BioVector® H446-DDP Cisplatin-Resistant Human Small Cell Lung Cancer Cell Line / H446-DDP 人小细胞肺癌顺铂抗性耐药特异性细胞株

一 产品基本信息与细胞生物学背景

• 细胞名称：H446-DDP（亦书写为 NCI-H446/DDP 或 H446/DDP）。

• 物种与组织来源：人类（Homo sapiens），源自一名患有小细胞肺癌（Small Cell Lung Cancer, SCLC）患者的胸水转移灶（其亲本细胞为 NCI-H446），经体外长期接触顺铂（Cisplatin/DDP）压力诱导筛选建立的特异性获得性耐药亚系。

• 细胞系建立背景（耐药株的衍生）：亲本 NCI-H446 细胞系是国际上研究小细胞肺癌最经典的模式细胞之一，属于变异型（Variant type）SCLC，具有典型的神经内分泌特征。顺铂（DDP）作为一种广谱的 DNA 交叉联结剂，是临床治疗小细胞肺癌联合化疗方案（如 EP 方案：依托泊苷 + 顺铂）的绝对核心。然而，小细胞肺癌极易产生继发性耐药导致临床治疗失败。科研人员为了在体外模拟这种耐药性的获得，将亲本 H446 细胞长期暴露于含有阶梯递增浓度顺铂的培养基中（Stepwise escalating drug selection method）。历经数月的生存压力诱导筛选，最终促使抗性克隆存活，锁定并成功建立了具备高稳定顺铂耐药表型的衍生亚系 H446-DDP。

• 核心表型与耐药机理特征：

  • 形态学改变：贴壁与半悬浮混合生长（以贴壁为主）。在倒置显微镜下，H446-DDP 细胞维持了基本的上皮样（Epithelial-like）或多角形形态，但相较于亲本 H446 细胞，耐药株细胞之间的黏附力发生改变，常表现为更为紧密的细胞团块贴壁生长，局部可见部分胞体增大、拉长，伴随显著的骨架重塑（部分克隆表现出上皮-间充质转化 EMT 样外观）。

  • 耐药谱系表征：对顺铂（Cisplatin）表现出极强的抵抗性，其半抑制浓度（IC50）较亲本 NCI-H446 细胞显著飙升。由于顺铂耐药的复杂性，该细胞通常对其他铂类化疗药（如卡铂、奥沙利铂）具有明显的交叉耐药性（Cross-resistance）。

  • 核心耐药分子机制：H446-DDP 细胞的抗性是由多因素协同介导的：

    1. DNA 损伤修复（DDR）能力增强：细胞内部高度激活了核苷酸切除修复（NER）通路（如 ERCC1 高表达）和错配修复（MMR）机制，能高效清除顺铂引发的 DNA-铂内加合物，阻断 DNA 双链断裂（DSBs）。

    2. 解毒系统激活：细胞内谷胱甘肽（GSH）水平及谷胱甘肽S-转移酶（GSTs）活性上调，在顺铂攻击 DNA 前将其鳌合中和。

    3. 药物外排泵上调：铜转运蛋白（如 CTR1 下调阻断摄入，ATP7A/7B 上调加速外排）或多药耐药相关蛋白（MRP 系列）高度活化。

    4. 抗凋亡通路激活：Bcl-2 表达上调，p53 信号通路发生功能缺陷，逃逸顺铂诱导的细胞凋亡级联反应。

• 生物安全级别：1级（BSL-1）。

二 核心科研价值与转化医学应用

H446-DDP 细胞系作为高度公认的肺癌一线化疗耐药模式底盘，在转化医学研究中扮演着核心角色：

1. 小细胞肺癌（SCLC）铂类耐药逆转剂（Sensitizers）的体外高通量筛选：H446-DDP 是寻找能打破顺铂耐药的小分子靶向药、中药天然提取物、非编码 RNA 或小干扰 RNA（siRNA）的标准靶板。科研人员常以此评估联合用药（如联用特定激酶抑制剂、重金属螯合剂）是否能重新将该细胞阻滞于顺铂引发的细胞周期。

2. DNA 损伤修复（DDR）通路靶向抗癌新药评价：由于其本身具备极强的 DNA 自我修复背景，该细胞被广泛用作靶底，用来测试新型 ATR/ATM 抑制剂、PARP 抑制剂、CHK1/2 阻断剂或 WEE1 抑制剂在铂类耐药状态下的独立或协同杀伤效能（利用“合成致死”策略打破耐药）。

