Increase in CD30 ligand/CD153 and TNF-alpha expressing mast cells in basal cell carcinoma

Multicenter proteome-wide Mendelian randomization study identifies causal plasma proteins in melanoma and non-melanoma skin cancers

This study addresses the diagnostic and therapeutic challenges in malignant melanoma (MM) and non-melanoma skin cancers (NMSC). We aim to identify circulating proteins causally linked to MM and NMSC traits using a multicenter Mendelian randomization (MR) framework. We utilized large-scale cis-MR to estimate the impact of numerous plasma proteins on MM, NMSC, squamous cell carcinoma (SCC), and basal cell carcinoma (BCC). To ensure robustness, additional analyses like MR Steiger and Bayesian colocalization are conducted, followed by replication through meta-analytical methods. The associations between identified proteins and outcomes are also validated at the tissue level using Transcriptome-Wide Association Study methods. Furthermore, a protein-protein interaction analysis is conducted to explore the relationship between identified proteins and existing cancer medication targets. The MR analysis has identified associations of 13 plasma proteins with BCC, 2 with SCC, and 1 with MM. Specifically, ASIP and KRT5 are associated with BCC, with ASIP also potentially targeting MM. CTSS and TNFSF8 are identified as promising druggability candidates for BCC. This multidimensional approach nominates ASIP, KRT5, CTSS, and TNFSF8 as potential diagnostic and therapeutic targets for skin cancers.

Corticotropin-releasing hormone receptor-1 is increased in mast cells in psoriasis and actinic keratosis, but not markedly in keratinocyte skin carcinomas

Corticotropin-releasing hormone receptor-1 (CRH-R1) is expressed in human mast cells, but its role in skin diseases is unknown. By using a sequential double-staining technique, the mast cell expression of CRH-R1 was investigated in biopsies from lesional and non-lesional skin samples of patients with actinic keratosis (AK), basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and psoriasis. Dermal tryptase+ mast cells expressed CRH-R1 immunoreactivity in the non-lesional skin in all patient groups. The CRH-R1 expression was significantly increased in the lesional skin of AK (p = 0.03) and psoriasis (p = 0.02), non-significantly in BCC (p = 0.129), but not increased in SCC. To investigate the regulation of CRH-R1, the LAD2 mast cell line was irradiated with UVB or stimulated with CRH or 1,25-dihydroxyvitamin D3 [1,25-(OH)2 D3 ]. Consequently, UVB at 90 mJ/cm2 (p = 0.041) and 120 mJ/cm2 (p = 0.039) decreased CRH-R1 expression. Instead, CRH at 100 and 1000 nM increased CRH-R1 immunostaining, but did not affect the proliferative response. The treatment with 10 and 100 nM 1,25-(OH)2 D3 led to a noticeable increase in CRH-R1 staining. After irradiating with UVB, the concentration of CRH increased in the conditioned medium, but not in sonicated LAD2 mast cells. In conclusion, the lack of sufficient levels of CRH-R1 in mast cells may be related to diminished antitumoural response in SCC and possibly in BCC.

The Immune Microenvironment in Basal Cell Carcinoma

The immune system plays a key role in the suppression and progression of basal cell carcinoma (BCC). The primary aetiological factor for BCC development is exposure to ultraviolet radiation (UVR) which, particularly in lighter Fitzpatrick skin types, leads to the accumulation of DNA damage. UVR has roles in the generation of an immunosuppressive environment, facilitating cancer progression. Rates of BCC are elevated in immunosuppressed patients, and BCC may undergo spontaneous immune-mediated regression. Histologic and immunohistochemical profiling of BCCs consistently demonstrates the presence of an immune infiltrate and associated immune proteins. Early studies of immune checkpoint inhibitors reveal promising results in BCC. Therefore, the host immune system and tumor responses to it are important in BCC pathogenesis. Understanding these interactions will be beneficial for disease prognostication and therapeutic decisions.

