Differences in sialyl-Tn antigen expression between keratoacanthomas and cutaneous squamous cell carcinomas

Differences in the mitochondrial microsatellite instability of Keratoacanthoma and cutaneous squamous cell carcinoma

Keratoacanthoma (KA) is a common cutaneous neoplasm which often resembles typical squamous cell carcinoma (SCC) in both its clinical and historical presentation. Several studies have attempted to identify methods for distinguishing between KA and SCC, however, none of these have proven to play any obvious roles in these tumors. Given this we went on to evaluate mitochondrial microsatellite instability (mtMSI) in KA and SCC in an effort to understand these tumors better. DNA was isolated from paired normal and tumoral tissues donated by 57 KA patients and 43 SCC patients. MtMSI was then analyzed using eight microsatellite markers and was observed in 2 (3.5%) of the 57 KA patients and 8 (18.6%) of the 43 SCC patients, respectively. MtMSI was also shown to affect different locations depending on tumor type. In KA patients, mtMSI was detected at mitochondrial D514 D-loop and presented with (CA) n repeats, in contrast, all of the SCC patient experienced mtMSI at the D310 with (C)n repeats of the D-loop region. These differences in location were found to be significant, which may support the hypothesis that KA and SCC have different pathogenetic pathways. Our results also suggest that mtMSI may be a candidate for developing novel differential diagnostic methods for KA and SCC.

Mucin glycosylating enzyme GALNT2 regulates the malignant character of hepatocellular carcinoma by modifying the EGF receptor

Extracellular glycosylation is a critical determinant of malignant character. Here, we report that N-acetylgalactosaminyltransferase 2 (GALNT2), the enzyme that mediates the initial step of mucin type-O glycosylation, is a critical mediator of malignant character in hepatocellular carcinoma (HCC) that acts by modifying the activity of the epidermal growth factor receptor (EGFR). GALNT2 mRNA and protein were downregulated frequently in HCC tumors where these events were associated with vascular invasion and recurrence. Restoring GALNT2 expression in HCC cells suppressed EGF-induced cell growth, migration, and invasion in vitro and in vivo. Mechanistic investigations revealed that the status of the O-glycans attached to the EGFR was altered by GALNT2, changing EGFR responses after EGF binding. Inhibiting EGFR activity with erlotinib decreased the malignant characters caused by siRNA-mediated knockdown of GALNT2 in HCC cells, establishing the critical role of EGFR in mediating the effects of GALNT2 expression. Taken together, our results suggest that GALNT2 dysregulation contributes to the malignant behavior of HCC cells, and they provide novel insights into the significance of O-glycosylation in EGFR activity and HCC pathogenesis.

Sorafenib-induced premalignant and malignant skin lesions

PURPOSE

To review characteristics of patients who develop premalignant and malignant skin lesions while on sorafenib therapy and discuss implications for subsequent treatment of their primary malignancies.

BACKGROUND

Sorafenib is a newly developed multitargeted protein kinase inhibitor reported to induce a variety of adverse cutaneous effects, rarely including actinic keratoses, keratocanthomas, and squamous cell carcinomas (SCCs).

METHODS

Published reports of individuals who have developed cutaneous lesions demonstrating atypia of the epidermis are reviewed. In addition, a 77-year-old man who developed not only an SCC but also verrucas within one month of taking sorafenib monotherapy for metastatic adenocarcinoma of the lung is described.

RESULTS

Cutaneous lesions develop most commonly in Caucasian men older than 40 years without previous histories of skin cancer, within two weeks to three years of starting sorafenib therapy. Currently there is no definitive explanation for the relationship between sorafenib and cutaneous neoplasms. Management typically involves treatment of skin lesions with cryotherapy or excision with at least a brief discontinuation of sorafenib. In patients whose primary malignancies were responding well, sorafenib therapy was continued with close follow-up.

