Matrix metalloproteinase‐7 activates heparin‐binding epidermal growth factor‐like growth factor in cutaneous squamous cell carcinoma

Background Tumour‐specific expression of matrix metalloproteinase (MMP)‐7 has been noted in cutaneous squamous cell carcinomas (SCCs) in patients with recessive dystrophic epidermolysis bullosa (RDEB). Objectives To examine the potential role of MMP‐7 in shedding of heparin‐binding epidermal growth factor‐like growth factor (HB‐EGF) in RDEB‐associated and sporadic SCCs. Methods Tissue microarrays of RDEB‐associated SCC (n = 20), non‐EB SCC (n = 60) and Bowen disease (n = 28) were immunostained for MMP‐7, CD44 variant 3 (CD44v3) and HB‐EGF. Shedding of HB‐EGF was studied in vitro using two cutaneous SCC cell lines. Results Immunohistochemical analysis showed that HB‐EGF was absent in tumour cells when MMP‐7 and CD44v3 colocalized, and that the absence of HB‐EGF was more pronounced in RDEB‐associated SCCs than in non‐EB SCCs. The loss of HB‐EGF in MMP‐7–CD44v3 double‐positive areas was interpreted to indicate shedding and activation of HB‐EGF; this was also detected in Bowen disease indicating its importance in the early phase of SCC development. Specific knockdown of MMP‐7 expression in human cutaneous SCC cells by small interfering RNA inhibited shedding of HB‐EGF and resulted in diminished activation of the EGF receptor (EGFR) and ERK1/2, and in reduced proliferation of SCC cells. Conclusions These findings provide evidence for the role of MMP‐7 in promoting the growth of cutaneous SCCs by shedding HB‐EGF, and identify EGFR signalling as a potential therapeutic target in RDEB‐associated SCC and unresectable sporadic cutaneous SCC.     

Matrix metalloproteinase-26 is present more frequently in squamous cell carcinomas of immunosuppressed compared with immunocompetent patients

Background: Skin cancers are the most frequent malignancies in organ transplant recipients (OTRs). Squamous cell carcinomas (SCCs) occur 65–250 times more frequently in OTRs and tend to be aggressive in behavior. Because matrix metalloproteinases (MMPs) have a central role in tumorigenesis and invasion, we investigated the epithelial and stromal MMP and tissue inhibitor of MMP (TIMP) expression profile in SCCs of immunosuppressed (IS) compared with immunocompetent (IC) patients to determine if differences could explain the more aggressive behavior of SCCs in OTRs.
Methods: Matched pairs from 20 SCCs of IS and IC patients were studied using immunohistochemistry for MMP-1, MMP-7, MMP-8, MMP-9, MMP-13 and MMP-26 and TIMP-1 and TIMP-3.
Results: Among all MMPs studied, only staining for MMP-26 was significantly more intense in cancer cells of the post-transplant group compared with the IC group (p = 0.01), whereas MMP-9 expression was more abundant in stromal macrophages surrounding SCCs of IC patients (p = 0.02). MMP-26 expression in cancer cells (p = 0.04) and that of MMP-9 in neutrophils (p = 0.005) were more abundant in SCCs of patients using cyclosporine.
Conclusions: We conclude that MMP-26 and MMP-9 may contribute to the more aggressive behavior of SCCs in OTRs.     

Matrix metalloproteinases as mediators of tissue injury in different forms of cutaneous lupus erythematosus

