Ultraviolet B(UVB)-induced cox-2 expression in murine skin: an immunohistochemical study

Cyclooxygenase (COX) is the rate-limiting enzyme in the production of prostaglandins from arachidonic acid. This enzyme exists in at least two isoforms, COX-1 and COX-2. COX-1 is constitutively expressed in most tissues and plays various physiological roles. However, COX-2 expression is induced by a variety of agents, which include pro-inflammatory agents and mitogens. Evidence exists to indicate that increased expression of COX-2 occurs in several types of epithelial neoplasms. In this study, we show the effect of chronic exposure of murine skin to carcinogenic UVB on cutaneous COX-2 expression. SKH-1 mice were irradiated with 180 mJ/cm(2) UVB daily for five days a week for periods ranging from 1 to 20 weeks. Nontumor bearing skin areas of irradiated mice, skin of age-matched controls and benign papillomas and malignant tumors were assessed immunohistochemically for COX-2 expression in these mice. No epidermal staining occurred in any of the non-UVB-treated controls throughout the experiment. Epidermal COX-2 expression only occurred in UVB-irradiated mice. After 1 and 5 weeks of irradiation, patchy epidermal staining mostly confined to the granular layer and stratum corneum was observed. At week 9, staining intensity had increased, particularly in the granular layer. At week 13, staining was uniformly seen in all epidermal layers with particular prominence in the basal cell layer underlying areas of visible epidermal hyperplasia. It is of interest that the most intense staining was seen in the perinuclear region of keratinocytes and at the plasma membrane. At week 20, COX-2 staining was predominant in the granular layer, although in some tissue sections, the entire epidermis was positive. In benign papillomas, staining was confined to the superficial layers of the epidermis and in squamous cell carcinomas (SCCs), patchy staining in the granular and spinous layers predominated. In general, COX-2 expression was more intense in well-differentiated SCCs than in papillomas. In summary, our results indicate that COX-2 serves as an early marker of epidermal UVB exposure and its expression increases in benign papillomas and in SCCs. These results suggest that pharmacological intervention using specific COX-2 inhibitors could have anticarcinogenic effects in UVB-induced human skin cancer.     

Karyometry of nuclei from actinic keratosis and squamous cell cancer of the skin

OBJECTIVE: To use karyometric analysis methods to compare actinic keratoses (AKs) to squamous cell carcinomas (SCCs) to determine if SCCs showed a logical progression beyond that seen in AKs and to explore variability within and between lesion types to better understand distinctions between the 2. STUDY DESIGN: Biopsies from 31 subjects with AKs were obtained from upper inner arm skin, forearm skin and AK lesions. Biopsies from 23 different subjects in a related subproject provided SCC biopsies for comparison. RESULTS: Karyometric measures of nuclear abnormality and sun damage were derived. Mean actinic damage levels progressed logically from inner arm to sun-exposed skin, to AK, to SCC. Considerable heterogeneity existed at the case level. Unsupervised learning methods revealed 2 distinct clusters of progressed lesions with different nuclear signatures, reflecting differing levels of actinic damage. Number of AKs and SCCs and invasiveness and differentiation of SCCs were distributed across both clusters in roughly equivalent proportions. CONCLUSION: Karyometric methods, shown previously to be capable of sensitively detecting subtle nuclear changes, revealed the possibility of 2 progression pathways, each containing AKs and SCCs. This finding may have prognostic implications.     

