COX-2 expression correlates with microvessel density in non-melanoma skin cancer from renal transplant recipients and immunocompetent individuals

Angiogenesis, the generation of a new vascular network, is regulated in part by inducers of endothelial cell migration and proliferation, such as cyclooxygenase-2 (COX-2). Microvessel density (MVD) measurement is widely used to quantify angiogenesis in tissue sections of tumors, including cutaneous malignancies. The increasing number of successful renal transplantations worldwide is producing a progressive increase in patients at risk for non-melanoma skin cancers, such as squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and Bowen's disease (BD), and at significantly increased risk for metastatic SCC. The aim of this study was to investigate whether there was any difference in angiogenesis between these tumor types in renal transplant recipients (RTRs) and immunocompetent individuals (ICIs) and whether angiogenesis in these tumors was related to COX-2 expression. The study measured angiogenesis and COX-2 expression in BD, SCC, BCC, and normal skin from both RTRs and ICIs. Vessel counts were performed, and COX-2 immunoexpression was assessed semiquantitatively. The MVD counts differed significantly between normal skin and all tumor types. Significant differences in MVD density were found between all SCCs and BCCs. BCCs from RTRs had significantly greater MVD at the invasive front of the tumor than BCCs from ICIs. Increased COX-2 expression correlated with increased MVD in all tumors examined. These findings indicate a difference in vascular profiles between RTRs and ICIs in BCCs and suggest a relationship between COX-2 and angiogenesis that may provide a possible treatment target for skin tumors in these 2 patient populations.     

Differences in the vascular patterns of basal and squamous cell skin carcinomas explain their differences in clinical behaviour

Tumour angiogenesis is essential for tumour growth and appears to play an important role both at the transition from hyperplasia to invasive growth and at a late stage in the dissemination process. Basal cell carcinomas (BCCs) and trichoepitheliomas (TEs) are related tumours that share the properties of invasive growth but without the capacity to metastasize. Squamous cell carcinomas (SCCs) of the skin are derived from a similar cell type and they have both invasive and metastatic potential. The aim of this study was to investigate whether the behaviour of these tumours could be explained by differences in their microvasculature. The study looked both qualitatively and quantitatively at the microvasculature of BCCs (n=50) and TEs (n=33) and compared them with normal skin (n=6) and with SCCs of the skin (n=22). Vessel counts were performed using a standard graticule count method after immunohistochemical staining for CD31. Counts were made of blood vessels in the stroma surrounding the tumour and also for vessels in the body of the tumour. The stromal counts for all the tumour groups differed significantly from normal skin. The SCC counts differed significantly from the counts for the BCCs and TEs. There was no significant difference between the counts for different subtypes of BCC or TE groups. While vessels could be found in the body of the SCCs, none was seen in the nodular BCC or the TE groups. There was no correlation between the vascular density and the depth of invasion. Overall, invasive growth correlated with an angiogenic response in the stroma, while metastatic potential correlated with microvessels being present in the body of the tumour.     

Maspin expression in normal skin and usual cutaneous carcinomas

Maspin is a serine protease inhibitor whose gene is located on 3q27. Several lines of evidence point towards its putative role as tumor suppressor gene and angiogenesis inhibitor; however, there are compelling data showing that maspin is also expressed in the nuclear compartment and might be associated with the differentiation of specific cell lineages. No systematic study of maspin expression in normal skin and usual skin carcinomas have been published so far. We semiquantitatively analyzed the distribution and immunoreactivity pattern of maspin in 14 squamous cell carcinomas (SCCs) and 16 basal cell carcinomas (BCCs) and in the adjacent normal epidermis of all cases. We also examined the correlation of maspin expression with histological type, grade, vascular invasion, perineural infiltration, and mitotic counting. Cytoplasmic expression of maspin was observed in suprabasal, prickle, and granular cell layers of normal epidermis; cells of the germinative hair matrix, Henle's and Huxley's layers, and cuticle of hair follicles; mature sebaceous cells and sweat gland's secretory cells. Nuclear expression was detected in some basal/myoepithelial cells of the sweat glands and scattered mature sebaceous cells. All SCCs but one grade IV SCC showed maspin expression, and it was correlated with the differentiation of these neoplasms. BCCs presented variable maspin expression, while metatypical carcinomas showed moderate to intense maspin expression, nodular BCCs variable contents of maspin and displayed a peculiar distribution, confined to the center of the neoplastic nodules. Two BCCs and one SCC showed maspin nuclear expression. No correlation with other clinical pathological features was observed. Our findings do not support the role of maspin as a tumor suppressor gene and suggest that this serpin is probably associated with specific lines of differentiation.     

