Rpmi medium

The HCC827 and H1975 cell lines (human NSCLC cell lines) were obtained from the American Type Culture Collection (ATCC), and the PC‐9 cell line (a human NSCLC cell line) was obtained from the European Collection of Authenticated Cell Cultures (ECACC). The PC9‐COR cell line was established from the PC‐9 cell line as previously reported.³¹ All cell lines were authenticated using the short tandem repeat method and were maintained in RPMI medium (FUJIFILM Wako Pure Chemical Corporation) supplemented with 10% fetal bovine serum (FBS; Cytiva, Marlborough, MA). The EGFR status of the cell lines is summarized in Table S2. All cell lines were used after they were confirmed to be negative for Mycoplasma contamination with a PCR Mycoplasma Detection Kit (TaKaRa Bio) according to the manufacturer's instructions. Erlotinib and osimertinib were obtained from Cayman Chemical Company. TAS‐121 and TAS‐116 were kindly provided by Taiho Pharmaceutical Co., Ltd.

Glucose-stimulated insulin secretion was measured according to a previously described method^{54 (link),55 (link)}. Briefly, 3.2 × 10⁵ IPCs were pre-incubated for 2 h in 2 mL of RPMI medium (Wako, Osaka, Japan) supplemented with 0.5% bovine serum albumin (BSA; Sigma-Aldrich) and 2.2 mM glucose (Fujifilm Wako Pure Chemical Corporation). Thereafter, IPCs were incubated in RPMI medium containing 2.2 mM (basal) or 22 mM glucose for 1 h at 37 °C in a 5% CO₂. After this, the supernatant of each sample was collected. The SI was calculated as the ratio of the insulin concentration after incubation in 22 mM glucose divided by the insulin concentration after incubation in 2.2 mM glucose.

A549, human alveolar adenocarcinoma cells, were transfected with pEBMulti-neo vector (Wako, Osaka, Japan) to obtain mouse LRG-expressing cells. Cells were cultured for 72 h in serum-free RPMI medium (Wako). LRG protein secreted into culture supernatant was purified with an antibody affinity column (NHS-activated Sepharose 4 Fast Flow conjugated with anti mLRG antibody mLRA0010) and concentrated by ultrafiltration (Amicon Ultra 10 K, Merk Millipore). Concentration of LRG was determined by mouse LRG ELISA as described subsequently.