Therapy of murine squamous cell carcinomas with 2-difluoromethylornithine

Targeted overexpression of an ornithine decarboxylase (ODC) transgene to mouse skin (the K6/ODC mouse) significantly enhances susceptibility to carcinogenesis. While in most strain backgrounds the predominant tumor type resulting from initiation-promotion protocols is benign squamous papilloma, K6/ODC mice on a FVB/N background develop malignant squamous cell carcinomas (SCCs) rapidly and in high multiplicity after carcinogen treatment. We have investigated the utility of polyamine-based therapy against SCCs in this model using the ODC inhibitor 2-difluoromethylornithine delivered orally. At a 2% concentration in drinking water, DFMO caused rapid tumor regression, but in most cases, tumors eventually regrew rapidly even in the presence of DFMO. The tumors that regrew were spindle cell carcinomas, an aggressive undifferentiated variant of SCC. At 1% DFMO in the drinking water, tumors also responded rapidly, but tumor regrowth did not occur. The majority of DFMO-treated SCCs were classified as complete responses, and in some cases, apparent tumor cures were achieved. The enzymatic activity of ODC, the target of DFMO, was substantially reduced after treatment with 1% DFMO and the high SCC polyamine levels, especially putrescine, were also significantly lowered. Based on the results of BrdUrd labeling and TUNEL assays, the effect of DFMO on SCC growth was accompanied by a significant reduction in tumor proliferation with no increase in the apoptotic index. These results demonstrate that SCCs, at least in the mouse, are particularly sensitive to polyamine-based therapy.     

Detection of Merkel cell polyomavirus in cervical squamous cell carcinomas and adenocarcinomas from Japanese patients

ABSTRACT: BACKGROUND: Merkel cell polyomavirus (MCPyV) was identified originally in Merkel cell carcinoma (MCC), a rare form of human skin neuroendocrine carcinoma. Evidence of MCPyV existence in other forms of malignancy such as cutaneous squamous cell carcinomas (SCCs) is growing. Cervical cancers became the focus of our interest in searching for potentially MCPyV-related tumors because: (i) the major histological type of cervical cancer is the SCC; (ii) the uterine cervix is a common site of neuroendocrine carcinomas histologically similar to MCCs; and (iii) MCPyV might be transmitted during sexual interaction as demonstrated for human papillomavirus (HPV). In this study, we aimed to clarify the possible presence of MCPyV in cervical SCCs from Japanese patients. Cervical adenocarcinomas (ACs) were also studied. RESULTS: Formalin-fixed paraffin-embedded tissue samples from 48 cervical SCCs and 16 cervical ACs were examined for the presence of the MCPyV genome by polymerase chain reaction (PCR) and sequencing analyses. PCR analysis revealed that 9/48 cervical SCCs (19 %) and 4/16 cervical ACs (25 %) were positive for MCPyV DNA. MCPyV-specific PCR products were sequenced to compare them with reference sequences. The nucleotide sequences in the MCPyV large-T (LT)-sequenced region were the same among MCPyV-positive cervical SCCs and AC. Conversely, in the MCPyV viral protein 1 (VP1)-sequenced, two cervical SCCs and three cervical ACs showed several nucleotide substitutions, of which three caused amino acid substitutions. These sequencing results suggested that three MCPyV variants of the VP1 were identified in our cases. Immunohistochemistry showed that the LT antigen was expressed in tumor cells in MCPyV-positive samples. Genotyping of human HPV in the MCPyV-positive samples revealed that infected HPVs were HPV types 16, 31 and 58 for SCCs and HPV types 16 and 18 for ACs. CONCLUSIONS: This study provides the first observation that MCPyV coexists in a subset of HPV-associated cervical cancers from Japanese patients. The prevalence of MCPyV in these lesions was close to that observed in the cutaneous SCCs. Further worldwide epidemiological surveys are warranted to determine the possible association of MCPyV with pathogenesis of cervical cancers.     

Lewis y antigen is expressed in oral squamous cell carcinoma cell lines and tissues, but disappears in the invasive regions leading to the enhanced malignant properties irrespective of sialyl-Lewis x

Expression and implication of carbohydrate antigens in squamous cell carcinomas (SCCs) in oral cavity was examined. In the cell lines, type 2H and Lewis y antigens were markedly expressed. In the tissues from SCC patients and benign disorders, type 2H was highly expressed in hyperplasia (96.4 %), displasia (92.9 %) and SCC (100 %). Lewis y was, in turn, expressed mainly in cancer tissues (91.3 %), suggesting that Lewis y is a cancer-associated antigen. Normal oral mucosa showed no expression of these blood group antigens. Surprisingly, Lewis y antigen disappeared in the invasion sites where Ki-67 was definitely stained. Over-expression of Lewis y with manipulation of a fucosyltransferase cDNA resulted in suppression of cell growth and invasion, and knockdown of Lewis y also brought about increased cell growth and invasion. In either situations, no changes in the expression of sialyl-Lewis x could be found. Lowered tumor growth and invasion into surrounding tissues were also shown in Lewis y-positive SCC grafts in nu/nu mice. All these results together with alternative staining between Lewis y and Ki-67 in cancer tissues and FUT1 transfectants suggested that loss of Lewis y is a crucial event for the late stage of SCCs.     