Differential expression of matrix metalloproteinase (MMP)-2, MMP-9 and tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in non-melanoma skin cancer: implications for tumour progression

AIMS: To investigate the expression of matrix metalloproteinase (MMP)-2, MMP-9, and tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 in non-melanoma skin cancer (NMSC) and to compare their expression between different tumour types and with clinicopathological factors. METHODS AND RESULTS: A study of 11 normal skin, 29 Bowen's disease (BD), 40 squamous cell carcinoma (SCC) and 38 basal cell carcinoma (BCC) samples for MMP-2, MMP-9, TIMP-1 and TIMP-2 expression was carried out using immunohistochemistry and in situ hybridization. The expression of all metalloproteinases was greater in tumours than in normal skin. MMP-2 and MMP-9 expression was more extensive in the stroma of SCC than of BCC or BD. TIMP-1 expression was greater in the stroma of BCC than of SCC or BD and TIMP-2 expression was greater in the stroma of SCC than of BD. There was a correlation between increased metalloproteinase expression and depth of lesion (MMP-2 and TIMP-2), inflammation (MMP-2, MMP-9, TIMP-1 and TIMP-2) and microvessel density (MMP-2, MMP-9 and TIMP-2). CONCLUSIONS: MMP-2, MMP-9, TIMP-1 and TIMP-2 play an important role in the pathogenesis of non-melanoma skin cancer, but differ significantly in their expression levels between the tumour types examined. The immunoexpression of these proteins may be useful indicators of cutaneous cancer invasion and progression.     

Expression of selectin ligands by cutaneous squamous cell carcinoma.

Recent evidence suggests that interactions between endothelial selectins and tumor surface selectin ligands may be of importance in cancer metastasis. To investigate the role of such mechanisms in cutaneous tumors, whole skin biopsies were examined immunohistochemically for a variety of selectin ligands including sialyl-Lewis-X, sialyl-Lewis-A (S-Le(a)), sulfatides, and CD15. In 12 of 12 squamous cell carcinomas (SCCs), there was expression of sialyl-Lewis-X and CD15, but no tumor expressed S-Le(a). Occasional keratinocytes in eight of 12 SCCs expressed sulfatides. All selectin ligands were absent on keratinocytes in basal cell carcinomas (BCCs, n = 8) and normal skin (n = 8), with the exception of one BCC that expressed S-Le(a). E-selectin was not present in normal skin, but was strongly expressed by dermal endothelium in both SCC and BCC. Keratinocyte cell lines A431, HaCaT, and SVK14 were investigated by flow cytometry, which demonstrated sialyl-Lewis-X and S-Le(a) expression by all three, whereas normal human keratinocytes did not express these molecules. These findings suggest a potential role for selectin-mediated events in early and late metastasis, and differential expression of these ligands by BCC and SCC may explain the relatively low metastatic potential of the former.     

Immunohistochemical expression of ezrin in cutaneous basal and squamous cell carcinomas

Ezrin is a member of the ezrin-radixin-moesin family of proteins, which link the actin-containing cytoskeleton to the plasma membrane. Overexpression of ezrin protein is correlated with the metastatic potential in several cancers. Little is known about the distribution of ezrin in normal epidermis and nonmelanoma skin cancer; therefore, in the current study, we examined the immunohistochemical expression of ezrin in normal skin (10 biopsies) and epithelial skin tumors (25 basal cell carcinoma [BCC] and 20 squamous cell carcinoma [SCC]). Ezrin was expressed in epidermis of all normal controls with a prominent membranous pattern compared with 93.3% positivity in malignant cases with a significant higher intensity (assessed by H score) in favor of the latter (P = .002). Cytoplasmic expression of ezrin either alone or associated with membranous expression was both seen in BCC and SCC. The median value of H score in SCC (160) cases was higher than that in BCC (60). H score values of ezrin expression in BCC was significantly higher in tumors arising in sites other than the head and neck (P = .04). In SCC, the intensity of ezrin expression tended to be associated with advanced stage (P = .08). Our study demonstrated the probable tumorigenic role of ezrin in epithelial skin tumor formation. It may enhance local invasion or metastasis of epithelial skin tumors, which necessitates further larger study to clarify. The intensity rather than the pattern of ezrin expression had a more probable impact on the tumor behavior.     