Background Matrix metalloproteinases (MMPs) contribute to tissue destruction, regeneration, inflammation and apoptosis and several of them are upregulated by ultraviolet (UV) radiation in skin. Although some MMPs associate with organ manifestations of systemic lupus erythematosus (SLE), their role in cutaneous lupus erythematosus (LE) is elusive. Objectives Our aim was to evaluate the expression of MMPs in SLE, subacute cutaneous LE (SCLE) and discoid LE (DLE) skin lesions and their relation to apoptosis and epidermal changes. Methods Lesional skin biopsies from 20 patients with SLE, 20 with DLE and 17 with SCLE, and from UVA/UVB‐photoprovoked skin of healthy volunteers were immunostained using antibodies to multiple MMPs and tissue inhibitors of metalloproteinases (TIMPs). The TUNEL (terminal deoxynucleotidyl transferase‐mediated deoxyuridine triphosphate nick end labelling) method was used for detection of apoptosis. Results MMP‐3, ‐10, ‐19 and ‐26 were abundantly expressed by keratinocytes in SLE, DLE and SCLE skin samples. MMP‐7 was detected in keratinocytes in regions of oedema and vacuolization especially in SLE and SCLE, while MMP‐14 was only occasionally observed in keratinocytes. Photoprovocation did not induce MMP‐10 or ‐26 expression in skin of healthy volunteers. Epithelial TIMP‐1 expression was low while occasional positive fibroblasts were seen in the dermis. TIMP‐3 was abundantly expressed in the epidermis, endothelial cells and macrophages. Conclusions Different subtypes of cutaneous LE are fairly similar in their MMP expression profile. MMP‐3 and ‐10 mediate both epidermal changes and dermal tissue remodelling but are not present in lymphocytes. Low expression of TIMP‐1 suggests that lupus skin is characterized by proteolytic events, and targeted action using selective MMP inhibitors may reduce lupus‐induced damage in inflamed tissues.     

Skin disruption is associated with indomethacin‐induced small intestinal injury in mice

One mechanism by which non‐steroidal anti‐inflammatory drugs (NSAIDs) cause intestinal injury is by inducing matrix metalloproteinases (MMPs) that degrade and remodel the extracellular matrix. In addition to the intestinal mucosa, MMPs are expressed in the skin and can be activated by mast cell‐secreted tryptase. We therefore investigated whether intestinal injury resulting from treatment with the NSAID indomethacin induced MMPs in the skin of mice and caused an associated disruption of skin function. Hairless mice and mast cell‐deficient mice were administered indomethacin, after which damage to the jejuna and skin was assessed with immunohistochemistry and Western blotting. The plasma concentration of inflammatory mediators was assessed to evaluate potential pathways for signalling skin disruption in response to intestinal injury. In hairless mice with intestinal injury, transepidermal water loss (TEWL) was higher and skin hydration was lower than in control mice. The expression levels of mast cells, tryptase, MMP‐1 and MMP‐9 were also increased, with concurrent degradation of types I and IV collagen. In contrast, no changes in skin TEWL or skin hydration were observed in mast cell‐deficient mice with indomethacin‐induced intestinal injury. In all mice evaluated, the plasma concentrations of IgE, IgA, histamine and TNF‐α were increased in response to indomethacin treatment. Skin disruption was strongly associated with indomethacin‐induced small intestinal injury, and the activation of mast cells and induction of tryptase, MMP‐1 and MMP‐9 are critical to this association.     

Fibroblasts support migration of monocyte‐derived dendritic cells by secretion of PGE2 and MMP‐1

The outcome of a cutaneous immune response is critically dependent upon the ability of dendritic cells (DC) to migrate from skin to the draining lymph nodes – a process that is influenced by the cutaneous tissue microenvironment. Here, the role of fibroblasts – a major component of the dermal microenvironment – on the migratory capacity of monocyte‐derived DC (MoDC) was investigated in a 3D collagen I matrix. Indeed, dermal fibroblasts supported the migration of pre‐activated MoDC through a 3D collagen I matrix. Activation of human MoDC resulted in the release of TNFα and IL‐1β that in turn stimulated MMP‐1 (human collagenase) and PGE₂ secretion by human dermal fibroblasts. Transmigration assays confirmed the importance of fibroblast‐derived MMP‐1 and PGE₂ for the migration of MoDC through a 3D collagen I matrix. Finally, in mice initiation of inflammation by induction of an irritant contact dermatitis or a psoriasis‐like skin inflammation, the expression of the PGE₂ generating cox‐2 and the mouse collagen I degrading enzyme matrix metalloproteinases (MMP)‐13 was strongly up‐regulated. Our study indicates that MoDC are able to instruct dermal fibroblasts resulting in enhanced migratory capability of MoDC, thus highlighting the role of a crosstalk of DC with their stromal microenvironment for the control of cutaneous immune responses.     

