigation of the molecular profile of basal cell carcinoma using whole genome microarrays

Illuminating Hope for Tumors: The Progress of Light-Activated Nanomaterials in Skin Cancer

Skin cancer is a common malignant tumor that poses significant global health and economic burdens. The main clinical types include malignant melanoma and non-melanoma. Complications such as post-surgical recurrence, wound formation, or disfigurement can severely impact the patient's mental well-being. Traditional treatments such as surgery, chemotherapy, radiation therapy, and immunotherapy often face limitations. These challenges not only reduce the effectiveness of treatments but also negatively impact patients' quality of life. Phototherapy, a widely used and long-standing method in dermatology, presents a promising alternative for skin cancer treatment. Light-triggered nanomaterials further enhance the potential of phototherapy by offering advantages such as improved therapeutic precision, controlled drug release, minimal invasiveness, and reduced damage to surrounding healthy tissues. This review summarizes the application of light-triggered nanomaterials in skin cancer treatment, focusing on the principles, advantages, and design strategies of photodynamic therapy (PDT), photothermal therapy (PTT), and photoacoustic therapy (PAT). In this manuscript we have an in-depth discussion on overcoming translational barriers, including strategies to enhance light penetration, mitigate toxicity, reduce production costs, and optimize delivery systems. Additionally, we discuss the challenges associated with their clinical translation, including limited light penetration in deep tissues, potential toxicity, high production costs, and the need for advanced delivery systems.

Molecular Profiling and the Interaction of Somatic Mutations with Transcriptomic Profiles in Non-Melanoma Skin Cancer (NMSC) in a Population Exposed to Arsenic

Exposure to inorganic arsenic (As) is recognized as a risk factor for non-melanoma skin cancer (NMSC). We followed up with 7000 adults for 6 years who were exposed to As. During follow-up, 2.2% of the males and 1.3% of the females developed basal cell carcinoma (BCC), while 0.4% of the male and 0.2% of the female participants developed squamous cell carcinoma (SCC). Using a panel of more than 400 cancer-related genes, we detected somatic mutations (SMs) in the first 32 NMSC samples (BCC = 26 and SCC = 6) by comparing paired (tissue-blood) samples from the same individual and then comparing them to the SM in healthy skin tissue from 16 participants. We identified (a) a list of NMSC-associated SMs, (b) SMs present in both NMSC and healthy skin, and (c) SMs found only in healthy skin. We also demonstrate that the presence of non-synonymous SMs in the top mutated genes (like PTCH1, NOTCH1, SYNE1, PKHD1 in BCC and TP53 in SCC) significantly affects the magnitude of differential expressions of major genes and gene pathways (basal cell carcinoma pathways, NOTCH signaling, IL-17 signaling, p53 signaling, Wnt signaling pathway). These findings may help select groups of patients for targeted therapy, like hedgehog signaling inhibitors, IL17 inhibitors, etc., in the future.

The Anticancer Activities of Natural Terpenoids That Inhibit Both Melanoma and Non-Melanoma Skin Cancers

The prevalence of two major types of skin cancer, melanoma and non-melanoma skin cancer, has been increasing worldwide. Skin cancer incidence is estimated to rise continuously over the next 20 years due to ozone depletion and an increased life expectancy. Chemotherapeutic agents could affect healthy cells, and thus may be toxic to them and cause numerous side effects or drug resistance. Phytochemicals that are naturally occurring in fruits, plants, and herbs are known to possess various bioactive properties, including anticancer properties. Although the effects of phytochemicals are relatively milder than chemotherapeutic agents, the long-term intake of phytochemicals may be effective and safe in preventing tumor development in humans. Diverse phytochemicals have shown anti-tumorigenic activities for either melanoma or non-melanoma skin cancer. In this review, we focused on summarizing recent research findings of the natural and dietary terpenoids (eucalyptol, eugenol, geraniol, linalool, and ursolic acid) that have anticancer activities for both melanoma and non-melanoma skin cancers. These terpenoids may be helpful to protect skin collectively to prevent tumorigenesis of both melanoma and nonmelanoma skin cancers.

Molecular Classifiers in Skin Cancers: Challenges and Promises

Skin cancers are common and heterogenous malignancies affecting up to two in three Australians before age 70. Despite recent developments in diagnosis and therapeutic strategies, the mortality rate and costs associated with managing patients with skin cancers remain high. The lack of well-defined clinical and histopathological features makes their diagnosis and classification difficult in some cases and the prognostication difficult in most skin cancers. Recent advancements in large-scale "omics" studies, including genomics, transcriptomics, proteomics, metabolomics and imaging-omics, have provided invaluable information about the molecular and visual landscape of skin cancers. On many occasions, it has refined tumor classification and has improved prognostication and therapeutic stratification, leading to improved patient outcomes. Therefore, this paper reviews the recent advancements in omics approaches and appraises their limitations and potential for better classification and stratification of skin cancers.

Xeroderma Pigmentosum C: A Valuable Tool to Decipher the Signaling Pathways in Skin Cancers

Xeroderma pigmentosum (XP) is a rare autosomal genodermatosis that manifests clinically with pronounced sensitivity to ultraviolet (UV) radiation and the high probability of the occurrence of different skin cancer types in XP patients. XP is mainly caused by mutations in XP-genes that are involved in the nucleotide excision repair (NER) pathway that functions in the removal of bulky DNA adducts. Besides, the aggregation of DNA lesions is a life-threatening event that might be a key for developing various mutations facilitating cancer appearance. One of the key players of NER is XPC that senses helical distortions found in damaged DNA. The majority of XPC gene mutations are nonsense, and some are missense leading either to the loss of XPC protein or to the expression of a truncated nonfunctional version. Given that no cure is yet available, XPC patients should be completely protected and isolated from all types of UV radiations (UVR). Although it is still poorly understood, the characterization of the proteomic signature of an XPC mutant is essential to identify mediators that could be targeted to prevent cancer development in XPC patients. Unraveling this proteomic signature is fundamental to decipher the signaling pathways affected by the loss of XPC expression following exposure to UVB radiation. In this review, we will focus on the signaling pathways disrupted in skin cancer, pathways modulating NER's function, including XPC, to disclose signaling pathways associated with XPC loss and skin cancer occurrence.