Immunolocalization of Glioma-Associated Oncogene Homolog 1 in Non Melanoma Skin Cancer

Glioma-associated oncogene homolog (GLI)1 is involved in controlling cell proliferation and angiogenesis. The aim of this work was to explore its possible role in non-melanoma skin cancer pathogenesis through its immunohistochemical (IHC) expression in skin biopsies of these diseases and correlating this expression with the clinico-pathological parameters of the studied cases. Seventy-six cutaneous specimens were studied; 30 cases with basal cell carcinoma (BCC), 30 cases with squamous cell carcinoma (SCC) and 16 normal skin samples, from age- and gender-matched subjects, as a control group. GLI1 was expressed in all BCC cases and in 60% of SCC cases. All SCC cases showed cytoplasmic, while 70% of BCC cases showed nucleocytoplasmic immunoreactivity. It was over expressed in BCC and SCC compared to normal skin (p?=?0.01 and 0.0006, respectively). Higher Histo (H) score in BCC cases was significantly associated with female gender (p?=?0.04), multiple lesions, desmoplastic stromal reaction and stromal angiogenesis (p?p?=?0.004 for all), inflammatory stromal reaction (p?=?0.01), lymph node involvement and absence of calcification (p?=?0.001 for both). In conclusion, GLI1 may play a role in BCC pathogenesis through its role in cell proliferation, migration, and angiogenesis. Its upregulation and cytoplasmic localization in SCC may suggest that its role in tumor pathogenesis is through mechanisms other than Hedgehog pathway activation. Further studies are needed to clarify the exact molecular basis of its oncogenic action.     

Serpin peptidase inhibitor clade A member 1 (SerpinA1) is a novel biomarker for progression of cutaneous squamous cell carcinoma

The incidence of keratinocyte-derived nonmelanoma skin cancers is increasing worldwide because of cumulative recreational exposure to sunlight. At present, no specific molecular markers are available for assessing the progression of premalignant actinic keratoses to invasive cutaneous squamous cell carcinoma (SCC). We examined the role of the Serpin family in skin SCCs. Expression profiling of cutaneous SCC cell lines (n = 8) revealed up-regulation of SerpinA1 compared with normal epidermal keratinocytes (n = 5). Analysis with quantitative RT-PCR showed that the mean level of SerpinA1 mRNA was markedly up-regulated in cutaneous SCC cell lines (n = 8) compared with in normal keratinocytes. SerpinA1 production by SCC cells was dependent on p38 mitogen-activated protein kinase activity and was up-regulated by epidermal growth factor, tumor necrosis factor-α, interferon-γ, and IL-1β. Immunostaining of tissue arrays with 148 human tissue samples revealed tumor cell-associated expression of SerpinA1 in 19 of 36 actinic keratoses, 22 of 29 Bowen's disease samples, 67 of 71 sporadic SCCs, and all 12 recessive dystrophic epidermolysis bullosa-associated SCCs examined. Moreover, tumor cell-associated SerpinA1 staining was detected in all chemically induced mouse skin SCCs studied (n = 17). Overexpression of SerpinA1 mRNA was also detected by quantitative RT-PCR in chemically induced mouse skin SCCs (n = 14) compared with control tissues (n = 14). These data identify SerpinA1 as a novel tumor cell-associated biomarker for progression of cutaneous SCCs.     

Expression of CD40 and Fas ligand in Bowen's disease,squamous cell carcinoma and basal cell carcinoma

Impaired regulation of apoptosis is known to be associated with the development of various cancers, and Fas/Fas-ligand (FasL) is known to play an important role in apoptosis. CD40 is a cell surface receptor, which when ligated modulates apoptosis in some cell types. The expressions of CD40 and FasL were examined in 10 normal skins, 7 Bowen's disease skins, 10 squamous cell carcinomas (SCCs) and 12 basal cell carcinomas (BCCs) immunohistochemically. In the normal epidermis, CD40 was more highly expressed in the keratinocytes of the squamous cell and granular layers than in those of the basal layer, and FasL expression was observed in the cell membrane of keratinocytes at the basal and squamous cell layers. CD40 expression was significantly higher in SCCs than in normal or Bowen's disease skin, while FasL expression was significantly higher in Bowen's disease than in SCCs. BCCs expressed the lowest levels of CD40 and FasL. These results suggest that altered CD40 and FasL expression may be related with the progression of SCC, and the marked reduced expression of CD40 and FasL may explain the biologic behavior of BCCs.     

