Glucose-regulated protein 78 mediates the anticancer efficacy of shikonin in hormone-refractory prostate cancer cells

Transketolase promotes colorectal cancer metastasis through regulating AKT phosphorylation

Transketolase (TKT) which is an important metabolic enzyme in the pentose phosphate pathway (PPP) participates in maintaining ribose 5-phosphate levels. TKT is necessary for maintaining cell growth. However, we found that in addition to this, TKT can also affect tumor progression through other ways. Our previous study indicate that TKT could promote the development of liver cancer by affecting bile acid metabolism. And in this study, we discovered that TKT expression was remarkably upregulated in colorectal cancer, abnormal high expression of TKT is associated with poor prognosis of colorectal cancer. Additionally, TKT promoted colorectal cancer cell growth and metastasis. Further study demonstrated that TKT interacted with GRP78 and promoted colorectal cancer cell glycolysis through increasing AKT phosphorylation, thereby enhancing colorectal cancer cell metastasis. Thus, TKT is expected to become an indicator for judging the prognosis of colorectal cancer, and provide a theoretical basis for drug development of new treatment targets for colorectal cancer.

The Multiple Roles and Therapeutic Potential of Molecular Chaperones in Prostate Cancer

Prostate cancer (PCa) is one of the most common cancer types in men worldwide. Heat shock proteins (HSPs) are molecular chaperones that are widely implicated in the pathogenesis, diagnosis, prognosis, and treatment of many cancers. The role of HSPs in PCa is complex and their expression has been linked to the progression and aggressiveness of the tumor. Prominent chaperones, including HSP90 and HSP70, are involved in the folding and trafficking of critical cancer-related proteins. Other members of HSPs, including HSP27 and HSP60, have been considered as promising biomarkers, similar to prostate-specific membrane antigen (PSMA), for PCa screening in order to evaluate and monitor the progression or recurrence of the disease. Moreover, expression level of chaperones like clusterin has been shown to correlate directly with the prostate tumor grade. Hence, targeting HSPs in PCa has been suggested as a promising strategy for cancer therapy. In the current review, we discuss the functions as well as the role of HSPs in PCa progression and further evaluate the approach of inhibiting HSPs as a cancer treatment strategy.

Shikonin derivatives for cancer prevention and therapy

Phytochemicals gained considerable interest during the past years as source to develop new treatment options for chemoprevention and cancer therapy. Motivated by the fact that a majority of established anticancer drugs are derived in one way or another from natural resources, we focused on shikonin, a naphthoquinone with high potentials to be further developed as preventive or therapeutic drug to fight cancer. Shikonin is the major chemical component of Lithospermum erythrorhizon (Purple Cromwell) roots. Traditionally, the root extract has been applied to cure dermatitis, burns, and wounds. Over the past three decades, the anti-inflammatory and anticancer effects of root extracts, isolated shikonin as well as semi-synthetic and synthetic derivatives and nanoformulations have been described. In vitro and in vivo experiments were conducted to understand the effect of shikonin at cellular and molecular levels. Preliminary clinical trials indicate the potential of shikonin for translation into clinical oncology. Shikonin exerts additive and synergistic interactions in combination with established chemotherapeutics, immunotherapeutic approaches, radiotherapy and other treatment modalities, which further underscores the potential of this phytochemical to be integrated into standard treatment regimens.

Glucose-Related Protein 78 Expression and Its Effects on Cisplatin-Resistance in Cervical Cancer

Background

GRP78, the 78-kDa glucose-regulated protein, occupies a significant position in endoplasmic reticulum stress. Emerging evidences have shown that GRP78 induces chemoresistance in several tumors; however, the role of GRP78 in cervical cancer (CVC) still needs to be elucidated clearly.

Material/Methods

In the present study, we evaluated the expression levels of GRP78 in CVC tissues collected from patients through immunocytochemistry, western blot, and real-time PCR. To explore the exact role of GRP78 in CVC cells in the presence of cisplatin, we generated GRP78 knockdown CVC cells through small interfering RNA. After transfection, the apoptosis rate was assessed by flow cytometry. Then the expression levels of caspase-3, CHOP, and Bcl-2 in GRP78 knockdown cells were determined by western blot.

Results

The GRP78 levels in CVC tissues were increased significantly. Three types of CVC cells HeLa, SiHa, and C33A were treated with different concentrations of cisplatin and cultured for 12 hours, 24 hours, and 48 hours respectively. And SiHa cells exhibited the highest resistance to cisplatin at all time. Specifically, after 25 μM cisplatin treatment, more than 80% of C33A cells underwent apoptosis, whereas the apoptotic rate of SiHa cells was only 30–40%. Data suggested that GRP78 silencing increased chemo-sensitivity and improved the effects of cisplatin-induced apoptosis in SiHa cells. Moreover, inhibition of GRP78 could upregulate caspase-3 and CHOP expression and downregulate Bcl-2 expression.

