Vorinostat upregulates MICA via the PI3K/Akt pathway to enhance the ability of natural killer cells to kill tumor cells.

Vorinostat has good therapeutic efficacy against primary cutaneous T-cell lymphoma in the refractory stage. However, the molecular mechanism by which it inhibits solid tumors has not been clarified. To investigate the tumor inhibitory mechanism of vorinostat in cervical cancer, this study used Cell Counting Kit-8, flow cytometry, cell invasion and migration assays and the wound healing assay to evaluate the effects of vorinostat on cervical cancer cell proliferation, apoptosis, cell cycle, migration, and invasion. Real-time quantitative PCR and immunoblotting were used to detect gene and protein expression, respectively, of major histocompatibility class I-related chain A, phosphoinositide 3-kinase, phosphorylated PI3K p55 (Tyr199), and p-Akt (Ser473). The lactate dehydrogenase cytotoxicity assay was used to evaluate the ability of natural killer-92 cells to lyse cervical cancer cells. A xenograft nude mouse model was established to analyze the anti-tumor effect of vorinostat in vivo. Our results showed that vorinostat inhibited the proliferation, migration, and invasion of cervical cancer cells. Vorinostat also induced apoptosis and cell-cycle arrest in the S phase, inhibited PI3K (p110α), p-PI3K p55 (Tyr199), and p-Akt (Ser473) protein expression and upregulated MICA expression in vitro and in vivo, and promoted NK-92 cell-mediated cervical cancer cell lysis. The ability of vorinostat to upregulate MICA expression in cervical cancer cells was related to PI3K/Akt signaling. In brief, vorinostat upregulated MICA through the PI3K/Akt pathway and enhanced the sensitivity of cervical cancer cells to the NK cell-mediated cytolytic reaction. The results of this study demonstrate that vorinostat has anti-solid tumor effects on cervical cancer.

Metformin combined with nelfinavir induces SIRT3/mROS-dependent autophagy in human cervical cancer cells and xenograft in nude mice.

The molecular mechanisms underlying the antineoplastic properties of metformin combined with nelfinavir remain elusive. To explore this question, transmission electron microscopy (TEM) was used to observe the combinatorial effect of inducing autophagosome formation in human cervical cancer cells. Western blotting respectively assayed protein expression of LC3I, LC3II, Beclin-1, Autophagy-related protein 7 (Atg7), Autophagy-related protein 3 (Atg3), NAD-dependent deacetylase sirtuin-3 (SIRT3) and major histocompatibility complex class I chain-related gene A (MICA). Lactate dehydrogenase (LDH) cytotoxicity assay evaluated natural killer (NK) cell cytotoxicity in the presence of metformin and nelfinavir in combination or each drug alone. Using tumor xenografts in a nude mouse model, antitumor efficacy of the drug combination was assessed. We found that the drug combination could induce autophagosome formation in human cervical cancer cells. The biomarker proteins of autophagy, including Beclin-1, Atg7 and Atg3, decreased, but the ratios of LC3I/II increased. We also found that this drug combination sensitizes human cervical cancer cells to NK cell-mediated lysis by increasing the protein of SIRT3 and MICA. Moreover, this drug combination markedly induced autophagy of SiHa xenografts in nude mice. Therefore, it can be concluded that metformin, in combination with nelfinavir, can induce SIRT3/mROS-dependent autophagy and sensitize NK cell-mediated lysis in human cervical cancer cells and cervical cancer cell xenografts in nude mice. Thus, our findings have revealed the detailed molecular mechanisms underlying the antitumor effects of metformin in combination with nelfinavir in cervical cancer.

Metformin, a first-line drug for type 2 diabetes mellitus, disrupts the MALAT1/miR-142-3p sponge to decrease invasion and migration in cervical cancer cells.

The molecular mechanisms underlying the anti-neoplastic properties of metformin, a first-line drug for type 2 diabetes, remain elusive. To explore the novel anti-neoplastic mechanisms of metformin, the transwell chamber and wound-healing assays were used to evaluate its effects on the migration and invasion of human cervical cancer cells. Real-time PCR and Western blotting were used to measure the gene and protein expression, respectively, of microRNA (miRNA) miR-142-3p, long non-coding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript-1 (MALAT1), and high-mobility group AT-hook 2 (HMGA2). The dual-luciferase reporter assay system was used to examine the direct interaction between miR-142-3p and lncRNA MALAT1 and HMGA2. Immunofluorescence was used to detect the protein expression of HMGA2. In addition, tumor xenografts in a nude mouse model were developed to evaluate the anti-tumor efficacy of metformin. We found that metformin could suppress cervical cancer migration and invasion. During the process of tumor metastasis, miR-142-3p was significantly upregulated, whereas lncRNA MATAL1 and HMGA2 were suppressed by metformin. The binding site that allow the direct interaction between miR-142-3p and MALAT1 were located in the 3' untranslated region (3' UTR) of lncRNA MATAL1 and HMGA2 at base pairs (bp) 4452-5255, while that between miR-142-3p and HMGA2 was located at bp 1562-2521 of HMGA2. Metformin markedly inhibited the growth and angiogenesis of SiHa xenografts in nude mice. In conclusion, this study provides evidence that metformin can prevent the MALAT1/miR-142-3p sponge from developing anti-neoplastic properties in human cervical cancer cells and cervical cancer cell xenografts in nude mice. Thus, our findings demonstrate the novel anti-tumor effects of metformin in cervical cancer.