Minocycline enhances mitomycin C-induced cytotoxicity through down-regulating ERK1/2-mediated Rad51 expression in human non-small cell lung cancer cells

Minocycline as a prospective therapeutic agent for cancer and non-cancer diseases: a scoping review

Minocycline is an FDA-approved secondary-generation tetracycline antibiotic. It is a synthetic antibiotic having many biological effects, such as antioxidant, anti-inflammatory, anti-cancer, and neuroprotective functions. This study discusses the pharmacological mechanisms of preventive and therapeutic effects of minocycline. Specifically, it provides a comprehensive overview of the molecular pathways by which minocycline acts on the different cancers, including ovarian, breast, glioma, colorectal, liver, pancreatic, lung, prostate, melanoma, head and neck, leukemia, and non-cancer diseases such as Alzheimer's disease, Parkinson, schizophrenia, multiple sclerosis, Huntington, polycystic ovary syndrome, and coronavirus disease 19. Minocycline may be a potential medication for these disorders due to its strong blood-brain barrier penetrance. It is also widely accepted as a specific medication, has a well-known side-effect characteristic, is reasonably priced, making it appropriate for continuous use in managing diseases, and has been demonstrated as an oral approach because it is effectively absorbed and accomplished almost all of the body's parts.

Minocycline induced apoptosis and suppressed expression of matrix metalloproteinases 2 and 9 in the breast cancer MCF-7 cells

BACKGROUND

In women, breast cancer is the second most frequent type of cancer. Looking for new and effective cancer-specific therapies with little to no adverse effects on healthy cells is critical.

OBJECTIVE

Minocycline, a second-generation tetracycline, has shown anticancer effects by targeting multiple pathways in various cancers. This study aimed to determine minocycline effects on the cell proliferation, apoptosis, and invasion of the human MCF-7 cells.

METHODS

MTT assay was used to evaluate the cytotoxicity of minocycline on the cells. Flow cytometry was performed to investigate the induction of apoptosis and the cell cycle progression. The expression levels of apoptotic and migration proteins and genes were assessed by western blotting and qRT-PCR. The scratch test was performed to evaluate the anti-migration effect of the drug.

RESULTS

The results indicated that the IC50 value of minocycline for MCF-7 cells was 36.10 µM. Minocycline treatment caused sub-G1 cell accumulation, indicating a significant apoptotic effect on the MCF-7 cells. Annexin-V/PI staining revealed a significant rise in early and late apoptotic cell percentages. Minocycline up-regulated Bax and Caspase-3 expression and down-regulated Bcl-2 and Pro-Cas3. The scratch test revealed significant anti-migration effects for minocycline. Furthermore, it caused down-regulation of MMP-2 and MMP-9 in a concentration-dependent method.

CONCLUSION

These findings further confirmed the anticancer effect of minocycline and highlighted that minocycline maybe considered as potential therapeutic agent for breast cancer treatment.

Minocycline in Treating Glioblastoma Multiforme: Far beyond a Conventional Antibiotic

One of the most lethal forms of CNS pathologies is glioblastoma multiforme (GBM) that represents high invasiveness, uncontrolled proliferation, and angiogenic features. Its invasiveness is responsible for the high recurrence even after maximal surgical interventions. Minocycline is a semisynthetic analog of tetracyclines with potential anti-inflammatory and anticancer effects, distinct from its antimicrobial activity. In this review, we highlight the importance and the cytotoxic mechanisms of minocycline on GBM pathophysiology. Considering the role of certain enzymes in autophagy, apoptosis, tumor cell invasion, and metastatic ability, the possible use of tetracyclines for cancer therapy should be investigated, especially GBM. The present study is, therefore, going to cover the main topics in minocycline pharmacology to date, encouraging its consideration as a new treatment approach for cancer and GBM.

Metformin overcomes resistance to cisplatin in triple-negative breast cancer (TNBC) cells by targeting RAD51

BACKGROUND

Chemotherapy is a standard therapeutic regimen to treat triple-negative breast cancer (TNBC); however, chemotherapy alone does not result in significant improvement and often leads to drug resistance in patients. In contrast, combination therapy has proven to be an effective strategy for TNBC treatment. Whether metformin enhances the anticancer effects of cisplatin and prevents cisplatin resistance in TNBC cells has not been reported.

METHODS

Cell viability, wounding healing, and invasion assays were performed on Hs 578T and MDA-MB-231 human TNBC cell lines to demonstrate the anticancer effects of combined cisplatin and metformin treatment compared to treatment with cisplatin alone. Western blotting and immunofluorescence were used to determine the expression of RAD51 and gamma-H2AX. In an in vivo 4T1 murine breast cancer model, a synergistic anticancer effect of metformin and cisplatin was observed.

