The Insulin-Like Growth Factor-I Receptor Inhibitor Picropodophyllin-Induced Selective Apoptosis of Hepatocellular Carcinoma Cell Through a Caspase-Dependent Mitochondrial Pathway

Targeting HSP90 with picropodophyllin suppresses gastric cancer tumorigenesis by disrupting the association of HSP90 and AKT

Gastric cancer (GC) is one of the most common malignant tumors worldwide. Thus, the development of safe and effective therapeutic compounds for GC treatment is urgently required. Here, we aimed to examine the role of picropodophyllin (PPP), a compound extracted from the rhizome of Dysosma versipellis (Hance) M. Cheng ex Ying, on the proliferation of GC cells. Our study revealed that PPP inhibits the proliferation of GC cells in a dose-dependent manner by inducing apoptosis. Moreover, our study elucidated that PPP suppresses the growth of GC tumor xenografts with no side effects of observable toxicity. Mechanistically, PPP exerts its effects by blocking the AKT/mammalian target of rapamycin (mTOR) signaling pathway; these effects are markedly abrogated by the overexpression of constitutively active AKT. Furthermore, drug affinity responsive target stability (DARTS) and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) revealed that heat shock protein 90 (HSP90) may be a potential target of PPP. Surface plasmon resonance and immunoprecipitation assay validated that PPP directly targets HSP90 and disrupts the binding of HSP90 to AKT, thereby suppressing GC cell proliferation. Thus, our study revealed that PPP may be a promising therapeutic compound for GC treatment.

Picropodophyllin inhibits type I endometrial cancer cell proliferation via disruption of the PI3K/Akt pathway

The type-I insulin-like growth factor receptor (IGF-IR) is overexpressed in endometrial cancer. High IGF-IR expression was considered as an important prognostic factor for tumor progression. The purpose of this study was to investigate the role and molecular mechanism of IGF-IR inhibitor picropodophyllin (PPP) in the growth and development of endometrial cancer. High expression of IGF-IR was observed in endometrial cancer tissues, as well as in ECC-1 and KLE cell lines. PPP suppressed the number of clones of ECC-1 and KLE cell lines; however, it had no significant effect on HEC-1-A cell line, which expressed lower IGF-IR than ECC-1 and KLE cell lines. Furthermore, PPP reduced cell proliferation capacity, inhibited the IGF-IR mRNA expression, and suppressed protein phosphorylation of IGF-IR and Akt in the three cell lines. In addition, PPP inhibited the protein expression of survivin in KLE cell line after 1 h of exposure, though this effect did not last for prolonged time. In conclusion, IGF-IR was mostly overexpressed in type I endometrial cancer. High IGF-IR expression was an important prognostic factor of tumor progression. PPP mediated the down-regulation of IGF-IR phosphorylation and inhibited cell proliferation via the PI3K/Akt signal pathway. PPP may have the potential to become a clinical treatment target in endometrial carcinoma.

PDGFR and IGF-1R Inhibitors Induce a G2/M Arrest and Subsequent Cell Death in Human Glioblastoma Cell Lines

Glioblastomas are highly resistant to radiation and chemotherapy. Currently, there are no effective therapies for this type of tumor. Signaling mechanisms initiated by PDGFR and IGF-1R are important in glioblastoma, and inhibition of the signal transduction pathways initiated by these receptors could be a useful alternative strategy for glioblastoma treatment. We have studied the effects of the PDGFR inhibitor JNJ-10198409 (JNJ) and the IGF-1R inhibitor picropodophyllin (PPP) in glioblastoma cell lines as well as in primary cultures derived from patients affected by this type of tumor. JNJ and PPP treatment blocked PDGFR and IGF-1R signaling respectively and reduced Akt and Erk 1/2 phosphorylation. Both inhibitors diminished cell proliferation, inducing a G2/M block of the cell cycle. Cell death induced by JNJ was caspase-dependent, Annexin-V positive and caused PARP cleavage, especially in T98 cells, suggesting an apoptotic mechanism. However, cell death induced by PPP was not completely inhibited by caspase inhibitors in all cell lines apart from LN-229 cells, indicating a caspase-independent mechanism. Several inhibitors targeted against different cell death pathways could not block this caspase-independent component, which may be a non-programmed necrotic mechanism. Apoptotic arrays performed in T98 and LN-229 cells upon JNJ and PPP treatment revealed that procaspase 3 levels were augmented by both drugs in T98 cells and only by JNJ in LN229-cells. Furthermore, XIAP and survivin levels were much higher in LN-229 cells than in T98 cells, revealing that LN-229 cells are more susceptible to undergo caspase-independent cell death mechanisms. JNJ and PPP combination was more effective than each treatment alone.

