Laboratory markers of melanoma progression

Extracellular tumour markers may have potential role in the follow-up of patients with malignant melanoma, in therapy monitoring and in prediction of prognosis. In our article circulating tumour markers in melanoma (melanoma inhibitory activity, lipid bound sialic acid, neuron specific enolase, TA90 immune complex, S-100B protein, 5-S-cysteinyldopa, tyrosinase, cytokines, metalloproteinases, LDH) were reviewed. Among laboratory melanoma markers the S-100B protein is the most investigated. S-100B protein has high specificity, appropriate sensitivity and proved to be significant prognostic factor independent from stages. High serum values are associated with shorter survival. However, before S-100B monitoring immunohistochemistry for the detection of S-100B is required. In the case of malignant melanomas with low expression serum S-100B monitoring may not be sensitive enough to follow disease progression. Although the serum concentration of 5-S-cysteinyldopa did not prove to be independent prognostic factor in our previous studies comprising the highest patient number in the literature, the marker was suggested for therapy monitoring. The survival analysis indicated that the elevated 5-S-cysteinyldopa level predicts shorter survival. In spite of the calculated low correlation between the two markers, parallel elevation of S-100B protein and 5-S-cysteinyldopa indicated shorter survival. On the basis of the literature LDH is the most appropriate tumour marker in stage IV to predict prognosis, but its sensitivity and specificity could not achieve that of S-100B protein. S-100B and LDH proved to be similarly reliable in respect to the clinical outcome. Determination of serum concentration of MIA and tyrosinase are also reliable markers in malignant melanoma. The other investigated markers are not well known yet or do not provide useful information to the clinicians.     

Soluble interleukin-2 receptor in stage I-III melanoma

The aim of the present study was to assess the prognostic value of soluble interleukin-2 receptor (sIL-2R) serum levels in stage I-III melanoma patients. The levels of sIL-2R were determined using an enzyme immunometric test kit in 329 patients affected by malignant melanoma (MM) from 1995 to 2004. Correlations between sIL-2R values, baseline patients and tumour features were studied by contingency tables and the chi-square test. The Kaplan-Meier product limit method was applied to plot disease-free survival (DFS) curves. Univariate analysis was performed with the Log-rank test. Cox proportional-hazards regression was used to analyse the effect of several risk factors on DFS. In total, 2330 blood samples were collected during follow-up of 329 MM patients. Forty-five (13.7%) patients had Breslow tumour thickness1.00 and 2.00 and 4.00 mm. Ulceration was present in 64 cases (19.4%). Thirty-nine sentinel lymph nodes (SLNs) (11.8%) were infiltrated by MM. Soluble IL-2R values ranged from 130 to 1420 U/ml; median value was 500 U/ml. One hundred twenty-one (36.8%) patients presented with sIL-2R>600 U/ml at first measure (FM), 194 patients (58.9%) with values increasing up to or more than 600 U/ml [increasing values (IV) pattern]. A correlation was found between Breslow's tumour values and the IV sIL-2R pattern group (P=0.0304 with chi2 test). Gender, presence of ulceration, Breslow tumour thickness, FM and IV sIL-2R pattern groups had a significant prognostic value for DFS. At multivariate analysis, presence of ulceration, gender, FM and IV sIL-2R pattern groups emerged as independent prognostic factors for DFS. The 5-year DFS rate was 88% for patients with FM<600 U/ml and 76.9% for patients with FM>600 U/ml. In IV pattern, the 5-year DFS rate was 69.5% compared to 87% for patients with no sIL-2R values>600 U/ml during follow-up. sIL-2R values are associated with progression of MM. Further studies are needed to address the role of the IL-2/IL-2R/sIL-2R axis in melanoma biology.     

Molecular diagnostics of malignant melanoma: molecular staging,minimal residual disease

Nucleic acid based molecular techniques have been introduced into the diagnosis of malignant melanoma similarly to other cancers. They were applied for refinement of staging and to detect minimal residual disease. There are several good melanocyte-specific genetic markers such as tyrosinase, gp100, Melan-A/MART-1 and MIA. Unlike in the case of the lymph nodes, peripheral blood or bone marrow do not contain melanocytes excluding the possibility of fals positive reactions. Considering the pronounced heterogeneity of melanoma cells the most reliable molecular marker is the expression of tyrosinase. Several studies indicate that the quantity of circulating melanoma cells correlates with tumor burden and disease progression and reflects the effect of therapy. On the other hand, molecular techniques detect circulating melanoma cells much more frequently than the clinical manifestation of the disease progression (molecular recurrence), questioning the clinical significance of the detection of a small number of melanoma cells in the circulation. Based on these data molecular diagnostics is not part of the melanoma protocols yet and further studies are necessary to define its diagnostic role.     

