BioVector? SBC-3/ETP Etoposide-Resistant Human Small Cell Lung Cancer Cell Line / SBC-3/ETP 人小細(xì)胞肺癌依托泊苷抗性耐藥特異性細(xì)胞株

一 產(chǎn)品基本信息與細(xì)胞生物學(xué)背景

• 細(xì)胞名稱：SBC-3/ETP（亦寫為 SBC3/ETP）。

• 物種與組織來(lái)源：人類（Homo sapiens），源自一名 24 歲日本男性的轉(zhuǎn)移性小細(xì)胞肺癌（Small Cell Lung Cancer, SCLC）骨髓標(biāo)本（其親本細(xì)胞為 SBC-3），經(jīng)體外長(zhǎng)期接觸依托泊苷（Etoposide/VP-16）壓力誘導(dǎo)篩選建立的特異性獲得性耐藥亞系。

• 細(xì)胞系建立背景（耐藥株的衍生）：親本 SBC-3 細(xì)胞系最初由日本科研團(tuán)隊(duì)從一名年輕 SCLC 患者的骨髓轉(zhuǎn)移灶中分離建立。依托泊苷（Etoposide）作為一種經(jīng)典的拓?fù)洚悩?gòu)酶 II（Topoisomerase II）抑制劑，是臨床治療小細(xì)胞肺癌的核心一線化療藥物，但患者極易產(chǎn)生繼發(fā)性耐藥。為了在體外還原這種耐藥進(jìn)化過(guò)程，研究人員將親本 SBC-3 細(xì)胞長(zhǎng)期暴露于含有階梯遞增濃度依托泊苷的培養(yǎng)基中（Stepwise escalating drug selection method）。歷經(jīng)數(shù)月的生存壓力篩選，最終促使抗性克隆存活并穩(wěn)定傳代，成功建立了高耐藥指數(shù)的衍生亞系 SBC-3/ETP。

• 核心表型與耐藥分子機(jī)制：

  • 形態(tài)學(xué)特征：貼壁生長(zhǎng)。在倒置顯微鏡下，SBC-3/ETP 細(xì)胞維持了基本的上皮樣（Epithelial-like）或多角形（Polygonal）形態(tài)。細(xì)胞體通常較小，核質(zhì)比高，常表現(xiàn)為密集的細(xì)胞集團(tuán)或連續(xù)的成片貼壁生長(zhǎng)。

  • 耐藥譜系特征：對(duì)依托泊苷（Etoposide）及同類拓?fù)洚悩?gòu)酶抑制劑（如替尼泊苷等）表現(xiàn)出強(qiáng)烈的抵抗性，其半抑制濃度（IC50）較親本 SBC-3 細(xì)胞顯著飆升。此外，由于細(xì)胞內(nèi)部藥物泵的改變，該細(xì)胞常伴隨有對(duì)多柔比星（Adriamycin/Doxorubicin）等部分廣譜化療藥的交叉耐藥（Cross-resistance）。

  • 核心耐藥機(jī)理：該細(xì)胞的耐藥性主要源于拓?fù)洚悩?gòu)酶 II（Topoisomerase II, Topo II）的基因突變、表達(dá)量選擇性下調(diào)或細(xì)胞核內(nèi)定位異常，導(dǎo)致依托泊苷無(wú)法有效穩(wěn)定“Topo II-DNA 裂解復(fù)合物”，從而逃逸了化療引發(fā)的 DNA 雙鏈斷裂（DSBs）與細(xì)胞凋亡。此外，藥物外排泵（如多藥耐藥相關(guān)蛋白 MRP 系列）的高表達(dá)也協(xié)同介導(dǎo)了其抗性表型。

• 生物安全級(jí)別：1級(jí)（BSL-1）。

二 核心科研價(jià)值與轉(zhuǎn)化醫(yī)學(xué)應(yīng)用

SBC-3/ETP 細(xì)胞系作為高度特異性的肺癌一線化療耐藥底盤，在腫瘤藥理學(xué)和轉(zhuǎn)化醫(yī)學(xué)研究中具有極高的應(yīng)用價(jià)值：