CONCLUSIONS

The possibility of rapidly developing actinic keratoses, keratocanthomas, verrucas, and SCC during treatment with sorafenib, warrants close dermatologic follow-up and a lower threshold for biopsy and treatment of suspicious cutaneous lesions. Development of a sorafenib-induced SCC is not an absolute contraindication for continued use of sorafenib therapy; however, the drug should be briefly discontinued until lesions are treated.

Differential expression of MUC1 and carbohydrate antigens in primary and secondary head and neck squamous cell carcinoma

BACKGROUND

In head and neck squamous cell carcinoma (HNSCC), tumor markers may be helpful to evaluate prognosis accurately as well as to improve therapy selection. Detection of human MUC1 has been widely employed for the evaluation of carcinoma patients. This article aims to study MUC1, Tn, sTn, and Lewis antigenic expression in primary HNSCC, lymph node metastasis, and local recurrences.

METHODS

We used immunohistochemistry, tissue homogenization and differential centrifugation, isopycnic density gradient centrifugation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western blot.

RESULTS

In primary tumors, MUC1 was detected in 80.0% of the samples; sLewis x in 23.2%, Lewis x in 45.6%, and Lewis y in 40.8%. Tn and sTn were found in 4.0% and 6.4% of samples, respectively. In metastatic lymph nodes, MUC1 showed a similar positive reaction as in primary tumors. Lewis y was detected in 20% lymph nodes whereas Lewis x, sLewis x, Tn, and sTn did not show differences. Some recurrences expressed MUC1 and only a few Lewis antigens, whereas Tn and sTn were not detected.

CONCLUSION

In primary HNSCC and metastatic nodes, a high expression of MUC1 and Lewis antigens was detected that diminished in local recurrences. We also found that differentiated tumors mainly expressed a linear pattern of MUC1CT and Lewis x.

Keratoacanthoma and infundibulocystic squamous cell carcinoma

One of the major controversies in dermatopathology is the relationship of keratoacanthoma to squamous cell carcinoma. Leaders in the field remain polarized in their views. Carcinomas with distinct follicular pattern of differentiation have been described in reference to the isthmus as trichilemmal carcinomas, to the follicular bulb as pilomatricomal carcinomas, and to the stem cell or rapidly amplifying cell compartment as basal cell carcinomas (trichoblastic carcinomas). We have employed the term infundibulocystic or infundibular squamous cell carcinoma to identify a subset of squamous cell carcinomas that demonstrate this pattern of differentiation. The recognition of infundibular squamous cell carcinoma is important in that well-differentiated examples are likely to have been diagnosed as keratoacanthoma, whereas moderately or poorly differentiated tumors would be more often reported as squamous cell carcinomas, leading to underrecognition of these infundibular variants of squamous cell carcinoma. The descriptive term infundibulocystic or infundibular squamous cell carcinoma may help to better define an alternative follicular-based pathway to squamous cell carcinoma distinct from the more common evolution from solar keratoses and also refine the classification of keratoacanthoma.

Are keratoacanthomas variants of squamous cell carcinomas? A comparison of chromosomal aberrations by comparative genomic hybridization

Keratoacanthoma (KA) is a benign keratinocytic neoplasm that usually presents as a solitary nodule on sun-exposed areas, develops within 6-8 weeks and spontaneously regresses after 3-6 months. KAs share features such as infiltration and cytological atypia with squamous cell carcinomas (SCCs). Furthermore, there are reports of KAs that have metastasized, invoking the question of whether or not KA is a variant of SCC. To date no reported criteria are sensitive enough to discriminate reliably between KA and SCC, and consequently there is a clinical need for discriminating markers. We screened fresh frozen material from 132 KAs and 37 SCCs for gross chromosomal aberrations by using comparative genomic hybridization (CGH). Forty-nine KAs (37.1%) and 31 SCCs (83.7%) showed genomic aberrations, indicating a higher degree of chromosomal instability in SCCs. Gains of chromosomal material from 1p, 14q, 16q, 20q, and losses from 4p were seen significantly more frequently in SCCs compared with KAs (P-values 0.0033, 0.0198, 0.0301, 0.0017, and 0.0070), whereas loss from 9p was seen significantly more frequently in KAs (P-value 0.0434). The patterns of recurrent aberrations were also different in the two types of neoplasms, pointing to different genetic mechanisms involved in their developments.