Recent Advances in Phenolic Metabolites and Skin Cancer

Skin cancer represents any tumor development from the cutaneous structures within the epidermis, dermis or subcutaneous tissue, and is considered to be the most prevalent type of cancer. Compared to other types of cancer, skin cancer is proven to have a positive growth rate of prevalence and mortality. There are available various treatments, including chemotherapy, immunotherapy, radiotherapy and targeted therapy, but because of the multidrug resistance development, a low success has been registered. By this, the importance of studying naturally occurring compounds that are both safe and effective in the chemoprevention of skin cancer is emphasized. This review focuses on melanoma because it is the deadliest form of skin cancer, with a significantly increasing incidence in the last decades. As chemopreventive agents, we present polyphenols and their antioxidant activity, anti-inflammatory effect, their ability to balance the cell cycle and to induce apoptosis and their various other effects on skin melanoma. Besides chemoprevention, studies suggest that polyphenols can have treating abilities in some conditions. The limitations of using polyphenols are also pointed out, which are related to their poor bioavailability and stability, but as the technology is well developed, it is possible to augment the efficacy of polyphenols in the case of melanoma.

The transcriptional landscape analysis of basal cell carcinomas reveals novel signalling pathways and actionable targets

Basal cell carcinoma (BCC) is the most common skin cancer and human malignancy. By analyzing BCC RNA sequencing data according to clinically important features, we identified novel differentially regulated genes and new targetable pathways. Several biomarkers were validated in patient-derived BCC samples.

Basal cell carcinoma (BCC) is the most common skin cancer and human malignancy. Although most BCCs are easily managed, some are aggressive locally, require Mohs micrographic surgery, or can even metastasize. In the latter, resistance to Sonic Hedgehog inhibitors may occur. Despite their frequent occurrence in clinical practice, their transcriptional landscape remains poorly understood. By analyzing BCC RNA sequencing data according to clinically important features (all BCCs versus normal skin, high-risk versus low-risk BCCs based solely on histopathological subtypes with aggressive features, advanced versus non-advanced BCCs, and vismodegib-resistant versus vismodegib-sensitive tumors), we have identified novel differentially regulated genes and new targetable pathways implicated in BCC tumorigenesis. Pathways as diverse as IL-17, TLR, Akt/PI3K, cadherins, integrins, PDGF, and Wnt/β-catenin are promising therapeutic avenues for local and systemic agents in managing this common malignancy, including through drug re-purposing of existing medications. We experimentally validated several of these targets as biomarkers in our patient-derived cohort of primary BCC tumors.

Essential oils: from prevention to treatment of skin cancer

The increasing incidence of cutaneous malignancies signifies the need for multiple treatment options. Several available reviews have emphasized the potential role of various botanical extracts and naturally occurring compounds as anti-skin-cancer agents. Few studies relate to the role of chemoprevention and therapeutic activity of essential oils (EOs) and EO components. The present review summarizes an overview of chemopreventive, anti-melanoma and anti-nonmelanoma activities of EOs from various plants and EO components in in vitro and in vivo models with special emphasis on skin cancer. Also, the mechanisms by which EOs and EO components exert their effects to induce cell death are presented.

Advanced basal cell cancer: concise review of molecular characteristics and novel targeted and immune therapeutics

Metastatic basal cell carcinoma is an ultra-rare manifestation of a common disease, appearing in 0.0028%-0.5% of basal cell carcinomas. Initial therapeutic efforts focused on cytotoxic chemotherapy administration. However, it is now known that the Hedgehog signaling pathway is crucial for basal cell proliferation and Hedgehog pathway mutations may lead to tumorigenesis; thus, small-molecule inhibitors of alterations in the components of this pathway, including smoothened (SMO) and GLI, have been the focus of recent therapeutic developments. Indeed, the European Medicines Agency and the Food and Drug Administration have approved the SMO inhibitors, vismodegib and sonidegib, with additional GLI inhibitors currently in clinical trials. Molecular profiling of these tumors has revealed other potential targets for therapy, including high tumor mutational burden and PD-L1 amplification, which predict response to immune checkpoint blockade (PD-1 and PD-L1 inhibitors). An illustrative patient with a giant, advanced, unresectable basal cell carcinoma who obtained an ongoing complete remission after treatment with a combination of an immune checkpoint inhibitor (due to the tumor's high mutational burden) and the Hedgehog inhibitor vismodegib is described. A fuller understanding of the genomic portfolio of these patients can assist in developing novel, rational therapeutic approaches that should continue to improve responses and outcomes.

Expression profile of the amino acid transporters SLC7A5, SLC7A7, SLC7A8 and the enzyme TDO2 in basal cell carcinoma

Background

The incidence of basal cell carcinoma (BCC) is increasing and the costs for care rising. Therefore, the need for simplified and cost‐effective treatment choices is substantial. Aberrant signalling in several pathways, induced by ultraviolet radiation, is of importance in the development of BCC. Alterations in tumour metabolic activity are part of general carcinogenesis; however, these alterations are only partially recognized in skin cancer.

Objectives

To study expression profiles in BCCs compared with individually matched nontumour skin, with a focus on finding differences associated with tumour metabolism.

Materials and methods

Gene expression in biopsies from BCCs (n = 14) compared with biopsies from nontumour gluteal skin was analysed with microarrays (n = 4 + 4) and/or quantitative real‐time polymerase chain reaction (qPCR, n = 14 + 14). Protein expression and localization was assessed using immunohistochemistry (IHC) in formalin‐fixed and paraffin‐embedded BCC samples.

Results

Microarray analysis revealed increased expression of the amino acid transporters SLC7A5, SLC7A7 and SLC7A8 as well as the cytosolic enzyme tryptophan 2,3‐dioxygenase (TDO) 2 in BCC. Higher expression of SLC7A5 (P < 0·001), SLC7A8 (P < 0·001) and TDO2 (P = 0·002), but not SLC7A7 (P = 0·50), was confirmed by qPCR, and IHC demonstrated correlating tumour cell protein expression of SLC7A5 and SLC7A8. Protein expression of SLC7A7 was observed in the stratum granulosum, and TDO2 in immune cells.

Conclusions

This study highlights the upregulation of SLC7A5, SLC7A8 and TDO2 in BCC compared with nontumour skin. Our findings imply that amino acid transporters may be further explored as potential targets for future medical treatment.

What's already known about this topic?

The incidence of basal cell carcinoma (BCC) is increasing and consequently also the costs of care.

The transport and metabolism of amino acids are often altered in tumours although the knowledge of whether this applies to BCCs is limited.

What does this study add?

Alterations of amino acid transporters SLC7A5 and SLC7A8 and the cytosolic enzyme TDO2 is suggested in BCC and are possible potential targets for treatment.

SLC7A7 (transporter of e.g. lysine) is expressed in the stratum granulosum of normal epidermis and may be involved in the cornification process.

What is the translational message?