1. 小細(xì)胞肺癌（SCLC）化療耐藥逆轉(zhuǎn)劑與增敏劑篩選：SBC-3/ETP 是尋找能攻克小細(xì)胞肺癌頑固性耐藥的小分子靶向藥、中藥天然提取物、非編碼 RNA 藥物的標(biāo)準(zhǔn)篩選平臺(tái)。常用于評(píng)估聯(lián)合用藥是否能重新讓耐藥細(xì)胞恢復(fù)對(duì)依托泊苷的敏感性。

2. 新型拓?fù)洚悩?gòu)酶抑制劑與 DNA 損傷修復(fù)（DDR）藥物評(píng)價(jià)：該細(xì)胞被廣泛用作靶底，用來(lái)測(cè)試新一代不依賴于經(jīng)典 Topo II 路徑的抗癌新藥（如新型拓?fù)洚悩?gòu)酶 I 抑制劑、PARP 抑制劑、ATR/ATM 抑制劑、CHK1/2 阻斷劑），評(píng)估它們?cè)诳朔劳胁窜漳退帬顟B(tài)下的獨(dú)立殺傷效能。

3. SCLC 腫瘤靶向新型療法（如 DLL3 靶向與免疫療法）評(píng)估：研究表明，SBC-3/ETP 細(xì)胞與其親本一致，表面仍高度且特異性地表達(dá)小細(xì)胞肺癌標(biāo)志物 Delta 樣蛋白 3（DLL3）。因此，它常被用作耐藥肺癌模型，來(lái)評(píng)估 DLL3 靶向抗體偶聯(lián)藥物（ADCs）、雙特異性 T 細(xì)胞銜接器（BiTEs）或近紅外光免疫療法（NIR-PIT）等前沿靶向手段的治療響應(yīng)。

4. 小鼠耐藥異種移植模型構(gòu)建（Resistant CDX Models）：將 SBC-3/ETP 細(xì)胞接種于免疫缺陷小鼠（如 BALB/c Nude 裸鼠、NOD-SCID 小鼠）皮下，能構(gòu)建穩(wěn)定的、高度模擬臨床晚期化療耐藥患者病理狀態(tài)的異種移植（CDX）體內(nèi)模型，用以定量評(píng)價(jià)候選抗癌新藥在體內(nèi)的抑瘤率。

三 實(shí)驗(yàn)室細(xì)胞復(fù)蘇、貼壁常規(guī)培養(yǎng)、傳代與保存標(biāo)準(zhǔn)步驟

SBC-3/ETP 細(xì)胞在日常維護(hù)中最大的控制核心是維持其耐藥表型的穩(wěn)定性，并且在消化傳代時(shí)需要精準(zhǔn)把控細(xì)胞密度。

1. 培養(yǎng)基配置與耐藥壓力維持

• 基礎(chǔ)培養(yǎng)基：RPMI-1640 基礎(chǔ)培養(yǎng)基。

• 維持期完全培養(yǎng)基配方（日常傳代）：RPMI-1640 基礎(chǔ)培養(yǎng)基 加 10% 優(yōu)質(zhì)胎牛血清（FBS） 加 1% 青霉素-鏈霉素雙抗。

• 耐藥壓力維持（關(guān)鍵質(zhì)量控制點(diǎn)）：

  • 在常規(guī)擴(kuò)增與日常傳代期間，通常需要在完全培養(yǎng)基中額外添加維持濃度的依托泊苷（Etoposide）藥物（具體維持濃度需嚴(yán)格遵照隨貨細(xì)胞說(shuō)明書或特定克隆株的耐藥指數(shù)），以防止細(xì)胞在完全無(wú)藥的環(huán)境下由于逆向進(jìn)化而導(dǎo)致耐藥特征發(fā)生部分回歸或丟失。

  • 重要提示：在正式用于下游實(shí)驗(yàn)（如 MTT/CCK-8 藥效檢測(cè)、Western Blot 蛋白檢測(cè)或小鼠體內(nèi)接種）前的 24 至 48 小時(shí)，必須將細(xì)胞更換為不含依托泊苷的常規(guī)完全培養(yǎng)基進(jìn)行洗脫（Washout），以徹底清除細(xì)胞內(nèi)外殘留游離藥物對(duì)實(shí)驗(yàn)數(shù)據(jù)的背景干擾。