Assessment of proliferating cell nuclear antigen and its relationship with proinflammatory cytokines and parameters of disease activity in multiple myeloma patients

Multiple myeloma (MM) is a malignant plasma cell disease. Several proinflammatory cytokines produced by malignant plasma cells and bone marrow (BM) stromal cells are involved in the pathogenesis of the disease. We evaluated serum levels of the proinflammatory cytokines Interleukin-1β (IL-1β), Interleukin-6 (IL-6), Interleukin-8 (IL-8), macrophage inflammatory protein-1α (MIP-1α), in MM patients before treatment, and determined its significance in tumor progression. We also analyzed the correlation between measured parameters with proliferating cell nuclear antigen (PCNA). Forty-four MM patients and 20 healthy controls were studied. Serum levels of the proinflammatory cytokines were measured using enzyme-linked immunosorbent assay (ELISA), whereas PCNA value in the BM was determined by immunohistochemistry staining. The mean concentrations of the measured cytokines were significantly different among the three stages of disease, with higher values in advanced disease stage. Furthermore, patients with MM had significantly higher serum levels of the measured cytokines than in controls. A positive correlation was found between IL-6 with IL-1β, IL-8 and MIP-1α. Similarly, IL-8 and MIP-1α were positively correlated with markers of disease activity such as β2 microglobulin and LDH. The proliferation index, determined by PCNA immunostaining, was higher in advanced disease stage. Furthermore PCNA value correlated significantly with β2 microglobulin, LDH and the levels of the measured cytokines. Our results showed that the proliferative activity, as measured with PCNA, increases in parallel with disease stage. The positive correlation between PCNA and other measured mediators supports the involvement of these factors in the biology of myeloma cell growth and can be used as markers of disease activity and as possible therapeutic targets.     

Prognostic value of S-100 immunostaining in tumour cells of non-small cell lung cancer

S-100 protein expression is present in various malignant tissues, yet its prognostic relevance is debatable. The aim was to assess in non-small cell lung cancer (NSCLC) patients' prognostic value of S-100 protein considered alone or in relation with other variables. Tumour samples taken from 86 NSCLC patients during resection were assayed for S-100 protein expression with the use of polyclonal DAKO ZO311 antibody. S-100 expression was found in 32 cases (37%). Positive staining was not correlated with clinical characteristics including age, sex, pathology type of tumour, stage and cigarette smoking. There was a tendency for simultaneous expression of S-100 and P53 protein (p=0.06). A median survival rate for the entire group was 2.3 years (95% CI, 0.9-3.6 years). The median and 5-year survival of patients with positive staining for S-100 protein was 1.5 years and 25%, respectively, compared with 3.0 years and 35%, respectively, in the S-100 negative group (p=0.17). In the final model of a multivariate analysis, S-100 protein expression in tumour cells was associated with significantly decreased survival (p=0.005). S-100 protein expression in tumour cells seems to be an independent predictor of poor prognosis in NSCLC patients.     

Prognostic value of [18F]-fluoro-deoxy-glucose PET/CT, S100 or MIA for assessment of cancer-associated mortality in patients with high risk melanoma

Purpose

To assess the prognostic value of FDG PET/CT compared to the tumor markers S100B and melanoma inhibitory activity (MIA) in patients with high risk melanoma.

Methods

Retrospective study in 125 consecutive patients with high risk melanoma that underwent FDG PET/CT for re-staging. Diagnostic accuracy and prognostic value was determined for FDG PET/CT as well as for S100B and MIA. As standard of reference, cytological, histological, PET/CT or MRI follow-up findings as well as clinical follow-up were used.

