The basic biology of malignant melanoma: molecular mechanisms of disease progression and comparative aspects

Malignant melanoma (MM) is a life-threatening disease characterized by a highly aggressive biologic behavior in both humans and dogs. Despite improvements in diagnosis and patient care, most deaths from MM are due to metastases that are resistant to conventional treatment modalities. To ultimately reduce the mortality associated with metastatic disease, it is necessary to better define the fundamental molecular mechanisms of malignant tumor progression. The progression of disease is a consequence of the complex interactions between malignantly transformed cells and host factors. Characterization of the stages of tumor progression and the changes occurring in highly malignant cells is important for the development of effective treatment regimens. The dys-regulated molecular mechanisms of transformed melanocytes are presently being characterized. In this review, we summarize the current understanding of the molecular phases in the progression of MM, which include genetic instability, dysregulated proliferation of melanocytes, increased invasion and metastasis, and angiogenesis.     

Roles of atypical chemokine receptors in progression and metastasis of tumor

Chemokines and their receptors have been implicated mostly in tumor progression and metastasis. Atypical chemokine receptors (ACKRs) comprise a group of 7-transmembrane domain proteins structurally similar to G protein-coupled receptors. However, ACKRs do not induce classical signaling via the typical G protein-mediated pathways. ACKRs efficiently internalize the cognate chemokine ligands and act as scavengers instead. ACJRs are composed of at least 3 members of chemokine receptors:Duffy antigen receptor for chemokines (DARC, also known as ACKR1), D6 (also known as ACKR2) and ChemoCentryx chemokine receptor (CCX-CKR, also known as ACKR4). These receptors bind to and/or internalize their chemoattractant ligands without activating signal transduction cascades leading to cell migration. In this review, we summarize the recent progress regarding the roles of ACKRs in the progression and metastasis of tumor.     

Progress of ELMO family on malignant tumor invasion and metastasis

It is one of the main characters of malignant tumors that malignant tumor cells invade surrounding tissues and metastasize to distant tissues. Multiple factors are involved in this complicated dynamic process. Metastasis is the major factor influencing recurrence and prognosis. Therefore, it is important to explore the mechanism of invasion and metastasis for reducing recurrence rate and mortality of malignant tumors. Engulfment and cell mobility (ELMO) family is one kind of conserved protein in evolutional process. It includes 3 members, ELMO1, ELMO2 and ELMO3. The members of ELMO family play an important role in cell phagocytosis and cell migration, and they also have close correlation with malignant tumor cell invasion and metastasis. In this paper, we review the progress of the relationship between ELMO family and malignant tumor invasion and metastasis.     

Differential expression of cell cycle regulators p21, p27 and p53 in metastasizing canine mammary adenocarcinomas versus normal mammary glands

The cyclin dependent kinase inhibitors p21 and p27 are important regulators of cell cycle progression. To analyze their role in the malignant progression of canine mammary tumors expression levels of p27 and p21 and its major regulator p53 were compared in simple adenomas, adenocarcinomas of the mammary gland and lymph node metastases with normal mammary gland. Laser microdissection of tissue samples and real-time PCR were used for quantification of mRNA expression levels. p21 was overexpressed in adenocarcinomas, whereas adenomas and metastases expressed p21 more heterogeneously. Comparison of p21 expression in adenocarcinomas and their metastases revealed a significant decrease in expression in metastases. In contrast, p27 expression was reduced in the adenocarcinomas but heterogeneously expressed in adenomas and metastases. Taken together the results suggest that loss of p21 overexpression is associated with tumor metastasis while reduced cell cycle inhibition by p27 is associated with malignant progression.     

Expression and significance of PTEN in canine mammary gland tumours

To explore the expression and clinical importance of the anti-oncogene phosphatase and tensin homologue deleted on chromosome 10 (PTEN) in canine mammary gland tumours, PTEN expression was compared in 50 cases of canine mammary tumour and four examples of normal mammary tissue using real-time quantitative PCR. PTEN expression was similar in benign mammary tumours and normal mammary tissues (P>0.05), but was lower in malignant tumours than in normal mammary tissues or benign mammary tumours (P<0.001). PTEN expression was also low in the lymph node metastases of malignant mammary tumours. The expression profile of PTEN in malignant mammary tumours compared to those without lymph node metastasis varied significantly. Low-level PETN expression might play an important role in carcinogenesis and the progression of canine mammary tumours, and PTEN protein detection might be useful in evaluating tumour development and prognosis.     