The emerging role of mast cells in skin cancers: involved cellular and molecular mechanisms

Skin cancers are the most common cancers worldwide. They can be divided into nonmelanoma skin cancers (NMSC) including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and less common lymphomas and merkel cell carcinoma, and melanomas. Melanomas comprise less than 5% of skin cancer rate but are responsible for more than 90% of skin cancer death. Mast cells (MCs) are multifunctional cells that play an important role in inflammatory and allergic reactions. They attract other key players of the immune system by releasing cytokines. Healthy human skin comprises MCs under physiological status, and the number can increase under certain conditions including skin malignancies postulating their possible role in pathogenesis of and immunity against skin cancers. MCs respond to cytokines released by tumor stromal cells, release mediators (including histamine and tryptase), and induce the neovascularization, degradation of extracellular matrix (ECM), and induce mitogenesis. However, MCs may use molecular mechanisms to exert immunosuppressive activity including releasing complement C3, lower expression of CD40L, and overexpression of enzymes with vitamin D3 metabolizing activity including CYP27A1 and CYP27B1. This review summarizes the current knowledge on the role of MCs in pathogenesis and immunity against skin cancers.

Establishment of Immune-related Gene Pair Signature to Predict Lung Adenocarcinoma Prognosis

Tumor microenvironment (TME) has critical impacts on the pathogenesis of lung adenocarcinoma (LUAD). However, the molecular mechanism of TME effects on the prognosis of LUAD patients remains unclear. Our study aimed to establish an immune-related gene pair (IRGP) model for prognosis prediction and internal mechanism investigation. Based on 702 TME-related differentially expressed genes (DEGs) extracted from The Cancer Genome Atlas (TCGA) training cohort using the ESTIMATE algorithm, a 10-IRGP signature was established to predict LUAD patient prognosis. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses showed that DEGs were significantly associated with tumor immune response. In both TCGA training and Gene Expression Omnibus validation datasets, the risk score was an independent prognostic factor for LUAD patients using Lasso-Cox analysis, and patients in the high-risk group had poorer prognosis than those in the low-risk one. In the high-risk group, M2 macrophage and neutrophil infiltrations were higher, while the levels of T cell follicular helpers were significantly lower. The gene set enrichment analysis results showed that DNA repair signaling pathways were involved. In summary, we established an IRGP signature as a potential biomarker to predict the prognosis of LUAD patients.

CD40 Ligand Is Increased in Mast Cells in Psoriasis and Actinic Keratosis but Less So in Epithelial Skin Carcinomas

The expression of CD40 ligand (CD40L) in mast cells was investigated in biopsies from lesional and non-lesional skin samples of patients with psoriasis, actinic keratosis (AK), basal cell carcinoma, and squamous cell carcinoma using a sequential double-staining technique. The percentage of CD40L⁺ mast cells was higher in the lesional than in the non-lesional skin (p < .003). Interestingly, this percentage was lower in both carcinomas than in psoriasis and actinic keratosis (p < .025). Cells immunopositive for CD40 receptor were increased in all lesion types but especially so in carcinomas. The results suggest a dysregulated anti-tumoral immune response by mast cell CD40L in skin carcinomas.

Controversial role of mast cells in skin cancers

Cancer development is a multistep process characterized by genetic and epigenetic alterations during tumor initiation and progression. The stromal microenvironment can promote tumor development. Mast cells, widely distributed throughout all tissues, are a stromal component of many solid and haematologic tumors. Mast cells can be found in human and mouse models of skin cancers such as melanoma, basal and squamous cell carcinomas, primary cutaneous lymphomas, haemangiomas and Merkel cell carcinoma. However, human and animal studies addressing potential functions of mast cells and their mediators in skin cancers have provided conflicting results. In several studies, mast cells play a pro-tumorigenic role, whereas in others, they play an anti-tumorigenic role. Other studies have failed to demonstrate a clear role for tumor-associated mast cells. Many unanswered questions need to be addressed before we understand whether tumor-associated mast cells are adversaries, allies or simply innocent bystanders in different types and subtypes of skin cancers.

Abnormal interactions between perifollicular mast cells and CD8+ T-cells may contribute to the pathogenesis of alopecia areata

