PLP2-derived peptide Rb4 triggers PARP-1-mediated necrotic death in murine melanoma cells.

Malignant melanoma is the main cause of death in patients with skin cancer. Overexpression of Proteolipid protein 2 (PLP2) increased tumor metastasis and the knockdown of PLP2 inhibited the growth and metastasis of melanoma cells. In the present work, we studied the antitumor activity of peptide Rb4 derived from protein PLP2. In vitro, Rb4 induced F-actin polymerization, prevented F-actin depolymerization and increased the ER-derived cytosolic calcium. Such effects were associated with necrosis of murine melanoma B16F10-Nex2 cells and with inhibition of the viability of human cancer cell lines. Loss of plasma membrane integrity, dilation of mitochondria, cytoplasm vacuolation and absence of chromatin condensation characterized tumor cell necrosis. Cleavage of PARP-1 and inhibition of RIP1 expression were also observed. In vivo, peptide Rb4 reduced the lung metastasis of tumor cells and delayed the subcutaneous melanoma growth in a syngeneic model. Rb4 induced the expression of two DAMPs molecules, HMGB1 and calreticulin, in B16F10-Nex2. Our results suggest that peptide Rb4 acts directly on tumor cells inducing the expression of DAMPs, which trigger the immunoprotective effect in vivo against melanoma cells. We suggest that peptide Rb4 is a promising compound to be developed as an anticancer drug.

CMTM5 inhibits the development of prostate cancer via the EGFR/PI3K/AKT signaling pathway.

Prostate cancer (PCa) endangers the life and health of older men. Most PCa cases develop into castration­resistant PCa (CRPC) within 2 years. At present, the molecular mechanisms of the occurrence and development of PCa and its transformation to CRPC remain unknown. The present study aimed to investigate the role of CKLF­like Marvel transmembrane domain containing family member 5 (CMTM5) in PCa and its molecular mechanism in vitro. PCa tissues and paired adjacent normal prostate tissues from 70 patients were collected to examine the expression levels of CMTM5 and EGFR via immunohistochemistry, reverse transcription­quantitative PCR and western blotting. Then, CMTM5­overexpressing DU145 cells were constructed, and CMTM5 expression in these transfected cells and vector control cells was examined via western blotting. Cell Counting Kit­8 and plate clone formation assays were used to evaluate the proliferation and colony number of CMTM5­overexpressing cells and vector control cells. Then, cell migration and invasion were assessed using wound healing assay, Transwell assay and immunofluorescence analysis with DAPI staining. The effect of CMTM5 on apoptosis and its underlying molecular mechanism were examined using western blotting and flow cytometry. The results demonstrated that CMTM5 expression in PCa tissues and cell lines was significantly downregulated, while EFGR expression was significantly upregulated. The proportion of high CMTM5 expression in PCa tissues was significantly lower compared with that in normal prostate tissues. By contrast, the proportion of high EGFR expression in PCa tissues was significantly increased compared with that in normal prostate tissues. Moreover, CMTM5 overexpression significantly inhibited cell proliferation, migration and invasion, and promoted cell apoptosis compared with vector control cells in vitro. Furthermore, the regulation of PCa by CMTM5 was associated with the downregulation of PI3K/AKT and its downstream Bcl­2 expression, as well as the upregulation of Bax expression. In conclusion, CMTM5 may be an effective tumor suppressor gene for PCa, especially for castration­resistant PCa, by downregulating EGFR and PI3K/AKT signaling pathway components.

Progress in pharmacological research of chemokine like factor 1 (CKLF1).

Currently, the research of chemokines has penetrated into many fields of life science. A new kind of chemokines, chemokine like factor 1 (CKLF1), which is cloned through suppression subtractive hybridisation (SSH) technology is expressed widely in human body, especially in the lung and peripheral blood leukocytes. CKLF1 has a broad spectrum of chemotaxic activity for many cells, such as lymphocytes, macrophages, bone marrow cells, nerve cells and so on. In addition, CKLF1 also stimulates the regeneration of skeletal muscle cells in vivo. Collecting data derived from our and other laboratories show that CKLF1 has an important relationship with allergic diseases, autoimmune diseases, tumors, cardio-cerebrovascular diseases and so on. Therefore, there be an important theoretical purport and applied value to make a summary of pharmacological progress of CKLF1.

Effects of chemokine-like factor 1 on vascular smooth muscle cell migration and proliferation in vascular inflammation.

OBJECTIVE: Vascular smooth muscle cell (VSMC) migration and proliferation are key components of vascular inflammation that may lead to atherosclerosis and restenosis, in which cytokines are considered as pivotal factors regarding recruitment of VSMC. A member of recently described family of chemokines, chemokine-like factor 1 (CKLF1), displays a wide spectrum of chemotaxis. This study investigated the role of CKLF1 in VSMC migration and proliferation during the process of vascular inflammation. METHODS AND RESULTS: : The effects of CKLF1 on migration, proliferation and neointimal formation were investigated in cultured VSMCs, rat balloon injured arteries and human atherosclerotic plaques. CKLF1 overexpression greatly enhanced, whereas shRNA knockdown markedly retarded, VSMC migration and proliferation in vitro. In addition, CKLF1 protein accumulated preferentially in neointima of the injured rat arteries in vivo. CKLF1 overexpression resulted in a 2.5-fold increase in intimal thickness. In contrast, shRNA-mediated CKLF1 knockdown significantly suppressed neointima formation by 70% compared that in control group. Intriguingly, besides animal model, higher level of CKLF1 was observed in human atherosclerotic plaques than that in normal arteries. CONCLUSION: CKLF1 plays an essential role in migration and proliferation of VSMCs, which in turn facilitated neointimal hyperplasia and atherosclerosis. Inhibition of CKLF1 activity provides a potential target for the prevention of atherosclerosis and restenosis.

[Inhibitory effect of CMTM5 on xenografted human prostatic cancer in nude mice].

OBJECTIVE: To investigate the inhibitory effect of CKLF-like MARVEL transmembrane domain containing 5 (CMTM5) on xenografted human prostatic cancer in nude mice and its action mechanism. METHODS: We established a model of xenografted prostatic cancer by inoculating PC-3 cells subcutaneously into nude mice, and 3 weeks later injected CMTM5 adenovirus locally into the tumor followed by daily observation of the tumor volume and body weight of the experimental animals. All the rats were killed 2 weeks after CMTM5 injection and the tumor tissue harvested for detection of the inhibitory effect of CMTM5 on the expressions of VEGF and NF-kappaB proteins by immunohistochemistry. RESULTS: The tumor volume was significantly smaller and body weight of the CMTM5-treated mice were (573.39 +/- 175.24) mm3 and (0.55 +/- 0.11) g, respectively, significantly decreased as compared with those of the controls ([1482.50 +/- 327.86] mm3 and [1.31 +/- 0.29] g) (P = 0.03 and P = 0.027). Immunohistochemistry showed that the expressions of VEGF and NF-kappaB were obviously down-regulated in the CMTM5 group in comparison with the control group. CONCLUSION: CMTM5 suppresses the growth of prostate cancer by down-regulating the expressions of VEGF and NF-kappaB.