NET-1 promotes metastasis of lung squamous-cell carcinoma by activating EMT

AIM: To explore the effect of neuroepithelial cell transforming gene-1 (NET-1) expression on the metastasis of lung squamous-cell carcinoma (LSC) and the underlying molecular mechanism. METHODS: Immunohistochemistry was used to detect the expression of NET-1 protein in 53 cases of lung squamous-cell carcinoma (LSC group), 24 cases of normal lung epithelium (NLE group) and 27 cases of lung squamous intraepithelial lesions (SIL group). The correlation of clinical and pathological factors was analyzed. The protein expression of NET-1 in human lung squamous-cell carcinoma cell lines H226, H1703, H2170, SK-MES-1, H520 and YTMLC-90 was determined by Western blot. The RNA interference recombinant adenovirus against NET-1 gene (Ad-NET-siRNA) and Ad-control with control sequence were constructed and infected with human lung squamous cell carcinoma cell YTMLC-90 to silence the expression of NET-1 gene. The protein expression of NET-1, E-cadherin, vimentin and Snail1 in the BEAS-2B cells and the YTMLC-90 cells was determined by Western blot. The mRNA expression of E-cadherin and vimentin in each group of the cells was detected by qPCR. The invasive ability of the cells in each group was detected by Transwell chamber assay. RESULTS: The positive expression rate of NET-1 in LSC group was significantly higher than that in NLE group and SIL group(P<0.05). The distribution of NET-1 protein positive expression population was correlated with histological grade, lymph node metastasis, and TNM stage. The NET-1 expression rate of LSC with lymph node metastasis was significantly higher than that without lymph node metastasis. Over-expression of NET-1 protein in YTMLC-90 cells was observed. The expression of E-cadherin was decreased, and the protein expression of vimentin and Snail1 was increased in YTMLC-90 cells. Knock-down of NET-1 expression increased the expression of E-cadherin, and decreased the expression of vimentin and Snail1 in the YTMLC-90 cells. CONCLUSION: The expression of NET-1 promotes the lymphatic metastasis of lung squamous-cell carcinoma. This promotion may be achieved through the activation of epithelial-mesenchymal transition (EMT) by NET-1 expression.     

Mortalin expression in cervical squamous-cell carcinoma and its effect on tumor metastasis

AIM: To investigate the significance of mortalin expression in clinical pathology of cervical squamous-cell carcinoma. METHODS: Immunofluorescence staining was used to detect the location of mortalin in human cervical squamous-cell carcinoma SiHa cells. The protein expression of mortalin was detected in 59 cases of normal cervical epithelial tissues and 93 cases of cervical squamous-cell carcinoma tissues by immunohistochemical staining, and its correlation with clinicopathological features of cervical squamous-cell carcinoma was also analyzed. MTT assay was used to evaluate the optimal concentration and dosing time of mortalin inhibitor MKT-077. After the protein expression of mortalin in SiHa cells was inhibited, wound-healing and migration assays were performed. The protein expression of epithelial-mesenchymal transition (EMT)-related molecules was determined by Western blot. RESULTS: Immunofluorescence staining showed that mortalin was located in the cytoplasm of SiHa cells. The positive rate and strongly positive rate of mortalin in the cervical squamous-cell carcinoma patients were 88.7% (55/62) and 61.3% (38/62), respectively, and they were significantly higher than those in normal cervical epithelial tissues (23.7% and 5.1%, P < 0.01). Additionally, mortalin expression was statistically correlated with the histological grade, clinical stage and lymph node metastasis. After inhibiting the expression of mortalin in the SiHa cells by MKT-077, the results of wound-healing and migration assays showed that the migration ability of SiHa cells was down-regulated. The protein expression of E-cadherin was up-regulated, and vimentin and Snail were significantly down-regulated. CONCLUSION: Mortalin over-expression is an effective biomarker for prediction of malignant potential and poor prognosis of cervical squamous-cell carcinoma.     