The haptoglobin phenotype influences the risk of cutaneous squamous cell carcinoma in kidney transplant patients

Background Cutaneous squamous cell carcinoma (SCC) is the most frequent skin cancer after organ transplantation. Currently, the pre‐identification of transplant patients at increased risk for non‐melanoma skin cancer remains difficult. Objective To investigate the Hp polymorphism as a marker for the identification of a subset of patients with an increased susceptibility to develop SCC/Bowen’s disease. Methods Haptoglobin phenotyping was performed with haemoglobin‐supplemented starch gel electrophoresis in 300 kidney transplant patients. High‐performance gel permeation chromatography was used in case of low serum haptoglobin concentration. Results Cox regression analysis (adjusted for age, gender and Mediterranean origin) showed a significant association of the Hp 1‐1 phenotype with a higher risk of SCC/Bowen’s disease (P = 0.035) and multiple primary SCCs (P = 0.002). No significant difference between the Hp phenotypes was found for the development of Bowen’s disease and SCCs in the first 10 years following renal transplantation. However, after a follow‐up of >10 years, a significant association between the Hp 1‐1 phenotype and the occurrence of Bowen’s disease and SCC was reported (P = 0.002 and P = 0.001 respectively). Conclusions This study shows an increased risk for the development of (multiple) SCCs in kidney transplant patients with the Hp 1‐1 phenotype. This finding points to the role of Hp 1‐1 phenotype as an important predictor in identifying a subset of patients with an increased need for preventive measures and is in agreement with the decreased anti‐inflammatory capacity of this phenotype.     

A novel technique to diagnose non‐melanoma skin cancer by thermal conductivity measurements: Correlations with cancer stromal factors

The skin surface temperature reflects the physiological state of the human body. Quantitative methods of identification of skin cancers based on accurate measurement of effective thermal conductivity (ETC) are among the promising diagnostic tools for differentiating non‐invasive and invasive melanomas before surgical treatment. To validate these findings, in this report, the diagnostic methods for invasive and non‐invasive extramammary Paget’s disease (EMPD) and squamous cell carcinoma (SCC) were further tested by measuring the absolute value of skin surface temperature and the ETC of the skin. In addition, to investigate the stromal factors that might affect ETC, immunohistochemical staining for LL37, periostin (POSTN), MMP12, and MMP28 was performed. The invasive SCC and EMPD group showed a relatively higher skin surface temperature compared to the in situ SCC group. The non‐invasive EMPD and SCC group showed significantly lower values of ETC at lesions, whereas the invasive EMPD group showed significantly higher ETC values at lesions compared to healthy skin. Immunohistochemical staining showed that the percentage of LL37‐producing cells was significantly increased in invasive EMPD and SCC compared to that in non‐invasive EMPD and SCC. Moreover, Spearman's rank correlation test showed a significant inverse correlation between the percentage of MMP12‐positive cells and increased levels of ETC‐expressing areas in EMPD and SCC (r = ?.5997). The present study suggested that differences in ETC could be a novel high‐accuracy diagnostic technique for non‐melanoma skin cancer, especially for detecting dermal invasion of SCC and EMPD.     

Immunohistochemical expression of matrix metalloproteinases in the granulomatous rosacea compared with the non‐granulomatous rosacea

Background There is a granulomatous variant which is recognized in the rosacea spectrum. However, the pathogenesis of granuloma formation in rosacea has not been clearly demonstrated. Matrix metalloproteinases (MMPs) are required for recruitment of inflammatory cells and for tissue remodelling, making way for the development of well‐organized granuloma. Objective The aim of this study was to investigate the expression of transforming growth factor (TGF)‐β, TGF‐β type II receptor (TβRII), Tumour necrosis factor (TNF)‐α, MMP‐1, 2 and 9 in the granulomatous rosacea (GR) compared with the non‐granulomatous rosacea (NGR) and test the hypothesis that the changes of these profiles in GR would be related with chronic ultraviolet radiation (UVR)‐exposure. Methods Facial skin samples were obtained from 20 patients with GR and NGR (control group). The sections were stained using haematoxylin and eosin, Verhoeff’s elastic stain, and antibodies to TGF‐β, TβRII, TNF‐α, MMP‐1, ‐2 and ‐9. Results The amount of elastotic material was significantly increased in the dermis of GR lesions. Expression of TGF‐β was significantly decreased in the epidermis of GR lesions compared with NGR lesions. In addition, the expression of MMP‐9 was significantly increased in the dermis of GR lesions compared with NGR lesions, especially at the centre of the granuloma on a semi‐quantitative analysis. MMP‐2 expression was also increased in GR lesions, although the difference between the two groups was not statistically significant. Conclusions The results of this study suggest that the increased expression of MMPs in the dermis may participate in granuloma formation of GR in association with UVR.     