Conclusions

GRP78 may represent a key bio-marker of CVC and silencing GRP78 may strengthen the resistance against cisplatin. GRP78 may be a potential molecular target for CVC therapies in future.

The evaluation of potent antitumor activities of shikonin coumarin-carboxylic acid, PMMB232 through HIF-1α-mediated apoptosis

In current study, a series of shikonin derivatives were synthesized and its anticancer activity was evaluated. As a result, PMMB232 showed the best antiproliferation activity with an IC₅₀ value of 3.25±0.35μM. Further, treatment of HeLa cells with a variety of concentrations of target drug resulted in dose-dependent event marked by apoptosis. What's more, the mitochondrial potential (Δym) analysis was consistent with the apoptosis result. In addition, PARP was involved in the progress of apoptosis revealed by western blotting. To identify the detailed role and mechanism of PMMB232 in the progression of human cervical cancer, we detected the expression of HIF-1α and E-cadherin in HeLa cells. Results showed that expression of HIF-1α was downregulated, while E-cadherin protein was upregulated. Meanwhile, glycolysis related protein PDK1 was decreased in HeLa cells. Conversely, the expression of PDH-E1α was upregulated. Docking simulation results further indicate that PMMB232 could be well bound to HIF-1α. Taken together, our data indicate that compound PMMB232 could be developed as a potential anticancer agent.

The phosphorylation-specific association of STMN1 with GRP78 promotes breast cancer metastasis

Metastasis is a major cause of death in patients with breast cancer. Stathmin1 (STMN1) is a phosphoprotein associated with cancer metastasis. It exhibits a complicated phosphorylation pattern in response to various extracellular signals, but its signaling mechanism is poorly understood. In this study, we report that phosphorylation of STMN1 at Ser25 and Ser38 is necessary to maintain cell migration capabilities and is associated with shorter disease-free survival (DFS) in breast cancer. In addition, we report that glucose-regulated protein of molecular mass 78 (GRP78) is a novel phospho-STMN1 binding protein upon STMN1 Ser25/Ser38 phosphorylation. This phosphorylation-dependent interaction is regulated by MEK kinase and is required for STMN1-GRP78 complex stability and STMN1-mediated migration. We also propose a prognostic model based on phospho-STMN1 and GRP78 to assess metastatic risk in breast cancer patients.

Maspin mediates the gemcitabine sensitivity of hormone-independent prostate cancer

Androgen deprivation therapy has constituted the main treatment for prostate cancer; however, tumors ultimately progress to hormone-independent prostate cancer (HIPC), and suitable therapeutic strategies for HIPC are not available. Maspin, which is also known as mammary serine protease inhibitor, has been suggested to be a valuable focus for targeted cancer therapy. Specifically, maspin has been shown to be upregulated after androgen ablation therapy. Gemcitabine is used as a first-line therapy for metastatic castration-resistant prostate cancer, but its disease control rate is low. Furthermore, the role of maspin in the therapeutic efficacy of gemcitabine for HIPC remains unclear. The expression levels of maspin in PC-3 and DU145 cells were determined by real-time PCR and Western blotting. Furthermore, the expression of maspin was silenced using shRNA technology to generate maspin-KD cells. The cytotoxicity of gemcitabine to prostate cancer cells was assessed using 3-[4,5-dimethylthiazol-2-yl]-3,5-diphenyl tetrazolium bromide (MTT) assays, whereas flow cytometry analyses and annexin V-propidium iodide (PI) apoptosis assays were used to assess the ability of gemcitabine to induce apoptosis in maspin-KD and control cells. Additionally, the expression patterns of anti-apoptosis proteins (myeloid cell leukemia 1 (Mcl-1) and B cell lymphoma 2 (Bcl-2)) and pro-apoptosis proteins (Bcl-2-associated death promoter (Bad) and Bcl-2-associated X protein (Bax)) were determined by Western blotting. In this study, PC-3 cells were more resistant to gemcitabine administration than DU145 cells, which correlated with the higher expression levels of maspin observed in PC-3 cells. Furthermore, maspin knockdown enhanced gemcitabine-induced cell death, as evidenced by the increased number of apoptotic cells. Gemcitabine treatment upregulated the levels of anti-apoptosis proteins (Mcl-2 and Bcl-2) in both scrambled control and maspin-KD cells; however, the fold changes in Mcl-1 and Bcl-2 expression were larger in gemcitabine-treated scrambled control cells than in maspin-KD cells. Finally, our findings indicate for the first time that maspin may mediate the therapeutic efficacy of gemcitabine in HIPC. Our results demonstrate that maspin knockdown enhanced the sensitivity of androgen-independent prostate cancer cells to gemcitabine. Therefore, combining gemcitabine with a drug that targets maspin might constitute a valuable strategy for prostate cancer treatment.