Efficacy of cytokine-induced killer cell transfusion combined with chemotherapy using gemcitabine and cisplatin for nasopharyngeal carcinoma with hepatic or pulmonary metastasis

AIM: To evaluate the recent and long-term efficacy of cytokine-induced killer(CIK) cell and transfusion plus chemotherapy with gemcitabine and cisplatin(GP) for patients of nasopharyngeal carcinoma(NPC) with hepatic or pulmonary metastasis.METHODS: From Aug. 2007 to Jul. 2008, 30 patients of nasopharyngeal carcinoma with hepatic or pulmonary metastasis were enrolled in the study and randomly divided into 3 groups. Ten patients(CIK+GP group) received CIK cell transfusion plus GP chemotherapy for 4 cycles. Another 10 patients(GP group)received the regimen of GP chemotherapy alone. The other 10 patients as well as 10 healthy volunteers did not receive any anti-cancer treatment. The early response, the changes of serum EBV-DNA by quantitative PCR detection and distribution of lympholeukocyte subset in the patients of the 3 groups were determined before and after treatment. The long-term effects were observed in a follow-up process of 2 years. RESULTS: The recent complete and partial response(CR+PR) rates were 90%, 70% and 10% in CIK+GP group, GP group and patient control group, respectively, and obviously statistical differences among these 3 groups were observed. The proportion of CD3⁺ lymphocytes in NPC patients with hepatic or pulmonary metastasis were obviously lower than that in healthy volunteer. It also descended after CIK+GP/GP therapy, but partly recovered in CIK+GP group. Furthermore, no statistical difference of CD4⁺/CD8⁺ ratio among NPC patients with hepatic or pulmonary metastasis and volunteers was found. The ratio of CD4⁺/CD8⁺ in CIK+GP group increased, but decreased in GP group after treatment. In the 2-year follow-up, the overall survival rate was 60.0%, 40.0% and 20.0% in CIK+GP, GP and control group,respectively. The Kaplan-Meier survival curves showed statistical difference. CONCLUSION: The recent and long-term effects of CIK cell transfusion combined with GP chemotherapy for patients of NPC with hepatic or pulmonary metastasis have been confirmed. The chemotherapy and biotherapy of CIK+GP improve the prognosis with synergistic effects, possibly owing to the changed proportion of CD3⁺and ratio of CD4⁺/CD8⁺.     

Doxorubicin and BAY 12-9566 for the treatment of osteosarcoma in dogs: a randomized, double-blind, placebo-controlled study

BACKGROUND: This study was designed to assess the efficacy of a matrix metalloproteinase inhibitor in prolonging posttreatment survival for dogs with appendicular osteosarcoma after treatment with amputation and doxorubicin chemotherapy. HYPOTHESIS: Survival will be prolonged in dogs receiving BAY 12-9566. ANIMALS: The study included 303 dogs with appendicular osteosarcoma. METHODS: Dogs were treated with doxorubicin (30 mg/m2) every 2 weeks for 5 treatments starting 2 weeks after amputation. Dogs were randomly allocated to receive a novel nonpeptidic biphenyl inhibitor of matrix metalloproteinases (MMPs, BAY 12-9566; 4-[4-4-(chlorophenyl)phenyl]-4-oxo-2S-(phenylthiomethyl) butanoic acid) or placebo after doxorubicin chemotherapy. RESULTS: Median survival for all 303 dogs was 8 months; and 1-year, 2-year, and 3-year survival rates were 35%, 17%, and 9%, respectively. Treatment with BAY 12-9566 did not influence survival. Multivariate analysis revealed that increasing age (P = .004), increasing weight (P = .006), high serum alkaline phosphatase (ALP) (P = .012) and high bone ALP (P < .001) were independently associated with shorter median survival times. Additional analyses on available data indicated that as the number of mitotic figures in the biopsy increased (P = .013), and as plasma active MMP-2 concentrations increased (P = .027), the risk of dying increased. CONCLUSIONS AND CLINICAL IMPORTANCE: Doxorubicin is an effective adjuvant to amputation in prolonging survival for dogs with appendicular osteosarcoma.