We have found tumour‐specific changes in proteins involved in nutrient transport and metabolism.

These changes may be of importance for carcinogenesis and should be explored further for future drug development.

Linked Comment: O’Shaughnessy. Br J Dermatol 2019; 180:16–17.

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Anaplastic Lymphoma Kinase in Cutaneous Malignancies

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase that has been implicated in the pathogenesis of a variety of neoplasms. As suggested by its name, ALK was first described as part of a translocation product in cases of anaplastic large-cell lymphoma, with other genetic and cytogenetic ALK mutations subsequently coming to attention in the development of many other hematologic and solid organ malignancies. ALK has now been shown to play a role in the pathogenesis of several cutaneous malignancies, including secondary cutaneous systemic anaplastic large-cell lymphoma (ALCL) and primary cutaneous ALCL, melanoma, spitzoid tumors, epithelioid fibrous histiocytoma, Merkel cell carcinoma, and basal cell carcinoma. The characterization of ALK-positivity in these cutaneous malignancies presents exciting opportunities for utilizing ALK-targeted inhibitors in the treatment of these diseases.

Identification of a six-lncRNA signature associated with recurrence of ovarian cancer

Ovarian cancer (OvCa) is the leading cause of death among all gynecological malignancies, and recurrent OvCa is almost always incurable. In this study, we developed a signature based on long non-coding RNAs (lncRNAs) associated with OvCa recurrence to facilitate personalized OvCa therapy. lncRNA expression data were extracted from GSE9891 and GSE30161. LASSO (least absolute shrinkage and selection operator) penalized regression was used to identify an lncRNA-based signature using the GSE9891 training cohort. The signature was then validated in GSE9891 internal and GSE30161 external validation cohorts. The Database for Annotation, Visualization and Integrated Discovery (DAVID) was used to explore the possible functions of identified lncRNAs. A six-lncRNA signature (RUNX1-IT1, MALAT1, H19, HOTAIRM1, LOC100190986 and AL132709.8) was identified in the training cohort and validated in internal and external validation cohorts using the LASSO method (P < 0.05). This signature was also independent of other clinical factors according to multivariate and sub-group analyses. The identified lncRNAs are involved in cancer-related biological processes and pathways. We selected a highly reliable signature based on six lncRNAs associated with OvCa recurrence. This six-lncRNA signature is a promising method to personalize ovarian cancer therapy and may improve patient quality of life quality according to patients' condition in the future.

GLI2 Is a Regulator of β-Catenin and Is Associated with Loss of E-Cadherin, Cell Invasiveness, and Long-Term Epidermal Regeneration

Uncontrolled hedgehog (HH)/glioma-associated oncogene (GLI) and WNT/β-catenin signaling are important events in the genesis of many cancers including skin cancer and are often implicated in tumor progression, invasion, and metastasis. However, because of the complexity and context dependency of both pathways, little is known about HH and WNT interactions in human carcinogenesis. In the current study, we provide evidence of HH/glioma-associated oncogene family zinc finger 2 (GLI2)-WNT/β-catenin signaling crosstalk in human keratinocytes. Overexpression of GLI2ΔN in human keratinocytes resulted in cytoplasmic accumulation and nuclear relocalization of β-catenin in vitro and in 3D organotypic cultures, accompanied by upregulation of WNT genes. Induction of GLI2ΔN enhanced the β-catenin-dependent transcriptional activation and the subsequent activation of β-catenin target genes including cyclin-D1. Additionally, GLI2 overexpression was associated with decreased E-cadherin protein levels; increased expression of SNAIL, matrix metalloproteinase 2, and integrin β1; and increased cell invasion in 3D organotypic cultures. Invasion was reduced by WNT inhibition, thus unveiling the direct role of GLI2/WNT crosstalk in cell invasion. We show that GLI2 overexpression supported long-term epidermal regeneration in 3D organotypic cultures, and resulted in the manifestation of an undifferentiated basal/stem cell-associated phenotype in human keratinocytes. Both these observations are consistent with the role of β-catenin and SNAIL in epidermal stem cell maintenance. This work suggests that GLI2 is a regulator of β-catenin and provides insights into its role in tumorigenesis.

Human epidermal stem cells: Role in adverse skin reactions and carcinogenesis from radiation

In human skin, keratinopoiesis is based on a functional hierarchy among keratinocytes, with rare slow-cycling stem cells responsible for the long-term maintenance of the tissue through their self-renewal potential, and more differentiated daughter progenitor cells actively cycling to permit epidermal renewal and turn-over every month. Skin is a radio-responsive tissue, developing all types of radiation damage and pathologies, including early tissue reactions such as dysplasia and denudation in epidermis, and later fibrosis in the dermis and acanthosis in epidermis, with the TGF-beta 1 pathway as a known master switch. Also there is a risk of basal cell carcinoma, which arises from epidermal keratinocytes, notably after oncogenic events in PTCH1 or TP53 genes. This review will cover the mechanisms of adverse human skin reactions and carcinogenesis after various types of exposures to ionizing radiation, with comparison with animal data when necessary, and will discuss the possible role of stem cells and their progeny in the development of these disorders. The main endpoints presented are basal cell intrinsic radiosensitivity, genomic stability, individual factors of risk, dose specific responses, major molecular pathways involved and the cellular origin of skin reactions and cancer. Although major advances have been obtained in recent years, the precise implications of epidermal stem cells and their progeny in these processes are not yet fully characterized.

Nucleotide Excision Repair and Vitamin D--Relevance for Skin Cancer Therapy

Ultraviolet (UV) radiation is involved in almost all skin cancer cases, but on the other hand, it stimulates the production of pre-vitamin D3, whose active metabolite, 1,25-dihydroxyvitamin D3 (1,25VD3), plays important physiological functions on binding with its receptor (vitamin D receptor, VDR). UV-induced DNA damages in the form of cyclobutane pyrimidine dimers or (6-4)-pyrimidine-pyrimidone photoproducts are frequently found in skin cancer and its precursors. Therefore, removing these lesions is essential for the prevention of skin cancer. As UV-induced DNA damages are repaired by nucleotide excision repair (NER), the interaction of 1,25VD3 with NER components can be important for skin cancer transformation. Several studies show that 1,25VD3 protects DNA against damage induced by UV, but the exact mechanism of this protection is not completely clear. 1,25VD3 was also shown to affect cell cycle regulation and apoptosis in several signaling pathways, so it can be considered as a potential modulator of the cellular DNA damage response, which is crucial for mutagenesis and cancer transformation. 1,25VD3 was shown to affect DNA repair and potentially NER through decreasing nitrosylation of DNA repair enzymes by NO overproduction by UV, but other mechanisms of the interaction between 1,25VD3 and NER machinery also are suggested. Therefore, the array of NER gene functioning could be analyzed and an appropriate amount of 1.25VD3 could be recommended to decrease UV-induced DNA damage important for skin cancer transformation.