Biological and molecular aspects of radiation carcinogenesis in mouse skin

The process of mouse skin carcinogenesis can be operationally subdivided into at least three stages which have been termed initiation, promotion, and progression. Ionizing radiation has been found to be a weak initiator of malignant squamous cell carcinomas (SCCs) when radiation was followed by repeated treatments of the skin with the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Besides SCCs, ionizing radiation was found to induce, independent of tumor promoters, basal cell carcinomas (BCCs), a tumor histology not normally seen with chemical carcinogens and mouse skin. Fractionated doses of 1 MeV electrons were found to enhance the conversion of chemically induced benign papillomas to malignant SCCs. In addition to the biological studies, questions related to dominant transforming genes and differential gene expression in the radiation-initiated mouse skin tumors have been explored. Distinct non-ras dominant transforming gene(s) have been detected in radiation-initiated, TPA-promoted SCCs. Differences in the expression pattern of tumor-associated genes were seen in comparing chemically to radiation-induced benign and malignant skin tumors. Therefore, ionizing radiation has been shown to be active in the initiation of malignant skin tumors and progression of benign to malignant tumors in the mouse skin. The ability to divide the process of carcinogenesis into multiple stages in the mouse skin model has facilitated mechanistic studies that may elucidate the molecular pathways involved in radiation-versus chemically induced tumor development.     

Osteopontin expression in normal skin and non-melanoma skin tumors.

Osteopontin (OPN) is an adhesive, matricellular glycoprotein, whose expression is elevated in many types of cancer and has been shown to facilitate tumorigenesis in vivo. To understand the role of OPN in human skin cancer, this study is designed to determine whether OPN is expressed in premalignant [solar/actinic keratosis (AK)] and in malignant skin lesions such as squamous cell carcinomas (SCC) and basal cell carcinomas (BCC), as well as in normal skin exposed or not exposed to sunlight. Immunohistochemical analyses showed that OPN is expressed in SCC (20/20 cases) and in AK (16/16 cases), which are precursors to SCC, but is absent or minimally expressed in solid BCC (17 cases). However, positive staining for OPN was observed in those BCC that manifest differentiation toward epidermal appendages such as keratotic BCC. In sunlight-exposed normal skin, OPN is minimally expressed in the basal cell layer, but in contrast to those not exposed to sunlight, OPN is more prominent in the spinous cell layer with increasing intensity toward the granular cell layer. Additionally, OPN is expressed in the hair follicles, sebaceous glands, and sweat glands of normal skin. In conclusion, these data suggest that OPN is associated with keratinocyte differentiation and that it is expressed in AK and SCC, which have metastatic potential, but minimally expressed in solid BCC.     

Expression of cyclo-oxygenase-2 in naturally occurring squamous cell carcinomas in dogs.