Alopecia areata (AA) is a CD8+ T-cell dependent autoimmune disease of the hair follicle (HF) in which the collapse of HF immune privilege (IP) plays a key role. Mast cells (MCs) are crucial immunomodulatory cells implicated in the regulation of T cell-dependent immunity, IP, and hair growth. Therefore, we explored the role of MCs in AA pathogenesis, focusing on MC interactions with CD8+ T-cells in vivo, in both human and mouse skin with AA lesions. Quantitative (immuno-)histomorphometry revealed that the number, degranulation and proliferation of perifollicular MCs are significantly increased in human AA lesions compared to healthy or non-lesional control skin, most prominently in subacute AA. In AA patients, perifollicular MCs showed decreased TGFβ1 and IL-10 but increased tryptase immunoreactivity, suggesting that MCs switch from an immuno-inhibitory to a pro-inflammatory phenotype. This concept was supported by a decreased number of IL-10+ and PD-L1+ MCs, while OX40L+, CD30L+, 4–1BBL+ or ICAM-1+ MCs were increased in AA. Lesional AA-HFs also displayed significantly more peri- and intrafollicular- CD8+ T-cells as well as more physical MC/CD8+ T-cell contacts than healthy or non-lesional human control skin. During the interaction with CD8+ T-cells, AA MCs prominently expressed MHC class I and OX40L, and sometimes 4–1BBL or ICAM-1, suggesting that MC may present autoantigens to CD8+ T-cells and/or co-stimulatory signals. Abnormal MC numbers, activities, and interactions with CD8+ T-cells were also seen in the grafted C3H/HeJ mouse model of AA and in a new humanized mouse model for AA. These phenomenological in vivo data suggest the novel AA pathobiology concept that perifollicular MCs are skewed towards pro-inflammatory activities that facilitate cross-talk with CD8+ T-cells in this disease, thus contributing to triggering HF-IP collapse in AA. If confirmed, MCs and their CD8+ T-cell interactions could become a promising new therapeutic target in the future management of AA.

Experimentally induced psoriatic lesion associates with interleukin (IL)-6 in mast cells and appearance of dermal cells expressing IL-33 and IL-6 receptor

Mast cells are involved in the development of psoriatic lesion, but it is not known how mast cells are activated or whether mast cell cytokines are expressed during the lesion development. In this study, the Köbner reaction was induced in uninvolved psoriatic skin of 18 patients using the tape-stripping technique, and a sequence of biopsies was collected at 0 days, 2 h and 3 days or at 0 days, 1 day and 7 days for histochemical analysis. Eight patients developed the Köbner reaction verified at the follow-up visit 2-2·5 weeks later. No significant differences were observed in total tryptase(+) mast cells, psoriasis area and severity index and age/sex. Instead, the percentage of tryptase(+) mast cells showing interleukin (IL)-6 immunoreactivity was significantly higher in biopsies from Köbner-positive patients than in those from Köbner-negative patients. IL-33 is a known inducer of IL-6 in mast cells, and the number of IL-33(+) cells increased significantly in Köbner-positive dermal skin at days 3-7. The number of dermal cells with IL-6 receptor (IL-6R, CD126) also increased in Köbner-positive skin at days 3-7. Unexpectedly, the number of IL-6R(+) cells was even higher in Köbner-negative skin at days 3-7. In the chronic plaque of 10 other psoriatic patients, the numbers of IL-6(+) mast cells and dermal cells showing IL-6R were higher than those in the non-lesional skin. In conclusion, the positive Köbner reaction is associated with IL-6 in mast cells and appearance of IL-6R(+) and IL-33(+) dermal cells. This suggests that a previously unrecognized vicious circle may develop in the early psoriatic lesion.

ATP induces protein arginine deiminase 2-dependent citrullination in mast cells through the P2X7 purinergic receptor

Posttranslational modifications regulate physiology either by directly modulating protein function or by impacting immune recognition of self-proteins. Citrullination is a posttranslational modification formed by the conversion of arginine residues into the citrulline amino acid by protein arginine deiminase (PAD) family members. We have identified mast cells as a major source of the PAD2 enzyme. Activation of the P2X7 purinergic receptor (P2X7) by the inflammatory "danger" signal ATP induces PAD2 activity and robust protein citrullination. P2X7-mediated activation of PAD2 is sensitive to p38 MAPK and protein kinase C inhibitors, and PAD2 regulates the expression of the TNFR2, Adamts-9, and Rab6b transcripts in mast cells. Further, the PAD2 enzyme and its citrullinated substrate proteins are released from mast cells on activation with ATP. PAD2 expression is closely linked with inflammation in rheumatoid arthritis (RA) synovial tissue, and PAD2 and citrullinated proteins are found in the synovial fluid of RA patients. In addition, RA is associated with the development of autoantibodies to citrullinated self-proteins. Our results suggest that P2X7 activation of mast cells may play a role in inflammation by providing PAD2 and PAD2 substrates access to the extracellular space.