The importance of basonuclin 2 in adult mice and its relation to basonuclin 1

BNC2 is an extremely conserved zinc finger protein with important functions in the development of craniofacial bones and male germ cells. Because disruption of the Bnc2 gene in mice causes neonatal lethality, the function of the protein in adult animals has not been studied. Until now BNC2 was considered to have a wider tissue distribution than its paralog, BNC1, but the precise cell types expressing Bnc2 are largely unknown. We identify here the cell types containing BNC2 in the mouse and we show the unexpected presence of BNC1 in many BNC2-containing cells. BNC1 and BNC2 are colocalized in male and female germ cells, ovarian epithelial cells, sensory neurons, hair follicle keratinocytes and connective cells of organ capsules. In many cell lineages, the two basonuclins appear and disappear synchronously. Within the male germ cell lineage, BNC1 and BNC2 are found in prospermatogonia and undifferentiated spermatogonia, and disappear abruptly from differentiating spermatogonia. During oogenesis, the two basonuclins accumulate specifically in maturing oocytes. During the development of hair follicles, BNC1 and BNC2 concentrate in the primary hair germs. As follicle morphogenesis proceeds, cells possessing BNC1 and BNC2 invade the dermis and surround the papilla. During anagen, BNC1 and BNC2 are largely restricted to the basal layer of the outer root sheath and the matrix. During catagen, the compartment of cells possessing BNC1 and BNC2 regresses, and in telogen, the two basonuclins are confined to the secondary hair germ. During the next anagen, the BNC1/BNC2-containing cell population regenerates the hair follicle. By examining Bnc2(-/-) mice that have escaped the neonatal lethality usually associated with lack of BNC2, we demonstrate that BNC2 possesses important functions in many of the cell types where it resides. Hair follicles of postnatal Bnc2(-/-) mice do not fully develop during the first cycle and thereafter remain blocked in telogen. It is concluded that the presence of BNC2 in the secondary hair germ is required to regenerate the transient segment of the follicle. Postnatal Bnc2(-/-) mice also show severe dwarfism, defects in oogenesis and alterations of palatal rugae. Although the two basonuclins possess very similar zinc fingers and are largely coexpressed, BNC1 cannot substitute for BNC2. This is shown incontrovertibly in knockin mice expressing Bnc1 instead of Bnc2 as these mice invariably die at birth with craniofacial abnormalities undistinguishable from those of Bnc2(-/-) mice. The function of the basonuclins in the secondary hair germ is of particular interest.

Identification of anaplastic lymphoma kinase as a potential therapeutic target in Basal Cell Carcinoma

The pathogenesis of BCC is associated with sonic hedgehog (SHH) signaling. Vismodegib, a smoothened inhibitor that targets this pathway, is now in clinical use for advanced BCC patients, but its efficacy is limited. Therefore, new therapeutic options for this cancer are required. We studied gene expression profiling of BCC tumour tissues coupled with laser capture microdissection to identify tumour specific receptor tyrosine kinase expression that can be targeted by small molecule inhibitors. We found a >250 fold increase (FDR<10⁻⁴) of the oncogene, anaplastic lymphoma kinase (ALK) as well as its ligands, pleiotrophin and midkine in BCC compared to microdissected normal epidermis. qRT-PCR confirmed increased expression of ALK (p<0.05). Stronger expression of phosphorylated ALK in BCC tumour nests than normal skin was observed by immunohistochemistry. Crizotinib, an FDA-approved ALK inhibitor, reduced keratinocyte proliferation in culture, whereas a c-Met inhibitor did not. Crizotinib significantly reduced the expression of GLI1 and CCND2 (members of SHH-pathway) mRNA by approximately 60% and 20%, respectively (p<0.01). Our data suggest that ALK may increase GLI1 expression in parallel with the conventional SHH-pathway and promote keratinocyte proliferation. Hence, an ALK inhibitor alone or in combination with targeting SHH-pathway molecules may be a potential treatment for BCC patients.

EpCAM Induction Functionally Links to the Wnt-Enhanced Cell Proliferation in Human Keratinocytes

Accelerating proliferation of primary keratinocytes benefits skin autografts for severely burned patients. Wnt signal, a conserved pathway controlling cell cycle and morphogenesis in embryo, also involves in cell proliferation and tumorigenesis in adult tissues. Here the effects of Wnt signal on the growth of human interfollicular keratinocytes were investigated. We demonstrated that recombinant Wnt3a significantly promoted the growth of primary keratinocytes at a low cell density. A well-characterized GSK-3b inhibitor, BIO, activated the Wnt signals and also enhanced the colony formation of keratinocytes dose dependently. Gene expression profile of the BIO-treated keratinocytes revealed the linkage of BIO with cell mitosis and indicated that epithelial cell adhesion molecule (EpCAM), a Wnt target gene, was significantly upregulated. Compared to the sorted EpCAM^- keratinocytes, the EpCAM⁺ cells showed a higher proliferation rate and efficacy of colony formation. Inhibiting the EpCAM expression by shRNA attenuated the proliferation effect of BIO and the growth advantage of the EpCAM⁺ keratinocytes. These evidences emphasize the positive roles of canonical Wnt and EpCAM on the regulation of cell growth and self-renewal of human keratinocytes.

TERT promoter mutations in skin cancer: the effects of sun exposure and X-irradiation

The reactivation or reexpression of telomerase (TERT) is a widespread feature of neoplasms. TERT promoter mutations were recently reported that were hypothesized to result from UV radiation. In this retrospective study, we assessed TERT promoter mutations in 196 cutaneous basal cell carcinomas (BCCs), including 102 tumors from X-irradiated patients, 94 tumors from patients never exposed to ionizing radiation treatment, and 116 melanomas. We sought to evaluate the effects of UV and X-ray irradiation on TERT mutation frequency. TERT mutations were detected in 27% of BCCs from X-irradiated patients, 51% of BCCs from nonirradiated patients, and 22% of melanoma patients. TERT mutations were significantly increased in non-X-irradiated BCC patients compared with X-irradiated BCC patients; the mutations also presented a different mutation signature. In nonirradiated patients, TERT mutations were more frequent in BCCs of sun-exposed skin, supporting a possible causative role of UV radiation. In melanoma, TERT promoter mutations were generally restricted to intermittent sun-exposed areas and were associated with nodular and superficial spreading subtypes, increased thickness, ulceration, increased mitotic rate, and BRAFV600E mutations. Our results suggest that various carcinogenic factors may cause distinct TERT promoter mutations in BCC and that TERT promoter mutations might be associated with a poorer prognosis in melanoma.

