Clinical Activity of Celecoxib in Metastatic Malignant Melanoma

New insights into the anti-inflammatory and anti-melanoma mechanisms of action of azelaic acid and other Fusarium solani metabolites via in vitro and in silico studies

Metabolites exploration of the ethyl acetate extract of Fusarium solani culture broth that was isolated from Euphorbia tirucalli root afforded five compounds; 4-hydroxybenzaldehyde (1), 4-hydroxybenzoic acid (2), tyrosol (3), azelaic acid (4), malic acid (5), and fusaric acid (6). Fungal extract as well as its metabolites were evaluated for their anti-inflammatory and anti-hyperpigmentation potential via in vitro cyclooxygenases and tyrosinase inhibition assays, respectively. Azelaic acid (4) exhibited powerful and selective COX-2 inhibition followed by fusaric acid (6) with IC50 values (2.21 ± 0.06 and 4.81 ± 0.14 μM, respectively). As well, azelaic acid (4) had the most impressive tyrosinase inhibitory effect with IC50 value of 8.75 ± 0.18 μM compared to kojic acid (IC50 = 9.27 ± 0.19 μM). Exclusive computational studies of azelaic acid and fusaric acid with COX-2 were in good accord with the in vitro results. Interestingly, this is the first time to investigate and report the potential of compounds 3-6 to inhibit cyclooxygenase enzymes. One of the most invasive forms of skin cancer is melanoma, a molecular docking study using a set of enzymes related to melanoma suggested pirin to be therapeutic target for azelaic acid and fusaric acid as a plausible mechanism for their anti-melanoma activity.

In-vitro and in-vivo inhibition of melanoma growth and metastasis by the drug combination of celecoxib and dacarbazine

Celecoxib has been found to be effective in cancer prevention and treatment. Its combination with other chemotherapeutic agents was reported to produce synergistic/additive effects on various cancers. Dacarbazine (DTIC) is one of the most commonly used drugs in the treatment of metastatic melanoma. This investigation aimed to determine the in-vitro and in-vivo effects of the drug combination of celecoxib and DTIC on melanoma growth and metastasis. Melanoma cells B16-F10 and SK-MEL-28, and female C57BL/6 mice were used for the study. Our in-vitro data showed that significant synergistic effects were obtained when celecoxib was used together with various concentrations of DTIC. A study with B16-F10 cells using flow cytometry analysis showed that the drug combination induced significantly more apoptosis than each drug used individually. Our in-vivo results showed that the drug combination was much more effective than each drug used alone for the inhibition of both melanoma growth and metastasis in the B16-F10+C57BL/6 mouse models. For melanoma growth, the median survival rates for phosphate-buffered saline (PBS) (control), celecoxib (30 mg/kg), DTIC-1 (10 mg/kg), DTIC-2 (positive control, 50 mg/kg), and the drug combination (DTIC 10 mg/kg+celecoxib 30 mg/kg) were 6, 6.5, 7.5, 7.5, and 9 days, respectively. For melanoma metastasis, the average number of metastatic tumors in murine lungs was 53.7±10.7, 31.8±18.6, 21.2±21.7, 7.0±9.0, and 0.8±2.0 for PBS, DTIC-1, celecoxib, the drug combination, and DTIC-2. Our results warrant further investigation of the combination as an effective treatment for melanoma patients.

Antitumor‑ and apoptosis‑inducing effects of pomolic acid against SK‑MEL‑2 human malignant melanoma cells are mediated via inhibition of cell migration and sub‑G1 cell cycle arrest

Malignant melanoma is the leading cause of mortality among the skin‑associated diseases because of its highly metastatic nature and lethality. The aim of the present study was to evaluate antitumor and apoptosis effects of pomolic acid, a pentacyclic triterpene, against SK‑MEL‑2 human malignant melanoma cells. Its effect on cell migration and cell cycle arrest were also studied. An MTT assay was used to assess the cell cytotoxicity effects induced by pomolic acid. Fluorescence microscopy using acridine orange/propidium iodide and Hoechst 33342 staining, along with transmission electron microscopy (TEM), was used to study the effects of pomolic acid on apoptosis induction in these cells. The effects of pomolic acid on cell migration were studied using an in vitro wound healing assay. The effects of pomolic acid on cell cycle phase distribution were evaluated by flow cytometry using propidium iodide as fluorescent probe. The results revealed that pomolic acid induced significant dose‑ and time‑dependent antiproliferative effects in SK‑MEL‑2 human malignant melanoma cells, with IC50 values of 110.3, 88.1 and 79.3 µM after 24, 48 and 72 h, respectively. Pomolic acid‑treated cells exhibited red fluorescence, and the intensity of this fluorescence increased in a dose‑dependent manner, indicating apoptosis induction. After the cells were treated with 25, 75 and 150 µM pomolic acid, significant morphological alterations characteristic of apoptosis were observed by TEM, including loss of microvilli, a damaged plasma membrane, damaged cellular organelles and enlarged lysosomes. Pomolic acid also led to sub‑G1 cell cycle arrest, and inhibited cancer cell migration in a dose‑dependent manner. These results implicate pomolic acid as a potential therapeutic agent for the treatment of malignant melanoma.