Suppressive effect of calcipotriol on the induction of matrix metalloproteinase (MMP)‐9 and MMP‐13 in a human squamous cell carcinoma cell line

Background. Vitamin D3 is a potent regulator of cell growth, differentiation and death, tumour invasion, and angiogenesis. Production of matrix metalloproteinase (MMP)‐9 and MMP‐13 by tumour cells may promote tumour growth, invasion and metastasis. Aim. To investigate whether calcipotriol could suppress the expression of MMP‐9 and MMP‐13 in a human squamous cell carcinoma (SCC) cell line (DJM cells), and to examine the mechanism of modulation of MMP‐9 and MMP‐13 by calcipotriol in DJM cells treated with tumour necrosis factor (TNF)‐α. Methods. Protein and mRNA levels of MMP‐9 and MMP‐13 were examined by ELISA and real‐time PCR, respectively. Activation of signalling cascades was assessed using several inhibitors of signalling molecules and western blot analysis. Results. Production of MMP‐9 and MMP‐13 markedly increased when the cells were treated with TNF‐α. Calcipotriol suppressed the production of MMP‐9 and MMP‐13 mRNA and proteins significantly, in a dose‐dependent manner. Induction of MMP‐9 by TNF‐α was suppressed by an extracellular signal‐regulated kinase (ERK) inhibitor but not by a p38 inhibitor, whereas induction of MMP‐13 was inhibited by a p38 inhibitor but not by an ERK inhibitor. Calcipotriol inhibited the phosphorylation of both ERK and p38, as shown by western blotting. Conclusion. Calcipotriol reduces MMP‐9 and MMP‐13 production through inhibiting the phosphorylation of ERK and p38, respectively.     

Expression of DNA mismatch repair proteins and MSH2 polymorphisms in nonmelanoma skin cancers of organ transplant recipients

Background Organ transplant recipients (OTRs) have an increased risk of skin cancer. Treatment with azathioprine, commonly used in post‐transplant immunosuppressive regimens, results in incorporation of 6‐thioguanine (6‐TG) into DNA. Mismatch repair (MMR)‐defective cells are resistant to killing by 6‐TG. Azathioprine exposure confers a survival advantage on MMR‐defective cells, which are hypermutable and may therefore contribute to azathioprine‐related nonmelanoma skin cancer, a phenomenon we have previously demonstrated in transplant‐associated sebaceous carcinomas. The MSH2 protein is an important component of DNA MMR. The ‐6 exon 13 T>C MSH2 polymorphism is associated with impaired MMR, drug resistance and certain cancers. Objectives To investigate (i) whether loss of MMR protein expression and microsatellite instability are over‐represented in squamous cell carcinomas (SCCs) from OTRs on azathioprine compared with SCCs from immunocompetent patients, and (ii) whether the MSH2 ‐6 exon 13 polymorphism is over‐represented in OTRs with skin cancer on azathioprine. Methods (i) Immunohistochemical staining was used to assess expression of the MMR proteins MSH2 and MLH1 in cutaneous SCCs from OTRs on azathioprine and from immunocompetent patients. (ii) Blood samples from OTRs on azathioprine with and without skin cancer were genotyped for the ‐6 exon 13 MSH2 polymorphism. Results (i) MSH2 and MLH1 protein expression was not altered in SCCs from OTRs on azathioprine and there was no difference in expression between SCCs from OTRs and immunocompetent patients. (ii) There was no association between MSH2 polymorphism genotype frequency and OTR skin cancer status. Conclusions Despite previous findings in transplant‐associated sebaceous carcinomas, defective MMR and the ‐6 exon 13 MSH2 polymorphism are unlikely to play a significant role in the development of SCC in OTRs on azathioprine.     