GLI2 induces genomic instability in human keratinocytes by inhibiting apoptosis

Abnormal Sonic Hedgehog signalling leads to increased transcriptional activation of its downstream effector, glioma 2 (GLI2), which is implicated in the pathogenesis of a variety of human cancers. However, the mechanisms underlying the tumorigenic role of GLI2 remain elusive. We demonstrate that overexpression of GLI2-β isoform, which lacks the N-terminal repressor domain (GLI2ΔN) in human keratinocytes is sufficient to induce numerical and structural chromosomal aberrations, including tetraploidy/aneuploidy and chromosomal translocations. This is coupled with suppression of cell cycle regulators p21^WAF1/CIP1 and 14-3-3σ, and strong induction of anti-apoptotic signalling, resulting in a reduction in the ability to eliminate genomically abnormal cells. Overexpression of GLI2ΔN also rendered human keratinocytes resistant to UVB-mediated apoptosis, whereas inhibition of B-cell lymphoma 2 (BCL-2) restored endogenous (genomic instability (GIN)) and exogenous (UVB) DNA damage-induced apoptosis. Thus, we propose that ectopic expression of GLI2 profoundly affects the genomic integrity of human epithelial cells and contributes to the survival of progenies with genomic alterations by deregulating cell cycle proteins and disabling the apoptotic mechanisms responsible for their elimination. This study reveals a novel role for GLI2 in promoting GIN, a hallmark of human tumors, and identifies potential mechanisms that may provide new opportunities for the design of novel forms of cancer therapeutic strategies.

Evasion of p53 and G2/M checkpoints are characteristic of Hh-driven basal cell carcinoma

Basal cell carcinoma (BCC), the most common type of cancer, is characterized by aberrant Hedgehog (Hh) pathway activity. Mutations in pathway components, such as PATCHED1 (PTCH1), are commonly found in BCC. While the tumor suppressor role of PTCH1 in BCC is well established, how Hh pathway activation disrupts normal skin homeostasis to promote BCC formationremains poorly understood. Like Ptc1, Sufu is a major negative regulator of the Hh pathway. Previously, we showed that inactivation of Sufu in the skin does not result in BCC formation. Why loss of Ptc1, but not Sufu, in the epidermis induces BCC formation is unclear. In this report, we utilized gene expression profiling to identify biological pathways and processes that distinguish Sufu from Ptc1 mutants, and discovered a novel role for Sufu in cell cycle regulation. We demonstrated that the Hh pathway activation inSufu and Ptc1 mutant skin is associated with abnormal cell cycle entry, ectopic expression of D-type cyclins and increasedDNA damage. However, despite the presence of DNA damage, p53 stabilization was impaired in the mutant skin. Alternative mechanism to halt genomic instability is the activation of G2/M cell cycle checkpoint, which can occur independent of p53. We found that while Ptc1 mutant cells continue to cycle, which would favor genomic instability, loss of Sufu results in G2/M cell cycle arrest.This finding may explain why inactivation of Sufu is not sufficient to drive BCC formation. Taken together, these studies revealed a unique role for Sufu in G2/M phase progression, and uncovered the molecular and cellular features associated with Hh-driven BCC.

Molecular signatures of basal cell carcinoma susceptibility and pathogenesis: a genomic approach

Gene expression profiling can be useful for phenotypic classification, investigation of functional pathways, and to facilitate the search for disease risk genes through the integration of transcriptional data with available genomic information. To enhance our understanding of the genetic and molecular basis of basal cell carcinoma (BCC) we performed global gene expression analysis to generate a disease-associated transcriptional profile. A gene signature composed of 331 differentially expressed genes (DEGs) was generated from comparing 4 lesional and 4 site-matched control samples using Affymetrix Human Genome U95A microarrays. Hierarchical clustering based on the obtained gene signature separated the samples into their corresponding phenotype. Pathway analysis identified several significantly overrepresented pathways including PPAR-γ signaling, TGF-β signaling and lipid metabolism, as well as confirmed the importance of SHH and p53 in the pathogenesis of BCC. Comparison of our microarray data with previous microarray studies revealed 13 DEGs overlapping in 3 studies. Several of these overlapping genes function in lipid metabolism or are components of the extracellular matrix, suggesting the importance of these and related pathways in BCC pathogenesis. BCC-associated DEGs were mapped to previously reported BCC susceptibility loci including 1p36, 1q42, 5p13.3, 5p15 and 12q11-13. Our analysis also revealed transcriptional 'hot spots' on chromosome 5 which help to confirm (5p13 and 5p15) and suggest novel (5q11.2-14.3, 5q22.1-23.3 and 5q31-35.3) disease susceptibility loci/regions. Integrating microarray analyses with reported genetic information helps to confirm and suggest novel disease susceptibility loci/regions. Identification of these specific genomic and/or transcriptional targets may lead to novel diagnostic and therapeutic modalities.

Correlation of Global MicroRNA Expression With Basal Cell Carcinoma Subtype

Basal cell carcinomas (BCCs) are the most common cancers in the United States. The histologic appearance distinguishes several subtypes, each of which can have a different biologic behavior. In this study, global miRNA expression was quantified by high-throughput sequencing in nodular BCCs, a subtype that is slow growing, and infiltrative BCCs, aggressive tumors that extend through the dermis and invade structures such as cutaneous nerves. Principal components analysis correctly classified seven of eight infiltrative tumors on the basis of miRNA expression. The remaining tumor, on pathology review, contained a mixture of nodular and infiltrative elements. Nodular tumors did not cluster tightly, likely reflecting broader histopathologic diversity in this class, but trended toward forming a group separate from infiltrative BCCs. Quantitative polymerase chain reaction assays were developed for six of the miRNAs that showed significant differences between the BCC subtypes, and five of these six were validated in a replication set of four infiltrative and three nodular tumors. The expression level of miR-183, a miRNA that inhibits invasion and metastasis in several types of malignancies, was consistently lower in infiltrative than nodular tumors and could be one element underlying the difference in invasiveness. These results represent the first miRNA profiling study in BCCs and demonstrate that miRNA gene expression may be involved in tumor pathogenesis and particularly in determining the aggressiveness of these malignancies.

