Expression of p16, CD95, CD95L and Helix pomatia agglutinin in relapsing and nonrelapsing very thin melanoma

Cell proliferation in cutaneous malignant melanoma: relationship with neoplastic progression

The establishment of the diagnosis of cutaneous malignant melanoma (CMM) always calls for histopathological confirmation. Further to the recognition of the CMM aspects, immunohistochemistry is helpful, in particular, in determining the size of the replicative compartment and the activity in each of the cell cycle phases (G(1), S, G(2), M). The involvement of cancer stem cells and transient amplifier cells in CMM genesis is beyond doubt. The proliferation activity is indicative of the neoplastic progression and is often related to the clinical growth rate of the neoplasm. It allows to distinguish high-risk CMM commonly showing a high growth rate, from those CMMs of lower malignancy associated with a more limited growth rate. The recruitment and progression of CMM cells in the cell cycle of proliferation depend on mitogen-activated protein kinase (MAPK) pathway and result from a loss of control normally involving a series of key regulatory cyclins. In addition, the apoptotic pathways potentially counteracting any excess in proliferative activity are out of the dependency of specific regulatory molecular mechanisms. Key molecular components involved in the deregulation of the growth fraction, the cell cycle phases of proliferation, and apoptosis are presently described in CMM.

P16 protein expression in primary cutaneous melanoma with positive and negative lymph node biopsies: Particular aspects of a study performed at the Hospital de Clinicas de Porto Alegre, Brazil

BACKGROUND

Cutaneous melanoma dermal invasion, identified through measurement of maximum tumour thickness and sentinel lymph node (SLN) biopsy, is important to establish melanoma prognosis and progression. P16 protein expression has been shown to be a predictive factor for melanoma evolution and prognosis.

OBJECTIVE

To investigate p16 protein expression in cutaneous melanomas with and without SLN metastasis.

PATIENTS AND METHODS

Sixty-seven paraffin-embedded cutaneous melanoma specimens of patients who had undergone SLN investigation were evaluated from 1995 to 2007. SLN biopsy was negative for metastasis in 34 of these patients (controls); in the remaining 33 patients, SLN biopsy was positive (cases). The expression of p16 protein in the primary tumour was measured using an immunohistochemical assay. The samples were classified according to their nuclear expression.

RESULTS

P16 nuclear expression was absent in 14 cases and in 15 controls; P=0.812. There was no statistically significant difference in p16 nuclear expression between cases and controls.

CONCLUSIONS

The present study does not support the findings of other studies that suggest p16 protein expression is important in the prognosis of cutaneous melanoma.

High frequency of p16(INK4A) promoter methylation in NRAS-mutated cutaneous melanoma

The p16(INK4A) tumor suppressor is often deleted, or otherwise inactivated, in malignant melanoma. To investigate the loss of p16(INK4A) in greater detail, we analyzed 77 cutaneous melanoma metastases. Of these 56 retained at least one p16(INK4A) allele, and 21 had biallelic deletions. Using methylation-specific PCR, direct sequencing, and immunohistochemical methods, we analyzed p16(INK4A) promoter methylation, mutations, and protein expression, respectively. In addition, 14 corresponding primary tumors were analyzed for protein expression. Results were compared to clinicopathological parameters and previously obtained data regarding mutations in proto-oncogenes NRAS and BRAF. Results revealed that p16(INK4A) promoter methylation was present in 15 of 59 (25%) metastases; nonsynonymous mutations in 9 of 56 (16%) metastases; and protein expression in 12 of 67 (18%) metastases. Protein expression was lost during progression from primary to metastatic tumors, 71% (10 of 14) and 43% (6 of 14) being positive, respectively. However, the genetic and epigenetic alterations of p16(INK4A) observed could not explain the lack of p16(INK4A) protein in 27 metastases, indicating the presence of additional inactivating mechanisms for p16(INK4A). Interestingly, p16(INK4A) promoter methylation was significantly overrepresented in NRAS-mutated samples compared to NRAS wild-type samples (P=0.0004), indicating an association between these two events.

[Skin cancer: what's new in clinical research?]

Every year skin cancer is the subject of many publications. In this review of the recent literature, we selected epidemiological, clinical, and therapeutic data published between October 2006 and September 2007. Some of the studies presented in conferences in 2007 are also mentioned. New epidemiological data have been provided regarding the incidence of different types of skin cancers, the effect of certain risk factors or drug or food protective factors, the overall improvement of survival in melanoma, the epidemiological, clinical, and/or therapeutic particularities of rapidely growing melanomas and thick melanomas, and the relations between sun exposure, skin cancers, and other solid tumors. New prognostic studies in melanoma have improved the evaluation of prognosis in specific situations such as thin melanoma, acrolentiginous melanoma, and melanoma with positive sentinel lymph nodes (depending on the type of positivity) or negative sentinel lymph nodes. Important results on adjuvant interferon in melanoma have been presented. Clinical trials evaluating new therapeutic approaches in stage III and IV melanoma are going on. Several studies confirmed the clinical benefit of adjuvant irradiation on the tumor site in Merkel cell carcinoma. New treatments are being studied or have been approved in refractory forms of cutaneous T-cell lymphoma and in inoperable forms of squamous cell carcinoma and dermatofibrosarcoma protuberans.

Cigarette smoke induces endoplasmic reticulum stress and the unfolded protein response in normal and malignant human lung cells

Background

Although lung cancer is among the few malignancies for which we know the primary etiological agent (i.e., cigarette smoke), a precise understanding of the temporal sequence of events that drive tumor progression remains elusive. In addition to finding that cigarette smoke (CS) impacts the functioning of key pathways with significant roles in redox homeostasis, xenobiotic detoxification, cell cycle control, and endoplasmic reticulum (ER) functioning, our data highlighted a defensive role for the unfolded protein response (UPR) program. The UPR promotes cell survival by reducing the accumulation of aberrantly folded proteins through translation arrest, production of chaperone proteins, and increased degradation. Importance of the UPR in maintaining tissue health is evidenced by the fact that a chronic increase in defective protein structures plays a pathogenic role in diabetes, cardiovascular disease, Alzheimer's and Parkinson's syndromes, and cancer.

Methods

Gene and protein expression changes in CS exposed human cell cultures were monitored by high-density microarrays and Western blot analysis. Tissue arrays containing samples from 110 lung cancers were probed with antibodies to proteins of interest using immunohistochemistry.

Results

We show that: 1) CS induces ER stress and activates components of the UPR; 2) reactive species in CS that promote oxidative stress are primarily responsible for UPR activation; 3) CS exposure results in increased expression of several genes with significant roles in attenuating oxidative stress; and 4) several major UPR regulators are increased either in expression (i.e., BiP and eIF2α) or phosphorylation (i.e., phospho-eIF2α) in a majority of human lung cancers.

Conclusion

These data indicate that chronic ER stress and recruitment of one or more UPR effector arms upon exposure to CS may play a pivotal role in the etiology or progression of lung cancers, and that phospho-eIF2α and BiP may have diagnostic and/or therapeutic potential. Furthermore, we speculate that upregulation of UPR regulators (in particular BiP) may provide a pro-survival advantage by increasing resistance to cytotoxic stresses such as hypoxia and chemotherapeutic drugs, and that UPR induction is a potential mechanism that could be attenuated or reversed resulting in a more efficacious treatment strategy for lung cancer.