MicroRNA‑539 inhibits cell proliferation, colony formation and invasion in pancreatic ductal adenocarcinoma by directly targeting IGF‑1R

MicroRNAs (miRNAs) possess oncogenic and tumour‑suppressive roles in the carcinogenesis and progression of pancreatic ductal adenocarcinoma (PDAC) by regulating the expression of numerous cancer‑related genes. Thus, the investigation on the expression and roles of miRNAs in PDAC may facilitate the identification of novel and effective targets for the clinical diagnosis and treatment of patients with PDAC. miRNA‑539 (miR‑539) has been studied in multiple types of human cancer. However, its expression and potential biological function in PDAC remain unclear. In the current study, the expression level, clinical significance, roles and underlying molecular mechanism of miR‑539 in PDAC. The present results demonstrated that miR‑539 expression was downregulated in PDAC tissues and cell lines. A low miR‑539 level was associated with TNM stage and lymph node metastasis of patients with PDAC. miR‑539 overexpression induced a significant reduction in the proliferation, colony formation and invasion of PDAC cells. Insulin‑like growth factor 1 receptor (IGF‑1R) was confirmed as a direct target gene of miR‑539 in PDAC. Further analysis indicated that IGF‑1R was overexpressed in PDAC tissues. Notably, the mRNA expression of IGF‑1R was negatively correlated with miR‑539 levels in PDAC tissues. In addition, the recovered IGF‑1R expression also partially counteracted the suppressive roles of miR‑539 overexpression in PDAC cells. Overall, miR‑539 may inhibit the aggressive behaviour of PDAC by directly targeting IGF‑1R and may serve as a novel therapeutic target for patients with this disease.

miR-342-3p suppresses hepatocellular carcinoma proliferation through inhibition of IGF-1R-mediated Warburg effect

Background

Insulin-like growth factor-1 receptor (IGF-1R) is a well-studied oncogenic factor that promotes cell proliferation and energy metabolism and is overexpressed in numerous cancers including hepatocellular carcinoma (HCC). Aerobic glycolysis is a hallmark of cancer, and drugs targeting its regulators, including IGF-1R, are being developed. However, the mechanisms of IGF-1R inhibition and the physiological significance of the IGF-1R inhibitors in cancer cells are unclear.

Materials and methods

Cell proliferation was evaluated by cell counting Kit-8 and colony formation assay. Western blot and real-time PCR were accordingly used to detect the relevant proteins, miRNA and gene expression. Luciferase reporter assays were used to illustrate the interaction between miR-342-3p and IGF-1R. The effect of miR-342-3p on glycolysis was determined by glucose uptake, ATP concentration, lactate generation, extracellular acidification rate and oxygen consumption rate assays. In vivo, subcutaneous tumor formation assay and PET were performed in nude mice.

Results

In this study, we demonstrate that by directly targeting the 3′-UTR (3′-untranslated regions) of IGF-1R, microRNA-342-3p (miR-342-3p) suppresses IGF-1R-mediated PI3K/AKT/GLUT1 signaling pathway both in vitro and in vivo. Through suppression of IGF-1R, miR-342-3p dampens glycolysis by decreasing glucose uptake, lactate generation, ATP production, and extracellular acidification rate (ECAR), and increasing oxygen consumption rate (OCR) in hepatoma cells. Importantly, glycolysis regulated by miR-342-3p is critical for its regulating HCC growth both in vitro and in vivo.

Conclusion

Our findings provide clues regarding the role of miR-342-3p as a tumor suppressor in liver cancer mainly through the inhibition of IGF-1R. Targeting IGF-1R by miR-342-3p could be a potential therapeutic strategy in liver cancer.

Catalytic Enantioselective Synthesis of (-)-Podophyllotoxin

The first catalytic enantioselective total synthesis of (-)-podophyllotoxin is accomplished by a challenging organocatalytic cross-aldol Heck cyclization and distal stereocontrolled transfer hydrogenation in five steps from three aldehydes. Reversal of selectivity in hydrogenation led to the syntheses of other stereoisomers from the common precursor.

Esculetin exerts antitumor effect on human gastric cancer cells through IGF-1/PI3K/Akt signaling pathway

In this study, we aimed to investigate the antitumor effect of esculetin, a coumarin derivative extracted from natural plants, on human gastric cancer cells, and to illustrate the potential mechanisms. The results showed that esculetin exhibited anti-proliferative effects against gastric cancer cells and induced their apoptosis in a dose dependent manner with lower toxicity against normal gastric epithelial cells. Mechanism study indicated that esculetin induced gastric cancer MGC-803 cells apoptosis by triggering the activation of mitochondrial apoptotic pathway through reducing the mitochondrial membrane potential (MMP), increasing Bax/Bcl-2 ratio, activating caspase-3 and caspase-9 activity, and increasing cytochrome c release from mitochondria. Further study showed that the pro-apoptotic effects of esculetin were associated with down-regulation of insulin-like growth factor-1/ phosphatidylinositide 3-kinase/protein kinase B (IGF-1/PI3K/Akt) signaling pathway. Activation of IGF-1/PI3K/Akt pathway by IGF-1 abrogated the pro-apoptotic effects of esculetin, while inhibition of IGF-1/PI3K/Akt pathway by triciribine or LY294002 enhanced the pro-apoptotic effects of esculetin. In addition, esculetin inhibited in vivo tumor growth with no obvious toxicity following subcutaneous inoculation of MGC-803 cells in nude mice, and inhibited activation of IGF-1/PI3K/Akt pathway in tumor tissue.