Anti-apoptotic BFL-1 is the major effector in activation-induced human mast cell survival

Mast cells are best known for their role in allergic reactions, where aggregation of FcεRI leads to the release of mast cell mediators causing allergic symptoms. The activation also induces a survival program in the cells, i.e., activation-induced mast cell survival. The aim of the present study was to investigate how the activation-induced survival is mediated. Cord blood-derived mast cells and the mast cell line LAD-2 were activated through FcεRI crosslinking, with or without addition of chemicals that inhibit the activity or expression of selected Bcl-2 family members (ABT-737; roscovitine). Cell viability was assessed using staining and flow cytometry. The expression and function of Bcl-2 family members BFL-1 and MCL-1 were investigated using real-time quantitative PCR and siRNA treatment. The mast cell expression of Bfl-1 was investigated in skin biopsies. FcεRI crosslinking promotes activation-induced survival of human mast cells and this is associated with an upregulation of the anti-apoptotic Bcl-2 family member Bfl-1. ABT-737 alone or in combination with roscovitine decreases viability of human mast cells although activation-induced survival is sustained, indicating a minor role for Bcl-X(L), Bcl-2, Bcl-w and Mcl-1. Reducing BFL-1 but not MCL-1 levels by siRNA inhibited activation-induced mast cell survival. We also demonstrate that mast cell expression of Bfl-1 is elevated in birch-pollen-provocated skin and in lesions of atopic dermatitis and psoriasis patients. Taken together, our results highlight Bfl-1 as a major effector in activation-induced human mast cell survival.

Association of a novel functional promoter variant (rs2075533 C>T) in the apoptosis gene TNFSF8 with risk of lung cancer--a finding from Texas lung cancer genome-wide association study

Published genome-wide association studies (GWASs) have identified few variants in the known biological pathways involved in lung cancer etiology. To mine the possibly hidden causal single nucleotide polymorphisms (SNPs), we explored all SNPs in the extrinsic apoptosis pathway from our published GWAS dataset for 1154 lung cancer cases and 1137 cancer-free controls. In an initial association analysis of 611 tagSNPs in 41 apoptosis-related genes, we identified only 10 tagSNPs associated with lung cancer risk with a P value<10(-2), including four tagSNPs in DAPK1 and three tagSNPs in TNFSF8. Unlike DAPK1 SNPs, TNFSF8 rs2181033 tagged other four predicted functional but untyped SNPs (rs776576, rs776577, rs31813148 and rs2075533) in the promoter region. Therefore, we further tested binding affinity of these four SNPs by performing the electrophoretic mobility shift assay. We found that only rs2075533T allele modified levels of nuclear proteins bound to DNA, leading to significantly decreased expression of luciferase reporter constructs by 5- to -10-fold in H1299, HeLa and HCT116 cell lines compared with the C allele. We also performed a replication study of the untyped rs2075533 in an independent Texas population but did not confirm the protective effect. We further performed a mini meta-analysis for SNPs of TNFSF8 obtained from other four published lung cancer GWASs with 12  214 cases and 47  721 controls, and we found that only rs3181366 (r2=0.69 with the untyped rs2075533) was associated to lung cancer risk (P=0.008). Our findings suggest a possible role of novel TNFSF8 variants in susceptibility to lung cancer.

Mast cell chymase is present in uterine cervical carcinoma and it detaches viable and growing cervical squamous carcinoma cells from substratum in vitro