Squamous cell carcinoma is one of the most common cancers in humans and is also a frequently diagnosed neoplasm in dogs. Induction of cyclo-oxygenase-2 (COX-2), a key rate-limiting enzyme in prostaglandin biosynthesis, has been implicated in the oncogenesis of various cancers in humans, including squamous cell carcinomas. However, expression of COX-2 has not been reported in spontaneous squamous cell carcinomas of non-human species. Canine squamous cell carcinomas share several similarities with the human disease. Therefore, the objective of this study was to determine whether COX isoenzymes were expressed in naturally occurring cases of squamous cell carcinomas in dogs. Canine normal skin (n=4) and squamous cell carcinomas (n=40) were studied by immunohistochemistry and immunoblotting analysis using polyclonal antibodies selective for COX-1 or COX-2. COX-2 was strongly expressed by neoplastic keratinocytes in all cases of squamous cell carcinomas, whereas no COX-2 was detected in normal skin and in the non-neoplastic skin and oral mucosa included in the tumor tissue samples (p<0.01). Immunoblotting analysis confirmed the restricted expression of COX-2 (72,000--74,000 molecular weight doublet) in squamous cell carcinomas only. In contrast, faint COX-1 staining was found in normal skin and in squamous cell carcinomas. This study demonstrates for the first time that COX-2 is induced in canine squamous cell carcinomas, and provides a new model to investigate the role and regulation of COX-2 gene expression in naturally occurring squamous cell carcinomas. (J Histochem Cytochem 49:867-875, 2001)     

Glycoprotein CD44 expression in benign, premalignant and malignant epithelial lesions of the larynx: an immunohistochemical study including correlation with Rb, p53, Ki-67 and PCNA.

CD44 is an integral membrane glycoprotein that has diverse functions in cell-cell and cell-substrate interactions. It has been suggested that it may be a determinant of metastatic and invasive behavior in carcinomas. The immunohistochemical expression of CD44 was examined in a series of 34 squamous cell carcinomas, 13 in situ carcinomas, 35 cases with various degrees of epithelial dysplasia, 10 papillomas and 17 cases of keratosis. We used the monoclonal mouse anti-human phagocytic glycoprotein-1 CD44 (clone DF 1485), on formalin-fixed, paraffin-embedded tissue. CD44 expression was correlated with the expression of Rb and p53 proteins, with the proliferative indices Ki-67 and PCNA as well as with conventional clinicopathological data. The mean value of CD44 expression was 78.84 in squamous cell carcinomas, 78.04 in situ carcinomas, 54.93 in dysplasia, 26.8 in papillomas and 24.97 in keratosis. There was no significant difference of CD44 expression between in situ and invasive carcinomas. However, a strong difference of reaction between carcinomas and the other cases was observed. CD44 expression was statistically higher in dysplastic lesions than the cases of keratosis (p < 0.0001) and papillomas (p = 0.01). In the group of invasive carcinomas, CD44 expression was statistically correlated with pRb (p = 0.011), while in preinvasive lesions it was correlated with PCNA (p = 0.016). The relationship with the degree of dysplasia or grade of carcinoma and p53 protein expression was insignificant. These observations suggest that CD44 expression may be involved in the multiple mechanism of the development and progression of laryngeal lesions and may help to predict the risk of transformation of the benign or precancerous lesions to cancer.     

IKK&alpha; enhances human keratinocyte differentiation and determines the histological variant of epidermal squamous cell carcinomas

Squamous cell carcinomas (SCCs) of the skin display different clinical features according to their epithelial differentiation grade and histological variant. Understanding the causes of these divergences might increase the curability of SCCs. Therefore, it is important to study the mechanisms of differentiation in keratinocytes. IKK (I&kappa;B kinase) &alpha; is an important protein for epidermal morphogenesis, although the pathways through which it exerts its function are unknown and controversy exists about its role in cancer development. We show that enhanced IKK&alpha; expression increases both early and terminal differentiation of human keratinocytes through an E-cadherin-dependent mechanism. Increased expression of IKK&alpha; in mouse tumorigenic epidermal cells leads to changes in the differentiation pattern of the resulting SCCs, originating a distinct histological variant that resembles the human acantholytic SCC (ASCC) variant. Although human ASCCs have an aggressive clinical course and high risk of metastasis, nothing is known about their etiology. We show that human ASCCs, as observed in the counterpart IKK&alpha; murine tumors, express high levels of both IKK&alpha; and E-cadherin, with absence of keratins K1 and K10, usually co-expressed with IKK&alpha; and E-cadherin. The tight correlation between the properties of both murine and human ASCC variants strongly suggests that IKK&alpha; is responsible for the development of this human SCC variant.     