Expression of sialyl-Tn epitopes on beta1 integrin alters epithelial cell phenotype, proliferation and haptotaxis

Sialyl-Tn (STn) is a tumor-associated carbohydrate antigen overexpressed in various carcinomas. To obtain its expression, murine carcinoma cells were transfected with the cDNA encoding ST6GalNAc I, a glycosyltransferase that acts exclusively on O-glycans. Overexpression of this enzyme led to the expected expression of cell surface STn epitopes. Surprisingly, the transfectants (STn+ cells) presented dramatic morphological changes and altered behavior. These STn+ cells lost the epithelial appearance of parental cells, became larger, more elongated and presented disorganized actin stress fibers. Additionally, their proliferation was impaired and their ability to migrate on fibronectin and hyaluronic acid was severely reduced. By contrast their adhesion on fibronectin remained unchanged. The major glycoprotein carrying the STn epitope was shown to be the integrin beta1 subunit. Anti-STn antibodies could restore migration of STn+ cells on fibronectin. A constitutively active permeant form of RhoA (TAT-RhoA(Val-14)) also restored motility on fibronectin of STn+ cells as well as a parental STn-cellular phenotype. These observations indicate that overexpression of ST6GalNAc I leads to a major change of the O-glycosylation of the integrin beta1 chain which in turn impairs the integrin-mediated signalling and leads to major alterations in morphology and cell behavior.

Biological behavior of keratoacanthoma and squamous cell carcinoma: telomerase activity and COX-2 as potential markers

Distinguishing keratoacanthoma from squamous cell carcinoma is a persistent issue in pathology practice. Solitary keratoacanthoma is a self-limiting lesion as opposed to rather aggressive clinical behavior of squamous cell carcinoma. Several markers were studied to understand their biology and to separate these two lesions on a firm basis, but without much success. In this study, we plan to utilize recent markers such as telomerase activity and cyclooxygenase-2 (COX-2) along with more established marker p53 in understanding the biologic differences between keratoacanthoma and squamous cell carcinoma. We studied 17 well to moderately differentiated squamous cell carcinoma and 24 early proliferative phase keratoacanthoma by immunohistochemistry for the expression of p53 protein, COX-2 and telomerase activity. Higher telomerase activity was found in 11/17 squamous cell carcinoma (65%) compared to 4/24 (17%) of keratoacanthoma. Similarly, stronger expression of p53 and COX-2 was detected in 12 (71%) and 11 (65%) cases of squamous cell carcinoma compared to 2 (8%) and 2 (8%) cases of keratoacanthoma respectively. A highly significant 'P' value was obtained for telomerase activity (0.001), p53 (0.000), and COX-2 (0.001). Telomerase activity, COX-2, and p53 expression provide evidence that keratoacanthoma and squamous cell carcinoma are indeed distinct entities and also help in discriminating these two lesions, which closely resemble each other on conventional morphology. Although these markers present new insights into the biologic variation of keratoacanthoma and squamous cell carcinoma, they are of limited value for routine application in histological distinction of these two lesions. The differential expression of markers also explains the sustained proliferation observed in squamous cell carcinoma, compared to a shorter lifespan and involution in keratoacanthoma.