MAGE-D4B is a novel marker of poor prognosis and potential therapeutic target involved in breast cancer tumorigenesis

Melanoma-associated antigen (MAGE) family members are generally described as tumor-specific antigens. An association between MAGE-D4B and breast cancer has yet to be reported and the functional role of the encoded protein has never been established. We performed microarray analysis of 104 invasive breast tumors and matched non-cancerous breast biopsies. qPCR was used for validation in an independent biobank. To investigate the biological relevance of MAGE-D4B in breast tumorigenesis, its phenotypic effects were assessed in vitro. Overall, MAGE-D4B was detected in 43% of tumors while undetected in normal breast tissue. MAGE-D4B was found to correlate with tumor progression and to be an independent prognostic marker for poor outcome in term of relapse-free and overall survival, with potential predictive relevance in relation to response to chemotherapy. RNA interference-mediated knockdown of MAGE-D4B significantly hampered the invasive properties of Hs578T cells by affecting anchorage-independent growth, adhesion, migration and invasion affecting anchorage-independent growth, adhesion, migration and invasion and by modulating expression of invasion-suppressor gene E-cadherin.

Ultraviolet radiation and skin cancer

Skin cancer is the most common type of cancer in fair-skinned populations in many parts of the world. The incidence, morbidity and mortality rates of skin cancers are increasing and, therefore, pose a significant public health concern. Ultraviolet radiation (UVR) is the major etiologic agent in the development of skin cancers. UVR causes DNA damage and genetic mutations, which subsequently lead to skin cancer. A clearer understanding of UVR is crucial in the prevention of skin cancer. This article reviews UVR, its damaging effects on the skin and its relationship to UV immunosuppression and skin cancer. Several factors influence the amount of UVR reaching the earth's surface, including ozone depletion, UV light elevation, latitude, altitude, and weather conditions. The current treatment modalities utilizing UVR (i.e. phototherapy) can also predispose to skin cancers. Unnecessary exposure to the sun and artificial UVR (tanning lamps) are important personal attributable risks. This article aims to provide a comprehensive overview of skin cancer with an emphasis on carefully evaluated statistics, the epidemiology of UVR-induced skin cancers, incidence rates, risk factors, and preventative behaviors & strategies, including personal behavioral modifications and public educational initiatives.

Tumor stroma-derived Wnt5a induces differentiation of basal cell carcinoma of Ptch-mutant mice via CaMKII

Basal cell carcinoma (BCC) is the most common skin tumor in humans. Although BCCs rarely metastasize, they can cause significant morbidity due to local aggressiveness. Approximately 20% of BCCs show signs of spontaneous regression. The understanding of molecular events mediating spontaneous regression has the potential to reduce morbidity of BCC and, potentially, other tumors, if translated into tumor therapies. We show that BCCs induced in conditional Ptch(flox/flox)ERT2(+/-) knockout mice regress with time and show a more differentiated phenotype. Differentiation is accompanied by Wnt5a expression in the tumor stroma, which is first detectable at the fully developed tumor stage. Coculture experiments revealed that Wnt5a is upregulated in tumor-adjacent macrophages by soluble signals derived from BCC cells. In turn, Wnt5a induces the expression of the differentiation marker K10 in tumor cells, which is mediated by Wnt/Ca(2+) signaling in a CaMKII-dependent manner. These data support a role of stromal Wnt5a in BCC differentiation and regression, which may have important implications for development of new treatment strategies for this tumor. Taken together, our results establish BCC as an easily accessible model of tumor regression. The regression of BCC despite sustained Hedgehog signaling activity seems to be mediated by tumor-stromal interactions via Wnt5a signaling.

Global Gene Expression Profiling of Hyperkeratotic Skin Lesions from Inner Mongolians Chronically Exposed to Arsenic

The skin is an organ that is highly sensitive to chronic arsenic (As) exposure. Skin lesions such as hyperkeratoses (HKs) are common early manifestations of arsenicosis in humans. HKs can be precursor lesions of nonmelanoma skin cancers (NMSCs), but the driving forces behind their formation and how they may ultimately progress to NMSCs are unknown. The goal of this study was to examine the global gene expression profiles of As-related HKs in an effort to better understand gene expression changes that are potentially associated with early stages of As carcinogenesis. HK biopsies were removed from individuals living in an arsenicosis-endemic region in Inner Mongolia who had been exposed to high As levels in their drinking water for >20 years. Gene expression profiling was performed on RNA isolated from 7 individuals in this group and from 4 lesion-free skin samples from healthy individuals. Consistent with the pathological characteristics of the HK lesions, major functional categories and known canonical pathways represented by altered transcripts include those involved in development, differentiation, apoptosis, proliferation, and stress response. The results of this study may help define a signature profile of gene expression changes associated with long-term As exposure in the skin.

A genome-wide association study identifies a new ovarian cancer susceptibility locus on 9p22.2

Epithelial ovarian cancer has a major heritable component, but the known susceptibility genes explain less than half the excess familial risk. We performed a genome-wide association study (GWAS) to identify common ovarian cancer susceptibility alleles. We evaluated 507,094 SNPs genotyped in 1,817 cases and 2,353 controls from the UK and approximately 2 million imputed SNPs. We genotyped the 22,790 top ranked SNPs in 4,274 cases and 4,809 controls of European ancestry from Europe, USA and Australia. We identified 12 SNPs at 9p22 associated with disease risk (P < 10(-8)). The most significant SNP (rs3814113; P = 2.5 x 10(-17)) was genotyped in a further 2,670 ovarian cancer cases and 4,668 controls, confirming its association (combined data odds ratio (OR) = 0.82, 95% confidence interval (CI) 0.79-0.86, P(trend) = 5.1 x 10(-19)). The association differs by histological subtype, being strongest for serous ovarian cancers (OR 0.77, 95% CI 0.73-0.81, P(trend) = 4.1 x 10(-21)).

Systematic comparison of nonmelanoma skin cancer microarray datasets reveals lack of consensus genes

BACKGROUND

DNA microarray technology has revealed vast numbers of gene expression alterations associated with human malignancies. Assigning validity and biological significance to these changes, however, remains a considerable hurdle. Recently, microarray analysis has been applied to the study of nonmelanoma skin cancer.

OBJECTIVES

To compare experimental data rigorously in order to strengthen conclusions regarding the pathogenesis of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), and to evaluate systematically the experimental and statistical parameters that may impact the degree of consensus among differentially expressed genes (DEGs) between studies.

METHODS

We performed a systematic comparison of 10 studies that applied DNA microarray technology to study BCC/SCC.