Results

Of 125 patients, FDG PET/CT was positive in 62 patients. 37 (29.6%) patients had elevated S100B (>100 pg/ml) and 24 (20.2%) had elevated MIA (>10 pg/ml) values. Overall specificities for FDG PET/CT, S100B and MIA were 96.8% (95% CI, 89.1% to 99.1%), 85.7% (75.0% to 92.3%), and 95.2% (86.9% to 98.4%), corresponding sensitivities were 96.8% (89.0% to 99.1%), 45.2% (33.4% to 55.5%), and 36.1% (25.2% to 48.6%), respectively. The negative predictive values (NPV) for PET/CT, S100B, and MIA were 96.8% (89.1% to 99.1%), 61.4% (50.9% to 70.9%), and 60.6% (50.8% to 69.7%). The positive predictive values (PPV) were 96.7% (89.0% to 99.1%), 75.7% (59.9% to 86.6%), and 88.0% (70.0% to 95.8%). Patients with elevated S100B- or MIA values or PET/CT positive findings showed a significantly (p<0.001 each, univariate Cox regression models) higher risk of melanoma associated death which was increased 4.2-, 6.5- or 17.2-fold, respectively.

Conclusion

PET/CT has a higher prognostic power in the assessment of cancer-associated mortality in melanoma patients compared with S100 and MIA.     

Prognostic value of S-100 immunostaining in tumour cells of non-small cell lung cancer

S-100 protein expression is present in various malignant tissues, yet its prognostic relevance is debatable. The aim was to assess in non-small cell lung cancer (NSCLC) patients’ prognostic value of S-100 protein considered alone or in relation with other variables. Tumour samples taken from 86 NSCLC patients during resection were assayed for S-100 protein expression with the use of polyclonal DAKO ZO311 antibody. S-100 expression was found in 32 cases (37%). Positive staining was not correlated with clinical characteristics including age, sex, pathology type of tumour, stage and cigarette smoking. There was a tendency for simultaneous expression of S-100 and P53 protein (p=0.06). A median survival rate for the entire group was 2.3 years (95% CI, 0.9–3.6 years). The median and 5-year survival of patients with positive staining for S-100 protein was 1.5 years and 25%, respectively, compared with 3.0 years and 35%, respectively, in the S-100 negative group (p=0.17). In the final model of a multivariate analysis, S-100 protein expression in tumour cells was associated with significantly decreased survival (p=0.005). S-100 protein expression in tumour cells seems to be an independent predictor of poor prognosis in NSCLC patients.     

Melanoma inhibitory activity (MIA): an important molecule in melanoma development and progression

Cutaneous malignant melanoma is the leading cause of skin cancer death in industrialized countries. Melanoma development and progression are well defined by clinical and histopathological aspects; however, detailed analysis of molecular changes is still ongoing. The protein MIA, which is strongly expressed in melanoma cells but not in melanocytes, is likely to represent a key molecule regulating melanoma progression. Consistent with this, several in vitro and in vivo model systems indicate a direct involvement of MIA in melanoma migration and invasion, with recent studies suggesting a central role for MIA in early melanoma development by regulating important melanoma-related pathways and molecules. The latest developments in MIA research are summarized in this review, which describes recently published data related to the MIA protein structure and function, the role of MIA in melanoma development and progression, and the regulation of MIA expression. Furthermore, newly discovered MIA-homologous genes are discussed.     

Regulation of integrin activity by MIA

MIA (melanoma inhibitory activity) has been identified as a small protein secreted from malignant melanoma cells, which interacts with extracellular matrix proteins including fibronectin. Here, we show that MIA negatively regulates the activity of the mitogen-activated protein kinase pathway in malignant melanoma. Using far Western blotting and co-immunoprecipitation we searched for MIA-binding cell surface proteins. We found that MIA interacts with integrin alpha4beta1 and alpha5beta1, leading to down-regulation of integrin activity and reduction of mitogen-activated protein kinase signaling. These findings also suggest that MIA may play a role in tumor progression and the spread of malignant melanomas via mediating detachment of cells from extracellular matrix molecules by modulating integrin activity. Inhibiting MIA functions in vivo may therefore provide a novel therapeutic strategy for metastatic melanoma disease.     