Keratinocyte growth factor induces gene expression signature associated with suppression of malignant phenotype of cutaneous squamous carcinoma cells

Keratinocyte growth factor (KGF, fibroblast growth factor-7) is a fibroblast-derived mitogen, which stimulates proliferation of epithelial cells. The expression of KGF by dermal fibroblasts is induced following injury and it promotes wound repair. However, the role of KGF in cutaneous carcinogenesis and cancer progression is not known. We have examined the role of KGF in progression of squamous cell carcinoma (SCC) of the skin. The expression of KGF receptor (KGFR) mRNA was lower in cutaneous SCCs (n = 6) than in normal skin samples (n = 6). Expression of KGFR mRNA was detected in 6 out of 8 cutaneous SCC cell lines and the levels were downregulated by 24-h treatment with KGF. KGF did not stimulate SCC cell proliferation, but it reduced invasion of SCC cells through collagen. Gene expression profiling of three cutaneous SCC cell lines treated with KGF for 24 h revealed a specific gene expression signature characterized by upregulation of a set of genes specifically downregulated in SCC cells compared to normal epidermal keratinocytes, including genes with tumor suppressing properties (SPRY4, DUSP4, DUSP6, LRIG1, PHLDA1). KGF also induced downregulation of a set of genes specifically upregulated in SCC cells compared to normal keratinocytes, including genes associated with tumor progression (MMP13, MATN2, CXCL10, and IGFBP3). Downregulation of MMP-13 and KGFR expression in SCC cells and HaCaT cells was mediated via ERK1/2. Activation of ERK1/2 in HaCaT cells and tumorigenic Ha-ras-transformed HaCaT cells resulted in downregulation of MMP-13 and KGFR expression. These results provide evidence, that KGF does not promote progression of cutaneous SCC, but rather suppresses the malignant phenotype of cutaneous SCC cells by regulating the expression of several genes differentially expressed in SCC cells, as compared to normal keratinocytes.     

Expression of p53, bcl-2 and Ki-67 in cervical intraepithelial neoplasia and invasive squamous cell carcinoma of the uterine cervix

OBJECTIVE: To assess the expression of p53, bcl-2 and Ki-67 in the progression of cervical neoplasia. STUDY DESIGN: A total of 131 cervical specimens, consisting of normal cervical epithelium (n = 43), cervical intraepithelial neoplasia (CIN) lesions (n =40) and cervical squamous cell carcinomas (SCCs) (n = 48) were examined immunohistochemically in paraffin sections for expression of p53, bcl-2 and Ki-67. RESULTS: Immunoreactivity of p53 was found in 27% of SCC cases, but it had no significant relationship with SCC staging (p = 0.791). Immunoreactivity of bcl-2 was observed in 33% of CIN 3 cases. We found a significant relationship (chi2 test: p = 0.009) between the expression of bcl-2 and CIN grading. Ki-67 index was higher in high grade CIN (HGCIN: CIN 2 and 3) and SCC lesions compared to normal cervices. Ki-67 index showed a correlation with bcl-2 protein expression (p = 0.030), but not with p53 protein expression (p = 0.239). CONCLUSION: HGCIN is an early stage to demonstrate the alteration of bcl-2 and Ki-67 expressions. Progression of neoplasia in the uterine cervix is accompanied by an increase of antiapoptotic protein, bcl-2 as well as cellular proliferation.     

Tumor-associated antigen expression and growth requirements predict tumorigenesis in squamous cell carcinoma