3. 小鼠顺铂耐药异种移植模型构建（Resistant CDX Models）：将 H446-DDP 细胞接种于免疫缺陷小鼠（如 BALB/c Nude 裸鼠、NOD-SCID 小鼠）皮下，能快速构建稳定的、高度模拟临床晚期化疗耐药患者病理状态的异种移植（CDX）体内模型，用以定量评价候选抗癌新药或联合免疫治疗在体内的肿瘤生长抑制率（TGI）及药代动力学（PK）表征。

三 实验室细胞复苏、常规培养、传代与保存标准步骤

H446-DDP 细胞呈贴壁与抱团半悬浮混合生长特征（通常贴壁较牢，但密度大时易形成抱团小球）。在日常维护中，最大的控制核心是维持其耐药表型的稳定性。

1. 培养基配置与耐药压力维持

• 基础培养基：RPMI-1640 基础培养基。

• 维持期完全培养基配方（日常传代）：RPMI-1640 基础培养基 加 10% 优质胎牛血清（FBS） 加 1% 青霉素-灭菌双抗。

• 耐药压力维持（关键质量控制点）：

  • 在常规扩增与日常传代期间，通常需要在完全培养基中额外添加维持浓度的顺铂（Cisplatin）药物（具体维持浓度需严格遵照随货细胞说明书或特定的耐药指数，常规维持浓度通常在 1 μg/mL - 2 μg/mL 左右），以防止细胞在完全无药的环境下由于逆向进化而导致耐药特征发生部分回归或丢失。

  • 重要提示：在正式用于下游实验（如 MTT/CCK-8 药效检测、Western Blot 蛋白检测或小鼠体内接种）前的 24 至 48 小时，必须将细胞更换为不含顺铂的常规完全培养基进行洗脱（Washout），以彻底清除细胞内外残留的游离顺铂对实验数据的背景干扰。

• 细胞解离液：0.25% Trypsin-0.02% EDTA 消化液。

• 环境参数：37 摄氏度，5% 二氧化碳，饱和湿度孵箱。

2. 冷冻细胞复苏步骤

1. 提前在无菌生物安全柜中配制好干净的 T25 培养瓶，注入 5 - 6 mL 预热至 37 摄氏度的常规完全培养基（注意：复苏第一代时，为了保证受损细胞的恢复与贴壁，切勿添加顺铂药物）。

2. 从液氮罐中取出 H446-DDP 冻存管，立刻全量投入 37 摄氏度恒温水浴箱中快速摇晃解冻，确保在 1 分钟内令管内冰块完全融化。

3. 用 75% 酒精喷洒冻存管外壁消毒，随后移入生物安全柜内。

4. 用无菌移液枪吸取融化的细胞悬液，缓慢滴加至盛有 4 mL 预热常规完全培养基的 15 mL 离心管中，轻柔颠倒一次以稀释冷冻保护剂（DMSO）。

5. 以 1000 rpm（约 200 g）离心 5 分钟，小心吸除含有 DMSO 的上清液。

6. 加入 1 mL 新鲜常规完全培养基轻轻重悬细胞沉淀。(注：由于 H446 细胞体较小且倾向于抱团，重悬时需使用 P1000 枪头轻柔化开)。

7. 将细胞全量接种至准备好的 T25 瓶中。前后轻柔十字晃动混匀，置于孵箱中。

8. 复苏 24 小时后，在显微镜下常规观察细胞贴壁状态。全量更换一次新鲜常规培养基以清除死细胞碎屑。待细胞完全恢复对数生长状态（通常复苏 2-3 天后），在下一次传代时再重新加入含维持剂量顺铂的完全培养基。

3. 日常贴壁常规传代操作

• 传代时机：当细胞融合度达到 80% - 90% 时必须进行传代。由于小细胞肺癌细胞倾向于密集靠拢并形成抱团堆叠，绝对不能允许其长满至 100%。一旦极度过密，抱团的细胞块极易大面积成片自发脱落，导致下层贴壁细胞受损，且易引发耐药表型漂移。

• 操作流程：

  1. 吸除旧培养基（若有较多未贴壁的健康悬浮胞团，可收集离心回配，若绝大多数已贴壁则直接吸除）。使用无菌的、不含钙镁离子的 PBS 缓冲液轻轻漂洗细胞表面 1 - 2 次，彻底洗去血清。