Intratumoral expression of cyclooxygenase-2 (COX-2) is a negative prognostic marker for patients with cutaneous melanoma

Because of the well-known heterogeneity of melanomas, prognosis of the disease is often difficult to assess even for lesions classified in similar stages. The aim of this study was to assess the usefulness of COX-2 as a melanoma prognostic marker and to establish an optimum algorithm for analysis of COX-2 expression levels in lesions of interest. Expression of COX-2 was detected immunohistochemically in standard sections of formalin-fixed paraffin-embedded tissue samples of 85 primary melanomas, 36 lymph node metastases, and five skin metastases including 39 cases of paired primary and metastatic lesions obtained from the same patient. Enhanced expression of COX-2 in primary melanomas is an indicator of poorer prognosis. A significant correlation was found between high expression of COX-2 in primary lesions and shorter survival. The enhancement of COX-2 expression is also positively correlated with other prognostic factors such as tumor thickness and infiltration level, ulceration, high mitotic index, more invasive histologic type, vertical growth phase, and lymph node metastasis. On the whole, the results suggest that intratumoral expression of COX-2 is a strong negative prognostic marker for patients with melanoma. Moreover, our work shows that a simple and objective immunohistochemical scoring algorithm involving the determination of only a percentage fraction of positively stained cells is sufficient to obtain the prognostic information.

Chemoprevention of melanoma

Despite advances in drug discovery programs and molecular approaches for identifying drug targets, incidence and mortality rates due to melanoma continue to rise at an alarming rate. Existing preventive strategies generally involve mole screening followed by surgical removal of the benign nevi and abnormal moles. However, due to lack of effective programs for screening and disease recurrence after surgical resection, there is a need for better chemopreventive agents. Although sunscreens have been used extensively for protecting from UV-induced melanomas, results of correlative population-based studies are controversial, with certain studies suggest increased skin cancer risk in sunscreen users. Therefore, these studies require further authentication to conclusively confirm the chemoprotective efficacy of sunscreens. This chapter reviews the current understanding regarding melanoma chemoprevention and the various strategies used to accomplish this objective.

Cyclooxygenase-2 expression is related with localization, proliferation, and overall survival in canine melanocytic neoplasms

A direct relationship has been firmly established between cyclooxygenase-2 (COX-2) expression and malignant behavior in human melanoma. This report examines the relationship between COX-2 expression and tumor location, mitotic and proliferative indices, degree of T CD3(+) lymphocyte infiltration, overall survival, and frequency of recurrence and metastasis of 57 melanocytic tumors (25 oral and 32 cutaneous). COX-2 was highly or moderately expressed in 88% of oral neoplasms (22 of 25), whereas for their cutaneous counterparts, COX-2 expression was low or insignificant in 75% of cases (24 of 32). High and moderate COX-2 expression levels were observed in 73% of melanocytic tumors with a mitotic index ≥ 3 per 10 high-power fields (26 of 36), whereas in 81% of tumors with a mitotic index < 3 (17 of 21), expression was mild or absent. There were 41 cases with known clinical outcomes; of those showing high, moderate, and mild COX-2 expression, 83.3% (10 of 12), 37.5% (3 of 8), and 25% (2 of 8) died, respectively, whereas 100% of animals showing no COX-2 expression (13 of 13) were still alive at the last follow-up. COX-2 expression was statistically correlated with tumor location, mitotic and percentage Ki-67 proliferative indices, and overall survival, frequency of neoplastic recurrence and metastasis. Regression analysis also showed disease-specific predictive value for COX-2 expression for subjects with melanocytic neoplasms. Additionally, only high COX-2 expression showed significant differences in overall survival, in comparison with moderate, mild, or absent expression. These results suggest that high COX-2 expression may be considered a prognostic biomarker and potentially as a target for therapeutic and preventive strategies in canine melanocytic neoplasms.

3,3',4,4',5,5'-hexahydroxystilbene impairs melanoma progression in a metastatic mouse model

Stilbenes comprise a group of polyphenolic compounds, which exert inhibitory effects on various malignancies. The aim of this study was to evaluate the antitumor effects of a previously unreported stilbene derivative-3,3',4,4',5,5'-hexahydroxystilbene, termed M8-on human melanoma cells. Cell-cycle analysis of the metastatic melanoma cell line M24met showed that M8 treatment induces G(2)/M arrest accompanied with a dose- and time-dependent upregulation of p21 and downregulation of CDK-2 and leads to apoptosis. M8 induces the expression of phosphorylated p53, proteins involved in the mismatch repair machinery (MSH6, MSH2, and MLH1) and a robust tail moment in a comet assay. In addition, M8 inhibited cell migration in Matrigel assays. Shotgun proteomics and western analysis showed the regulation among others of paxillin, integrin-linked protein kinase, p21-activated kinase, and ROCK-1 indicating that M8 inhibits mesenchymal and amoeboid cell migration. These in vitro data were confirmed in vivo in a metastatic human melanoma severe combined immunodeficient (SCID) mouse model. We showed that M8 significantly impairs tumor growth. M8 also interfered with the metastatic process, as M8 treatment prevented the metastatic spread of melanoma cells to distant lymph nodes in vivo. In summary, M8 exerts strong antitumor effects with the potential to become a new drug for the treatment of metastatic melanoma.