Delineation of two distinct deleted regions on chromosome 9 in human non-melanoma skin cancers

The mapping of the naevoid basal cell carcinoma syndrome (NBCCS) and the Ferguson-Smith syndrome to the same region on chromosome arm 9q has led to speculation that the two conditions may reflect different mutations within the same gene. Loss of heterozygosity of 9q alleles in both familial and sporadic basal cell carcinomas (BCCs) suggests that the NBCCS gene on 9q is acting as a tumour suppressor gene. Although LOH of 9q markers has not been studied in squamous cell neoplasms from patients with the Ferguson-Smith syndrome, chromosome 9 allele loss has been reported in sporadic squamous cell carcinomas (SCCs) of the skin. In order to characterise further the deleted region on chromosome 9 in BCCs and SCCs of the skin we have examined a series of non-melanoma skin cancers using a panel of highly informative microsatellite markers. Forty-four BCCs and 49 SCCs were studied. Loss of heterozygosity of one or more 9q markers was seen in 33 of the 44 BCCs. Only 4 of the 33 BCCs with 9q loss showed loss of 9p markers. Twenty-two BCCs showed loss of all informative 9q markers. Partial or interstitial 9q deletions were seen in 5 BCCs, and in 3 of these 5 BCCs the breakpoint occurred within the currently defined NBCCS locus. Chromosome 9 loss was seen in 16 of 49 SCCs. In contrast to the low frequency of 9p loss in BCCs, LOH of 9p markers was a common finding in SCCs, occurring in 15 of the 16 SCCs with chromosome 9 loss. In 5 SCCs 9p loss occurred with retention of 9q alleles. The different patterns of chromosome 9 loss in BCCs and SCCs and the failure to detect loss of markers at the Ferguson-Smith/NBCCS locus in 5 of 7 informative SCCs with partial chromosome 9 losses suggest that the targets for allelic deletion on chromosome 9 in BCCs and SCCs are different.     

Galectin-3 Expression in Tumor Progression and Metastasis of Papillary Thyroid Carcinoma

Galectin-3 plays important roles in cell adhesion, cell proliferation, apoptosis, neoplastic transformation, and metastasis. Galectin-3 expression has been evaluated in various malignant neoplasms to determine its effectiveness in differential diagnosis from benign lesions and its effects on carcinogenesis. There are few and somewhat controversial results regarding its changes through cancer progression in thyroid malignancies. We studied the presence of galectin-3 expression immunohistochemically and its relation with tumor invasiveness and lymph node metastasis in 89 cases of papillary carcinoma of the thyroid. Galectin overexpression was less frequent in cases with lymph node metastases compared with cases without lymph node metastasis (P = 0.001). Metastatic foci in lymph nodes showed a lower degree of galectin-3 overexpression than their primary lesions (P = 0.001). Degree of galectin-3 overexpression was also lower in larger tumors (P = 0.009). Additionally, a decreased level of galectin-3 overexpression was observed at the invasive edges of the tumors (P = 0.001). Galectin-3 overexpression is more profound in early stages of papillary carcinoma, and its expression intensity decreases during tumor progression. This finding is consistent with roles for galectin-3 in cell adhesion to other tumor cells and the matrix.     

Reduced human mismatch repair protein expression in the development of precancerous skin lesions to squamous cell carcinoma