Skin wound healing in MMP2‐deficient and MMP2 / Plasminogen double‐deficient mice

Please cite this paper as: Skin wound healing in MMP2‐deficient and MMP2/Plasminogen double‐deficient mice. Experimental Dermatology 2010; 19 : e234–e240. Abstract: During healing of incisional skin wounds, migrating keratinocytes dissect their way under the crust to re‐epithelialize the wounded area. The efficiency of this tissue remodelling process depends on the concomitant activity of several extracellular proteases, including members of the plasminogen activation (PA) system and the matrix metalloproteinase (MMP) family. Treatment with the broad spectrum MMP inhibitor, galardin, delays wound healing in wildtype mice and completely arrest wound healing in plasminogen (Plg)‐deficient mice, indicating a functional overlap between plasmin‐ and galardin‐sensitive MMPs during wound healing. To address whether MMP2 is accountable for the galardin‐induced healing deficiency in wildtype and Plg‐deficient mice, incisional skin wounds were generated in MMP2 single‐deficient mice and in MMP2/Plg double‐deficient mice and followed until healed. Alternatively, tissue was isolated 7 days post wounding for histological and biochemical analyses. No difference was found in the time from wounding to overt gross restoration of the epidermal surface between MMP2‐deficient and wildtype control littermate mice. MMP2/Plg double‐deficient mice were viable and fertile, and displayed an unchallenged general phenotype resembling that of Plg‐deficient mice, including development of rectal prolapses. MMP2/Plg double‐deficient mice displayed a slight increase in the wound length throughout the healing period compared with Plg‐deficient mice. However, the overall time to complete healing was not significantly different between Plg‐deficient and MMP2/Plg double‐deficient mice. These results show that MMP2 activity is not essential for wound healing and indicate that lack of MMP2 only marginally potentiates the effect of Plg deficiency.     

Activation of toll‐like receptors 2, 3 or 5 induces matrix metalloproteinase‐1 and ‐9 expression with the involvement of MAPKs and NF‐κB in human epidermal keratinocytes

Please cite this paper as: Activation of toll‐like receptors 2, 3 or 5 induces matrix metalloproteinase‐1 and ‐9 expression with the involvement of MAPKs and NF‐κB in human epidermal keratinocytes. Experimental Dermatology 2010; 19 : e44–e49. Abstract: Toll‐like receptors (TLRs) on epidermal keratinocytes are the first line of defense against microbe invasion, and matrix metalloproteases (MMPs) regulate inflammation, cell migration and wound healing. In this study, we demonstrate that the mRNA and protein expressions of MMP‐1 and MMP‐9 in human epidermal keratinocytes are induced by ligands for TLR2, TLR3 and TLR5 [Pam3CSK4, Poly(I:C) and flagellin, respectively] in a dose‐dependent manner. We also found that the ligands for TLR2, TLR3 and TLR5 activate the MAP kinases, JNK and p38 MAPK, but not ERK1/2. Furthermore, treatment with the ligands for TLR2, TLR3 and TLR5 also induced the degradation of IκB‐α and activated the nuclear translocation of NF‐κB. MMP‐1 induction by the ligands for TLR2, TLR3 and TLR5 was inhibited by pretreatment with BAY11‐7082 (NF‐κB inhibitor) or SP600125 (JNK inhibitor), whereas MMP‐9 expression was inhibited by pretreatment with BAY11‐7082, SP600125 or SB203580. These findings demonstrate that the activation of TLR2, TLR3 or TLR5 induces the expression of MMP‐1 and MMP‐9 in human epidermal keratinocytes. In addition, NF‐κB or JNK mediated the MMP‐1 expression induced by TLR2, TLR3 and TLR5, whereas NF‐κB, JNK or p38 MAPK mediated the MMP‐9 expression induced by TLR2, TLR3 and TLR5.     

Expression of matrix metalloproteinase (MMP)-2, MMP-9, MMP-13, and MT1-MMP in skin tumors of human papillomavirus type 8 transgenic mice

Human papillomaviruses (HPV) are small DNA viruses that induce a wide variety of hyperproliferative lesions in cutaneous and mucosal epithelia. It is proposed that HPV is involved in non-melanoma skin cancer development. We have previously shown that HPV8 transgenic mice spontaneously develop papillomatous skin tumors. Histology revealed epidermal hyperplasia, acanthosis and hypergranulosis and in some cases squamous cell carcinomas (SCC). Zymographic and immunoblot analysis of normal skin extracts identified increased amounts of matrix metalloproteinase (MMP)-9, MMP-13 and MT1-MMP in HPV8-positive mice compared with HPV8-negative animals. In situ gelatin zymography of tumor specimens displayed a strong proteolytic activity in papillomas, and SCC putatively attributed to the increased amounts of activated MMP-9 found in tissue extracts. In addition, immunoblot analysis revealed increased amounts of active MMP-13 and MT1-MMP in tumor extracts as compared with control extracts. Immunohistochemical stainings of SCC specimens depicted MMP-13 to be specifically expressed in stromal fibroblasts neighboring the tumor islands, whereas MT1-MMP was detected both in tumor cells and in stromal cells. Taken together, these results implicate a role for MMPs in the development of HPV8-induced cutaneous tumors.     

