mTOR inhibition reduces growth and adhesion of hepatocellular carcinoma cells in vitro

Abstract

Mechanistic target of rapamycin (mTOR) signaling is typically increased in hepatocellular carcinoma (HCC). A panel of HCC cell lines (HepG2, Hep3B and HuH6) was exposed to various concentrations of the mTOR inhibitors, everolimus and temsirolimus, in order to investigate their effects on cell growth, clonal formation, cell cycle progression, and adhesion and chemotactic migration using MTT and clonal cell growth assays, fluorometric detection of cell cycle phases and a Boyden chamber assay. In addition, integrin α and β adhesion receptors were analyzed by flow cytometry and blocking studies using function blocking monoclonal antibodies were conducted to explore functional relevance. The results demonstrated that everolimus and temsirolimus significantly suppressed HCC cell growth and clonal formation, at 0.1 or 1 nM (depending on the cell line). In addition, the number of cells in G0/G1 phase was increased in response to drug treatment, whereas the number of G2/M phase cells was decreased. Drug treatment also considerably suppressed HCC cell adhesion to immobilized collagen. Integrin profiling revealed strong expression of integrin α1, α2, α6 and β1 subtypes; and integrin α1 was upregulated in response to mTOR inhibition. Suppression of integrin α1 did not affect cell growth; however, it did significantly decrease adhesion and chemotaxis, with the influence on adhesion being greater than that on motility. Due to a positive association between integrin α1 expression and the extent of adhesion, whereby reduced receptor expression was correlated to decreased cell adhesion, it may be hypothesized that the adhesion‑blocking effects of mTOR inhibitors are not associated with mechanical contact inhibition of the α1 receptor but with integrin α1‑dependent suppression of oncogenic signaling, thus preventing tumor cell‑matrix interaction.

Inhibitor for protein disulfide‑isomerase family A member 3 enhances the antiproliferative effect of inhibitor for mechanistic target of rapamycin in liver cancer: An in vitro study on combination treatment with everolimus and 16F16

“…It is thought that the activation of mTOR is associated with the pathogenesis and aggressiveness of liver cancer. In vitro and animal studies have shown that mTOR inhibitors could be effective for the treatment of liver cancer (11,13,15,29). However, clinical trials have failed to demonstrate significant improvement in the prognosis in of patients with liver cancer (17).…”

“…mTOR is overexpressed in approximately 40% of liver cancer, and liver cancer with overexpression of mTOR follows an unfavorable clinical course (11). Preclinical studies showed that inhibition of the mTOR pathway suppress the development of liver cancer (12)(13)(14)(15)(16). However, clinical trials of mTOR inhibitors Inhibitor for protein disulfide-isomerase family A member 3 enhances the antiproliferative effect of inhibitor for mechanistic target of rapamycin in liver cancer: An in vitro study on combination treatment with everolimus and 16F16…”

Dairy consumption and hepatocellular carcinoma risk

“…Loss-of-function of tuberin (TSC2), a key negative regulator of mTORC1, is common in HCC (338). Finally, the majority of therapeutic interventions in HCC aim at decreasing AKT-mTORC1 signaling (339)(340)(341)(342).…”

The Effect of Immunosuppression on Coagulation After Liver Transplantation

“…EVR in combination with a reduced dose of TAC results in better renal function than that seen with standard immunosuppression (IS) with TAC alone . Furthermore, EVR had been shown to exert antiproliferative effects and antitumor activity on hepatoma cells in vitro . However, in either clinical or in vivo trials, clear evidence is still missing confirming that the application of EVR could reduce recurrence rates of hepatocellular carcinoma (HCC) after LT .…”

“…(1)(2)(3) Furthermore, EVR had been shown to exert antiproliferative effects and antitumor activity on hepatoma cells in vitro. (4,5) However, in either clinical or in vivo trials, clear evidence is still missing confirming that the application of EVR could reduce recurrence rates of hepatocellular carcinoma (HCC) after LT. (6)(7)(8) New evidence suggests that EVR protects LT patients from the development of donor-specific antibodies, which may complicate longterm graft viability. (9,10) Moreover, the administration of EVR is related to a reduction in the risk of cytomegalovirus infections among immunosuppressed patients (11)(12)(13) and has been shown to reduce the viral load of LT patients infected with hepatitis C virus genotypes 2a and 3.…”