RESULTS

A total of 1133 DEGs collectively reported across the studies were compared, and 64 DEG overlaps were found: 18 DEG overlaps in SCC vs. SCC study comparisons, 18 DEG overlaps in BCC vs. BCC study comparisons and 28 DEG overlaps in BCC vs. SCC study comparisons. We documented differences in several experimental methods that may account for the relative lack of consensus between studies, including sample type, tissue procurement/handling, microarray chip and statistical analysis. The two most dysregulated biological pathways across all studies involved genes with enzymatic and structural/adhesion functions.

CONCLUSIONS

DEGs that were found to overlap across two or more studies and biological pathways with the largest representation of DEGs across studies may be particularly relevant to disease pathogenesis and serve as targets for future therapy. In future work, more consistent experimental methods across laboratories may improve the validity of reported DEGs and strengthen conclusions drawn from microarray data.

PTCH1 +/- dermal fibroblasts isolated from healthy skin of Gorlin syndrome patients exhibit features of carcinoma associated fibroblasts

Gorlin's or nevoid basal cell carcinoma syndrome (NBCCS) causes predisposition to basal cell carcinoma (BCC), the commonest cancer in adult human. Mutations in the tumor suppressor gene PTCH1 are responsible for this autosomal dominant syndrome. In NBCCS patients, as in the general population, ultraviolet exposure is a major risk factor for BCC development. However these patients also develop BCCs in sun-protected areas of the skin, suggesting the existence of other mechanisms for BCC predisposition in NBCCS patients. As increasing evidence supports the idea that the stroma influences carcinoma development, we hypothesized that NBCCS fibroblasts could facilitate BCC occurence of the patients. WT (n = 3) and NBCCS fibroblasts bearing either nonsense (n = 3) or missense (n = 3) PTCH1 mutations were cultured in dermal equivalents made of a collagen matrix and their transcriptomes were compared by whole genome microarray analyses. Strikingly, NBCCS fibroblasts over-expressed mRNAs encoding pro-tumoral factors such as Matrix Metalloproteinases 1 and 3 and tenascin C. They also over-expressed mRNA of pro-proliferative diffusible factors such as fibroblast growth factor 7 and the stromal cell-derived factor 1 alpha, known for its expression in carcinoma associated fibroblasts. These data indicate that the PTCH1^+/− genotype of healthy NBCCS fibroblasts results in phenotypic traits highly reminiscent of those of BCC associated fibroblasts, a clue to the yet mysterious proneness to non photo-exposed BCCs in NBCCS patients.

Downstream targets of heterogeneous nuclear ribonucleoprotein A2 mediate cell proliferation

Over-expression of heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 is regarded as an early marker for several cancers. This protein is associated with proto-oncogenes and tumor suppressor genes and has itself been described as a proto-oncogene. Our earlier experiments drew a connection between hnRNP A2/B1 levels and cell proliferation and raised the possibility that this protein contributes to the uncontrolled cell division that characterizes cancer. Limited knowledge of the downstream targets of hnRNP A2/B1 has, however, precluded a clear understanding of their roles in cancer cell growth. To define the pathways in which this protein acts we have now carried out microarray experiments with total RNA from Colo16 epithelial cells transfected with an shRNA that markedly suppresses hnRNP A2/B1 expression. The microarray data identified 123 genes, among 22 283 human gene probe sets, with altered expression levels in hnRNP A2/B1-depleted cells. Ontological analysis showed that many of these downstream targets are involved in regulation of the cell cycle and cell proliferation and that this group of proteins is significantly over-represented amongst the affected proteins. The changes detected in the microarray experiments were confirmed by real-time PCR for a subset of proliferation-related genes. Immunoprecipitation-RT-PCR demonstrated that hnRNP A2/B1 formed complexes with the transcripts of many of the verified downstream genes, suggesting that hnRNP A2/B1 contributes to the regulation of these genes. These results reinforce the conclusion that hnRNP A2/B1 is associated with cellular processes that affect the cell cycle and proliferation.

Common variants on 1p36 and 1q42 are associated with cutaneous basal cell carcinoma but not with melanoma or pigmentation traits

To search for new sequence variants that confer risk of cutaneous basal cell carcinoma (BCC), we conducted a genome-wide SNP association study of 930 Icelanders with BCC and 33,117 controls. After analyzing 304,083 SNPs, we observed signals from loci at 1p36 and 1q42, and replicated these associations in additional sample sets from Iceland and Eastern Europe. Overall, the most significant signals were from rs7538876 on 1p36 (OR = 1.28, P = 4.4 x 10(-12)) and rs801114 on 1q42 (OR = 1.28, P = 5.9 x 10(-12)). The 1p36 locus contains the candidate genes PADI4, PADI6, RCC2 and ARHGEF10L, and the gene nearest to the 1q42 locus is the ras-homolog RHOU. Neither locus was associated with fair pigmentation traits that are known risk factors for BCC, and no risk was observed for melanoma. Approximately 1.6% of individuals of European ancestry are homozygous for both variants, and their estimated risk of BCC is 2.68 times that of noncarriers.

Basal cell carcinomas: attack of the hedgehog

Basal cell carcinomas (BCCs) were essentially a molecular 'black box' until some 12 years ago, when identification of a genetic flaw in a rare subset of patients who have a great propensity to develop BCCs pointed to aberrant Hedgehog signalling as the pivotal defect leading to formation of these tumours. This discovery has facilitated a remarkable increase in our understanding of BCC carcinogenesis and has highlighted the carcinogenic role of this developmental pathway when aberrantly activated in adulthood. Importantly, a phase 1 first-in-human trial of a Hedgehog inhibitor has shown real progress in halting and even reversing the growth of these tumours.

Implications of hedgehog signaling antagonists for cancer therapy

The hedgehog (Hh) pathway, initially discovered in Drosophila by two Nobel laureates, Dr. Eric Wieschaus and Dr. Christiane Nusslein-Volhard, is a major regulator for cell differentiation, tissue polarity and cell proliferation. Studies from many laboratories, including ours, reveal activation of this pathway in most basal cell carcinomas and in approximately 30% of extracutaneous human cancers, including medulloblastomas, gastrointestinal, lung, breast and prostate cancers. Thus, it is believed that targeted inhibition of Hh signaling may be effective in treating and preventing many types of human cancers. Even more exciting is the discovery and synthesis of specific signaling antagonists for the Hh pathway, which have significant clinical implications in novel cancer therapeutics. This review discusses the major advances in the current understanding of Hh signaling activation in different types of human cancers, the molecular basis of Hh signaling activation, the major antagonists for Hh signaling inhibition and their potential clinical application in human cancer therapy.