CONCLUSION

These results indicate that esculetin could inhibit cell proliferation and induce apoptosis of gastric cancer cells through IGF-1/PI3K/Akt mediated mitochondrial apoptosis pathway, and may be a novel effective chemotherapeutic agent against gastric cancer.

Esculetin induces apoptosis of SMMC-7721 cells through IGF-1/PI3K/Akt-mediated mitochondrial pathways

Esculetin (6,7-dihydroxycoumarin) is a coumarin derivative extracted from natural plants and has been reported to have anticancer activity. However, the mechanism by which esculetin prevents human hepatic cancer cell growth is still largely unknown. In this study, we investigated the effect of esculetin on human hepatocellular carcinoma (HCC) SMMC-7721 cells and explored the cell signal mechanism. Our data indicated that esculetin induced apoptosis in SMMC-7721 cells, which were supported by DAPI staining and Annexin V/PI staining. Meanwhile, esculetin increased the activities of caspase-3 and caspase-9, promoted bax expression, decreased bcl-2 expression, and triggered collapse of mitochondrial membrane potential, and increased cytochrome c release from mitochondria. In addition, the inactivation of IGF-1, PI3K, and Akt was observed after esculetin administration. Furthermore, pretreatment with IGF-1 before esculetin administration abrogated the pro-apoptotic effects of esculetin, while PI3K inhibitor increased the pro-apoptotic effects of esculetin. These results indicated that esculetin induced the apoptosis of SMMC-7721 cells through IGF-1/PI3K/Akt-regulated mitochondrial dysfunction.

MicroRNA-187 inhibits tumor growth and metastasis via targeting of IGF-1R in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the primary and most frequently occurring type of malignant liver cancer, accounting for 70-85% of total liver cancer cases worldwide. It has previously been demonstrated that the aberrant expression of microRNAs (miR) contributes to carcinogenesis and progression of various human malignancies, including HCC. However, mechanisms underlying the differential expression and specific roles of miR‑187 in HCC remain to be elucidated, particularly regarding how the modulation of malignant phenotypes in HCC cells occurs. The present study demonstrated that miR‑187 was significantly downregulated in HCC tissues and cell lines. Restoration of miR‑187 expression inhibited cell proliferation, migration and invasion in HCC. Furthermore, insulin‑like growth factor 1 receptor (IGF‑1R) was demonstrated to act as a direct target gene of miR‑187 in HCC. IGF‑1R knockdown mimicked the effects of miR‑187 overexpression in HCC, resulting in a significant inhibition of cell proliferation, migration and invasion. The results of the present study demonstrated that miR‑187 acted as a tumor suppressor in HCC progression via direct targeting of IGF‑1R. miR‑187 may therefore exhibit the potential to act as a novel and therapeutic target for HCC treatment in the future.

Expression of GRK2 and IGF1R in hepatocellular carcinoma: clinicopathological and prognostic significance

AIM

It has been shown that G-protein-coupled receptor kinase 2 (GRK2) negatively regulates the insulin-like growth factor 1 receptor (IGF1R) signalling pathway in hepatocellular carcinoma (HCC). The aim of this study was to evaluate the clinicopathological and prognostic significance of GRK2 and IGF1R in HCC.

METHODS

Expression of GRK2 and IGF1R was first detected by tissue microarray-based immunohistochemistry in 156 patients with HCC. Staining results, termed the H-score, were then correlated with clinicopathological variables and patient survival. Finally, the prognostic value of GRK2 and IGF1R was validated in the publically available TCGA (The Cancer Genome Atlas) RNA-sequencing database.

RESULTS

The H-score of GRK2 staining (which was significantly lower in tumour than non-tumour tissue) was negatively associated with that of IGF1R with a reverse trend. No clinicopathological significance of the proteins was found except for a relationship between tumoral IGF1R expression and tumour-node-metastasis stage. In univariate analysis, high IGF1R expression predicted poor overall and disease-free survival, whereas GRK2 was not prognostic. In multivariate analysis, IGF1R was significant for overall survival. Furthermore, IGF1R was also of prognostic value in the TCGA database.

CONCLUSIONS

Our data indicate that GRK2 and IGF1R show a negative correlation in HCC. IGF1R could be a potential marker of poor prognosis for this malignancy.