Protein and non-protein biomarkers in melanoma: a critical update

Melanoma is the most malignant type of all skin neoplasms. Its worldwide incidence has steadily increased during the past decades, suggesting a probable melanoma ‘epidemic’. Although current clinical, morphologic, and histopathologic methods provide insights into disease behavior and outcome, melanoma is still an unpredictable disease. Once in an advanced stage, it remains a disastrous affliction with scarce therapeutic options. Therefore, significant efforts need to be made in finding informative biomarkers or surrogate markers that could aid or improve early diagnosis of melanoma, its correct staging, the discrimination of other pathological conditions as well as indicate patients’ prognosis or the most appropriate therapeutic regimes. Ideally these markers are secreted into body fluids and easily amenable to the design of non-invasive clinical tests. A critical view on the current debate on serologic protein markers, e.g., lactate dehydrogenase, tyrosinase, and melanoma inhibiting activity, and some selected non-protein markers, e.g., 5-S-cysteinyl-dopa and circulating nucleic acids, will be offered and novel innovative approaches currently being explored will be discussed. Special emphasis is put on the S100 family of calcium binding proteins that is more and more emerging as a potentially important group of both molecular key players and biomarkers in the etiology, progression, manifestation, and therapy of neoplastic disorders, including malignant melanoma. Notably, S100B and, possibly, other S100 proteins like S100A4 are assumed to fulfill requirements which make them strong biomarker candidates in melanoma. Moreover, S100 proteins receive attention as possible targets of therapeutic intervention moving closer to clinical impact.     

The extracellular human melanoma inhibitory activity (MIA) protein adopts an SH3 domain-like fold

Melanoma inhibitory activity (MIA) protein is a clinically valuable marker in patients with malignant melanoma, as enhanced values diagnose metastatic melanoma stages III and IV. Here we show that the recombinant human MIA adopts an SH3 domain-like fold in solution, with two perpendicular, antiparallel, three- and five-stranded beta-sheets. In contrast to known structures with the SH3 domain fold, MIA is a single-domain protein, and contains an additional antiparallel beta-sheet and two disulfide bonds. MIA is also the first extracellular protein found to have the SH3 domain-like fold. Furthermore, we show that MIA interacts with fibronectin and that the peptide ligands identified for MIA exhibit a matching sequence to type III human fibronectin repeats, especially to FN14, which is close to an integrin alpha4beta1 binding site. The present study, therefore, may explain the role of MIA in metastasis in vivo, and supports a model in which the binding of human MIA to type III repeats of fibronectin competes with integrin binding, thus detaching cells from the extracellular matrix.     

Tyrosinase of hamster melanoma: its purification and estimation by radioimmunoassay

1. Tyrosinase was purified from melanosomal fraction of hamster melanoma. 2. A radioimmunoassay was developed to quantitate the tyrosinase protein in hamster serum and hamster melanoma tissue using polyclonal anti-tyrosinase antibodies and 125I-labeled enzyme. 3. The serum tyrosinase levels were found to be about 0.24 micrograms and 1.14-4.48 micrograms/ml in normal hamsters and melanoma-bearing hamsters, respectively. 4. Tyrosinase protein in serum correlated significantly with the enzyme activity in hamsters with melanoma (r = 0.733). 5. In the cytosol fraction of hamster melanoma, a level of 2.2 micrograms of tyrosinase/mg protein was determined. 6. The usefulness and possible applications of the tyrosinase radioimmunoassay are discussed.     

Early diagnosis of lung cancer by detection of tumor liberated protein

Tumor liberated protein (TLP) is a protein that can be used to reveal the early development of a tumor. Besides being formed in the tumor, TLP is released in the blood when a patient starts producing cancer cells, which in turn enables the physician to intervene at a stage when the cancer is operable. To date, the available studies of tumor markers in lung cancer patients are CEA, NSE, TPA, Chromogranine, CA125, CA19-9, and Cyfra 21-1. The sensitivity and specificity for serum markers ranges between 50 and 90%, depending on the study and the clinical samples analyzed. Most of these markers show an increased rate of positivity as the stage advances. There are very limited data on TLP to draw any firm conclusion regarding the diagnostic value of this marker. TLP has been detected in 53.1% of non-small cell lung cancer (NSCLC) patients (N = 534) with 75% being positive in the early stage (stage I) and dropping to 45% in the late stage (stage IV). However, 7.6% blood donor sera and 17.4% chronic lung disease sera have also tested positive. In a confirmation study, the specificity was 89.94% and the sensibility was 63.63% from stage III to IV NSCLC patients. In an initial study of TLP as a marker for early detection in stage I, NSCLC patients showed a sensitivity of 66.7% and a specificity of 80% for TLP compared to a sensitivity of 33.3% for CA19-9, 11.1% for Cyfra 21-1 and CA125, and 0% for CEA; the specificity for all four of the latter markers was 100%. Using immunohistochemical analysis with peroxidase anti-peroxidase (PAP), we observed that NSCLC cells were positive; we used the specific rabbit antiserum to TLP, which turned out negative in the presence of 1 mg/ml of the synthetized peptide. The pre-serum was also negative. The same reactivity was found early in the modified epithelial cells of interstitial lung fibrosis and might be a predictive marker of cell transformation. The site of the peroxidase positivity was cytoplasmic, of diffuse and/or granular type.     

