Lung cancer has a high incidence rate, often causes death, due to its aggressive nature, rapid metastasis, and widespread prevalence. More than 2 million newly diagnosed lung cancer cases were reported worldwide in 2020, accounting for 11.4% of all malignant tumor cases [1]. Moreover, the mortality rate may also exceed 2 million, which cannot be ignored in cancer-related deaths [2]. Non–small cell lung cancer (NSCLC), the main pathological type of lung cancer, is highly malignant and insidious, and causes delayed medical treatment and rapid disease development. Recently, screening, diagnosis, and treatment methods for NSCLC have greatly improved. Advances in systemic therapy are mainly driven by the development of molecular targeted therapies, immune checkpoint inhibitors and antiangiogenic agents, all of which have led to remarkable changes in this field of research and significantly improved patients’ prognosis [3], [4]. However, targeted therapy is applicable only to patients with sensitive gene mutations, and drug tolerance is inevitable as well as the high expense. Additionally, immunotherapy is still low-accepted and faces risks such as colitis and pneumonia, which can cause severe damage to the already weak lung reserves, and sometimes, may be fatal [5], [6], [7]. Chemotherapy, indeed, plays an important role as an adjunct therapy for patients with early-stage resected NSCLC, as palliative care for patients with advanced-stage NSCLC, and as a dual/multimodal therapy for patients with locally advanced NSCLC [8]. Platinum-based chemotherapeutic drugs are widely used and are effective at treatment initiation. However, tumor cells gradually begin to lose sensitivity to these chemotherapy drugs in the late stage of treatment, affecting treatment efficacy and patients’ prognosis severely. Owing to its complex drug resistance mechanism and side effects, some patients become intolerant, necessitating the identification of alternative clinical protocols [9].

The development of multifunctional nanomaterials (NMs) such as nanoparticles (NPs) and nanoclusters (NCs) are one of the most interesting and advanced research hotspots in nanotechnology [10]. Nanomedicines have gradually garnered people’s attention in recent years and are expected to revolutionize cancer diagnosis and treatment. Due to the unique structure, optical features and catalytic characteristics, platinum NMs (Pt-NMs) have become a promising candidate for biomedical applications. Pt-NMs have successfully been used as a catalyst, drug, nano diagnostic tool, and drug delivery nanocarriers, thus, advancing the development of biomedicines [11], [12]. Recently, the antitumor effect of Pt-NMs has gained attention as an alternative treatment approach for patients with cancer. Gurunathan et al. reported that Pt-NPs exert significant inhibitory and toxic effects on acute single-cell leukemia cells, and their combination with retinoic acid increased the antitumor effect of cisplatin in human neuroblastoma [13], [14]. Almarzoug et al. demonstrated that Pt-NPs induced genotoxicity and apoptosis in hepatocellular carcinoma cells by activating the Bax/Bcl-2 signaling pathways [15]. As shown previously, compared with cisplatin, amine-caged Pt nanoclusters (short for “Nano-Pt”) effectively suppressed the viability of A549 cells at a relatively low dosage and had a less killing effect on normal cells [16]. However, the detailed and specific mechanism of action of Nano-Pt in NSCLC cells remains unclear.

Autophagy is the cell self-renewal process that is essential for maintaining basic celluar functions. Many NMs can trigger autophagy by promoting cell survival, cell death, or no effect [17], [18], [19], and the efficiency of the NMs to trigger autophagy is affected by NMs’ shape, size, spatial structure, surface modification, and cell type. For example, gold NMs (Au-NMs) can improve the levels of autophagy protein LC3-II to induce autophagy and mitochondrial damage, and the generation of reactive oxygen species was considered a possible mechanism [20]. Silver NPs (Ag-NPs) activated extensive autophagy in HeLa cells. ATG5 small interference RNA enhanced the antitumor effects of Ag-NPs [21]. Zhang et al. suggested that Nano-Pt induced autophagy by inhibiting the PI3K/AKT/mTOR pathway while inducing apoptosis in cisplatin-resistant ovarian cancer cells, but the authors did not further explore the interaction between apoptosis and autophagy induced by Nano-Pt [22], [23]. Generally, autophagy plays a bidirectional role in tumors, wherein they can either suppress tumor formation or enhance the adaptability of tumor cells to the unfavorable metabolic environment, thereby promoting tumor cell survival. However, the interaction between Nano-Pt and autophagy induction in terms of the toxicity or apoptosis of NSCLC cells has not been explored in detail.

Therefore, this study investigated the effects of Nano-Pt on biological behaviors, including cell cycle, migration, and proliferation in NSCLC using scratch wound test and colony formation assay, wherein NSCLC H460 cells (large-cell carcinoma) and A549 cells (adenocarcinoma) were used as the treatment objects. Additionally, the cell apoptosis mechanism was unraveled using mitochondrial membrane potential (MMP) assay and apoptosis-associated proteins analysis. Autophagy induction by Nano-Pt was tracked using the monodansylcadaverine (MDC) assay as well as western blotting assay, transmission electron microscopy (TEM) was used for observing the ultra-microstructure of cells. More importantly, the autophagy inhibitor 3-methyladenine (3-MA) was employed to investigate the effect of autophagy on NSCLC apoptosis. This research on the biological behaviors, the interaction between autophagy and apoptosis can provide the clear anti-NSCLC molecular mechanism of Nano-Pt, which apply a promising potential for developing novel Pt-based antitumor chemotherapy drugs with excellent curative efficiency and fewer side effects.