• 細(xì)胞解離液：0.25% Trypsin-0.02% EDTA 消化液。

• 環(huán)境參數(shù)：37 攝氏度，5% 二氧化碳，飽合濕度孵箱。

2. 冷凍細(xì)胞復(fù)蘇步驟

1. 提前在無(wú)菌生物安全柜中配制好干凈的 T25 培養(yǎng)瓶，注入 5 - 6 mL 預(yù)熱至 37 攝氏度的常規(guī)完全培養(yǎng)基（注意：復(fù)蘇第一代時(shí)，為了保證受損細(xì)胞的恢復(fù)與貼壁，切勿添加依托泊苷藥物）。

2. 從液氮罐中取出 SBC-3/ETP 凍存管，立刻全量投入 37 攝氏度恒溫水浴箱中快速搖晃解凍，確保在 1 分鐘內(nèi)令管內(nèi)冰塊完全融化。

3. 用 75% 酒精噴灑凍存管外壁消毒，隨后移入生物安全柜內(nèi)。

4. 用無(wú)菌移液槍吸取融化的細(xì)胞懸液，緩慢滴加至盛有 4 mL 預(yù)熱常規(guī)完全培養(yǎng)基的 15 mL 離心管中，前后輕柔顛倒一次以稀釋冷凍保護(hù)劑（DMSO）。

5. 以 1000 rpm（約 200 g）離心 4 - 5 分鐘，小心吸除上清液。

6. 加入 1 mL 新鮮常規(guī)完全培養(yǎng)基輕輕重懸細(xì)胞沉淀，將其接種至準(zhǔn)備好的 T25 瓶中。前后輕柔十字晃動(dòng)混勻，置于孵箱中。

7. 復(fù)蘇 24 小時(shí)后，在顯微鏡下常規(guī)觀察細(xì)胞貼壁狀態(tài)。全量更換一次新鮮培養(yǎng)基以清除死細(xì)胞碎屑。待細(xì)胞完全恢復(fù)對(duì)數(shù)生長(zhǎng)狀態(tài)（通常復(fù)蘇 2-3 天后），在下一次傳代時(shí)再重新加入含維持劑量依托泊苷的完全培養(yǎng)基。

3. 日常貼壁常規(guī)傳代操作

• 傳代時(shí)機(jī)：當(dāng)細(xì)胞融合度達(dá)到 80% - 90% 時(shí)必須進(jìn)行傳代。由于小細(xì)胞肺癌細(xì)胞體較小且傾向于密集靠攏，絕對(duì)不能允許其長(zhǎng)滿至 100% 疊層生長(zhǎng)。一旦過(guò)度擠壓，底層細(xì)胞易因缺氧缺營(yíng)養(yǎng)發(fā)生成片自發(fā)脫落，并會(huì)導(dǎo)致耐藥表型發(fā)生漂移。

• 操作流程：

  1. 吸除舊培養(yǎng)基，使用無(wú)菌的、不含鈣鎂離子的 PBS 緩沖液輕輕漂洗細(xì)胞表面 1 - 2 次，徹底洗去血清。

  2. 加入適量 0.25% 胰酶消化液（T25 瓶常規(guī)加入 1 mL），搖晃使其全面覆蓋細(xì)胞層。置于 37 攝氏度孵箱中消化 1 - 3 分鐘。

  3. 在倒置顯微鏡下實(shí)時(shí)動(dòng)態(tài)觀察。當(dāng)發(fā)現(xiàn)多角形細(xì)胞體邊緣回縮變圓、胞間裂隙增大、輕敲瓶壁細(xì)胞可見(jiàn)移動(dòng)脫落時(shí)，立刻加入 2 到 3 倍體積的含血清完全培養(yǎng)基以終止胰酶的消化反應(yīng)。

  4. 用移液槍在瓶壁輕輕吹打，使細(xì)胞徹底剝離并分散成單細(xì)胞懸液。收集入管，1000 rpm 離心 5 分鐘。

  5. 棄去上清，加入含維持劑量依托泊苷的完全培養(yǎng)基重懸。按照 1 比 3 至 1 比 5 的常規(guī)稀釋比例，接種至新的培養(yǎng)瓶中。

  6. 通常每 2 - 3 天傳代一次。為了防止其耐藥基因發(fā)生長(zhǎng)期的體外非特異性變異，建議體外連續(xù)傳代代數(shù)控制在 15 代以內(nèi)，嚴(yán)禁無(wú)限制無(wú)限期連續(xù)往下傳代。