COX-2 expression in malignant melanoma: a novel prognostic marker?

Several studies illustrated considerably elevated levels of cyclooxygenase-2 (COX-2) protein in various types of human cancer including malignant melanoma. Recently, it was reported that COX-2 is strongly expressed in malignant melanoma and may be correlated with the development and progression of disease. In contrast, other groups did not detect COX-2 protein in primary melanoma cells but did in infiltrating inflammatory cells or metastases. However, there are no reports about patterns or alterations of COX-2 expression in melanoma cells during disease progression or of a correlation between COX-2 expression and overall survival. The aim of this study was to investigate whether there is a correlation between expression of COX-2 protein and disease prognosis in malignant melanoma. We therefore analyzed the expression of COX-2 protein by immunohistochemistry in 101 primary malignant melanomas and 28 metastases and correlated our data with Breslow tumor thickness, Clark levels, different melanoma subtypes, metastases, and overall survival. We detected a strong COX-2 expression in 95% of all primary melanomas, primarily restricted to melanoma cells as shown by various immunohistochemical methods. Levels of COX-2 expression in primary melanoma and corresponding metastases remained stable. A significant correlation between immunohistochemical staining intensity and tumor thickness was demonstrated. Furthermore, Kaplan-Meier curves illustrated a significant correlation between staining intensity and disease-specific survival. Our findings emphasize that the COX-2 protein might be a novel prognostic marker. Owing to its strong expression in melanoma cells it might also be a reasonable therapeutic target.

A large cohort study of nonsteroidal anti-inflammatory drug use and melanoma incidence

Results of laboratory studies indicate that nonsteroidal anti-inflammatory drugs (NSAIDs) may have chemopreventive activity and therapeutic efficacy against melanoma. However, few published epidemiological studies have examined the association between NSAID use and melanoma risk. We examined whether NSAID use was associated with melanoma risk among 63 809 men and women in the Vitamins and Lifestyle (VITAL) cohort study. Participants self-reported NSAID use (low-dose aspirin, regular or extra-strength aspirin, and nonaspirin NSAIDs) during the previous 10 years and data related to their melanoma risk factors on a baseline questionnaire. After linkage of the VITAL database to the NCI Surveillance, Epidemiology, and End Results cancer registry, 349 patients with incident melanoma were identified through December 31, 2005. Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of melanoma by NSAID use as categorized by overall use, duration of use, and dose (expressed as average number of days of use during the past 10 years). All statistical tests were two-sided. After adjusting for melanoma risk factors and indications for NSAID use, no association between NSAID use and melanoma risk was found. When use of at least 4 d/wk was compared with nonuse, no melanoma risk reduction was detected for any NSAID dose (HR = 1.12, 95% CI = 0.84 to 1.48), for any NSAID excluding low-dose aspirin (HR = 1.03, 95% CI = 0.74 to 1.43), for regular- or extra-strength aspirin (HR = 1.10, 95% CI = 0.76 to 1.58), or for nonaspirin NSAIDs (HR = 1.22, 95% CI = 0.75 to 1.99). Moreover, NSAID use was not associated with tumor invasion (P(interaction) = .38), tumor thickness (P(trend) = .98), or risk of metastasis (HR = 1.09, 95% CI = 0.32 to 3.62). NSAIDs do not appear to be good candidates for the chemoprevention of melanoma.

Targeted combined anti-inflammatory and angiostatic therapy in advanced melanoma: a randomized phase II trial

An angiostatic approach was used to assess the impact of anti-inflammatory therapy in combination with metronomic low-dose chemotherapy. A randomized multi-institutional phase II trial was designed to select metronomic chemotherapy (arm A: trofosfamide 50 mg orally three times daily, day 1+) or combined anti-inflammatory/angiostatic treatment (arm B: trofosfamide as above mentioned plus rofecoxib 25 mg orally, day 1+, and pioglitazone 60 mg orally, day 1+) for further evaluation. A total of 76 patients, mostly (>60%) refractory to at least one previous chemotherapy with maximum tolerated doses, and progression of metastatic melanoma were included. The estimated progression-free survival (PFS) rates at one year were 0% for metronomic chemotherapy (A), but 9% for additional anti-inflammatory therapy (B). Vice versa the hazard ratio for the intent-to-treat analysis of A versus B was 1.9 (P=0.008). By Cox analysis, the impact of anti-inflammatory therapy on PFS achieved significance (P=0.016) as well as C-reactive protein response on overall survival (P=0.045). WHO grade 3 (no grade 4) toxicities were reported in arm A/B in 19 and 28%, respectively. In conclusion, control of tumour-associated inflammatory processes (C-reactive protein response) is associated with longer PFS than achieved with metronomic chemotherapy alone in metastatic melanoma.