GLI1 repression of ERK activity correlates with colony formation and impaired migration in human epidermal keratinocytes

Basal cell carcinoma (BCC) of the skin is a highly compact, non-metastatic epithelial tumour type that may arise from the aberrant propagation of epidermal or progenitor stem cell (SC) populations. Increased expression of GLI1 is a common feature of BCC and is linked to the induction of epidermal SC markers in immortalized N/Tert-1 keratinocytes. Here, we demonstrate that GLI1 over-expression is linked to additional SC characteristics in N/Tert-1 cells including reduced epidermal growth factor receptor (EGFR) expression and compact colony formation that is associated with repressed extracellular signal-regulated kinase (ERK) activity. Colony formation and repressed ERK activity remain evident when EGFR is increased exogenously to the basal levels in GLI1 cells revealing that ERK is additionally inhibited downstream of the receptor. Exposure to epidermal growth factor (EGF) to increase ERK activity and promote migration negates GLI1 colony formation with cells displaying an elongated, fibroblast-like morphology. However, as determined by Snail messenger RNA and E-cadherin protein expression this is not associated with epithelial-mesenchymal transition (EMT), and GLI1 actually represses induction of the EMT marker vimentin in EGF-stimulated cells. Instead, live cell imaging revealed that the elongated morphology of EGF/GLI1 keratinocytes stems from their being 'stretched' due to migrating cells displaying inefficient cell-cell detachment and impaired tail retraction. Taken together, these data suggest that GLI1 opposes EGFR signalling to maintain the epithelial phenotype. Finally, ERK activity was predominantly negative in 13/14 BCCs (superficial/nodular), indicating that GLI1 does not routinely co-operate with ERK to induce the formation of this common skin tumour.

Superficial, nodular, and morpheiform basal-cell carcinomas exhibit distinct gene expression profiles

Basal-cell carcinoma (BCC), the most common neoplasm in humans, occurs in a variety of morphological presentations. The mechanisms of BCC development downstream of the initial genetic mutations are not well understood, and different BCC morphological presentations might exhibit distinct gene expression patterns. We investigated superficial (n=8), nodular (n=8), and morpheiform (n=7) BCCs using 21K cDNA microarrays. Global gene expression profiles between respective BCC subtypes, and as compared with normal skin (n=8), were statistically defined by significance analysis of microarrays (SAM). Thirty-seven genes were subsequently validated by quantitative reverse transcriptase-PCR analysis using an expanded set of 31 BCCs. Gene ontology analysis indicated that gene expression patterns of BCC subtypes in multiple biological processes showed significant variation, particularly in genes associated with the mitogen-activated protein kinase (MAPK) pathway. Notably, genes involved in response to DNA-damage stimulus were uniquely upregulated in morpheiform BCCs. Our results indicate a relative similarity in gene expression between nodular and superficial BCC subtypes. In contrast, morpheiform BCCs are more diverse, with gene expression patterns consistent with their more "invasive" phenotype. These data may help us understand the complex behavior of BCC subtypes and may eventually lead to new therapeutic strategies.

Drug metabolism-related genes as potential biomarkers: analysis of expression in normal and tumour breast tissue

The complex role of drug metabolism-related enzymes and their possible influence in cancer development, treatment and outcome has not yet been completely elucidated. There is evidence that these enzymes can activate certain environmental procarcinogens to more toxic derivatives and thus a role has been proposed for them in carcinogenesis. The fact that they can also inactivate a number of chemotherapeutic drugs has raised the possibility of these enzymes influencing the sensitivity of tumour cells to anticancer agents. In this report, we analyse the expression of drug metabolism-related genes within a whole genome microarray study of 104 breast cancer and 17 normal breast specimens. Kaplan-Meier survival curves, Chi-squared, and Cox Regression analyses were used to identify associations between expression of gene transcripts and patients' clinicopathological and survival data. Our results show that several of these genes are significantly expressed in both normal and tumour tissue; in many cases, expression is altered in the tumour specimens as compared to normal breast tissue. Moreover, expression of ARNT2 and GST A1 was correlated with prognosis. Kaplan-Meier analysis showed expression of ARNT2 mRNA to correlate significantly with favourable disease outcome for patients, in terms of both their disease-free survival (P = 0.0094) and overall survival (P = 0.0018) times from diagnosis, while detection of GST A1 mRNA correlated with shortened disease-free survival (P = 0.0131) and overall survival (P = 0.0028). Multivariate analysis indicated GST A1 expression to be an independent prognostic factor for overall survival (P = 0.045). Our results suggest a possible use of ARNT2 and GST A1 as prognostic breast cancer biomarkers.

N-glycan alterations are associated with drug resistance in human hepatocellular carcinoma

BACKGROUND

Correlations of disease phenotypes with glycosylation changes have been analysed intensively in the tumor biology field. Glycoforms potentially associated with carcinogenesis, tumor progression and cancer metastasis have been identified. In cancer therapy, drug resistance is a severe problem, reducing therapeutic effect of drugs and adding to patient suffering. Although multiple mechanisms likely underlie resistance of cancer cells to anticancer drugs, including overexpression of transporters, the relationship of glycans to drug resistance is not well understood.

RESULTS

We established epirubicin (EPI)--and mitoxantrone (MIT)--resistant cell lines (HLE-EPI and HLE-MIT) from the human hepatocellular carcinoma cell line (HLE). HLE-EPI and HLE-MIT overexpressed transporters MDR1/ABCB1 and BCRP/ABCG2, respectively. Here we compared the glycomics of HLE-EPI and HLE-MIT cells with the parental HLE line. Core fucosylated triantennary oligosaccharides were increased in the two resistant lines. We investigated mRNA levels of glycosyltransferases synthesizing this oligosaccharide, namely, N-acetylglucosaminyltransferase (GnT)-IVa, GnT-IVb and alpha1,6-fucosyltransferase (alpha1,6-FucT), and found that alpha1,6-FucT was particularly overexpressed in HLE-MIT cells. In HLE-EPI cells, GnT-IVa expression was decreased, while GnT-IVb was increased. Both GnT-IVs were downregulated in HLE-MIT cells. HLE-MIT cells also showed decreases in fucosylated tetraantennary oligosaccharide, the product of GnT-V. GnT-V expression was decreased in both lines, but particularly so in HLE-MIT cells. Thus both N-glycan and glycosyltransferase expression was altered as cells acquired tolerance, suggesting novel mechanisms of drug resistance.

CONCLUSION

N-glycan and glycosyltransferase expression in HLE-EPI and HLE-MIT were analysed and presented that glycans altered according with acquired tolerance. These results suggested novel mechanisms of drug resistance.