4. 細(xì)胞長(zhǎng)期保存標(biāo)準(zhǔn)

• 凍存液配方：90% 優(yōu)質(zhì)完全培養(yǎng)基（無(wú)依托泊苷） 加 10% 分析級(jí)二甲基亞砜（DMSO）。

• 冷凍規(guī)范：

  1. 收集處于對(duì)數(shù)生長(zhǎng)最旺盛期、健康指數(shù)高、密度在 80% 左右、形態(tài)結(jié)構(gòu)處于標(biāo)桿耐藥維持狀態(tài)的 SBC-3/ETP 細(xì)胞。

  2. 經(jīng)溫和消化、離心沉淀后，用配置好的無(wú)藥凍存液懸浮，調(diào)整細(xì)胞密度至 每毫升 1,500,000 到 2,500,000 個(gè)細(xì)胞。

  3. 分裝入無(wú)菌凍存管中，立刻移入標(biāo)準(zhǔn)程序降溫盒（如 Mr. Frosty），并置于 零下 80 攝氏度冰箱中過(guò)夜梯度降溫（遵循約每分鐘降溫 1 攝氏度的穩(wěn)態(tài)速率）。

  4. 次日，必須迅速將凍存管轉(zhuǎn)移入液氮罐（零下 196 攝氏度）長(zhǎng)期鎖死保存。絕對(duì)禁止在 零下 80 攝氏度普通冰箱內(nèi)長(zhǎng)期存放，以防長(zhǎng)期的微小熱幅射導(dǎo)致細(xì)胞內(nèi)部冰晶重塑，嚴(yán)重破壞后續(xù)復(fù)蘇時(shí)的復(fù)蘇存活率與特殊的藥物抵抗表型。

Part 2 English Section

I General Information and Cell Biological Background

• Cell Line Name: SBC-3/ETP (Standardly cataloged as SBC3/ETP, or SBC3-ETP).

• Organism and Tissue Extraction Origin: Homo sapiens (human); derived from a metastatic bone marrow specimen of a 24-year-old Japanese male patient diagnosed with Small Cell Lung Cancer (SCLC). The parental baseline lineage is SBC-3, and this subline was established through long-term in vitro evolutionary selection against Etoposide (VP-16).

• Cell Line Establishment Background (Derivation of the Drug-Resistant Line):The parental SBC-3 reference line was originally isolated from a bone marrow metastatic niche in a young SCLC donor. Etoposide—a classic topoisomerase II inhibitor—functions as a cornerstone first-line chemotherapeutic for small cell lung cancer; however, clinical outcomes are heavily compromised by rapid secondary drug resistance. To recapitulate this evasion mechanism in vitro, investigators exposed parental SBC-3 cultures to an escalating chemical selection pressure regimen (Stepwise escalating drug selection method) across multiple months. Surviving drug-tolerant colonies were expanded and cloned to yield SBC-3/ETP, fixing an acquired, high-index etoposide-resistant phenotype.

• Core Morphological Phenotype and Resistance Machinery:

  • Morphological Form: Adherent growth; under inverted phase-contrast microscopy, SBC-3/ETP preserves a characteristic epithelial-like or polygonal morphology. The cells are small with a high nuclear-to-cytoplasmic (N/C) ratio, expanding in tight interlocking colonies or contiguous monolayers.

  • Resistance Profile Designation: Demonstrates significant tolerance to Etoposide and related topoisomerase II targeted agents, manifesting a profound surge in its half-maximal inhibitory concentration (IC50) index compared to parental cells. Due to altered intracellular transport dynamics, the line often possesses cross-resistance phenotypes against other broad-spectrum cytostatics, such as Doxorubicin (Adriamycin).

  • Molecular Escape Cascades: The cell's resistance is primarily driven by structural point mutations, selective transcriptional downregulation, or anomalous nuclear localization of Topoisomerase II (Topo II). Consequently, etoposide fails to stabilize the "Topo II-DNA cleavage complex," allowing cells to bypass drug-induced DNA Double-Strand Breaks (DSBs) and programmed apoptosis. This is further augmented by upregulated drug efflux pumps, including elements of the Multidrug Resistance-Associated Protein (MRP) family.

