PI3K/Akt/mTOR · target hub

PIK3CA

Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha (p110α)

PIK3CA encodes the class I PI3K p110α catalytic subunit; assembled with regulatory subunits (e.g. p85), it phosphorylates PIP2 to PIP3, recruiting PH-domain proteins such as PDK1 and Akt. Hotspot mutations (helical and kinase domains, among others) often increase lipid kinase output or membrane recruitment and are frequent drivers or resistance lesions across solid tumors.

Back to pathway overviewSearch: PIK3CAUniProt (P42336)

Research notes

  • Couples to RTK–Ras, GPCRs, and IRS–insulin inputs; pair phospho readouts with PTEN/INPP4 and other negative regulators.
  • PI3Kα-selective vs pan–class I inhibitors differ mechanistically; annotate genotypes and bypass signaling (MAPK, RTK feedback) in preclinical models.
  • Common readouts: p-AKT Ser473/Thr308, downstream p-S6K / p-4E-BP1, and PIK3CA mutation status (sequencing/IHC per project).

On the pathway hub (sections)

Frequent hotspot mutations (quick reference)

Mutation (examples)Domain / context (brief)
E542KHelical domain
E545KHelical domain
Q546R / Q546KNear helical domain
H1047RKinase domain
H1047LKinase domain
G1049RKinase domain (less common)

Mutation naming and prevalence vary by cohort and assay—annotate clinically with COSMIC, OncoKB, assay reports, and datasheets; information here is for research context only.

Assay readouts for p110α / PIK3CA

  • Lipid side: PIP₃ probes/lipidomics or PH-domain pulldowns—mind class II/III PI3Ks and compartmentation.
  • Biochemistry: IP–kinase or membrane recruitment assays vs WT/hotspot controls.
  • Downstream: p-AKT Thr308/Ser473, p-S6K1, p-4E-BP1—pair totals and stimulus/inhibitor titrations.
  • Context: PTEN/INPP4/PIK3R1 (p85) status; confirm hotspots and copy number (NGS/ddPCR).

PIK3CA experimental notes

Examples below reflect common literature and public resources (e.g., CCLE, DepMap)—validate genotypes, expression, and passage in your own stocks before committing assays.

[1] Cell lines commonly used for PIK3CA studies (examples)

  • Breast cancer context: MCF-7, T47D, BT-474, ZR-75-1—many harbor PIK3CA hotspots or PI3K-active backgrounds (confirm via CCLE/DepMap/your sequencing).
  • Colorectal context: HCT116 (classic H1047R), DLD-1, HT-29, SW480, LoVo—for mutant vs WT contrasts or inhibitor readouts.
  • Endometrial/ovarian context: Ishikawa, ECC-1, selected ovarian lines depending on PIK3CA status.
  • Other solid tumors: PC-3 (prostate), A549 (lung) as pathway controls or combination studies.
  • Tooling lines: HEK293T/HEK293 for WT/mutant PIK3CA expression, co-expression with p85, or pulldowns; stable lines support rescue experiments.
  • Isogenic/genetic models: RKO derivatives, Cas9 KO/hotspot knock-in, shRNA/sgRNA titrations—to test mutation dependency vs bypass.

[2] Cell samples commonly used for PIK3CA (p110α) Western blot

  • Adherent tumor lysates: whole-cell lysates from breast/colorectal lines above (optimize RIPA/NP-40 per antibody datasheet).
  • Primary tumor cells / short-term PDCs—when ethically approved—to bridge cell-line findings; expect batch variability.
  • Organoid lysates—when tissue architecture matters—optimize lysis yield and concentration empirically.
  • Practice: equalize by total protein (BCA); for phospho cascades use fresh lysates + phosphatase inhibitors; validate antibody specificity with KD/KO/siRNA where possible.

[3] Tissue samples commonly used for PIK3CA (p110α) Western blot

  • Matched tumor/adjacent frozen tissues—especially breast, endometrium, colorectal contexts—after pathology review for content and subtype.
  • Xenograft/PDX tissues for efficacy/resistance time courses—watch mouse vs human antibody specificity.
  • GEMM tissues from conditional PIK3CA activation ± PTEN loss models.
  • FFPE is possible but crosslinked—requires specialized extraction and variable antigen recovery; frozen tissue is usually preferred for WB.

[4] Cell samples commonly used for PIK3CA (p110α) immunoprecipitation

  • Tagged overexpression: HEK293T with FLAG/HA/Myc-PIK3CA (WT or hotspots) for robust capture—often co-express PIK3R1/p85 for holoenzyme studies.
  • Endogenous IP: high-expression mutant lines such as MCF-7, BT-474, HCT116, T47D—scale input (often ≥1–5×10⁶ cells, tune per antibody).
  • Stimulation: serum starvation followed by insulin/EGF can enrich receptor–PI3K complexes; time-course pilots reduce degradation.
  • Controls: isotype IgG, KD/KO negatives, empty-vector controls; optional crosslinkers for weak interactions (optimize per literature).

Human tissues and primary cells require ethics/IRB approval; tumors are heterogeneous—record histotype, site, and preservation conditions.

Resistance & bypass (often co-discussed with PIK3CA lesions)

Models & genetics note

Hotspot knock-in vs cDNA overexpression can differ in dosage, splicing, and membrane recruitment; in organoids/PDX, record passage, matrix, and drug exposure history.

Quick search presets

PIK3CAPI3K α antibodyAlpelisibCopanlisibPI3K inhibitorLY294002

PIK3CA-related antibodies (keyword-biased)

Adds PIK3CA keyword bias atop the PI3K/Akt/mTOR antibody pool—if sparse, use presets above or global search.

Neighboring targets (same hub)

PIK3CBPIK3CDPIK3CGPIK3R1PIK3R2PIK3R3PIK3R4PIK3AP1

External databases & resources

FAQ

This content supports research reagents and pathway education—not medical advice. Annotate mutations, drug indications, and protocols with authoritative databases, datasheets, and institutional oversight.

Last reviewed: 2026-05-03

Related on this site

See the PI3K/Akt/mTOR hub for neighboring nodes and assay guidance—cross-check MAPK, RTK, metabolism, and autophagy pages as needed.

PI3K/Akt/mTOR·MAPK/ERK·Receptor tyrosine kinase·Metabolism