Suppression of basement membrane type IV collagen degradation and cell invasion in human melanoma cells expressing an antisense RNA for MMP-1

During progression from benign nevus to vertical growth phase melanoma, melanocytes acquire the ability to invade into the dermis. This process requires rupture of the basal lamina and dissolution of dermal type I collagen. Metastases-derived human melanoma MIM cells have an invasive ability in vitro which is dependent on metalloproteinases. In the present study we analysed the role of type I collagenase (MMP-1) in melanoma invasion using MIM cells in which the constitutive expression of MMP-1 was suppressed by stable transfection with a plasmid vector expressing a 777 bp antisense fragment of MMP-1 genomic DNA. Two clones were isolated in which MMP-1 mRNA expression was blocked by 90–96% with a corresponding loss in protein synthesis. In their morphological appearance and growth rate in vitro these cells were indistinguishable from wild type cells or control cells transfected with the same vector expressing the MMP-1 fragment in the sense orientation. Their mRNA and protein levels for type IV collagenase (MMP-2) were unchanged as assessed by Northern and Western blot analyses and by gelatin zymography. However, when the invasive ability of the cells was measured, we found that in addition to type I collagen, invasion through type IV collagen and a reconstituted, type IV collagen-containing basement membrane (Matrigel) were also significantly inhibited as compared to normal or sense-transfected cells. The results indicate that despite the presence of functional MMP-2, degradation of type IV collagen matrices by the melanoma cells was dependent on expression of MMP-1. © 1997 Elsevier Science B.V. All rights reserved.     

Comparison of four different assays for determination of serum S-100B

BACKGROUND: S-100B determination has been shown to be clinically useful in the management of melanoma patients. After the development of a test for determination of the isoforms S100-A1B and S100-BB in serum (S-100B), several sensitive assays for the detection of serum S-100B have become available. We compared four S-100B assays, two automated (LIAISON Sangtec 100 and Elecsys S100) and two manual ones (Sangtec 100 ELISA and CanAg S100 EIA), with respect to clinical data, reference values and correlation. METHODS: In a total of 280 samples from 155 melanoma patients and 98 healthy individuals S-100B values were measured simultaneously with the different assays. RESULTS: The inter and intra coefficients of variation were best for the automated assays. The functional sensitivity of both manual assays was 0.15 microg/L. Method comparison revealed satisfactory correlation coefficients of 0.9 or higher, but the slopes ranged from 0.29 to 3.36. Except for the Sangtec 100 ELISA, the linearity between the assays was acceptable. The overall sensitivity for melanoma ranged from 37% (Elecsys S100) to 47% (LIAISON Sangtec 100) and the sensitivity increased with stage. ROC curves showed the best accuracy for the LIAISON Sangtec 100 assay. CONCLUSIONS: All assays gave satisfactory results, but it is advisable to improve the performance of the manual assays for better sensitivity. Agreement about an international reference standard is needed.     

Serologic analysis of human tumor antigens

Summary The immune adherence (IA) assay was used to measure serum reactivity of patients with melanoma and osteosarcoma against paired cell lines (tumor cells and normal skin fibroblasts obtained from the same individuals) grown in tissue culture. Sera from 224 patients with various stages of melanoma were compared with sera from 100 normal age- and sex-matched donors. None of the 18 stage I sera (0%), 23 of 166 (14%) stage II sera, 3 of 40 (7%) stage III sera, and 3 of 100 (3%) normal sera were highly reactive to a standard allogeneic melanoma-fibroblast pair. None of the sera exhibited unique activity against melanoma. There was no correlation between stage of melanoma and high serum reactivity, nor was this reactivity predictive of recurrence. Sera from 39 tumor-bearing osteosarcoma patients prior to amputation were compared with sera from 50 normal age-and sex-matched donors. Eight of 39 (21%) patient sera and 1 of 50 (2%) normal sera were highly reactive to an osteosarcoma-fibroblast pair. No sera had reactivity uniquely directed against osteosarcoma. Eight osteosarcoma and two melanoma patients were tested simultaneously against their autologous cultured tumor and skin cells. Only one of these patients exhibited high reactivity towards autologous cells, and this reactivity was equal against both osteosarcoma and normal cells. None of seven highly reactive osteosarcoma or six highly reactive melanoma sera had residual tumor-specific reactivity against allogeneic osteosarcoma or melanoma after absorption with cultured fibroblasts, cultured fetal fibroblasts, or fetal calf serum.     