Increased numbers of mast cells is a typical feature of a variety of human cancers. The major mediators in the secretory granules of the MC(TC) type of mast cells, serine proteinases tryptase and chymase, may be involved in squamous cell carcinoma (SCC) lesions by inducing matrix remodeling and epithelial cell detachment. The objective of this study was to analyze immunohistochemically whether MC(TC) mast cells as well as protease inhibitors, squamous cell carcinoma antigens (SCCAs), are present in the uterine cervical SCC. In addition, the effect of tryptase and chymase on uterine cervical SCC cell lines was studied in vitro. Here we report that tryptase- and chymase-positive mast cells are present in significant numbers in the peritumoral stroma of SCC lesions. Also, weak SCCA-2 immunoreactivity is observed in the SCC lesions, but only SCCA-1 in uterine cervical specimens with nonspecific inflammation. In cell cultures, especially chymase, but not tryptase, was shown to induce effective detachment of viable, growing and non-apoptotic SiHa SCC cells from substratum. Chymase also detached viable ME-180 SCC cells from substratum as well as degraded fibronectin. In contrast, normal keratinocytes underwent apoptotic cell death after similar prolonged chymase treatment. No inhibition of chymase was detected by SiHa cell sonicates nor did these cells express marked SCCA immunopositivity. MC(TC) mast cells containing tryptase and chymase are present in the peritumoral stroma of uterine cervical SCC and the malignant cells are only weakly immunoreactive for the chymase inhibitor SCCA-2. It is chymase that appears to be capable of inducing effective detachment of viable and growing SCC cells and therefore, it may release SCC cells from a tumor leading to spreading of malignant cells.

Mast cells enhance proliferation of B lymphocytes and drive their differentiation toward IgA-secreting plasma cells

The evidence of a tight spatial interaction between mast cells (MCs) and B lymphocytes in secondary lymphoid organs, along with the data regarding the abundance of MCs in several B-cell lymphoproliferative disorders prompted us to investigate whether MCs could affect the proliferation and differentiation of B cells. To this aim, we performed coculture assays using mouse splenic B cells and bone marrow-derived MCs. Both nonsensitized and activated MCs proved able to induce a significant inhibition of cell death and an increase in proliferation of naive B cells. Such proliferation was further enhanced in activated B cells. This effect relied on cell-cell contact and MC-derived interleukin-6 (IL-6). Activated MCs could regulate CD40 surface expression on unstimulated B cells and the interaction between CD40 with CD40 ligand (CD40L) on MCs, together with MC-derived cytokines, was involved in the differentiation of B cells into CD138(+) plasma cells and in selective immunoglobulin A (IgA) secretion. These data were corroborated by in vivo evidence of infiltrating MCs in close contact with IgA-expressing plasma cells within inflamed tissues. In conclusion, we reported here a novel role for MCs in sustaining B-cell expansion and driving the development of IgA-oriented humoral immune responses.

Increased mast cell expression of PAR-2 in skin inflammatory diseases and release of IL-8 upon PAR-2 activation

Mast cells are increasingly present in the lesional skin of chronic skin inflammatory diseases including psoriasis and basal cell carcinoma (BCC). It has previously been shown that proteinase-activated receptor (PAR)-2 is expressed by mast cells, and tryptase is a potent activator of this receptor. In this study, skin biopsies from both healthy-looking and lesional skin of patients with psoriasis and superficial spreading BCC were collected and the expression of PAR-2 immunoreactivity in tryptase-positive mast cells was analysed. PAR-2 expression was confirmed in vitro in different mast cell populations. Cord-blood derived mast cells (CBMC) were stimulated with a PAR-2 activating peptide, 2-furoyl-LIGRLO-NH(2). Consequently, IL-8 and histamine production was analysed in the supernatants. We observed a significant increase in the percentage of mast cells expressing PAR-2 in the lesional skin of psoriasis and BCC patients compared with the healthy-looking skin. HMC-1.2, LAD-2 and CBMC mast cells all expressed PAR-2 both intracellularly and on the cell surface. CBMC activation with the PAR-2 activating peptide resulted in an increased secretion of IL-8, but no histamine release was observed. Furthermore, both PAR-2 and IL-8 were co-localized to the same tryptase-positive mast cells in the lesional BCC skin. These results show that mast cells express increased levels of PAR-2 in chronic skin inflammation. Also, mast cells can be activated by a PAR-2 agonist to secrete IL-8, a chemokine which can contribute to the progress of inflammation.