• Biosafety Matrix: Classified under Biosafety Level 1 (BSL-1) containment parameters.

II Strategic Research Value and Translational Fields

SCLC behaves aggressively and acquires resistance rapidly. SBC-3/ETP serves as an important tool for evaluating clinical evasion nodes and testing advanced preclinical drug modalities:

1. High-Throughput Screening of SCLC Chemoresistance Reversers:The line acts as a standardized screening substrate to identify small-molecule targeted inhibitors, natural products, or non-coding RNA candidates capable of breaking etoposide resistance. It allows investigators to discover synergistic combinations that can restore conventional chemotherapeutic efficacy.

2. Evaluating Novel Topoisomerase and DNA Damage Repair (DDR) Inhibitors:SBC-3/ETP is deployed as a baseline platform to evaluate the cytotoxicity of next-generation anticancer agents that function independently of classical Topo II networks, such as novel topoisomerase I inhibitors, PARP inhibitors, ATR/ATM antagonists, and CHK1/2 blockers.

3. Validating Advanced SCLC-Targeted Strategies (DLL3-Targeted Therapies):Preclinical characterization confirms that, matching its parental counterpart, SBC-3/ETP retains high surface expression of Delta-like ligand 3 (DLL3), a prominent SCLC neuroendocrine biomarker. It is used to evaluate advanced DLL3-targeted configurations, including Antibody-Drug Conjugates (ADCs), Bispecific T-cell Engagers (BiTEs), and near-infrared photoimmunotherapy (NIR-PIT) platforms under chemoresistant settings.

4. Predictable In Vivo Tumor Modeling via CDX Interfacing:Inoculated subcutaneously into athymic nude or advanced immunodeficient (NOD-SCID) murine recipients, SBC-3/ETP consistently establishes solid Cell Line-Derived Xenograft (CDX) models. These models accurately mimic the pathology of advanced, chemoresistant SCLC patients, allowing for the quantitative evaluation of Tumor Growth Inhibition (TGI) rates of novel preclinical candidates.

III Laboratory Thawing, Cultivation, Passaging, and Cryopreservation Protocols

The primary metric of daily cultivation is maintaining the stability of the drug-resistant phenotype through strict adherence to drug-maintenance windows and subconfluent passaging controls.

1. Growth Medium & Chemo-Pressure Maintenance Protocols

• Basal Medium: Standard RPMI-1640 medium.

• Maintenance Complete Medium Formulation (Routine Passaging): Basal RPMI-1640 medium enriched with 10% premium Fetal Bovine Serum (FBS) and fortified with 1% Penicillin-Streptomycin dual antibiotics.

• Drug Maintenance Control Window (Critical Protocol):

  • To preserve resistance stability during routine maintenance and expansion, the complete growth medium must be spiked with a maintenance dose of Etoposide (tailored strictly to specific lot parameters or clonal resistance indexes). Cultivating cells in a drug-free matrix for extended intervals risks gradual regression or loss of the resistant phenotype due to backward evolutionary adaptation.

  • Critical Operational Note: The maintenance medium must be evacuated and replaced with drug-free complete growth medium 24 to 48 hours prior to downstream functional assays (e.g., in vitro CCK-8/MTT cytotoxicity screens, Western blotting, or live animal CDX inoculation) to wash out residual intracellular and free drug fractions, eliminating background chemical interference.

• Cell Dissociation Enzyme: Standard 0.25% Trypsin-0.02% EDTA solution.

• Environmental Cultivation Constants: Incubate at 37 degrees Celsius inside a humidified atmosphere charged with 5% Carbon Dioxide.

2. Cryovial Thawing and Recovery Sequence

1. Pre-warm a pristine T25 tissue culture flask filled with 5 - 6 mL of standard drug-free complete growth medium inside the Class II Biosafety Cabinet. (Note: Do not add etoposide during initial recovery to shield fragile, post-thaw membranes from acute cytotoxic stress).

2. Retrieve the SBC-3/ETP cryovial from liquid nitrogen storage and submerge it instantly into a 37 degrees Celsius constant-temperature water bath. Shake rapidly and continuously to secure absolute thawing within 60 seconds.

