Lung cancer is one of the most common cancers in the world and the leading cause of cancer-related deaths, with more than 2 million new cases and more than 1.8 million deaths each year [1], [2], [3]. According to histopathological classification, small cell lung cancer accounts for about 15 % of all diagnosed cases, while non-small cell lung cancer (NSCLC) accounts for about 85 % of all diagnosed cases [4], [5]. At present, the treatment strategies for NSCLC are mainly divided into surgical treatment, radiotherapy, chemotherapy, molecular targeted therapy and immunotherapy [6], [7], [8], [9]. Unfortunately, less than 25 % of patients with NSCLC benefit from molecular targeted therapy, but drug resistance is almost universal during subsequent treatment [10], [11].

Hypoxia inducible factor-1 (HIF-1) plays an important role in the adaptation of tumor cells to hypoxia [12] and it can specifically bind to the hypoxia response element (HRE, 50-RCGTG-30) [13]. HIF-1 consists of a 120 kD HIF-1α subunit and a 91–94 kD HIF-1β subunit [14]. HIF-1α is unique to HIF-1, it is both a regulatory subunit and an active subunit of HIF-1, and its protein stability and transcriptional activity are both regulated by the intracellular oxygen concentration. Therefore, the physiological activity of HIF-1 mainly depends on the expression and activity of the HIF-1α subunit. Elevated HIF-1 levels mediate tumor metastasis and invasion, angiogenesis, and resistance to chemotherapy and radiotherapy, and are associated with poor prognosis and post-treatment recurrence in cancer patients [15], [16]. In addition, HIF-1 α Inhibitors can not only inhibit the occurrence and development of tumors, but also be widely used in the treatment of various diseases related to HIF-1 overexpression, such as diabetes and its complications, leukemia, ischemic, cardiovascular and brain diseases and inflammatory diseases etc [17]. In diabetic tissues, hypoxia triggered by insufficient activation of HIF-1α signaling and impaired adaptive responses to hypoxia are fundamental pathogenic factors during the development of diabetes and diabetic complications [18]. Therefore, therapeutically blocking HIF-1 signaling pathways in tumor cells provides an attractive strategy for developing anticancer drugs [19]. Various HIF-1 inhibitors, such as 2-ME2, 103D5R, GL331, and PX-478, have been developed (Fig. 1) and have been extensively studied in preclinical and clinical studies [20]. In many studies, although these drugs can inhibit the transcriptional activity of HIF-1 both in vitro and in vivo, their clinical efficacy is unsatisfactory, which may be due to intratumoral heterogeneity and possible drug resistance of HIF-1 inhibitors [21].

Since some chemotherapy drugs are limited by treatment resistance [22], [23], more efficient and less toxic drugs are needed. Targeting epigenetic regulators are a novel strategy for cancer treatment [24]. Enhancer of zeste homolog 2 (EZH2), a core subunit of polycomb repressive complex 2 (PRC2), catalyzes the trimethylation of histone 3 lysine 27 (H3K27me3) to mediate gene silencing [25], [26]. The trimethylation of H3K27 catalyzed by PRC2 is an epigenetic marker for transcriptional suppression and silencing of target genes [27]. EZH2 is overexpressed in prostate cancer [28], lung cancer [29], breast cancer [30], kidney cancer [31], melanoma [32] and other cancers, and its expression is associated with tumor progression, metastasis and poor prognosis [30], [33]. EZH2 gene is highly expressed in NSCLC, and the expression level is closely related to the prognosis of patients. EZH2 inhibitors can effectively reduce the invasion and migration of NSCLC and induce tumor cell apoptosis [34], [35], [36], [37], [38]. At present, Tazemetostat plus Pembrolizumab against non-small cell lung cancer is phase Ib/II study (Fig. 1). CPI-1205 (orally) (Fig. 1) in combination with Ipilimumab (intravenously) was evaluated the safety and efficacy in patients with metastatic lung (non-small cell) and bladder (transitional-cell) cancer in phase I study. Our research group has previously screened and identified PRC2 member EZH2 as a crucial factor to mediate HIF-1 inhibitor resistance. Pharmacology inhibition or gene manipulation of HIF-1 would result in the enhancement of EZH2 enzyme activity through transcription activation of SUZ12, a member of the PRC2 complex. Conversely, pharmacology inhibition or knock-out of EZH2 also promotes HIF-1α transcription, but not other HIF family members. These results suggested that HIF-1α and EZH2 interact to form a negative feedback loop that reinforces each other's activity [39].

Therefore, based to the relationship between HIF-1α and EZH2 in non-small cell lung cancer, we hoped to inhibit the occurrence and development of NSCLC and reduce the occurrence of drug resistance by simultaneously targeting these two proteins. As a result, a novel 2,2-dimethylbenzopyranoid HIF-1α and EZH2 dual-targeting inhibitors containing pyridone structural fragments were designed and synthesized. The inhibitory activities of HIF-1α and EZH2 were evaluated, respectively. In vitro experiments proved that the compounds had significant therapeutic effects on NSCLC.