Human mast cells adhere to and migrate on epithelial and vascular basement membrane laminins LM-332 and LM-511 via alpha3beta1 integrin

Mast cells (MCs) are multifunctional effectors of the immune system that are distributed in many tissues, often in close association with the basement membrane of blood vessels, epithelium and nerves. Laminins (LMs), a family of large alphabetagamma heterotrimeric proteins, are major components of basement membrane that strongly promote cell adhesion and migration. In this study, we investigated the role of LM isoforms and their integrin receptors in human MC biology in vitro. In functional assays, alpha3-(LM-332) and alpha5-(LM-511) LMs, but not alpha1-(LM-111), alpha2-(LM-211), or alpha4-(LM-411) LMs, readily promoted adhesion and migration of cultured MCs. These activities were strongly enhanced by various stimuli. alpha3-LM was also able to costimulate IL-8 production. Among LM-binding integrins, MCs expressed alpha(3)beta(1), but not alpha(6)beta(1), alpha(7)beta(1), or alpha(6)beta(4), integrins. Blocking Abs to alpha(3)beta(1) integrin caused inhibition of both cell adhesion and migration on alpha3- and alpha5-LMs. Immunohistochemical studies on skin showed that MCs colocalized with epithelial and vascular basement membranes that expressed alpha3- and alpha5-LMs and that MCs expressed alpha(3) integrin but not alpha(6) integrin(s). These results demonstrate a role for alpha3- and alpha5-LMs and their alpha(3)beta(1) integrin receptor in MC biology. This may explain the intimate structural and functional interactions that MCs have with specific basement membranes.

Is there a role for mast cells in psoriasis?

Mast cells have traditionally been considered as effector cells in allergy but during the last decade it has been realized that mast cells are essentially involved in the mechanisms of innate and acquired immunity. Upon activation by anaphylactic, piecemeal degranulation or degranulation-independent mechanisms mast cells can secrete rapidly or slowly a number of soluble mediators, such as serine proteinases, histamine, lipid-derived mediators, cytokines, chemokines and growth factors. Mast cells can express cell surface co-stimulatory receptors and ligands, and they can express MHC class II molecules and thereby present antigens. These soluble factors and cell surface molecules can interact with other cells, such as endothelial cells, keratinocytes, sensory nerves, neutrophils, T cell subsets and antigen presenting cells which are essential effectors in the development of skin inflammation. Besides promoting inflammation, mast cells may attempt in some circumstances to suppress the inflammation and epidermal growth but the regulation between suppressive and proinflammatory mechanisms is unclear. Psoriasis is characterized by epidermal hyperplasia and chronic inflammation where tryptase- and chymase-positive MC(TC) mast cells are activated early in the developing lesion and later the cells increase in number in the upper dermis with concomitant expression of cytokines and TNF superfamily ligands as well as increased contacts with neuropeptide-containing sensory nerves. Due to the intimate involvement of mast cells in immunity and chronic inflammation the role of mast cells in psoriasis is discussed in this review.

Cervical squamous carcinoma cells are resistant to the combined action of tumor necrosis factor-alpha and histamine whereas normal keratinocytes undergo cytolysis

BACKGROUND

Previous reports showed that mast cells can typically be found in the peritumoral stroma of cervix carcinomas as well as in many other cancers. Both histamine and TNF-alpha are potent preformed mast cell mediators and they can act simultaneously after release from mast cells. Thus, the effect of TNF-alpha and histamine on cervical carcinoma cell lines was studied.

METHODS AND RESULTS

TNF-alpha alone induced slight growth inhibition and cell cycle arrest at G0/G1 phase in SiHa cells, but increased their migration. Histamine alone had no effect on cells. In addition, TNF-alpha and histamine in combination showed no additional effect over that by TNF-alpha alone, although SiHa cells were even pretreated with a protein synthesis inhibitor. Furthermore, TNF-alpha-sensitive ME-180 carcinoma cells were also resistant to the combination effect of TNF-alpha and histamine. In comparison, TNF-alpha or histamine alone induced growth inhibition in a non-cytolytic manner in normal keratinocytes, an effect that was further enhanced to cell cytolysis when both mediators acted in combination. Keratinocytes displayed strong TNF receptor (TNFR) I and II immunoreactivity, whereas SiHa and ME-180 cells did not. Furthermore, cervix carcinoma specimens revealed TNF-alpha immunoreactivity in peritumoral cells and carcinoma cells. However, the immunoreactivity of both TNFRs was less intense in carcinoma cells than that in epithelial cells in cervical specimens with non-specific inflammatory changes.

CONCLUSION

SiHa and ME-180 cells are resistant to the cytolytic effect of TNF-alpha and histamine whereas normal keratinocytes undergo cytolysis, possibly due to the smaller amount of TNFRs in SiHa and ME-180 cells. In the cervix carcinoma, the malignant cells may resist this endogenous cytolytic action and TNF-alpha could even enhance carcinoma cell migration.