Backbone dynamics of the human MIA protein studied by (15)N NMR relaxation: implications for extended interactions of SH3 domains

The melanoma inhibitory activity (MIA) protein is a clinically valuable marker in patients with malignant melanoma as enhanced values diagnose metastatic melanoma stages III and IV. Here, we report the backbone dynamics of human MIA studied by (15)N NMR relaxation experiments. The folded core of human MIA is found to be rigid, but several loops connecting beta-sheets, such as the RT-loop for example, display increased mobility on picosecond to nanosecond time scales. One of the most important dynamic features is the pronounced flexibility of the distal loop, comprising residues Asp 68 to Ala 75, where motions on time scales up to milliseconds occur. Further, significant exchange contributions are observed for residues of the canonical binding site of SH3 domains including the RT-loop, the n-Src loop, for the loop comprising residues 13 to 19, which we refer to as the"disulfide loop", in part for the distal loop, and the carboxyl terminus of human MIA. The functional importance of this dynamic behavior is discussed with respect to the biological activity of several point mutations of human MIA. The results of this study suggest that the MIA protein and the recently identified highly homologous fibrocyte-derived protein (FDP)/MIA-like (MIAL) constitute a new family of secreted proteins that adopt an SH3 domain-like fold in solution with expanded ligand interactions.     

Glucocorticoid modulation of adrenocorticotropin-induced melanogenesis in the Cloudman S-91 melanoma in vitro.

The acute in vitro action of adrenocorticotropin (ACTH) and corticosterone alone and in combination were determined in the Cloudman S-91 melanoma grown in vivo. Hormone-treated melanoma dice (5-240 min) were analyzed for tyrosinase activity (EC 1.14.18.1), cyclic AMP (cAMP) and cyclic GMP (cGMP). ACTH elevated cAMP levels in the S-91 melanoma. However, these increases in cAMP were not accompanied by increased tyrosinase activity. Corticosterone depressed cAMP levels while stimulating tyrosinase activity. ACTH plus corticosterone produced an early cAMP peak followed by depression. ACTH plus corticosterone stimulated tyrosine activity coincident with the early cAMP peak followed by a drop in tyrosinase activity which was subsequently elevated. cGMP levels were not altered by any hormone treatment. The results indicate that cAMP is not the sole modulator of tyrosinase activity and suggest the interaction of ACTH, corticosterone and cAMP in the regulation of melanoma tyrosinase activity.     

Serum levels of interleukin-15 and interleukin-10 and their correlation with proliferating cell nuclear antigen in multiple myeloma

In order to determine prognostic factors characterizing multiple myeloma (MM) cell kinetics, bone marrow proliferative activity and serum Interleukin-10 (IL-10), and Interleukin-15 (IL-15) levels were measured in 40 newly diagnosed MM patients, compared with 10-age and sex-matched-healthy controls. Cell proliferation was evaluated by employing a monoclonal antibody directed against the proliferating cell nuclear antigen (PCNA), whereas IL-10 and IL-15 were measured with quantitative sandwich enzyme immunoassay methods. IL-15, IL-10 and PCNA were higher in the patient group than in controls (P<0.001). IL-10 levels, and PCNA increased significantly with increasing Durie-Salmon disease stage (I-III, P<0.002, and P=0.001, respectively). Serum IL-15 levels in MM stage III patients were elevated in comparison with stages I and II, the difference however, did not reach statistical significance. There was a significant positive correlation between serum IL-15 and IL-10 levels (r: 0.372, P<0.01), and between serum IL-10 and PCNA (r: 0.608, P<0.0001), as well as a positive correlation of serum IL-15 with PCNA, which marginally failed to reach statistical significance. Serum IL-15 levels are elevated in MM patients, increase with advancing stage, and correlate with Il-10 and PCNA. These proliferative factors may be useful in assessing disease progression in MM.