  2. 加入适量 0.25% 胰酶消化液（T25 瓶常规加入 1 mL），摇晃使其全面覆盖细胞层。置于 37 摄氏度孵箱中消化 2 - 4 分钟。

  3. 在倒置显微镜下实时动态观察。当发现贴壁的细胞集团边缘变圆、胞间裂隙增大、轻敲瓶壁可见大部分细胞成片移动或滑落时，立刻加入 2 到 3 倍体积的含血清完全培养基以终止胰酶的消化反应。

  4. 用移液枪在瓶壁轻轻吹打。由于耐药株细胞黏附性较强且易抱团，可适当增加吹打次数，使成片的细胞团剥离并尽可能打散形成均匀的细胞悬液。收集悬液入管，1000 rpm 离心 5 分钟。

  5. 弃去上清，加入含维持剂量顺铂的完全培养基重悬。按照 1 比 3 至 1 比 5 的常规稀释比例，接种至新的培养瓶中。

  6. 通常每 2 - 3 天传代一次。为了防止其耐药基因发生长期的体外非特异性变异，建议体外连续传代代数严格控制在 15 代以内，严禁无限制无限期连续往下传代。

4. 细胞长期保存标准

• 冻存液配方：90% 优质完全培养基（无顺铂） 加 10% 分析级二甲基亚砜（DMSO）。

• 冷冻规范：

  1. 收集处于对数生长最旺盛期、健康指数高、密度在 80% 左右、形态结构处于标杆加药维持状态的 H446-DDP 细胞。

  2. 经温和消化、离心沉淀后，用配置好的无药冻存液悬浮，调整细胞密度至 每毫升 1,500,000 到 2,500,000 个细胞。

  3. 分装入无菌冻存管中，立刻移入标准程序降温盒（如 Mr. Frosty），并置于 零下 80 摄氏度冰箱中过夜梯度降温（遵循约每分钟降温 1 摄氏度的稳态速率）。

  4. 次日，必须迅速将冻存管转移入液氮罐（零下 196 摄氏度）长期锁死保存。绝对禁止在 零下 80 摄氏度普通冰箱内长期存放，以防长期的微小热辐射导致细胞内部冰晶重塑，严重破坏后续复苏时的存活率与特殊的顺铂抵抗表型。

Part 2 English Section

I General Information and Cell Biological Background

• Cell Line Name: H446-DDP (Standardly cataloged as NCI-H446/DDP, or H446/DDP).

• Organism and Tissue Extraction Origin: Homo sapiens (human); derived from a pleural effusion metastatic site of a donor diagnosed with Small Cell Lung Cancer (SCLC). The parental reference lineage is NCI-H446, and this subline was engineered through chronic in vitro selection exposure to Cisplatn (DDP).

• Cell Line Establishment Background (Derivation of the Drug-Resistant Line):The parental NCI-H446 reference line represents one of the most prominent globally utilized models of variant-type small cell lung cancer, characterized by robust neuroendocrine features. Cisplatin (DDP)—a broad-spectrum DNA cross-linking agent—serves as the cornerstone chemotherapeutic backbone for SCLC intervention regimens (such as the standard Etoposide + Cisplatin [EP] protocol). However, clinical prognosis is severely bottlenecked by the rapid onset of acquired drug resistance. To recapitulate this adaptive pathway in vitro, investigators cultivated parental H446 lineages under an escalating chemical selection pressure matrix (Stepwise escalating drug selection method) spanning several months. Surviving drug-tolerant clones were systematically expanded and validated to yield H446-DDP, locking in a highly stable cisplatin-resistant phenotype.

• Core Morphological Phenotype and Resistance Machinery:

  • Morphological Form: Mixed adherent and semi-suspension growth (primarily adherent). Under inverted phase-contrast microscopy, H446-DDP preserves a basic epithelial-like or polygonal architecture. However, compared to parent cells, the resistant variants manifest altered paracellular adhesion dynamics, proliferating in tighter, condensed cellular clusters that tightly grip the plastic plane. Localized clones may show cell enlargement, elongation, and profound cytoskeleton remodeling (resembling an Epithelial-Mesenchymal Transition [EMT]-like status).

  • Resistance Profile Designation: Demonstrates profound tolerance to Cisplatin, manifesting a marked surge in its half-maximal inhibitory concentration (IC50) index compared to parental H446 matrices. Due to the multi-layered biology of cisplatin resistance, the line consistently displays cross-resistance to related platinum analogs, such as Carboplatin and Oxaliplatin.