Dihydroavenanthramide D prevents UV‐irradiated generation of reactive oxygen species and expression of matrix metalloproteinase‐1 and ‐3 in human dermal fibroblasts

Ultraviolet B (UVB) radiation induces photoageing by upregulating the expression of matrix metalloproteinases (MMPs) in human skin cells. Dihydroavenanthramide D (DHAvD) is a synthetic analog to naturally occurring avenanthramide, which is the active component in oats. Although anti‐inflammatory, anti‐atherosclerotic and antioxidant effects have been reported, the antiphotoageing effects of DHAvD are yet to be understood. In this study, we investigated the inhibitory effects of DHAvD on UVB‐induced production of reactive oxygen species (ROS) and expression of MMPs, and its molecular mechanism in UVB‐irradiated human dermal fibroblasts. Western blot and real‐time PCR analyses revealed that DHAvD inhibited UVB‐induced MMP‐1 and MMP‐3 expression. It also significantly blocked UVB‐induced ROS generation in fibroblasts. Additionally, DHAvD attenuated UVB‐induced phosphorylation of MAPKs, activation of NF‐κB and AP‐1. DHAvD regulates UVB‐irradiated MMP expression by inhibiting ROS‐mediated MAPK/NF‐κB and AP‐1 activation. DHAvD may be a useful candidate for preventing UV light‐induced skin photoageing.     

Immunohistochemical staining of p16 in squamous cell carcinomas of the genital and extragenital area

Background and objectivesPositive immunostaining for the tumor suppressor protein p16 is associated with the presence of mucosal or αsubtypes of human papillomavirus (HPV) in cervical and genital squamous cell carcinoma (SCC). The aim of this study was to determine whether p16 immunostaining is also associated with mucosal HPV in extragenital SCC.Material and methodsParaffin sections of lesions located in the genital region (8 genital warts, 3 intraepidermal SCCs, and 7 invasive SCCs) and extragenital area (29 intraepidermal SCCs corresponding to Bowen disease and 10 invasive SCCs) were stained for p16 by immunohistochemistry. Mucosal HPV was detected by polymerase chain reaction (PCR).ResultsIn the genital area, p16 immunostaining was negative in genital warts and positive in all 3 intraepidermal SCCs and 2 invasive SCCs (29%). Mucosal HPV was detected in 6 genital warts and 2 intraepidermal SCCs (100% after exclusion of 3 lesions that could not be analyzed by PCR) and in the 2 invasive SCCs that were positive for p16. In the extragenital area, 19 intraepidermal SCCs (95%) and 2 invasive SCCs (20%) were immunopositive for p16. Mucosal HPV was detected in 4 intraepidermal SCCs (p16 immunopositive) and 1 invasive SCC (p16 immunonegative). In intraepidermal SCCs, p16 immunostaining facilitated the identification of dermal microinfiltration or invasion of normal skin appendages.ConclusionsAccording to our results, unlike in genital SCCs, p16 immunopositivity is independent of the presence of HPV in extragenital SCCs. Compared with intraepidermal SCCs, the absence of p16 protein in invasive SCCs in the extragenital area would indicate progression of the disease.     

Therapeutic and immune effects of 5‐aminolevulinic acid photodynamic therapy on UVB‐induced squamous cell carcinomas in hairless mice

The therapeutic effects of 5‐aminolevulinic acid (ALA)‐mediated photodynamic therapy (PDT) on cutaneous squamous cell carcinoma (SCC) are not fully understood, and the usefulness of topical PDT in the treatment of SCC is still debatable. The most interesting aspect in SCC PDT is perhaps its potential in inducing antitumor immune responses. In this study, cutaneous SCCs were established by UVB irradiation of hairless mice and treated with multiple ALA PDT. Immunohistochemistry assays showed that ALA PDT could induce quick apoptosis, overexpression of TNFα and marked increases in DCs, CD4⁺ and CD8⁺ cells in tumor interstitium and subcutaneous connective tissues. However, a complete response was only achieved for small SCCs. The clinical value of ALA PDT‐induced specific antitumor immune responses in long‐term control of SCCs deserves further study.     