3. Decontaminate the exterior shell with 75% ethanol before transfer into the biosafety cabinet.

4. Using a sterile pipettor, smoothly extract the thawed suspension and deliver it dropwise into a 15 mL conical tube packed with 4 mL of pre-warmed drug-free complete medium, inverting gently once to equalize osmotic pressures.

5. Centrifuge the suspension at 1000 rpm (approximately 200 g) for 4 - 5 minutes at room temperature, then carefully decant the DMSO-laden supernatant.

6. Resuspend the cell pellet in 1 mL of fresh drug-free complete growth medium, transfer the entire volume into the prepared T25 flask, distribute evenly via a gentle cross-shake movement, and place in the incubator.

7. Inspect the adherent status approximately 24 hours post-thaw. Perform a complete medium change to remove non-adherent dead cell fragments. Once the cells regain robust log-phase division metrics (typically 2-3 days post-thaw), reintroduce the complete growth medium spiked with the maintenance dose of etoposide at the next passage.

3. Routine Adherent Passaging Mechanics and Maintenance

• Confluency Control Window: Subculturing routines must be initiated when monolayers achieve an optimal 80% - 90% confluency scale. Because SCLC cells have small diameters and naturally grow in tight clusters, never allow SBC-3/ETP sheets to achieve 100% full saturation or multilayer stratification. Overcrowding triggers sheet detachment due to underlying localized nutrient depletion and leads to phenotypic resistance drift.

• Passaging Execution Steps:

  1. Aspirate the spent growth matrix and gently rinse the cell layer 1 - 2 times with sterile, calcium/magnesium-free PBS to remove all remaining serum proteins that could deactivate the trypsin.

  2. Administer a suitable volume of 0.25% Trypsin-EDTA enzyme (typically 1 mL for a T25 flask format), tilt the flask to ensure total monolayer coverage, and place inside the 37 degrees Celsius incubator for 1 - 3 minutes.

  3. Monitor cell detachment kinetics under an inverted microscope. As the polygonal cells round up, separate from neighbors, and slide upon gentle physical tapping of the flask wall, immediately add 2 to 3 volumes of serum-fortified complete growth medium to arrest enzymatic cleavage.

  4. Gently pipette the solution against the flask walls to rinse down remaining cells and dissociate clusters into a single-cell suspension. Transfer the suspension into a conical tube and centrifuge at 1000 rpm for 5 minutes.

  5. Discard the supernatant, resuspend the cell pellet in fresh complete growth medium supplemented with the maintenance dose of etoposide, and inoculate into new flasks utilizing standard split ratios of 1:3 to 1:5. Subculture every 2 - 3 days.

  6. To prevent unintended long-term genetic drift in vitro, it is highly recommended to restrict continuous cultivation to under 15 total passages from thaw.

4. Long-Term Cryopreservation Standards

• Cryoprotectant Preservation Matrix: 90% premium complete growth medium (without etoposide) supplemented with 10% analytical-grade Dimethyl Sulfoxide (DMSO).

• Freezing Protocol Validation:

  1. Exclusively harvest healthy, log-phase cultures showing an optimal confluency of approximately 80% under standard maintenance drug conditions.

  2. Post-enzymatic treatment and centrifugation, adjust the cell concentration inside the formulated drug-free cryoprotectant matrix to a target range of 1,500,000 to 2,500,000 cells per milliliter.

  3. Dispense the suspension into sterile cryovials, insert them immediately into a controlled-rate freezing device (e.g., Mr. Frosty), and place into a minus 80 degrees Celsius freezer overnight to achieve steady gradient cooling (approximately 1 degree Celsius per minute).

  4. The following day, swiftly transfer the frozen cryovials into liquid nitrogen storage tanks (minus 196 degrees Celsius) for definitive long-term preservation. Do not store vials indefinitely inside a minus 80 degrees Celsius freezer; minor temperature oscillations can compromise post-thaw recovery rates and lead to the degradation of resistant traits.

The diagnostic framework and immunotherapy testing methodologies for such refractory hematological and small cell phenotypes can be explored in The diagnosis of early T-cell precursor (ETP) ALL. This video outlines the molecular biology and characterization protocols used to identify highly refractory, immature, and multi-lineage resistant cellular phenotypes in translational medical laboratories.

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