Squamous cell carcinomas (SCCs) are the most common malignancies in man. While clinical specimens are theoretically ideal to study tumor development and progression, practical difficulties such as normal cell contamination, the presence of different cell types. and limited material make preclinical studies of model systems involving a homogeneous population of normal or transformed cells preferable. Tumor-associated antigens (TAAs) found on the cell surface, including integrins, mucins, cadherins, growth factor receptors, membrane bound antigens, and glycoproteins are known to play an important role in squamous carcinogenesis. We hypothesized that (1) alterations in TAA expression in vitro predict in vivo alterations, (2) analysis of a group of TAAs would provide a better indication of SCC tumorigenesis than any single marker, and (3) SCCs with independence from exogenous growth factors in vitro would demonstrate the most aggressive growth in vivo. The cell line which grew best in vitro without serum or other supplements demonstrated the most rapid tumor growth. whereas cell lines which grew only with supplements rarely formed tumors. Normal keratinocytes. eight SCC and two immortal keratinocyte cell lines were evaluated by flow cytometry for the expression of 10 cell surface markers, including alpha and beta integrins, minor blood group-related carbohydrate determinants. carcinoembryonic antigen-related proteins, E-cadherin, and GA733 (epithelial glycoprotein. epithelial cell adhesion molecule). None of the cell lines with abnormal expression of < or = 2 markers formed tumors, whereas all lines with altered expression of > or = 3 markers formed tumors. Using GA733 expression as an example, we found that altered TAA expression in vitro predicted the presence of TAA alterations in clinical specimens. In summary, in vitro independence from supplements for optimal growth and altered expression of > or = 3 cell surface markers were good predictors of SCC tumorigenesis. These findings may be useful in decreasing the need for whole animal tumorigenicity experiments.     

Increased expression of inducible nitric oxide synthase and cyclooxygenase-2 in pancreatic cancer

Despite recognition of the devastating malignant potential of the pancreatic ductal cancer, the exact pathophysiological events contributing to tumor growth remain to be elucidated. Expression levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 were found to be frequently elevated in several types of human cancer and have also been directly linked to carcinogenesis. The purpose of this study was to determine the expression of COX-1, COX-2 and iNOS in human pancreatic cancer and matched normal adjacent tissue by the Western blot assay. Marked COX-2 expression was observed in cancer tissue compared with the normal surrounding tissue. The iNOS protein was markedly expressed only in pancreatic cancer while the expression of COX-1 was similar in both normal and cancerous tissue. Our findings indicate that COX-2 up-regulation and the expression of iNOS in pancreatic cancer, not seen in normal tissue, may play a role in the pathogenesis of human pancreatic adenocarcinomas. These observations suggest that COX-2 and iNOS may be a target for prevention or treatment of pancreatic carcinomas.     

Relationship of up-regulation of 67-kd laminin receptor to grade of cervical intraepithelial neoplasia and to high-risk HPV types and prognosis in cervical cancer

OBJECTIVE: To evaluate the 67-kd laminin receptor (67LR) in cervical cancer and its molecular links to oncogenic HPV types. STUDY DESIGN: As part of the HPV-PathogenlSS Study, a series of 150 squamous cell carcinomas (SCCs) and 152 carcinoma in situ (CIN) lesions were examined using immunohistochemical staining for LR67 and tested for HPV using polymerase chain reaction (PCR) with 3 primer sets (MY09/11, GP5+/GP6+, SPF). Followup data were available for all SCC patients, and 67 CIN lesions had been monitored with serial PCR for HPV clearance/persistence after cone treatment. RESULTS: 67LR expression increased in parallel with increasing grade of CIN (p = 0. 0001), with the most dramatic up-regulation upon the transition from CIN 2 to CIN 3 and further to SCC. This increased expression was associated with CIN 3/cancer at OR 17.04 (95% CI 7.28-39.87). The seemingly significant association of 67LR with high-risk HPV (HR-HPV) detection (OR 2.20, 95% CI 1.27-3.80) was due to confounding by the histologic grade (Mantel-Haenszel common OR = 1.118, 95% CI 0.576-2.168). Using performance indicators, 67LR expression was of little value as a marker of HR-HPV type, and it did not predict clearance/persistence of HR-HPV after treatment of CIN. Similarly, 67LR expression was not an independent prognostic factor in cervical cancer. CONCLUSION: In cervical carcinogenesis, both integrin- and nonintegrin-type LRs (67LR) probably have functions complementary to each other, mediating transient early and stable adhesions, respectively. Up-regulated 67LR expression is significantly associated with progression from CIN 2 to CIN 3 as a marker of cell proliferation. 67LR is probably orchestrated by mechanisms independent of HR-HPV oncoproteins, which seem to be more closely associated with integrin-type laminin receptors.