Depletion of cell surface CD44 in nonmelanoma skin tumours is associated with increased expression of matrix metalloproteinase 7

Background  Expression of matrix metalloproteinase (MMP)-7 and MMP-9 is low in the normal epidermis and is induced by physiological processes such as wound healing, but also malignant transformation of epidermal cells. The activity of both MMPs has been associated with the hyaluronan (HA) receptor CD44. We previously reported that the levels of CD44 and HA differ between the two types of epidermal tumours, basal (BCC) and squamous cell carcinoma (SCC), as well as between different grades of SCC.
Objectives  To investigate if the immunostaining patterns of MMP-7 and MMP-9 correlate to those of CD44 and HA in BCC and SCC.
Methods  Paraffin sections from 71 BCCs, 21 in situ SCCs and 27 SCCs were immunostained for MMP-7 and -9.
Results  Positive immunostaining for MMP-7 and MMP-9 was found in tumour cells of both BCC and SCC, while the staining intensity tended to be stronger in SCC. The staining intensity of MMP-7 was inversely correlated with that of CD44 in both tumour types. In well-differentiated SCC, the intensity of MMP-7 was generally weak, while CD44 staining was strong and homogeneously distributed. In poorly differentiated SCC, an increase in MMP-7 was seen, and the staining intensity of CD44 became weak and was locally absent. No correlation was seen between MMP-9 and CD44 or either of the two MMPs and HA.
Conclusions  Our results show that in nonmelanoma skin tumours MMP-7 and -9 are present in the tumour cells, and suggest a link between MMP-7 activity and the depletion of cell surface CD44.     

The role of Syk kinase in ultraviolet-mediated skin damage

Background Ultraviolet (UV) irradiation is the main cause of skin photodamage; the resulting modulation of matrix metalloproteinases (MMPs) leads to collagen degradation. There is no easily accessible molecular indicator of early skin UV damage. Objectives In this study, we investigated the effects of Syk kinase on MMP expression and evaluated the sensitivity and usefulness of Syk as an early indicator of skin UV damage. Methods Human dermal fibroblasts (HDFs) were transfected with Syk cDNA to overexpress Syk. MMP‐1 expression and Syk activity were determined by Western blot after UV exposure. The effect of Syk on MMP‐1 expression in HDFs was further explored by either Syk siRNA or a selective Syk inhibitor. Possible downstream molecules of Syk were also evaluated in HDFs upon UV exposure. The relationship between Syk and collagenase was further explored in vivo (MMP‐13, hairless mice). Results Our studies in HDFs demonstrated that both a Syk inhibitor and Syk siRNA were able to inhibit MMP‐1 expression in HDFs exposed to UV and that overexpression of Syk increased MMP‐1 expression and the activity of JNK kinase, but not p38 or Erk1/2 MAP kinase. UV exposure enhanced both expression and activity of Syk in HDFs. Experiments with hairless mice suggested that Syk expression is an earlier indicator of UV exposure than MMP‐13 expression. Conclusions Our results demonstrate that Syk expression correlates well with increase of MMPs (MMP‐1 in humans and MMP‐13 in mice) in response to UV exposure. The findings suggest that Syk may be a novel target for the prevention and treatment of skin photodamage by modulating MMPs.     

Histopathologic features of multiple cutaneous squamous cell carcinomas of the lower extremity

Recent studies suggest cutaneous squamous cell carcinomas (SCCs) of the leg, particularly those occurring multiply in sun exposed skin of nonimmunosuppressed women, are a distinct clinical subtype. There are few reports of the histopathologic features of this subtype. A retrospective chart review of 4 patients with multiple SCCs on the leg was performed and a total of 35 biopsies from the legs examined. Histopathologically, the tumors lacked adjacent actinic keratosis (AK) and often had adjacent basaloid retiform proliferations. Most lesions (all but one) were well differentiated and about 40% could be classified histopathologically as keratoacanthoma. Perineural invasion was absent in all but one case. Using the American Joint Committee on Cancer (AJCC) staging criteria for SCC, 21 tumors were Stage I, and 9 Stage II. During 7–10 years of follow‐up, no recurrence or metastasis occurred. Patients with multiple SCCs on the lower extremities can have a range of histopathologic features, from keratoacanthoma‐like to well‐differentiated SCC.