Tumor-associated carbohydrate antigens defining tumor malignancy: basis for development of anti-cancer vaccines

Tumors expressing a high level of certain types of tumor-associated carbohydrate antigens (TACAs) exhibit greater metastasis and progression than those expressing low level of TACAs, as reflected in decreased patient survival rate. Well-documented examples of such TACAs are: (i) H/Le(y)/Le(a) in primary non-small cell lung carcinoma; (ii) sialyl-Le(x) (SLe(x)) and sialyl-Le(a) (SLe(a)) in various types of cancer; (iii) Tn and sialyl-Tn in colorectal, lung, breast, and many other cancers; (iv) GM2, GD2, and GD3 gangliosides in neuroectodermal tumors (melanoma and neuroblastoma); (v) globo-H in breast, ovarian, and prostate cancer; (vi) disialylgalactosylgloboside in renal cell carcinoma. Some glycosylations and TACAs suppress invasiveness and metastatic potential. Well-documented examples are: (i) blood group A antigen in primary lung carcinoma; (ii) bisecting beta1 --> 4GlcNAc of N-linked structure in melanoma and other cancers; (iii) galactosylgloboside (GalGb4) in seminoma. The biochemical mechanisms by which the above glycosylation changes promote or suppress tumor metastasis and invasion are mostly unknown. A few exceptional cases in which we have some knowledge are: (i) SLe(x) and SLe(a) function as E-selectin epitopes promoting tumor cell interaction with endothelial cells; (ii) some tumor cells interact through binding of TACA to specific proteins other than selectin, or to specific carbohydrate expressed on endothelial cells or other target cells (carbohydrate-carbohydrate interaction); (iii) functional modification of adhesive receptor (integrin, cadherin, CD44) by glycosylation. So far, a few successful cases of anti-cancer vaccine in clinical trials have been reported, employing TACAs whose expression enhances malignancy. Examples are STn for suppression of breast cancer, GM2 and GD3 for melanoma, and globo-H for prostate cancer. Vaccine development canbe extended using other TACAs, with the following criteria for success: (i) the antigen is expressed highly on tumor cells; (ii) high antibody production depending on two factors: (a) clustering of antigen used in vaccine; (b) choice of appropriate carrier protein or lipid; (iii) high T cell response depending on choice of appropriate carrier protein or lipid; (iv) expression of the same antigen in normal epithelial tissues (e.g., renal, intestinal, colorectal) may not pose a major obstacle, i.e., these tissues are not damaged during immune response. Idiotypic anti-carbohydrate antibodies that mimic the surface profile of carbohydrate antigens, when administered to patients, elicit anti-carbohydrate antibody response, thus providing an effect similar to that of TACAs for suppression of tumor progression. An extension of this idea is the use of peptide mimetics of TACAs, based on phage display random peptide library. Although examples are so far highly limited, use of such "mimotopes" as immunogens may overcome the weak immunogenicity of TACAs in general.

Comparison of oncostatin M expression in keratoacanthoma and squamous cell carcinoma

Oncostatin M (OSM) is a 28-kDa glycoprotein, produced by stimulated macrophages and T lymphocytes, that inhibits the proliferation and induces differentiation of a number of different cell lines derived from solid tumors. To determine whether keratoacanthoma (KA) is unique or a variant of squamous cell carcinoma (SCC), we compared the immunohistochemical expression of OSM in the tumor cells and peri- and intratumoral macrophages of 21 mature KAs, 7 regressing KAs, and 27 SCCs. An inverse correlation was identified between OSM tumor labeling and the density of OSM-labeled tumor-associated macrophages for KAs (r = -.4; P = .09). OSM tumor expression was significantly more frequent and more intense in KAs than in SCCs (95% versus 63%; P < .01). In contrast, the density of OSM-labeled macrophages was significantly higher in SCCs compared with mature KAs (7/3 high power fields versus 4/3 high power fields; P = .02). These OSM-positive macrophages were predominantly located at the advancing, infiltrative margins of both neoplasms. Regressing KAs demonstrated a decreased level of OSM tumor expression compared with mature KAs (53% versus 95%; P = .001), but there was no difference in density of OSM-labeled macrophages. Both the above differences and the overlapping patterns of OSM expression suggest that KAs are a variant of SCC where OSM, possibly as an autocrine factor, may mediate KA's overwhelming but not absolute tendency to involute.