RESULTS

Cisplatin combined with metformin decreased cell viability and metastatic effect more than cisplatin alone. Metformin suppressed cisplatin-mediated RAD51 upregulation by decreasing RAD51 protein stability and increasing its ubiquitination. In contrast, cisplatin increased RAD51 expression in an ERK-dependent manner. In addition, metformin also increased cisplatin-induced phosphorylation of γ-H2AX. Overexpression of RAD51 blocked the metformin-induced inhibition of cell migration and invasion, while RAD51 knockdown enhanced cisplatin activity. Moreover, the combination of metformin and cisplatin exhibited a synergistic anticancer effect in an orthotopic murine model of 4T1 breast cancer in vivo.

CONCLUSIONS

Metformin enhances anticancer effect of cisplatin by downregulating RAD51 expression, which represents a novel therapeutic target in TNBC management.

Minocycline Reduces Chemoradiation-Related Symptom Burden in Patients with Non-Small Cell Lung Cancer: A Phase 2 Randomized Trial

PURPOSE

In patients with non-small cell lung cancer (NSCLC), concurrent chemoradiation therapy (CRT) exacerbates a cluster of difficult-to-manage symptoms, especially cancer-related fatigue. Minocycline is a readily available, low-cost antibiotic with antiinflammatory properties. We conducted a phase 2 randomized, double-blinded, placebo-controlled trial to investigate the effect of minocycline in reducing CRT-symptom burden in NSCLC.

METHODS AND MATERIALS

Patients with NSCLC scheduled to receive CRT provided consent and were randomized to receive either minocycline (100 mg twice daily) or a matching placebo during 6 to 7 weeks of CRT. Patient-reported fatigue and other symptoms were assessed on MD Anderson Symptom Inventory weekly from the start of CRT for 12 weeks. The primary outcome was 12-week (±2 days) area under the curve for symptom burden, which was compared between treatment groups.

RESULTS

Forty of 49 enrolled patients (80%) were evaluable (19 on minocycline and 21 on placebo). There were no grade 3 + adverse events related to the study medication. Fatigue was significantly reduced in the minocycline group compared with placebo group during the 12-week trial period (area under the curve = 31.2 ± 14.2 vs 45.0 ± 20.9, P = .011), with a large effect size (Cohen's d = 0.77). Pain (Cohen's d = 0.54) and shortness of breath (Cohen's d = 0.55) were also significantly reduced in the minocycline group (all P < .05).

CONCLUSIONS

Minocycline during CRT for NSCLC was feasible, had a low toxicity profile, and yielded a clinically and statistically significant positive signal in reducing symptom burden related to NSCLC and CRT. This study is a proof of concept so a larger trial in CRT patients is warranted.

The homologous recombination protein RAD51 is a promising therapeutic target for cervical carcinoma

RAD51 is one of the pivotal enzymes for DNA double-strand break (DSB) repair by the homologous recombination (HR) pathway, which implies it as a promising and novel target for cancer therapy. Recent findings have indicated RAD51 protein is overexpressed in a variety of tumors. The high-expression of RAD51 is related to poor prognosis. RAD51 is involved in the repair of DNA damage and the generation of genetic diversity by an evolutionarily conserved mechanism. However, the exact mechanism of Rad51 in the progression of cervical cancer remains unclear. RI-1 is a small molecule that inhibits the central recombination protein RAD51. In this study, we found that RAD51 was highly expressed in invasive squamous cervical cancer (SCC). The administration of RI-1 inhibited cell growth in vitro and reduced growth of tumor xenografts in vivo with cervical cancer cells (HeLa and SiHa). Further investigation suggested that RAD51 protein significantly promoted the cell cycle transition from the G0/G1 to S phase. In addition, the inhibition of RAD51 reduced the level of the cell cycle related protein cyclin D1, but increased the levels of p21 mRNA and protein. As a DNA DSB repair enzyme, the expression of RAD51 in tumor cells possibly affects their sensitivity to anti-cancer agents. Additionally, in experiments using cisplatin and ionizing radiation, RI-1 treated cervical cancer cells, HeLa and SiHa, were sensitized to a greater extent than the untreated control. Thus, HR inhibition of RAD51 may provide yet another mechanism of therapeutic target for the chemosensitization and radiosensitization of cervical cancer with RI-1. Collectively, our data demonstrated for the first time that inhibition of RAD51 suppressed the cervical cancer cell proliferation and the growth of cervical cancer xenografts by attenuating cell cycle transition, which could be a functional link between RAD51 and cyclin D1 and p21.