  • Molecular Escape Cascades: The cell's resistance profile is governed by multiple synchronous defense nodes:

    1. Enhanced DNA Damage Repair (DDR) Capacity: Upregulation of the Nucleotide Excision Repair (NER) network (e.g., elevated ERCC1 expression) alongside modified Mismatch Repair (MMR) frameworks, allowing efficient excision of cisplatin-induced intra-strand DNA-platinum adducts and preventing downstream DNA Double-Strand Breaks (DSBs).

    2. Hyper-Activated Detoxification Cascades: Elevation of intracellular Glutathione (GSH) synthesis and Glutathione S-Transferase (GSTs) enzymatic kinetics, which scavenge and neutralize free cisplatin molecules before they can target the genomic structure.

    3. Modified Transporter Architecture: Downregulation of the copper influx transporter CTR1 (blocking drug entry) paired with upregulated expression of ATP7A/ATP7B efflux pumps or multidrug resistance-associated proteins (MRP family).

    4. Suppression of Apoptosis: Hyper-activation of survival networks, including Bcl-2 upregulation and functional defects in the p53 tumor-suppressor cascade, shielding cells from cisplatin-triggered apoptotic breakdown.

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

II Strategic Research Value and Translational Fields

SCLC is known for its aggressive nature and rapid development of resistance. H446-DDP serves as an important tool for evaluating clinical evasion nodes and testing advanced preclinical drug modalities:

1. High-Throughput Screening of SCLC Platinum Chemoresistance Reversers:The line functions as a standardized screening platform to identify small-molecule targeted inhibitors, natural products, or small interfering RNAs (siRNAs) capable of breaking cisplatin resistance. It enables investigators to discover synergistic combinations that can restore conventional chemotherapeutic efficacy.

2. Evaluating Advanced DNA Damage Repair (DDR) Pathway Inhibitors:Given its strong DNA self-repair profile, H446-DDP is widely used to evaluate the cytotoxicity of novel anticancer agents exploiting "synthetic lethality" concepts. This includes testing ATR/ATM inhibitors, PARP inhibitors, CHK1/2 blockers, and WEE1 antagonists to bypass platinum resistance nodes.

3. Predictable In Vivo Tumor Modeling via CDX Interfacing:Inoculated subcutaneously into athymic nude, NOD-SCID, or advanced immunodeficient rodent recipients, H446-DDP establishes reproducible Cell Line-Derived Xenograft (CDX) solid tumor models. These systems accurately replicate the clinical presentation of advanced, chemoresistant SCLC patients, serving as a reliable framework for quantifying Tumor Growth Inhibition (TGI) rates and validating preclinical pharmacokinetic (PK) parameters.

III Laboratory Thawing, Cultivation, Passaging, and Cryopreservation Protocols

H446-DDP cells exhibit a mixture of adherent and clustered semi-suspension expansion traits. 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 Cisplatin (tailored strictly to specific lot parameters or clonal resistance indexes; conventional baseline maintenance typically ranges from 1 μg/mL to 2 μg/mL). 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 cisplatin 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 cisplatin during initial recovery to shield fragile, post-thaw membranes from acute cytotoxic stress).

2. Retrieve the H446-DDP 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 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. Because H446 cells have small diameters and naturally aggregate, perform gentle pipetting with a P1000 tip to disperse clusters.

7. Transfer the entire volume into the prepared T25 flask, distribute evenly via a gentle cross-shake movement, and place in the incubator.

8. 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 cisplatin 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 naturally grow in tight clusters, never allow H446-DDP sheets to achieve 100% full saturation. Overcrowding triggers massive cell mass detachment due to underlying localized nutrient depletion, leading to cell stress and phenotypic resistance drift.

• Passaging Execution Steps:

  1. Aspirate the spent growth matrix (if healthy non-adherent cell clusters are present, they can be harvested via centrifugation and re-pooled; otherwise, discard). 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 2 - 4 minutes.

  3. Monitor cell detachment kinetics under an inverted microscope. As the adherent clusters round up, separate from neighbors, and slide upon firm 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. Due to the high mechanical stickiness and clumping tendency of resistant SCLC strains, perform systematic pipetting to dissociate aggregates into a single-cell suspension. Transfer the fluid 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 cisplatin, 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 cisplatin) 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 1,000,000 to 2,000,000 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.

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