Loss of human mismatch repair (hMSH2) gene function has been linked to hereditary non-polyposis colorectal cancer (HNPCC), Muir-Torre syndrome (MTS), and sporadic cancers, excluding skin cancers unrelated to MTS. We immunohistochemically examined 125 squamous cell carcinomas (SCCs) using a monoclonal antibody to the hMSH2 protein and compared the results with those for 106 precursor lesions of SCC, consisting of actinic keratosis (AK), Bowenoid type of actinic keratosis (BAK), and Bowen's disease (BOD). In contrast to the homogeneous immunoreactivity of proliferating cells composed of AK, BAK, and BOD, heterogeneous and diminished immunostaining to hMSH2 was observed in tumor cells of SCCs examined. In addition, two SCCs (2 of 125; 1.6%) at multiple loci exhibited a complete lack of immunoreaction to hMSH2. Immunohistochemical staining of hMSH2 was semiquantitatively scored as 0 (0% of total cells examined), 1 (less than 10%), 2 (10-50%), or 3 (more than 50%). Percentage preservation of and average score for hMSH2 expression in normal, AK, BAK, BOD, and SCC were 56% and 2.06, 100% and 2.80, 94% and 2.88, 83% and 2.78, 63% and 2.36, respectively. The percentage preservation of and average scores for hMSH2 in AK, BAK, and BOD were significantly higher than those in presumably normal skin (P<0.01). There were no significant differences in the percentage preservation of and average scores for hMSH2 between presumably normal skin and SCC. The score for hMSH2 expression was significantly correlated with score for sun exposure in presumably normal skin of each lesion (R=0.70). These findings for hMSH2 expression in precursor lesions and SCC suggest that promotion or activation of hMSH2 expression may be induced by the increased DNA damage caused by sun exposure and that diminished expression of it might occur according to the transformation from precancerous lesions to SCC.     

Expression of endogenous galectin-1 and galectin-3 in intrahepatic cholangiocarcinoma

Galectins, a family of beta-galactoside-binding animal lectins, might be involved in tumor progression. In this study, the expression patterns of galectin-1 and -3 were examined immunohistochemically in intrahepatic cholangiocarcinoma (ICC), with emphasis on its development and progression as well as its histopathologic features, by use of samples of normal intrahepatic bile duct (n = 20), biliary epithelial dysplasia (n = 15), ICC (n = 40), and a cholangiocarcinoma cell line, CCKS1. In normal intrahepatic bile ducts, galectin-3 was constitutively but weakly expressed, whereas galectin-1 was not expressed. In hepatolithiasis, biliary epithelial dysplasia was strongly positive for galectin-3 but negative for galectin-1. Galectin-3 was frequently and strongly expressed in the cytoplasm of well-differentiated ICCs, and its expression was significantly decreased and less intense or even absent in poorly differentiated ICCs. Galectin-1 was expressed in carcinoma cells in ICC, and its incidence and extent were correlated with histologic dedifferentiation of ICC. Proliferative cell nuclear antigen (PCNA) labeling index (LI) was higher in ICC cases positive for galectin-1 than in those that were negative. Galectin-1 was strongly expressed in cancerous stroma of ICC, and this stromal expression was related to histologic dedifferentiation of ICC. In the carcinoma cell line CCKS1, galectin-1 and -3 were expressed in the cytoplasm of carcinoma cells, and galectin-1 was additionally detected in the culture medium. These results suggest that galectin-1 was newly expressed on carcinoma cells of ICC, and its overexpression seems to be associated with neoplastic progression and proliferative activities, and the expression of galectin-1 in cancerous stroma may also be related to the progression of ICC. Galectin-3 expression in epithelial cells is up-regulated in the preneoplastic and early neoplastic stages of ICC, although galectin-3 tends to disappear at later stages of ICC. HUM PATHOL 32:302-310.     

Expression of cell cycle and apoptosis regulatory proteins in keratoacanthoma and squamous cell carcinoma

Some authors view keratoacanthoma (KA) as a variant of squamous cell carcinoma (SCC), while others consider it a separate entity that must be distinguished from SCC. Involution displayed by KA is an important difference between these two entities. It has been suggested that apoptosis plays a role in the involution process of KA, although the exact trigger for it remains unclear. A hundred and fifty specimens were included in this study, 30 cases for each of the following groups: normal skin (NS), proliferative keratoacanthoma (pKA), regressing keratoacanthoma (rKA), well-differentiated squamous cell carcinoma (wdSCC), and poorly differentiated squamous cell carcinoma (pdSCC). They were immunohistochemically examined for the expression of p53, Ki-67, bak, and bcl-2. Significantly higher p53 and Ki-67 expressions were observed in all tumor lesions examined as compared with NS. There was higher bak expression in KAs compared to NS and a significant reduction of bak expression in pdSCC together with a significant reduction of bak expression in SCCs compared to pKA. Bcl-2 expression was similar in NS and SCCs, but was lower in rKA. We found a significant positive correlation between p53 and Ki-67, p53 and Bak in NS and examined skin tumors. Lower bcl-2 expression in conjunction with higher bak expression in rKA suggests a possible role of these apoptosis-regulating proteins in tumor regression. In contrast to this finding, a steady level of bcl-2 expression in pdSCC combined with lower bak expression levels and a high proliferation rate could contribute to progression and aggressiveness in these tumors. Bak and p53 expression is a sun-related and age-dependent process in NS and skin tumors.     

Expression of the nucleoside diphosphate kinase in human skin cancers: an immunohistochemical study.

Expression of nucleoside diphosphate(NDP) kinase, which is homologous to the nm23 gene product in a variety of species, has been found to be inversely associated with metastatic potential. However, the relationship remains controversial according to the tumor cell types and experimental system, with conflicting results from different research groups. In order to determine whether NDP kinase expression serves as a marker for metastatic potential in human skin cancer, we assessed the levels of NDP kinase expression in 9 keratoacanthomas (KAs), 26 squamous cell carcinomas (SCCs), and 25 basal cell carcinomas (BCCs) using immunohistochemistry. The expression of NDP kinase was intense in KA and SCC compared with BCC. However, the difference of NDP kinase expression between KA and SCC was not statistically significant. And there was no statistically significant difference in NDP kinase expression between SCC with metastasis and SCC without metastasis. Our results contradict the hypothesis concerning the possible role of nm23 gene as a metastatic suppressor gene in human skin cancer. The mechanism of overexpression in various tumor cell types and its biological significance in cutaneous carcinogenesis remain to be determined.     

Expression of galectin-1 and galectin-3 in renal cell carcinoma; immunohistochemical study

Background and aimsGalectins comprise a large family of calcium independent lectins. Galectin-1 and galectin-3 contribute to neoplastic transformation, angiogenesis, and tumor metastasis in some cancers. This study aimed at studying the immunohistochemical expression of both galectin-1 and galectin-3 in renal cell carcinoma (RCC) variants and detecting the possible association of galectins with various clinicopathological parameters.Materials and methodsSections from 67 formalin-fixed paraffin-embedded tissue blocks of RCC variants were stained with galectin-1 and galectin-3. Expression was assessed in tumor tissue and adjacent renal parenchyma and was correlated with clinicopathological criteria.ResultsIn apparently normal renal parenchyma adjacent to tumor tissue, galectin-1 was expressed in 27 (40.2%) of specimens in renal tubules and glomeruli, while 34 (50.7%) of specimens showed galectin-3 expression in renal tubules sparing glomeruli. In tumor tissue, galectin-1 showed high expression in 47 (70.1%) and low expression in 20 (29.9%) of specimens. Galectin-3 had high expression in 15 (22.4%) and low expression in 52 (77.6%) of specimens. Significant association was detected between expression of galectin-1 and galectin-3 and the type of RCC (P = 0.032) and (P = 0.006), respectively. Significant inverse association was detected between the expression of galectin-3 and the presence of tumor haemorrhage and necrosis (P = 0.014) and (P = 0.039), respectively.ConclusionGalectin-1 and galectin-3 are overexpressed in RCC with different percentage in different subtypes. Galactin-1expression is more in tumor tissue than surrounding renal parenchyma suggesting that it has a carcinogenic role. Galectin-1 and galectin-3 overexpression in chromophobe RCC suggests that they may have diagnostic role.     

Immunohistochemical analysis of TIMP-3 and MMP-9 in actinic keratosis,squamous cell carcinoma of the skin,and basal cell carcinoma

The expression of metalloproteinases and their inhibitors has been related to different invasive and metastatic potentials in cancer. This study aims to investigate the immunohistochemical expression of TIMP-3 and MMP-9 in samples of basal cell carcinoma (BCC), squamous cell carcinoma of the skin (SCC), and actinic keratosis (AK). Immunohistochemistry was performed to evaluate the expression of TIMP-3 and MMP-9 in samples of BCC (n = 22), SCC (n = 10), and AK (n = 15). Ten fields of both tumor parenchyma and tumor stroma were photographed and counted in image software. The ratio of positive cells to total cells was used to quantify the staining. A higher expression of MMP-9 was found in tumor stroma of SCC compared to BCC and AK. No significant differences in TIMP-3 expression were observed among the groups. Considering the well-described differences between these neoplasms, these results provide additional evidence of the role of MMP-9 in tumor invasiveness of keratinocyte-derived tumors.